flurry/map.rs
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566 1567 1568 1569 1570 1571 1572 1573 1574 1575 1576 1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624 1625 1626 1627 1628 1629 1630 1631 1632 1633 1634 1635 1636 1637 1638 1639 1640 1641 1642 1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654 1655 1656 1657 1658 1659 1660 1661 1662 1663 1664 1665 1666 1667 1668 1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 1679 1680 1681 1682 1683 1684 1685 1686 1687 1688 1689 1690 1691 1692 1693 1694 1695 1696 1697 1698 1699 1700 1701 1702 1703 1704 1705 1706 1707 1708 1709 1710 1711 1712 1713 1714 1715 1716 1717 1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742 1743 1744 1745 1746 1747 1748 1749 1750 1751 1752 1753 1754 1755 1756 1757 1758 1759 1760 1761 1762 1763 1764 1765 1766 1767 1768 1769 1770 1771 1772 1773 1774 1775 1776 1777 1778 1779 1780 1781 1782 1783 1784 1785 1786 1787 1788 1789 1790 1791 1792 1793 1794 1795 1796 1797 1798 1799 1800 1801 1802 1803 1804 1805 1806 1807 1808 1809 1810 1811 1812 1813 1814 1815 1816 1817 1818 1819 1820 1821 1822 1823 1824 1825 1826 1827 1828 1829 1830 1831 1832 1833 1834 1835 1836 1837 1838 1839 1840 1841 1842 1843 1844 1845 1846 1847 1848 1849 1850 1851 1852 1853 1854 1855 1856 1857 1858 1859 1860 1861 1862 1863 1864 1865 1866 1867 1868 1869 1870 1871 1872 1873 1874 1875 1876 1877 1878 1879 1880 1881 1882 1883 1884 1885 1886 1887 1888 1889 1890 1891 1892 1893 1894 1895 1896 1897 1898 1899 1900 1901 1902 1903 1904 1905 1906 1907 1908 1909 1910 1911 1912 1913 1914 1915 1916 1917 1918 1919 1920 1921 1922 1923 1924 1925 1926 1927 1928 1929 1930 1931 1932 1933 1934 1935 1936 1937 1938 1939 1940 1941 1942 1943 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 2038 2039 2040 2041 2042 2043 2044 2045 2046 2047 2048 2049 2050 2051 2052 2053 2054 2055 2056 2057 2058 2059 2060 2061 2062 2063 2064 2065 2066 2067 2068 2069 2070 2071 2072 2073 2074 2075 2076 2077 2078 2079 2080 2081 2082 2083 2084 2085 2086 2087 2088 2089 2090 2091 2092 2093 2094 2095 2096 2097 2098 2099 2100 2101 2102 2103 2104 2105 2106 2107 2108 2109 2110 2111 2112 2113 2114 2115 2116 2117 2118 2119 2120 2121 2122 2123 2124 2125 2126 2127 2128 2129 2130 2131 2132 2133 2134 2135 2136 2137 2138 2139 2140 2141 2142 2143 2144 2145 2146 2147 2148 2149 2150 2151 2152 2153 2154 2155 2156 2157 2158 2159 2160 2161 2162 2163 2164 2165 2166 2167 2168 2169 2170 2171 2172 2173 2174 2175 2176 2177 2178 2179 2180 2181 2182 2183 2184 2185 2186 2187 2188 2189 2190 2191 2192 2193 2194 2195 2196 2197 2198 2199 2200 2201 2202 2203 2204 2205 2206 2207 2208 2209 2210 2211 2212 2213 2214 2215 2216 2217 2218 2219 2220 2221 2222 2223 2224 2225 2226 2227 2228 2229 2230 2231 2232 2233 2234 2235 2236 2237 2238 2239 2240 2241 2242 2243 2244 2245 2246 2247 2248 2249 2250 2251 2252 2253 2254 2255 2256 2257 2258 2259 2260 2261 2262 2263 2264 2265 2266 2267 2268 2269 2270 2271 2272 2273 2274 2275 2276 2277 2278 2279 2280 2281 2282 2283 2284 2285 2286 2287 2288 2289 2290 2291 2292 2293 2294 2295 2296 2297 2298 2299 2300 2301 2302 2303 2304 2305 2306 2307 2308 2309 2310 2311 2312 2313 2314 2315 2316 2317 2318 2319 2320 2321 2322 2323 2324 2325 2326 2327 2328 2329 2330 2331 2332 2333 2334 2335 2336 2337 2338 2339 2340 2341 2342 2343 2344 2345 2346 2347 2348 2349 2350 2351 2352 2353 2354 2355 2356 2357 2358 2359 2360 2361 2362 2363 2364 2365 2366 2367 2368 2369 2370 2371 2372 2373 2374 2375 2376 2377 2378 2379 2380 2381 2382 2383 2384 2385 2386 2387 2388 2389 2390 2391 2392 2393 2394 2395 2396 2397 2398 2399 2400 2401 2402 2403 2404 2405 2406 2407 2408 2409 2410 2411 2412 2413 2414 2415 2416 2417 2418 2419 2420 2421 2422 2423 2424 2425 2426 2427 2428 2429 2430 2431 2432 2433 2434 2435 2436 2437 2438 2439 2440 2441 2442 2443 2444 2445 2446 2447 2448 2449 2450 2451 2452 2453 2454 2455 2456 2457 2458 2459 2460 2461 2462 2463 2464 2465 2466 2467 2468 2469 2470 2471 2472 2473 2474 2475 2476 2477 2478 2479 2480 2481 2482 2483 2484 2485 2486 2487 2488 2489 2490 2491 2492 2493 2494 2495 2496 2497 2498 2499 2500 2501 2502 2503 2504 2505 2506 2507 2508 2509 2510 2511 2512 2513 2514 2515 2516 2517 2518 2519 2520 2521 2522 2523 2524 2525 2526 2527 2528 2529 2530 2531 2532 2533 2534 2535 2536 2537 2538 2539 2540 2541 2542 2543 2544 2545 2546 2547 2548 2549 2550 2551 2552 2553 2554 2555 2556 2557 2558 2559 2560 2561 2562 2563 2564 2565 2566 2567 2568 2569 2570 2571 2572 2573 2574 2575 2576 2577 2578 2579 2580 2581 2582 2583 2584 2585 2586 2587 2588 2589 2590 2591 2592 2593 2594 2595 2596 2597 2598 2599 2600 2601 2602 2603 2604 2605 2606 2607 2608 2609 2610 2611 2612 2613 2614 2615 2616 2617 2618 2619 2620 2621 2622 2623 2624 2625 2626 2627 2628 2629 2630 2631 2632 2633 2634 2635 2636 2637 2638 2639 2640 2641 2642 2643 2644 2645 2646 2647 2648 2649 2650 2651 2652 2653 2654 2655 2656 2657 2658 2659 2660 2661 2662 2663 2664 2665 2666 2667 2668 2669 2670 2671 2672 2673 2674 2675 2676 2677 2678 2679 2680 2681 2682 2683 2684 2685 2686 2687 2688 2689 2690 2691 2692 2693 2694 2695 2696 2697 2698 2699 2700 2701 2702 2703 2704 2705 2706 2707 2708 2709 2710 2711 2712 2713 2714 2715 2716 2717 2718 2719 2720 2721 2722 2723 2724 2725 2726 2727 2728 2729 2730 2731 2732 2733 2734 2735 2736 2737 2738 2739 2740 2741 2742 2743 2744 2745 2746 2747 2748 2749 2750 2751 2752 2753 2754 2755 2756 2757 2758 2759 2760 2761 2762 2763 2764 2765 2766 2767 2768 2769 2770 2771 2772 2773 2774 2775 2776 2777 2778 2779 2780 2781 2782 2783 2784 2785 2786 2787 2788 2789 2790 2791 2792 2793 2794 2795 2796 2797 2798 2799 2800 2801 2802 2803 2804 2805 2806 2807 2808 2809 2810 2811 2812 2813 2814 2815 2816 2817 2818 2819 2820 2821 2822 2823 2824 2825 2826 2827 2828 2829 2830 2831 2832 2833 2834 2835 2836 2837 2838 2839 2840 2841 2842 2843 2844 2845 2846 2847 2848 2849 2850 2851 2852 2853 2854 2855 2856 2857 2858 2859 2860 2861 2862 2863 2864 2865 2866 2867 2868 2869 2870 2871 2872 2873 2874 2875 2876 2877 2878 2879 2880 2881 2882 2883 2884 2885 2886 2887 2888 2889 2890 2891 2892 2893 2894 2895 2896 2897 2898 2899 2900 2901 2902 2903 2904 2905 2906 2907 2908 2909 2910 2911 2912 2913 2914 2915 2916 2917 2918 2919 2920 2921 2922 2923 2924 2925 2926 2927 2928 2929 2930 2931 2932 2933 2934 2935 2936 2937 2938 2939 2940 2941 2942 2943 2944 2945 2946 2947 2948 2949 2950 2951 2952 2953 2954 2955 2956 2957 2958 2959 2960 2961 2962 2963 2964 2965 2966 2967 2968 2969 2970 2971 2972 2973 2974 2975 2976 2977 2978 2979 2980 2981 2982 2983 2984 2985 2986 2987 2988 2989 2990 2991 2992 2993 2994 2995 2996 2997 2998 2999 3000 3001 3002 3003 3004 3005 3006 3007 3008 3009 3010 3011 3012 3013 3014 3015 3016 3017 3018 3019 3020 3021 3022 3023 3024 3025 3026 3027 3028 3029 3030 3031 3032 3033 3034 3035 3036 3037 3038 3039 3040 3041 3042 3043 3044 3045 3046 3047 3048 3049 3050 3051 3052 3053 3054 3055 3056 3057 3058 3059 3060 3061 3062 3063 3064 3065 3066 3067 3068 3069 3070 3071 3072 3073 3074 3075 3076 3077 3078 3079 3080 3081 3082 3083 3084 3085 3086 3087 3088 3089 3090 3091 3092 3093 3094 3095 3096 3097 3098 3099 3100 3101 3102 3103 3104 3105 3106 3107 3108 3109 3110 3111 3112 3113 3114 3115 3116 3117 3118 3119 3120 3121 3122 3123 3124 3125 3126 3127 3128 3129 3130 3131 3132 3133 3134 3135 3136 3137 3138 3139 3140 3141 3142 3143 3144 3145 3146 3147 3148 3149 3150 3151 3152 3153 3154 3155 3156 3157 3158 3159 3160 3161 3162 3163 3164 3165 3166 3167 3168 3169 3170 3171 3172 3173 3174 3175 3176 3177 3178 3179 3180 3181 3182 3183 3184 3185 3186 3187 3188 3189 3190 3191 3192 3193 3194 3195 3196 3197 3198 3199 3200 3201 3202 3203 3204 3205 3206 3207 3208 3209 3210 3211 3212 3213 3214 3215 3216 3217 3218 3219 3220 3221 3222 3223 3224 3225 3226 3227 3228 3229 3230 3231 3232 3233 3234 3235 3236 3237 3238 3239 3240 3241 3242 3243 3244 3245 3246 3247 3248 3249 3250 3251 3252 3253 3254 3255 3256 3257 3258 3259 3260 3261 3262 3263 3264 3265 3266 3267 3268 3269 3270 3271 3272 3273 3274 3275 3276 3277 3278 3279 3280 3281 3282 3283 3284 3285 3286 3287 3288 3289 3290 3291 3292 3293 3294 3295 3296 3297 3298 3299 3300 3301 3302 3303 3304 3305 3306 3307 3308 3309 3310 3311 3312 3313 3314 3315 3316 3317 3318 3319 3320 3321 3322 3323 3324 3325 3326 3327 3328 3329 3330 3331 3332 3333 3334 3335 3336 3337 3338 3339 3340 3341 3342 3343 3344 3345 3346 3347 3348 3349 3350 3351 3352 3353 3354 3355 3356 3357 3358 3359 3360 3361 3362 3363 3364 3365 3366 3367 3368 3369 3370 3371 3372 3373 3374 3375 3376 3377 3378 3379 3380 3381 3382 3383 3384 3385 3386 3387 3388 3389 3390 3391 3392 3393 3394 3395 3396 3397 3398 3399 3400 3401 3402 3403 3404 3405 3406 3407 3408 3409 3410 3411 3412 3413 3414 3415 3416 3417 3418 3419 3420 3421 3422 3423 3424 3425 3426 3427 3428 3429 3430 3431 3432 3433 3434 3435 3436 3437 3438 3439 3440 3441 3442 3443 3444 3445 3446 3447 3448 3449 3450 3451 3452 3453 3454 3455 3456 3457 3458 3459 3460 3461 3462 3463 3464 3465 3466 3467 3468 3469 3470 3471 3472 3473 3474 3475 3476 3477 3478 3479 3480 3481 3482 3483 3484 3485 3486 3487 3488 3489 3490 3491 3492 3493 3494 3495 3496 3497 3498 3499 3500 3501 3502 3503 3504 3505 3506 3507 3508 3509 3510 3511 3512 3513 3514 3515 3516 3517 3518 3519 3520 3521 3522 3523 3524 3525 3526 3527 3528 3529 3530 3531 3532 3533 3534 3535 3536 3537 3538 3539 3540 3541 3542 3543 3544 3545 3546 3547 3548 3549 3550 3551 3552
use seize::Linked;
use crate::iter::*;
use crate::node::*;
use crate::raw::*;
use crate::reclaim::{Atomic, Collector, Guard, RetireShared, Shared};
use std::borrow::Borrow;
use std::error::Error;
use std::fmt::{self, Debug, Display, Formatter};
use std::hash::{BuildHasher, Hash};
use std::sync::atomic::{AtomicIsize, Ordering};
const ISIZE_BITS: usize = core::mem::size_of::<isize>() * 8;
/// The largest possible table capacity. This value must be
/// exactly 1<<30 to stay within Java array allocation and indexing
/// bounds for power of two table sizes, and is further required
/// because the top two bits of 32bit hash fields are used for
/// control purposes.
const MAXIMUM_CAPACITY: usize = 1 << 30; // TODO: use ISIZE_BITS
/// The default initial table capacity. Must be a power of 2
/// (i.e., at least 1) and at most `MAXIMUM_CAPACITY`.
const DEFAULT_CAPACITY: usize = 16;
/// The bin count threshold for using a tree rather than list for a bin. Bins are
/// converted to trees when adding an element to a bin with at least this many
/// nodes. The value must be greater than 2, and should be at least 8 to mesh
/// with assumptions in tree removal about conversion back to plain bins upon
/// shrinkage.
const TREEIFY_THRESHOLD: usize = 8;
/// The bin count threshold for untreeifying a (split) bin during a resize
/// operation. Should be less than TREEIFY_THRESHOLD, and at most 6 to mesh with
/// shrinkage detection under removal.
const UNTREEIFY_THRESHOLD: usize = 6;
/// The smallest table capacity for which bins may be treeified. (Otherwise the
/// table is resized if too many nodes in a bin.) The value should be at least 4
/// * TREEIFY_THRESHOLD to avoid conflicts between resizing and treeification
/// thresholds.
const MIN_TREEIFY_CAPACITY: usize = 64;
/// Minimum number of rebinnings per transfer step. Ranges are
/// subdivided to allow multiple resizer threads. This value
/// serves as a lower bound to avoid resizers encountering
/// excessive memory contention. The value should be at least
/// `DEFAULT_CAPACITY`.
const MIN_TRANSFER_STRIDE: isize = 16;
/// The number of bits used for generation stamp in `size_ctl`.
/// Must be at least 6 for 32bit arrays.
const RESIZE_STAMP_BITS: usize = ISIZE_BITS / 2;
/// The maximum number of threads that can help resize.
/// Must fit in `32 - RESIZE_STAMP_BITS` bits for 32 bit architectures
/// and `64 - RESIZE_STAMP_BITS` bits for 64 bit architectures
const MAX_RESIZERS: isize = (1 << (ISIZE_BITS - RESIZE_STAMP_BITS)) - 1;
/// The bit shift for recording size stamp in `size_ctl`.
const RESIZE_STAMP_SHIFT: usize = ISIZE_BITS - RESIZE_STAMP_BITS;
#[cfg(not(miri))]
static NCPU_INITIALIZER: std::sync::Once = std::sync::Once::new();
#[cfg(not(miri))]
static NCPU: std::sync::atomic::AtomicUsize = std::sync::atomic::AtomicUsize::new(0);
macro_rules! load_factor {
($n: expr) => {
// ¾ n = n - n/4 = n - (n >> 2)
$n - ($n >> 2)
};
}
/// A concurrent hash table.
///
/// Flurry uses [`Guards`] to control the lifetime of the resources that get stored and
/// extracted from the map. [`Guards`] are acquired through the [`HashMap::pin`] and
/// [`HashMap::guard`] functions. For more information, see the [notes in the crate-level
/// documentation].
///
/// [notes in the crate-level documentation]: index.html#a-note-on-guard-and-memory-use
/// [`Guards`]: index.html#a-note-on-guard-and-memory-use
pub struct HashMap<K, V, S = crate::DefaultHashBuilder> {
/// The array of bins. Lazily initialized upon first insertion.
/// Size is always a power of two. Accessed directly by iterators.
table: Atomic<Table<K, V>>,
/// The next table to use; non-null only while resizing.
next_table: Atomic<Table<K, V>>,
/// The next table index (plus one) to split while resizing.
transfer_index: AtomicIsize,
count: AtomicIsize,
/// Table initialization and resizing control. When negative, the
/// table is being initialized or resized: -1 for initialization,
/// else -(1 + the number of active resizing threads). Otherwise,
/// when table is null, holds the initial table size to use upon
/// creation, or 0 for default. After initialization, holds the
/// next element count value upon which to resize the table.
size_ctl: AtomicIsize,
/// Collector that all `Guard` references used for operations on this map must be tied to. It
/// is important that they all assocate with the _same_ `Collector`, otherwise you end up with
/// unsoundness as described in https://github.com/jonhoo/flurry/issues/46. Specifically, a
/// user can do:
///
/// ```rust,should_panic
/// # use flurry::HashMap;
/// let map: HashMap<_, _> = HashMap::default();
/// map.insert(42, String::from("hello"), &map.guard());
///
/// let evil = seize::Collector::new();
/// let guard = evil.enter();
/// let oops = map.get(&42, &guard);
///
/// map.remove(&42, &map.guard());
/// // at this point, the default collector is allowed to free `"hello"`
/// // since no guard from `map`s collector is active.
/// // `oops` is tied to the lifetime of a Guard that is not a part of
/// // the same collector, and so can now be dangling.
/// // but we can still access it!
/// assert_eq!(oops.unwrap(), "hello");
/// ```
///
/// We avoid that by checking that every external guard that is passed in is associated with
/// the `Collector` that was specified when the map was created (which may be the global
/// collector).
collector: Collector,
build_hasher: S,
}
#[derive(Eq, PartialEq, Debug)]
enum PutResult<'a, T> {
Inserted {
new: &'a T,
},
Replaced {
old: &'a T,
new: &'a T,
},
Exists {
current: &'a T,
not_inserted: Box<Linked<T>>,
},
}
impl<'a, T> PutResult<'a, T> {
fn before(&self) -> Option<&'a T> {
match *self {
PutResult::Inserted { .. } => None,
PutResult::Replaced { old, .. } => Some(old),
PutResult::Exists { current, .. } => Some(current),
}
}
#[allow(dead_code)]
fn after(&self) -> Option<&'a T> {
match *self {
PutResult::Inserted { new } => Some(new),
PutResult::Replaced { new, .. } => Some(new),
PutResult::Exists { .. } => None,
}
}
}
/// The error type for the [`HashMap::try_insert`] method.
#[derive(Copy, Clone, Debug, PartialEq, Eq)]
pub struct TryInsertError<'a, V> {
/// A reference to the current value mapped to the key.
pub current: &'a V,
/// The value that [`HashMap::try_insert`] failed to insert.
pub not_inserted: V,
}
impl<'a, V> Display for TryInsertError<'a, V>
where
V: Debug,
{
fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
write!(
f,
"Insert of \"{:?}\" failed as key was already present with value \"{:?}\"",
self.not_inserted, self.current
)
}
}
impl<'a, V> Error for TryInsertError<'a, V>
where
V: Debug,
{
#[inline]
fn source(&self) -> Option<&(dyn Error + 'static)> {
None
}
}
// ===
// the following methods only see Ks and Vs if there have been inserts.
// modifications to the map are all guarded by thread-safety bounds (Send + Sync ).
// but _these_ methods do not need to be, since they will never introduce keys or values, only give
// out ones that have already been inserted (which implies they must be thread-safe).
// ===
impl<K, V> HashMap<K, V, crate::DefaultHashBuilder> {
/// Creates an empty `HashMap`.
///
/// The hash map is initially created with a capacity of 0, so it will not allocate until it
/// is first inserted into.
///
/// # Examples
///
/// ```
/// use flurry::HashMap;
/// let map: HashMap<&str, i32> = HashMap::new();
/// ```
pub fn new() -> Self {
Self::default()
}
/// Creates an empty `HashMap` with the specified capacity.
///
/// The hash map will be able to hold at least `capacity` elements without
/// reallocating. If `capacity` is 0, the hash map will not allocate.
///
/// # Examples
///
/// ```
/// use flurry::HashMap;
/// let map: HashMap<&str, i32> = HashMap::with_capacity(10);
/// ```
///
/// # Notes
///
/// There is no guarantee that the HashMap will not resize if `capacity`
/// elements are inserted. The map will resize based on key collision, so
/// bad key distribution may cause a resize before `capacity` is reached.
/// For more information see the [`resizing behavior`]
///
/// [`resizing behavior`]: index.html#resizing-behavior
pub fn with_capacity(capacity: usize) -> Self {
Self::with_capacity_and_hasher(capacity, crate::DefaultHashBuilder::default())
}
}
impl<K, V, S> Default for HashMap<K, V, S>
where
S: Default,
{
fn default() -> Self {
Self::with_hasher(S::default())
}
}
impl<K, V, S> HashMap<K, V, S> {
/// Creates an empty map which will use `hash_builder` to hash keys.
///
/// The created map has the default initial capacity.
///
/// Warning: `hash_builder` is normally randomly generated, and is designed to
/// allow the map to be resistant to attacks that cause many collisions and
/// very poor performance. Setting it manually using this
/// function can expose a DoS attack vector.
///
/// # Examples
///
/// ```
/// use flurry::{HashMap, DefaultHashBuilder};
///
/// let map = HashMap::with_hasher(DefaultHashBuilder::default());
/// map.pin().insert(1, 2);
/// ```
pub fn with_hasher(hash_builder: S) -> Self {
Self {
table: Atomic::null(),
next_table: Atomic::null(),
transfer_index: AtomicIsize::new(0),
count: AtomicIsize::new(0),
size_ctl: AtomicIsize::new(0),
build_hasher: hash_builder,
collector: Collector::new(),
}
}
/// Creates an empty map with the specified `capacity`, using `hash_builder` to hash the keys.
///
/// The map will be sized to accommodate `capacity` elements with a low chance of reallocating
/// (assuming uniformly distributed hashes). If `capacity` is 0, the call will not allocate,
/// and is equivalent to [`HashMap::new`].
///
/// Warning: `hash_builder` is normally randomly generated, and is designed to allow the map
/// to be resistant to attacks that cause many collisions and very poor performance.
/// Setting it manually using this function can expose a DoS attack vector.
///
/// # Examples
///
/// ```
/// use flurry::HashMap;
/// use std::collections::hash_map::RandomState;
///
/// let s = RandomState::new();
/// let map = HashMap::with_capacity_and_hasher(10, s);
/// map.pin().insert(1, 2);
/// ```
pub fn with_capacity_and_hasher(capacity: usize, hash_builder: S) -> Self {
if capacity == 0 {
return Self::with_hasher(hash_builder);
}
let mut map = Self::with_hasher(hash_builder);
map.presize(capacity);
map
}
/// Associate a custom [`seize::Collector`] with this map.
///
/// By default, the global collector is used. With this method you can use a different
/// collector instead. This may be desireable if you want more control over when and how memory
/// reclamation happens.
///
/// Note that _all_ `Guard` references provided to access the returned map _must_ be
/// constructed using guards produced by `collector`.
#[must_use]
pub fn with_collector(mut self, collector: Collector) -> Self {
self.collector = collector;
self
}
/// Pin a `Guard` for use with this map.
///
/// Keep in mind that for as long as you hold onto this `Guard`, you are preventing the
/// collection of garbage generated by the map.
pub fn guard(&self) -> Guard<'_> {
self.collector.enter()
}
#[inline]
fn check_guard(&self, guard: &Guard<'_>) {
// guard.collector() may be `None` if it is unprotected
if let Some(c) = guard.collector() {
assert!(Collector::ptr_eq(c, &self.collector));
}
}
/// Returns the number of entries in the map.
///
/// # Examples
///
/// ```
/// use flurry::HashMap;
///
/// let map = HashMap::new();
///
/// map.pin().insert(1, "a");
/// map.pin().insert(2, "b");
/// assert!(map.pin().len() == 2);
/// ```
pub fn len(&self) -> usize {
let n = self.count.load(Ordering::Relaxed);
if n < 0 {
0
} else {
n as usize
}
}
/// Returns `true` if the map is empty. Otherwise returns `false`.
///
/// # Examples
///
/// ```
/// use flurry::HashMap;
///
/// let map = HashMap::new();
/// assert!(map.pin().is_empty());
/// map.pin().insert("a", 1);
/// assert!(!map.pin().is_empty());
/// ```
pub fn is_empty(&self) -> bool {
self.len() == 0
}
#[cfg(test)]
/// Returns the capacity of the map.
fn capacity(&self, guard: &Guard<'_>) -> usize {
self.check_guard(guard);
let table = self.table.load(Ordering::Relaxed, guard);
if table.is_null() {
0
} else {
// Safety: we loaded `table` under the `guard`,
// so it must still be valid here
unsafe { table.deref() }.len()
}
}
/// Returns the stamp bits for resizing a table of size n.
/// Must be negative when shifted left by `RESIZE_STAMP_SHIFT`.
fn resize_stamp(n: usize) -> isize {
n.leading_zeros() as isize | (1_isize << (RESIZE_STAMP_BITS - 1))
}
/// An iterator visiting all key-value pairs in arbitrary order.
///
/// The iterator element type is `(&'g K, &'g V)`.
pub fn iter<'g>(&'g self, guard: &'g Guard<'_>) -> Iter<'g, K, V> {
self.check_guard(guard);
let table = self.table.load(Ordering::SeqCst, guard);
let node_iter = NodeIter::new(table, guard);
Iter { node_iter, guard }
}
/// An iterator visiting all keys in arbitrary order.
///
/// The iterator element type is `&'g K`.
pub fn keys<'g>(&'g self, guard: &'g Guard<'_>) -> Keys<'g, K, V> {
self.check_guard(guard);
let table = self.table.load(Ordering::SeqCst, guard);
let node_iter = NodeIter::new(table, guard);
Keys { node_iter }
}
/// An iterator visiting all values in arbitrary order.
///
/// The iterator element type is `&'g V`.
pub fn values<'g>(&'g self, guard: &'g Guard<'_>) -> Values<'g, K, V> {
self.check_guard(guard);
let table = self.table.load(Ordering::SeqCst, guard);
let node_iter = NodeIter::new(table, guard);
Values { node_iter, guard }
}
fn init_table<'g>(&'g self, guard: &'g Guard<'_>) -> Shared<'g, Table<K, V>> {
loop {
let table = self.table.load(Ordering::SeqCst, guard);
// safety: we loaded the table while the thread was marked as active.
// table won't be deallocated until the guard is dropped at the earliest.
if !table.is_null() && !unsafe { table.deref() }.is_empty() {
break table;
}
// try to allocate the table
let mut sc = self.size_ctl.load(Ordering::SeqCst);
if sc < 0 {
// we lost the initialization race; just spin
std::thread::yield_now();
continue;
}
if self
.size_ctl
.compare_exchange(sc, -1, Ordering::SeqCst, Ordering::Relaxed)
.is_ok()
{
// we get to do it!
let mut table = self.table.load(Ordering::SeqCst, guard);
// safety: we loaded the table while the thread was marked as active.
// table won't be deallocated until the guard is dropped at the earliest.
if table.is_null() || unsafe { table.deref() }.is_empty() {
let n = if sc > 0 {
sc as usize
} else {
DEFAULT_CAPACITY
};
table = Shared::boxed(Table::new(n, &self.collector), &self.collector);
self.table.store(table, Ordering::SeqCst);
sc = load_factor!(n as isize)
}
self.size_ctl.store(sc, Ordering::SeqCst);
break table;
}
}
}
/// Presize the table to accommodate the given number of elements.
fn presize(&mut self, size: usize) {
// NOTE: this is a stripped-down version of try_presize for use only when we _know_ that
// the table is new, and that therefore we won't have to help out with transfers or deal
// with contending initializations.
// safety: we are creating this map, so no other thread can access it,
// while we are initializing it.
let guard = unsafe { Guard::unprotected() };
let requested_capacity = if size >= MAXIMUM_CAPACITY / 2 {
MAXIMUM_CAPACITY
} else {
// round the requested_capacity to the next power of to from 1.5 * size + 1
// TODO: find out if this is neccessary
let size = size + (size >> 1) + 1;
std::cmp::min(MAXIMUM_CAPACITY, size.next_power_of_two())
} as usize;
// sanity check that the map has indeed not been set up already
assert_eq!(self.size_ctl.load(Ordering::SeqCst), 0);
assert!(self.table.load(Ordering::SeqCst, &guard).is_null());
// the table has not yet been initialized, so we can just create it
// with as many bins as were requested
// create a table with `new_capacity` empty bins
let new_table = Shared::boxed(
Table::new(requested_capacity, &self.collector),
&self.collector,
);
// store the new table to `self.table`
self.table.store(new_table, Ordering::SeqCst);
// resize the table once it is 75% full
let new_load_to_resize_at = load_factor!(requested_capacity as isize);
// store the next load at which the table should resize to it's size_ctl field
// and thus release the initialization "lock"
self.size_ctl.store(new_load_to_resize_at, Ordering::SeqCst);
}
}
// ===
// the following methods require Clone and Ord, since they ultimately call
// `transfer`, which needs to be able to clone keys and work with tree bins.
// however, they do _not_ need to require thread-safety bounds (Send + Sync +
// 'static) since if the bounds do not hold, the map is empty, so no keys or
// values will be transfered anyway.
// ===
impl<K, V, S> HashMap<K, V, S>
where
K: Clone + Ord,
{
/// Tries to presize table to accommodate the given number of elements.
fn try_presize(&self, size: usize, guard: &Guard<'_>) {
let requested_capacity = if size >= MAXIMUM_CAPACITY / 2 {
MAXIMUM_CAPACITY
} else {
// round the requested_capacity to the next power of to from 1.5 * size + 1
// TODO: find out if this is neccessary
let size = size + (size >> 1) + 1;
std::cmp::min(MAXIMUM_CAPACITY, size.next_power_of_two())
} as isize;
loop {
let size_ctl = self.size_ctl.load(Ordering::SeqCst);
if size_ctl < 0 {
break;
}
let table = self.table.load(Ordering::SeqCst, guard);
// The current capacity == the number of bins in the current table
let current_capactity = if table.is_null() {
0
} else {
unsafe { table.deref() }.len()
};
if current_capactity == 0 {
// the table has not yet been initialized, so we can just create it
// with as many bins as were requested
// since the map is uninitialized, size_ctl describes the initial capacity
let initial_capacity = size_ctl;
// the new capacity is either the requested capacity or the initial capacity (size_ctl)
let new_capacity = requested_capacity.max(initial_capacity) as usize;
// try to aquire the initialization "lock" to indicate that we are initializing the table.
if self
.size_ctl
.compare_exchange(size_ctl, -1, Ordering::SeqCst, Ordering::Relaxed)
.is_err()
{
// somebody else is already initializing the table (or has already finished).
continue;
}
// we got the initialization `lock`; Make sure the table is still unitialized
// (or is the same table with 0 bins we read earlier, althought that should not be the case)
if self.table.load(Ordering::SeqCst, guard) != table {
// NOTE: this could probably be `!self.table.load(...).is_null()`
// if we decide that tables can never have 0 bins.
// the table is already initialized; Write the `size_ctl` value it had back to it's
// `size_ctl` field to release the initialization "lock"
self.size_ctl.store(size_ctl, Ordering::SeqCst);
continue;
}
// create a table with `new_capacity` empty bins
let new_table =
Shared::boxed(Table::new(new_capacity, &self.collector), &self.collector);
// store the new table to `self.table`
let old_table = self.table.swap(new_table, Ordering::SeqCst, guard);
// old_table should be `null`, since we don't ever initialize a table with 0 bins
// and this branch only happens if table has not yet been initialized or it's length is 0.
assert!(old_table.is_null());
// TODO: if we allow tables with 0 bins. `defer_destroy` `old_table` if it's not `null`:
// if !old_table.is_null() {
// // TODO: safety argument, for why this is okay
// unsafe { guard.defer_destroy(old_table) }
// }
// resize the table once it is 75% full
let new_load_to_resize_at = load_factor!(new_capacity as isize);
// store the next load at which the table should resize to it's size_ctl field
// and thus release the initialization "lock"
self.size_ctl.store(new_load_to_resize_at, Ordering::SeqCst);
} else if requested_capacity <= size_ctl || current_capactity >= MAXIMUM_CAPACITY {
// Either the `requested_capacity` was smaller than or equal to the load we would resize at (size_ctl)
// and we don't need to resize, since our load factor will still be acceptable if we don't
// Or it was larger than the `MAXIMUM_CAPACITY` of the map and we refuse
// to resize to an invalid capacity
break;
} else if table == self.table.load(Ordering::SeqCst, guard) {
// The table is initialized, try to resize it to the requested capacity
let rs: isize = Self::resize_stamp(current_capactity) << RESIZE_STAMP_SHIFT;
// TODO: see #29: `rs` is postive even though `resize_stamp` says:
// "Must be negative when shifted left by RESIZE_STAMP_SHIFT"
// and since our size_control field needs to be negative
// to indicate a resize this needs to be addressed
if self
.size_ctl
.compare_exchange(size_ctl, rs + 2, Ordering::SeqCst, Ordering::Relaxed)
.is_ok()
{
// someone else already started to resize the table
// TODO: can we `self.help_transfer`?
self.transfer(table, Shared::null(), guard);
}
}
}
}
// NOTE: transfer requires that K and V are Send + Sync if it will actually transfer anything.
// If K/V aren't Send + Sync, the map must be empty, and therefore calling tansfer is fine.
#[inline(never)]
fn transfer<'g>(
&'g self,
table: Shared<'g, Table<K, V>>,
mut next_table_ptr: Shared<'g, Table<K, V>>,
guard: &'g Guard<'_>,
) {
// safety: table was read while `guard` was held. the code that drops table only drops it
// after it is no longer reachable, and any outstanding references are no longer active.
// this references is still active (marked by the guard), so the target of the references
// won't be dropped while the guard remains active.
let n = unsafe { table.deref() }.len();
let ncpu = num_cpus();
let stride = if ncpu > 1 { (n >> 3) / ncpu } else { n };
let stride = std::cmp::max(stride as isize, MIN_TRANSFER_STRIDE);
if next_table_ptr.is_null() {
// we are initiating a resize
let table = Shared::boxed(Table::new(n << 1, &self.collector), &self.collector);
let now_garbage = self.next_table.swap(table, Ordering::SeqCst, guard);
assert!(now_garbage.is_null());
self.transfer_index.store(n as isize, Ordering::SeqCst);
next_table_ptr = self.next_table.load(Ordering::Relaxed, guard);
}
// safety: same argument as for table above
let next_n = unsafe { next_table_ptr.deref() }.len();
let mut advance = true;
let mut finishing = false;
let mut i = 0;
let mut bound = 0;
loop {
// try to claim a range of bins for us to transfer
while advance {
i -= 1;
if i >= bound || finishing {
advance = false;
break;
}
let next_index = self.transfer_index.load(Ordering::SeqCst);
if next_index <= 0 {
i = -1;
advance = false;
break;
}
let next_bound = if next_index > stride {
next_index - stride
} else {
0
};
if self
.transfer_index
.compare_exchange(next_index, next_bound, Ordering::SeqCst, Ordering::Relaxed)
.is_ok()
{
bound = next_bound;
i = next_index;
advance = false;
break;
}
}
if i < 0 || i as usize >= n || i as usize + n >= next_n {
// the resize has finished
if finishing {
// this branch is only taken for one thread partaking in the resize!
self.next_table.store(Shared::null(), Ordering::SeqCst);
let now_garbage = self.table.swap(next_table_ptr, Ordering::SeqCst, guard);
// safety: need to guarantee that now_garbage is no longer reachable. more
// specifically, no thread that executes _after_ this line can ever get a
// reference to now_garbage.
//
// first, we need to argue that there is no _other_ way to get to now_garbage.
//
// - it is _not_ accessible through self.table any more
// - it is _not_ accessible through self.next_table any more
// - what about forwarding nodes (BinEntry::Moved)?
// the only BinEntry::Moved that point to now_garbage, are the ones in
// _previous_ tables. to get to those previous tables, one must ultimately
// have arrived through self.table (because that's where all operations
// start their search). since self.table has now changed, only "old" threads
// can still be accessing them. no new thread can get to past tables, and
// therefore they also cannot get to ::Moved that point to now_garbage, so
// we're fine.
//
// this means that no _future_ thread (i.e., that was inactive before
// the swap may be freed) can get a reference to now_garbage.
//
// next, let's talk about threads with _existing_ references to now_garbage.
// such a thread must have gotten that reference before the call to swap.
// because of this, that thread must have been marked as active, and included
// in the reference count, meaning the garbage will not be freed until
// that thread drops its guard at the earliest.
unsafe { guard.retire_shared(now_garbage) };
self.size_ctl
.store(((n as isize) << 1) - ((n as isize) >> 1), Ordering::SeqCst);
return;
}
let sc = self.size_ctl.load(Ordering::SeqCst);
if self
.size_ctl
.compare_exchange(sc, sc - 1, Ordering::SeqCst, Ordering::Relaxed)
.is_ok()
{
if (sc - 2) != Self::resize_stamp(n) << RESIZE_STAMP_SHIFT {
return;
}
// we are the chosen thread to finish the resize!
finishing = true;
// ???
advance = true;
// NOTE: the java code says "recheck before commit" here
i = n as isize;
}
continue;
}
let i = i as usize;
// safety: these were read while `guard` was held. the code that drops these, only
// drops them after a) they are no longer reachable, and b) any outstanding references
// are no longer active. these references are still active (marked by the guard), so
// the target of these references won't be dropped while the guard remains active.
let table = unsafe { table.deref() };
let bin = table.bin(i, guard);
if bin.is_null() {
advance = table
.cas_bin(
i,
Shared::null(),
table.get_moved(next_table_ptr, guard),
guard,
)
.is_ok();
continue;
}
// safety: as for table above
let next_table = unsafe { next_table_ptr.deref() };
// safety: bin is a valid pointer.
//
// there are three cases when a bin pointer is invalidated:
//
// 1. if the table was resized, bin is a move entry, and the resize has completed. in
// that case, the table (and all its heads) have already been retired.
// 2. if the table is being resized, bin may be swapped with a move entry. the old bin
// will only be retired after that happens.
// 3. when elements are inserted into or removed from the map, bin may be changed into
// or from a TreeBin from or into a regular, linear bin. the old bin will be
// retired only once that happens.
//
// in all cases, we held the guard when we got the reference to the bin. if any such
// swap happened, it must have happened _after_ we read. since we did the read while
// the current thread was marked as active, we must be included in the reference count,
// and the drop must happen _after_ we decrement the count (i.e drop our guard).
match **unsafe { bin.deref() } {
BinEntry::Moved => {
// already processed
advance = true;
}
BinEntry::Node(ref head) => {
// bin is non-empty, need to link into it, so we must take the lock
let head_lock = head.lock.lock();
// need to check that this is _still_ the head
let current_head = table.bin(i, guard);
if current_head != bin {
// nope -- try again from the start
continue;
}
// yes, it is still the head, so we can now "own" the bin
// note that there can still be readers in the bin!
// TODO: ReservationNode
let mut run_bit = head.hash & n as u64;
let mut last_run = bin;
let mut p = bin;
loop {
// safety: p is a valid pointer.
//
// p is only retired when its bin is replaced with a move node
// (see safety comment near table.store_bin below). we read the
// bin, and got to p, so its bin has not yet been swapped with a
// move node. and, our thread is marked as active, so any retirement
// must include us in the reference count. therefore, it can only be
// dropped _after_ we drop our guard, and is safe to use now.
let node = unsafe { p.deref() }.as_node().unwrap();
let next = node.next.load(Ordering::SeqCst, guard);
let b = node.hash & n as u64;
if b != run_bit {
run_bit = b;
last_run = p;
}
if next.is_null() {
break;
}
p = next;
}
let mut low_bin = Shared::null();
let mut high_bin = Shared::null();
if run_bit == 0 {
// last run is all in the low bin
low_bin = last_run;
} else {
// last run is all in the high bin
high_bin = last_run;
}
p = bin;
while p != last_run {
// safety: p is a valid pointer.
//
// p is only retired when its bin is replaced with a move node
// (see safety comment near table.store_bin below). we read the
// bin, and got to p, so its bin has not yet been swapped with a
// move node. and, our thread is marked as active, so any retirement
// must include us in the reference count. therefore, it can only be
// dropped _after_ we drop our guard, and is safe to use now.
let node = unsafe { p.deref() }.as_node().unwrap();
let link = if node.hash & n as u64 == 0 {
// to the low bin!
&mut low_bin
} else {
// to the high bin!
&mut high_bin
};
*link = Shared::boxed(
BinEntry::Node(Node::with_next(
node.hash,
node.key.clone(),
node.value.clone(),
Atomic::from(*link),
)),
&self.collector,
);
p = node.next.load(Ordering::SeqCst, guard);
}
next_table.store_bin(i, low_bin);
next_table.store_bin(i + n, high_bin);
table.store_bin(i, table.get_moved(next_table_ptr, guard));
// everything up to last_run in the _old_ bin linked list is now garbage.
// those nodes have all been re-allocated in the new bin linked list.
p = bin;
while p != last_run {
// safety:
//
// we need to argue that there is no longer a way to access p. the only way
// to get to p is through table[i]. since table[i] has been replaced by a
// BinEntry::Moved, p is no longer accessible.
//
// any existing reference to p must have been taken before table.store_bin.
// any threads that have such a reference must have been active before we
// retired p, so they are protected by the reference count.
let next = unsafe { p.deref() }
.as_node()
.unwrap()
.next
.load(Ordering::SeqCst, guard);
unsafe { guard.retire_shared(p) };
p = next;
}
advance = true;
drop(head_lock);
}
BinEntry::Tree(ref tree_bin) => {
let bin_lock = tree_bin.lock.lock();
// need to check that this is _still_ the correct bin
let current_head = table.bin(i, guard);
if current_head != bin {
// nope -- try again from the start
continue;
}
let mut low = Shared::null();
let mut low_tail = Shared::null();
let mut high = Shared::null();
let mut high_tail = Shared::null();
let mut low_count = 0;
let mut high_count = 0;
let mut e = tree_bin.first.load(Ordering::Relaxed, guard);
while !e.is_null() {
// safety: we read under our guard, at which point the tree
// structure was valid. Since our guard marks the current thread
// as active, the TreeNodes remain valid for at least as long as
// we hold onto the guard.
// Structurally, TreeNodes always point to TreeNodes, so this is sound.
let tree_node = unsafe { TreeNode::get_tree_node(e) };
let hash = tree_node.node.hash;
let new_node = TreeNode::new(
hash,
tree_node.node.key.clone(),
tree_node.node.value.clone(),
Atomic::null(),
Atomic::null(),
);
let run_bit = hash & n as u64;
if run_bit == 0 {
new_node.prev.store(low_tail, Ordering::Relaxed);
let new_node =
Shared::boxed(BinEntry::TreeNode(new_node), &self.collector);
if low_tail.is_null() {
// this is the first element inserted into the low bin
low = new_node;
} else {
// safety: `low_tail` was just created by us and not shared.
// Structurally, TreeNodes always point to TreeNodes, so this is sound.
unsafe { TreeNode::get_tree_node(low_tail) }
.node
.next
.store(new_node, Ordering::Relaxed);
}
low_tail = new_node;
low_count += 1;
} else {
new_node.prev.store(high_tail, Ordering::Relaxed);
let new_node =
Shared::boxed(BinEntry::TreeNode(new_node), &self.collector);
if high_tail.is_null() {
// this is the first element inserted into the high bin
high = new_node;
} else {
// safety: `high_tail` was just created by us and not shared.
// Structurally, TreeNodes always point to TreeNodes, so this is sound.
unsafe { TreeNode::get_tree_node(high_tail) }
.node
.next
.store(new_node, Ordering::Relaxed);
}
high_tail = new_node;
high_count += 1;
}
e = tree_node.node.next.load(Ordering::Relaxed, guard);
}
let mut reused_bin = false;
let low_bin = if low_count <= UNTREEIFY_THRESHOLD {
// use a regular bin instead of a tree bin since the
// bin is too small. since the tree nodes are
// already behind shared references, we have to
// clean them up manually.
let low_linear = self.untreeify(low, guard);
// safety: we have just created `low` and its `next`
// nodes and have never shared them
unsafe { TreeBin::drop_tree_nodes(low, false, guard) };
low_linear
} else if high_count != 0 {
// the new bin will also be a tree bin. if both the high
// bin and the low bin are non-empty, we have to
// allocate a new TreeBin.
// safety: we have just created `low` and its `next` nodes using `Shared::boxed`
// and have never shared them
let low_bin = unsafe { BinEntry::Tree(TreeBin::new(low, guard)) };
Shared::boxed(low_bin, &self.collector)
} else {
// if not, we can re-use the old bin here, since it will
// be swapped for a Moved entry while we are still
// behind the bin lock.
reused_bin = true;
// since we also don't use the created low nodes here,
// we need to clean them up.
// safety: we have just created `low` and its `next`
// nodes and have never shared them
unsafe { TreeBin::drop_tree_nodes(low, false, guard) };
bin
};
let high_bin = if high_count <= UNTREEIFY_THRESHOLD {
let high_linear = self.untreeify(high, guard);
// safety: we have just created `high` and its `next`
// nodes and have never shared them
unsafe { TreeBin::drop_tree_nodes(high, false, guard) };
high_linear
} else if low_count != 0 {
// safety: we have just created `high` and its `next` nodes using `Shared::boxed`
// and have never shared them
let high_bin = unsafe { BinEntry::Tree(TreeBin::new(high, guard)) };
Shared::boxed(high_bin, &self.collector)
} else {
reused_bin = true;
// since we also don't use the created low nodes here,
// we need to clean them up.
// safety: we have just created `high` and its `next`
// nodes and have never shared them
unsafe { TreeBin::drop_tree_nodes(high, false, guard) };
bin
};
next_table.store_bin(i, low_bin);
next_table.store_bin(i + n, high_bin);
table.store_bin(i, table.get_moved(next_table_ptr, guard));
// if we did not re-use the old bin, it is now garbage,
// since all of its nodes have been reallocated. However,
// we always re-use the stored values, so we can't drop those.
if !reused_bin {
// safety: the entry for this bin in the old table was
// swapped for a Moved entry, so no thread can obtain a
// new reference to `bin` from there. we only defer
// dropping the old bin if it was not used in
// `next_table` so there is no other reference to it
// anyone could obtain.
unsafe { TreeBin::defer_drop_without_values(bin, guard) };
}
advance = true;
drop(bin_lock);
}
BinEntry::TreeNode(_) => unreachable!(
"The head of a bin cannot be a TreeNode directly without BinEntry::Tree"
),
}
}
}
fn help_transfer<'g>(
&'g self,
table: Shared<'g, Table<K, V>>,
guard: &'g Guard<'_>,
) -> Shared<'g, Table<K, V>> {
if table.is_null() {
return table;
}
// safety: table is only retired after it is swapped to null.
// we read it as not null while holding `guard`, so any thread
// retiring the table must have seen us as active and included us
// in the reference count. therefore our reference is valid until
// we decrement the reference count (i.e drop our guard).
let next_table = unsafe { table.deref() }.next_table(guard);
if next_table.is_null() {
return table;
}
// safety: same as above
let rs = Self::resize_stamp(unsafe { table.deref() }.len()) << RESIZE_STAMP_SHIFT;
while next_table == self.next_table.load(Ordering::SeqCst, guard)
&& table == self.table.load(Ordering::SeqCst, guard)
{
let sc = self.size_ctl.load(Ordering::SeqCst);
if sc >= 0
|| sc == rs + MAX_RESIZERS
|| sc == rs + 1
|| self.transfer_index.load(Ordering::SeqCst) <= 0
{
break;
}
if self
.size_ctl
.compare_exchange(sc, sc + 1, Ordering::SeqCst, Ordering::Relaxed)
.is_ok()
{
self.transfer(table, next_table, guard);
break;
}
}
next_table
}
fn add_count(&self, n: isize, resize_hint: Option<usize>, guard: &Guard<'_>) {
// TODO: implement the Java CounterCell business here
use std::cmp;
let mut count = match n.cmp(&0) {
cmp::Ordering::Greater => self.count.fetch_add(n, Ordering::SeqCst) + n,
cmp::Ordering::Less => self.count.fetch_sub(n.abs(), Ordering::SeqCst) - n,
cmp::Ordering::Equal => self.count.load(Ordering::SeqCst),
};
// if resize_hint is None, it means the caller does not want us to consider a resize.
// if it is Some(n), the caller saw n entries in a bin
if resize_hint.is_none() {
return;
}
// TODO: use the resize hint
let _saw_bin_length = resize_hint.unwrap();
loop {
let sc = self.size_ctl.load(Ordering::SeqCst);
if count < sc {
// we're not at the next resize point yet
break;
}
let table = self.table.load(Ordering::SeqCst, guard);
if table.is_null() {
// table will be initalized by another thread anyway
break;
}
// safety: table is only retired after it is swapped to null.
// we read it as not null while holding `guard`, so any thread
// retiring the table must have seen us as active and included us
// in the reference count. therefore our reference is valid until
// we decrement the reference count (i.e drop our guard).
let n = unsafe { table.deref() }.len();
if n >= MAXIMUM_CAPACITY {
// can't resize any more anyway
break;
}
let rs = Self::resize_stamp(n) << RESIZE_STAMP_SHIFT;
if sc < 0 {
// ongoing resize! can we join the resize transfer?
if sc == rs + MAX_RESIZERS || sc == rs + 1 {
break;
}
let nt = self.next_table.load(Ordering::SeqCst, guard);
if nt.is_null() {
break;
}
if self.transfer_index.load(Ordering::SeqCst) <= 0 {
break;
}
// try to join!
if self
.size_ctl
.compare_exchange(sc, sc + 1, Ordering::SeqCst, Ordering::Relaxed)
.is_ok()
{
self.transfer(table, nt, guard);
}
} else if self
.size_ctl
.compare_exchange(sc, rs + 2, Ordering::SeqCst, Ordering::Relaxed)
.is_ok()
{
// a resize is needed, but has not yet started
// TODO: figure out why this is rs + 2, not just rs
// NOTE: this also applies to `try_presize`
self.transfer(table, Shared::null(), guard);
}
// another resize may be needed!
count = self.count.load(Ordering::SeqCst);
}
}
/// Tries to reserve capacity for at least `additional` more elements to be inserted in the
/// `HashMap`.
///
/// The collection may reserve more space to avoid frequent reallocations.
///
/// # Examples
///
/// ```
/// use flurry::HashMap;
///
/// let map: HashMap<&str, i32> = HashMap::new();
///
/// map.pin().reserve(10);
/// ```
///
/// # Notes
///
/// Reserving does not panic in flurry. If the new size is invalid, no
/// reallocation takes place.
pub fn reserve(&self, additional: usize, guard: &Guard<'_>) {
self.check_guard(guard);
let absolute = self.len() + additional;
self.try_presize(absolute, guard);
}
}
// ===
// the following methods never introduce new items (so they do not need the thread-safety bounds),
// but they _do_ perform lookups, which require hashing and equality.
// ===
impl<K, V, S> HashMap<K, V, S>
where
K: Hash + Ord,
S: BuildHasher,
{
#[inline]
fn hash<Q: ?Sized + Hash>(&self, key: &Q) -> u64 {
self.build_hasher.hash_one(key)
}
fn get_node<'g, Q>(&'g self, key: &Q, guard: &'g Guard<'_>) -> Option<&'g Node<K, V>>
where
K: Borrow<Q>,
Q: ?Sized + Hash + Ord,
{
let table = self.table.load(Ordering::SeqCst, guard);
if table.is_null() {
return None;
}
// safety: we loaded the table while holding a guard.
// table won't be deallocated until we drop our guard
// at the earliest.
let table = unsafe { table.deref() };
if table.is_empty() {
return None;
}
let h = self.hash(key);
let bini = table.bini(h);
let bin = table.bin(bini, guard);
if bin.is_null() {
return None;
}
// safety: bin is a valid pointer.
//
// there are three cases when a bin pointer is invalidated:
//
// 1. if the table was resized, bin is a move entry, and the resize has completed. in
// that case, the table (and all its heads) have already been retired.
// 2. if the table is being resized, bin may be swapped with a move entry. the old bin
// will only be retired after that happens.
// 3. when elements are inserted into or removed from the map, bin may be changed into
// or from a TreeBin from or into a regular, linear bin. the old bin will be
// retired only once that happens.
//
// in all cases, we held the guard when we got the reference to the bin. if any such
// swap happened, it must have happened _after_ we read. since we did the read while
// the current thread was marked as active, we must be included in the reference count,
// and the drop must happen _after_ we decrement the count (i.e drop our guard).
let node = table.find(unsafe { bin.deref() }, h, key, guard);
if node.is_null() {
return None;
}
// safety: we loaded the bin while holding a guard, so any retirements
// must have seen us as active, and any future retirements must see us as active.
// the bin and its nodes cannot be dropped until at least after we drop our guard.
let node = unsafe { node.deref() };
Some(match **node {
BinEntry::Node(ref n) => n,
BinEntry::TreeNode(ref tn) => &tn.node,
_ => panic!("`Table::find` should always return a Node"),
})
}
/// Returns `true` if the map contains a value for the specified key.
///
/// The key may be any borrowed form of the map's key type, but
/// [`Hash`] and [`Ord`] on the borrowed form *must* match those for
/// the key type.
///
/// [`Ord`]: std::cmp::Ord
/// [`Hash`]: std::hash::Hash
///
/// # Examples
///
/// ```
/// use flurry::HashMap;
///
/// let map = HashMap::new();
/// let mref = map.pin();
/// mref.insert(1, "a");
/// assert_eq!(mref.contains_key(&1), true);
/// assert_eq!(mref.contains_key(&2), false);
/// ```
pub fn contains_key<Q>(&self, key: &Q, guard: &Guard<'_>) -> bool
where
K: Borrow<Q>,
Q: ?Sized + Hash + Ord,
{
self.check_guard(guard);
self.get(key, guard).is_some()
}
/// Returns a reference to the value corresponding to the key.
///
/// The key may be any borrowed form of the map's key type, but
/// [`Hash`] and [`Ord`] on the borrowed form *must* match those for
/// the key type.
///
/// [`Ord`]: std::cmp::Ord
/// [`Hash`]: std::hash::Hash
///
/// To obtain a `Guard`, use [`HashMap::guard`].
///
/// # Examples
///
/// ```
/// use flurry::HashMap;
///
/// let map = HashMap::new();
/// let mref = map.pin();
/// mref.insert(1, "a");
/// assert_eq!(mref.get(&1), Some(&"a"));
/// assert_eq!(mref.get(&2), None);
/// ```
#[inline]
pub fn get<'g, Q>(&'g self, key: &Q, guard: &'g Guard<'_>) -> Option<&'g V>
where
K: Borrow<Q>,
Q: ?Sized + Hash + Ord,
{
self.check_guard(guard);
let node = self.get_node(key, guard)?;
let v = node.value.load(Ordering::SeqCst, guard);
assert!(!v.is_null());
// safety: the lifetime of the reference is bound to the guard
// supplied which means that the memory will not be modified
// until at least after the guard goes out of scope
unsafe { v.as_ref().map(|linked| &**linked) }
}
/// Returns the key-value pair corresponding to `key`.
///
/// Returns `None` if this map contains no mapping for `key`.
///
/// The key may be any borrowed form of the map's key type, but
/// [`Hash`] and [`Ord`] on the borrowed form *must* match those for
/// the key type.
///
/// [`Ord`]: std::cmp::Ord
/// [`Hash`]: std::hash::Hash
#[inline]
pub fn get_key_value<'g, Q>(&'g self, key: &Q, guard: &'g Guard<'_>) -> Option<(&'g K, &'g V)>
where
K: Borrow<Q>,
Q: ?Sized + Hash + Ord,
{
self.check_guard(guard);
let node = self.get_node(key, guard)?;
let v = node.value.load(Ordering::SeqCst, guard);
assert!(!v.is_null());
// safety: the lifetime of the reference is bound to the guard
// supplied which means that the memory will not be modified
// until at least after the guard goes out of scope
unsafe { v.as_ref() }.map(|v| (&node.key, &**v))
}
pub(crate) fn guarded_eq(
&self,
other: &Self,
our_guard: &Guard<'_>,
their_guard: &Guard<'_>,
) -> bool
where
V: PartialEq,
{
if self.len() != other.len() {
return false;
}
self.iter(our_guard)
.all(|(key, value)| other.get(key, their_guard).map_or(false, |v| *value == *v))
}
}
// ===
// the following methods only ever _remove_ items, but never introduce them, so they do not need
// the thread-safety bounds.
// ===
impl<K, V, S> HashMap<K, V, S>
where
K: Clone + Ord,
{
/// Clears the map, removing all key-value pairs.
///
/// # Examples
///
/// ```
/// use flurry::HashMap;
///
/// let map = HashMap::new();
///
/// map.pin().insert(1, "a");
/// map.pin().clear();
/// assert!(map.pin().is_empty());
/// ```
pub fn clear(&self, guard: &Guard<'_>) {
// Negative number of deletions
let mut delta = 0;
let mut idx = 0usize;
let mut table = self.table.load(Ordering::SeqCst, guard);
// Safety: self.table is a valid pointer because we checked it above.
while !table.is_null() && idx < unsafe { table.deref() }.len() {
let tab = unsafe { table.deref() };
let raw_node = tab.bin(idx, guard);
if raw_node.is_null() {
idx += 1;
continue;
}
// Safety: node is a valid pointer because we checked
// it in the above if stmt.
match **unsafe { raw_node.deref() } {
BinEntry::Moved => {
table = self.help_transfer(table, guard);
// start from the first bin again in the new table
idx = 0;
}
BinEntry::Node(ref node) => {
let head_lock = node.lock.lock();
// need to check that this is _still_ the head
let current_head = tab.bin(idx, guard);
if current_head != raw_node {
// nope -- try the bin again
continue;
}
// we now own the bin
// unlink it from the map to prevent others from entering it
// NOTE: The Java code stores the null bin _after_ the loop, and thus also has
// to hold the lock until that point. However, after the store happens new
// threads and threads waiting on the lock will read the new bin, so we can
// drop the lock early and do the counting and garbage collection outside the
// critical section.
tab.store_bin(idx, Shared::null());
drop(head_lock);
// next, walk the nodes of the bin and free the nodes and their values as we go
// note that we do not free the head node yet, since we're holding the lock it contains
let mut p = node.next.load(Ordering::SeqCst, guard);
while !p.is_null() {
delta -= 1;
p = {
// safety: we loaded p under guard, and guard is still pinned, so p has not been dropped.
let node = unsafe { p.deref() }
.as_node()
.expect("entry following Node should always be a Node");
let next = node.next.load(Ordering::SeqCst, guard);
let value = node.value.load(Ordering::SeqCst, guard);
// NOTE: do not use the reference in `node` after this point!
// free the node's value
// safety: any thread that sees this p's value must have read the bin before we stored null
// into it above. it must also have already been marked as active. therefore, the
// defer_destroy below won't be executed until that thread's guard is dropped, at which
// point it holds no outstanding references to the value anyway.
unsafe { guard.retire_shared(value) };
// free the bin entry itself
// safety: same argument as for value above.
unsafe { guard.retire_shared(p) };
next
};
}
// finally, we can drop the head node and its value
let value = node.value.load(Ordering::SeqCst, guard);
// NOTE: do not use the reference in `node` after this point!
// safety: same as the argument for being allowed to free the nodes beyond the head above
unsafe { guard.retire_shared(value) };
unsafe { guard.retire_shared(raw_node) };
delta -= 1;
idx += 1;
}
BinEntry::Tree(ref tree_bin) => {
let bin_lock = tree_bin.lock.lock();
// need to check that this is _still_ the correct bin
let current_head = tab.bin(idx, guard);
if current_head != raw_node {
// nope -- try the bin again
continue;
}
// we now own the bin
// unlink it from the map to prevent others from entering it
// NOTE: The Java code stores the null bin _after_ the loop, and thus also has
// to hold the lock until that point. However, after the store happens new
// threads and threads waiting on the lock will read the new bin, so we can
// drop the lock early and do the counting and garbage collection outside the
// critical section.
tab.store_bin(idx, Shared::null());
drop(bin_lock);
// next, walk the nodes of the bin and count how many values we remove
let mut p = tree_bin.first.load(Ordering::SeqCst, guard);
while !p.is_null() {
delta -= 1;
p = {
// safety: we read under our guard, at which point the tree
// structure was valid. Since our guard marks the current thread
// as active, the TreeNodes remain valid for at least as long as
// we hold onto the guard.
// Structurally, TreeNodes always point to TreeNodes, so this is sound.
let tree_node = unsafe { TreeNode::get_tree_node(p) };
// NOTE: we do not drop the TreeNodes or their
// values here, since they will be dropped together
// with the containing TreeBin (`tree_bin`) in its
// `drop`
tree_node.node.next.load(Ordering::SeqCst, guard)
};
}
// safety: same as in the BinEntry::Node case above
unsafe { guard.retire_shared(raw_node) };
idx += 1;
}
BinEntry::TreeNode(_) => unreachable!(
"The head of a bin cannot be a TreeNode directly without BinEntry::Tree"
),
};
}
if delta != 0 {
self.add_count(delta, None, guard);
}
}
}
// ===
// the following methods _do_ introduce items into the map, and so must require that the keys and
// values are thread safe, and can be garbage collected at a later time.
// ===
impl<K, V, S> HashMap<K, V, S>
where
K: Sync + Send + Clone + Hash + Ord,
V: Sync + Send,
S: BuildHasher,
{
/// Inserts a key-value pair into the map.
///
/// If the map did not have this key present, [`None`] is returned.
///
/// If the map did have this key present, the value is updated, and the old
/// value is returned. The key is left unchanged. See the [std-collections
/// documentation] for more.
///
/// [`None`]: std::option::Option::None
/// [std-collections documentation]: https://doc.rust-lang.org/std/collections/index.html#insert-and-complex-keys
///
/// # Examples
///
/// ```
/// use flurry::HashMap;
///
/// let map = HashMap::new();
/// assert_eq!(map.pin().insert(37, "a"), None);
/// assert_eq!(map.pin().is_empty(), false);
///
/// // you can also re-use a map pin like so:
/// let mref = map.pin();
///
/// mref.insert(37, "b");
/// assert_eq!(mref.insert(37, "c"), Some(&"b"));
/// assert_eq!(mref.get(&37), Some(&"c"));
/// ```
pub fn insert<'g>(&'g self, key: K, value: V, guard: &'g Guard<'_>) -> Option<&'g V> {
self.check_guard(guard);
self.put(key, value, false, guard).before()
}
/// Inserts a key-value pair into the map unless the key already exists.
///
/// If the map does not contain the key, the key-value pair is inserted
/// and this method returns `Ok`.
///
/// If the map does contain the key, the map is left unchanged and this
/// method returns `Err`.
///
/// [std-collections documentation]: https://doc.rust-lang.org/std/collections/index.html#insert-and-complex-keys
///
/// # Examples
///
/// ```
/// use flurry::{HashMap, TryInsertError};
///
/// let map = HashMap::new();
/// let mref = map.pin();
///
/// mref.insert(37, "a");
/// assert_eq!(
/// mref.try_insert(37, "b"),
/// Err(TryInsertError { current: &"a", not_inserted: &"b"})
/// );
/// assert_eq!(mref.try_insert(42, "c"), Ok(&"c"));
/// assert_eq!(mref.get(&37), Some(&"a"));
/// assert_eq!(mref.get(&42), Some(&"c"));
/// ```
#[inline]
pub fn try_insert<'g>(
&'g self,
key: K,
value: V,
guard: &'g Guard<'_>,
) -> Result<&'g V, TryInsertError<'g, V>> {
match self.put(key, value, true, guard) {
PutResult::Exists {
current,
not_inserted,
} => Err(TryInsertError {
current,
not_inserted: not_inserted.value,
}),
PutResult::Inserted { new } => Ok(new),
PutResult::Replaced { .. } => {
unreachable!("no_replacement cannot result in PutResult::Replaced")
}
}
}
fn put<'g>(
&'g self,
mut key: K,
value: V,
no_replacement: bool,
guard: &'g Guard<'_>,
) -> PutResult<'g, V> {
let hash = self.hash(&key);
let mut table = self.table.load(Ordering::SeqCst, guard);
let mut bin_count;
let value = Shared::boxed(value, &self.collector);
let mut old_val = None;
loop {
// safety: see argument below for !is_null case
if table.is_null() || unsafe { table.deref() }.is_empty() {
table = self.init_table(guard);
continue;
}
// safety: table is a valid pointer.
//
// we are in one of three cases:
//
// 1. if table is the one we read before the loop, then we read it while holding the
// guard, so it won't be dropped until after we drop that guard b/c this thread must
// have been included in the reference count of a retirement.
//
// 2. if table is read by init_table, we did so while holding a guard, so the
// argument is as for point 1. or, we allocated the table while holding a guard,
// so the earliest it can be deallocated is after we drop our guard.
//
// 3. if table is set by a Moved node (below) through help_transfer, it will _either_
// keep using `table` (which is fine by 1. and 2.), or use the `next_table` raw
// pointer from inside the Moved. to see that if a Moved(t) is _read_, then t must
// still be valid, see the safety comment on Table.next_table.
let t = unsafe { table.deref() };
let bini = t.bini(hash);
let mut bin = t.bin(bini, guard);
if bin.is_null() {
// fast path -- bin is empty so stick us at the front
let node =
Shared::boxed(BinEntry::Node(Node::new(hash, key, value)), &self.collector);
match t.cas_bin(bini, bin, node, guard) {
Ok(_old_null_ptr) => {
self.add_count(1, Some(0), guard);
// safety: we have not moved the node's value since we placed it into
// its `Atomic` in the very beginning of the method, so the ref is still
// valid. since the value is not currently marked as garbage, and since
// `value` was loaded under a guard, the returned reference will remain valid
// for the guard's lifetime.
return PutResult::Inserted {
new: unsafe { value.deref() },
};
}
Err(changed) => {
assert!(!changed.current.is_null());
bin = changed.current;
let BinEntry::Node(node) = unsafe { changed.new.into_box() }.value else {
unreachable!("we declared node and it is a BinEntry::Node");
};
key = node.key;
}
}
}
// slow path -- bin is non-empty
//
// safety: bin is a valid pointer.
//
// there are three cases when a bin pointer is invalidated:
//
// 1. if the table was resized, bin is a move entry, and the resize has completed. in
// that case, the table (and all its heads) have already been retired.
// 2. if the table is being resized, bin may be swapped with a move entry. the old bin
// will only be retired after that happens.
// 3. when elements are inserted into or removed from the map, bin may be changed into
// or from a TreeBin from or into a regular, linear bin. the old bin will be
// retired only once that happens.
//
// in all cases, we held the guard when we got the reference to the bin. if any such
// swap happened, it must have happened _after_ we read. since we did the read while
// the current thread was marked as active, we must be included in the reference count,
// and the drop must happen _after_ we decrement the count (i.e drop our guard).
match **unsafe { bin.deref() } {
BinEntry::Moved => {
table = self.help_transfer(table, guard);
continue;
}
BinEntry::Node(ref head)
if no_replacement && head.hash == hash && head.key == key =>
{
// fast path if replacement is disallowed and first bin matches
let v = head.value.load(Ordering::SeqCst, guard);
// safety (for v): since the value is present now, and we've held a guard from
// the beginning of the search, the value cannot be dropped after we drop our guard.
// safety (for value): since we never inserted the value in the tree, `value`
// is the last remaining pointer to the initial value.
return PutResult::Exists {
current: unsafe { v.deref() },
not_inserted: unsafe { value.into_box() },
};
}
BinEntry::Node(ref head) => {
// bin is non-empty, need to link into it, so we must take the lock
let head_lock = head.lock.lock();
// need to check that this is _still_ the head
let current_head = t.bin(bini, guard);
if current_head != bin {
// nope -- try again from the start
continue;
}
// yes, it is still the head, so we can now "own" the bin
// note that there can still be readers in the bin!
// TODO: ReservationNode
bin_count = 1;
let mut p = bin;
old_val = loop {
// safety: we loaded the bin while holding a guard, so any retirements
// must have seen us as active. the bin and its nodes cannot be dropped
// until at least after we drop our guard.
let n = unsafe { p.deref() }.as_node().unwrap();
if n.hash == hash && n.key == key {
// the key already exists in the map!
let current_value = n.value.load(Ordering::SeqCst, guard);
// safety: since the value is present now, and we've held a guard from
// the beginning of the search, the value cannot be dropped until after
// we drop our guard.
let current_value = unsafe { current_value.deref() };
if no_replacement {
// the key is not absent, so don't update because of
// `no_replacement`, we don't use the new value, so we need to clean
// it up and return it back to the caller
// safety: we own value and did not share it
return PutResult::Exists {
current: current_value,
not_inserted: unsafe { value.into_box() },
};
} else {
// update the value in the existing node
let now_garbage = n.value.swap(value, Ordering::SeqCst, guard);
// NOTE: now_garbage == current_value
// safety: need to guarantee that now_garbage is no longer
// reachable. more specifically, no thread that executes _after_
// this line can ever get a reference to now_garbage.
//
// here are the possible cases:
//
// - another thread already has a reference to now_garbage.
// they must have read it before the call to swap while
// marked as active (holding a guard), and are included in
// the reference count. therefore t won't be freed until _after_
// it decrements the reference count, which can only happen
// when that thread drops its guard, and with it, any reference
// to the value.
// - another thread is about to get a reference to this value.
// they execute _after_ the swap, and therefore do _not_ get a
// reference to now_garbage (they get `value` instead). there are
// no other ways to get to a value except through its Node's
// `value` field (which is what we swapped), so freeing
// now_garbage is fine.
unsafe { guard.retire_shared(now_garbage) };
}
break Some(current_value);
}
// TODO: This Ordering can probably be relaxed due to the Mutex
let next = n.next.load(Ordering::SeqCst, guard);
if next.is_null() {
// we're at the end of the bin -- stick the node here!
let node = Shared::boxed(
BinEntry::Node(Node::new(hash, key, value)),
&self.collector,
);
n.next.store(node, Ordering::SeqCst);
break None;
}
p = next;
bin_count += 1;
};
drop(head_lock);
}
// NOTE: BinEntry::Tree(ref tree_bin) if no_replacement && head.hash == h && &head.key == key
// cannot occur as in the Java code, TreeBins have a special, indicator hash value
BinEntry::Tree(ref tree_bin) => {
// bin is non-empty, need to link into it, so we must take the lock
let head_lock = tree_bin.lock.lock();
// need to check that this is _still_ the correct bin
let current_head = t.bin(bini, guard);
if current_head != bin {
// nope -- try again from the start
continue;
}
// yes, it is still the head, so we can now "own" the bin
// note that there can still be readers in the bin!
// we don't actually count bins, just set this low enough
// that we don't try to treeify the bin later
bin_count = 2;
let p = tree_bin.find_or_put_tree_val(hash, key, value, guard, &self.collector);
if p.is_null() {
// no TreeNode was returned, so the key did not previously exist in the
// TreeBin. This means it was successfully put there by the call above
// and we are done.
break;
}
// safety: the TreeBin was read under our guard, at which point the tree
// structure was valid. Since our guard marks the current thread as active,
// the TreeNodes remain valid for at least as long as we hold onto the
// guard.
// Structurally, TreeNodes always point to TreeNodes, so this is sound.
let tree_node = unsafe { TreeNode::get_tree_node(p) };
old_val = {
let current_value = tree_node.node.value.load(Ordering::SeqCst, guard);
// safety: since the value is present now, and we've held a guard from
// the beginning of the search, the value cannot be dropped until after
// we drop our guard.
let current_value = unsafe { current_value.deref() };
if no_replacement {
// the key is not absent, so don't update because of
// `no_replacement`, we don't use the new value, so we need to clean
// it up and return it back to the caller
// safety: we own value and did not share it
return PutResult::Exists {
current: current_value,
not_inserted: unsafe { value.into_box() },
};
} else {
let now_garbage =
tree_node.node.value.swap(value, Ordering::SeqCst, guard);
// NOTE: now_garbage == current_value
// safety: need to guarantee that now_garbage is no longer
// reachable. more specifically, no thread that executes _after_
// this line can ever get a reference to now_garbage.
//
// here are the possible cases:
//
// - another thread already has a reference to now_garbage.
// they must have read it before the call to swap while
// marked as active (holding a guard), and are included in
// the reference count. therefore t won't be freed until _after_
// it decrements the reference count, which can only happen
// when that thread drops its guard, and with it, any reference
// to the value.
// - another thread is about to get a reference to this value.
// they execute _after_ the swap, and therefore do _not_ get a
// reference to now_garbage (they get `value` instead). there are
// no other ways to get to a value except through its Node's
// `value` field (which is what we swapped), so freeing
// now_garbage is fine.
unsafe { guard.retire_shared(now_garbage) };
}
Some(current_value)
};
drop(head_lock);
}
BinEntry::TreeNode(_) => unreachable!(
"The head of a bin cannot be a TreeNode directly without BinEntry::Tree"
),
}
// NOTE: the Java code checks `bin_count` here because they also
// reach this point if the bin changed while obtaining the lock.
// However, our code doesn't (it uses continue) and `bin_count`
// _cannot_ be 0 at this point.
debug_assert_ne!(bin_count, 0);
if bin_count >= TREEIFY_THRESHOLD {
self.treeify_bin(t, bini, guard);
}
if let Some(old_val) = old_val {
return PutResult::Replaced {
old: old_val,
// safety: we have not moved the node's value since we placed it into
// its `Atomic` in the very beginning of the method, so the ref is still
// valid. since the value is not currently marked as garbage, and since
// `value` was loaded under a guard, the returned reference will remain valid
// for the guard's lifetime.
new: unsafe { value.deref() },
};
}
break;
}
// increment count, since we only get here if we did not return an old (updated) value
debug_assert!(old_val.is_none());
self.add_count(1, Some(bin_count), guard);
PutResult::Inserted {
// safety: we have not moved the node's value since we placed it into
// its `Atomic` in the very beginning of the method, so the ref is still
// valid. since the value is not currently marked as garbage, and since
// `value` was loaded under a guard, the returned reference will remain valid
// for the guard's lifetime.
new: unsafe { value.deref() },
}
}
fn put_all<I: Iterator<Item = (K, V)>>(&self, iter: I, guard: &Guard<'_>) {
for (key, value) in iter {
self.put(key, value, false, guard);
}
}
/// If the value for the specified `key` is present, attempts to
/// compute a new mapping given the key and its current mapped value.
///
/// The new mapping is computed by the `remapping_function`, which may
/// return `None` to signalize that the mapping should be removed.
/// The entire method invocation is performed atomically.
/// The supplied function is invoked exactly once per invocation of
/// this method if the key is present, else not at all. Some
/// attempted update operations on this map by other threads may be
/// blocked while computation is in progress, so the computation
/// should be short and simple.
///
/// Returns the new value associated with the specified `key`, or `None`
/// if no value for the specified `key` is present.
///
/// The key may be any borrowed form of the map's key type, but
/// [`Hash`] and [`Ord`] on the borrowed form *must* match those for
/// the key type.
///
/// [`Ord`]: std::cmp::Ord
/// [`Hash`]: std::hash::Hash
pub fn compute_if_present<'g, Q, F>(
&'g self,
key: &Q,
remapping_function: F,
guard: &'g Guard<'_>,
) -> Option<&'g V>
where
K: Borrow<Q>,
Q: ?Sized + Hash + Ord,
F: FnOnce(&K, &V) -> Option<V>,
{
self.check_guard(guard);
let hash = self.hash(&key);
let mut table = self.table.load(Ordering::SeqCst, guard);
let mut new_val = None;
let mut removed_node = false;
let mut bin_count;
loop {
// safety: see argument below for !is_null case
if table.is_null() || unsafe { table.deref() }.is_empty() {
table = self.init_table(guard);
continue;
}
// safety: table is a valid pointer.
//
// we are in one of three cases:
//
// 1. if table is the one we read before the loop, then we read it while holding the
// guard, so it won't be dropped until after we drop that guard b/c this thread must
// have been included in the reference count of a retirement.
//
// 2. if table is read by init_table, we did so while holding a guard, so the
// argument is as for point 1. or, we allocated the table while holding a guard,
// so the earliest it can be deallocated is after we drop our guard.
//
// 3. if table is set by a Moved node (below) through help_transfer, it will _either_
// keep using `table` (which is fine by 1. and 2.), or use the `next_table` raw
// pointer from inside the Moved. to see that if a Moved(t) is _read_, then t must
// still be valid, see the safety comment on Table.next_table.
let t = unsafe { table.deref() };
let bini = t.bini(hash);
let bin = t.bin(bini, guard);
if bin.is_null() {
// fast path -- bin is empty so key is not present
return None;
}
// slow path -- bin is non-empty
//
// safety: bin is a valid pointer.
//
// there are three cases when a bin pointer is invalidated:
//
// 1. if the table was resized, bin is a move entry, and the resize has completed. in
// that case, the table (and all its heads) have already been retired.
// 2. if the table is being resized, bin may be swapped with a move entry. the old bin
// will only be retired after that happens.
// 3. when elements are inserted into or removed from the map, bin may be changed into
// or from a TreeBin from or into a regular, linear bin. the old bin will be
// retired only once that happens.
//
// in all cases, we held the guard when we got the reference to the bin. if any such
// swap happened, it must have happened _after_ we read. since we did the read while
// the current thread was marked as active, we must be included in the reference count,
// and the drop must happen _after_ we decrement the count (i.e drop our guard).
match **unsafe { bin.deref() } {
BinEntry::Moved => {
table = self.help_transfer(table, guard);
continue;
}
BinEntry::Node(ref head) => {
// bin is non-empty, need to link into it, so we must take the lock
let head_lock = head.lock.lock();
// need to check that this is _still_ the head
let current_head = t.bin(bini, guard);
if current_head != bin {
// nope -- try again from the start
continue;
}
// yes, it is still the head, so we can now "own" the bin
// note that there can still be readers in the bin!
// TODO: ReservationNode
bin_count = 1;
let mut p = bin;
let mut pred: Shared<'_, BinEntry<K, V>> = Shared::null();
new_val = loop {
// safety: we loaded the bin while holding a guard, so any retirements
// must have seen us as active. the bin and its nodes cannot be dropped
// until at least after we drop our guard.
let n = unsafe { p.deref() }.as_node().unwrap();
// TODO: This Ordering can probably be relaxed due to the Mutex
let next = n.next.load(Ordering::SeqCst, guard);
if n.hash == hash && n.key.borrow() == key {
// the key already exists in the map!
let current_value = n.value.load(Ordering::SeqCst, guard);
// safety: since the value is present now, and we've held a guard from
// the beginning of the search, the value cannot be dropped until after
// we drop our guard.
let new_value =
remapping_function(&n.key, unsafe { current_value.deref() });
if let Some(value) = new_value {
let value = Shared::boxed(value, &self.collector);
let now_garbage = n.value.swap(value, Ordering::SeqCst, guard);
// NOTE: now_garbage == current_value
// safety: need to guarantee that now_garbage is no longer
// reachable. more specifically, no thread that executes _after_
// this line can ever get a reference to now_garbage.
//
// here are the possible cases:
//
// - another thread already has a reference to now_garbage.
// they must have read it before the call to swap while
// marked as active (holding a guard), and are included in
// the reference count. therefore t won't be freed until _after_
// it decrements the reference count, which can only happen
// when that thread drops its guard, and with it, any reference
// to the value.
// - another thread is about to get a reference to this value.
// they execute _after_ the swap, and therefore do _not_ get a
// reference to now_garbage (they get `value` instead). there are
// no other ways to get to a value except through its Node's
// `value` field (which is what we swapped), so freeing
// now_garbage is fine.
unsafe { guard.retire_shared(now_garbage) };
// safety: since the value is present now, and we've held a guard from
// the beginning of the search, the value cannot be dropped until after
// we drop our guard.
break Some(unsafe { value.deref() });
} else {
removed_node = true;
// remove the BinEntry containing the removed key value pair from the bucket
if !pred.is_null() {
// either by changing the pointer of the previous BinEntry, if present
// safety: see remove
unsafe { pred.deref() }
.as_node()
.unwrap()
.next
.store(next, Ordering::SeqCst);
} else {
// or by setting the next node as the first BinEntry if there is no previous entry
t.store_bin(bini, next);
}
// in either case, mark the BinEntry as garbage, since it was just removed
// safety: need to guarantee that the old value is no longer
// reachable. more specifically, no thread that executes _after_
// this line can ever get a reference to val.
//
// here are the possible cases:
//
// - another thread already has a reference to now_garbage.
// they must have read it before the call to swap while
// marked as active (holding a guard), and are included in
// the reference count. therefore t won't be freed until _after_
// it decrements the reference count, which can only happen
// when that thread drops its guard, and with it, any reference
// to the value.
// - another thread is about to get a reference to this value.
// they execute _after_ the swap, and therefore do _not_ get a
// reference to now_garbage (they get `value` instead). there are
// no other ways to get to a value except through its Node's
// `value` field (which is what we swapped), so freeing
// now_garbage is fine.
unsafe { guard.retire_shared(p) };
unsafe { guard.retire_shared(current_value) };
break None;
}
}
pred = p;
if next.is_null() {
// we're at the end of the bin
break None;
}
p = next;
bin_count += 1;
};
drop(head_lock);
}
BinEntry::Tree(ref tree_bin) => {
// bin is non-empty, need to link into it, so we must take the lock
let bin_lock = tree_bin.lock.lock();
// need to check that this is _still_ the head
let current_head = t.bin(bini, guard);
if current_head != bin {
// nope -- try again from the start
continue;
}
// yes, it is still the head, so we can now "own" the bin
// note that there can still be readers in the bin!
bin_count = 2;
let root = tree_bin.root.load(Ordering::SeqCst, guard);
if root.is_null() {
// TODO: Is this even reachable?
// The Java code has `NULL` checks for this, but in theory it should not be possible to
// encounter a tree that has no root when we have its lock. It should always have at
// least `UNTREEIFY_THRESHOLD` nodes. If it is indeed impossible we should replace
// this with an assertion instead.
break;
}
new_val = {
let p = TreeNode::find_tree_node(root, hash, key, guard);
if p.is_null() {
// the given key is not present in the map
None
} else {
// a node for the given key exists, so we try to update it
// safety: the TreeBin was read under our guard, at which point the tree
// structure was valid. Since our guard marks the current thread as active,
// the TreeNodes remain valid for at least as long as we hold onto the
// guard.
// Structurally, TreeNodes always point to TreeNodes, so this is sound.
let n = &unsafe { TreeNode::get_tree_node(p) }.node;
let current_value = n.value.load(Ordering::SeqCst, guard);
// safety: since the value is present now, and we've held a guard from
// the beginning of the search, the value cannot be dropped until after
// we drop our guard.
let new_value =
remapping_function(&n.key, unsafe { current_value.deref() });
if let Some(value) = new_value {
let value = Shared::boxed(value, &self.collector);
let now_garbage = n.value.swap(value, Ordering::SeqCst, guard);
// NOTE: now_garbage == current_value
// safety: need to guarantee that now_garbage is no longer
// reachable. more specifically, no thread that executes _after_
// this line can ever get a reference to now_garbage.
//
// here are the possible cases:
//
// - another thread already has a reference to now_garbage.
// they must have read it before the call to swap while
// marked as active (holding a guard), and are included in
// the reference count. therefore t won't be freed until _after_
// it decrements the reference count, which can only happen
// when that thread drops its guard, and with it, any reference
// to the value.
// - another thread is about to get a reference to this value.
// they execute _after_ the swap, and therefore do _not_ get a
// reference to now_garbage (they get `value` instead). there are
// no other ways to get to a value except through its Node's
// `value` field (which is what we swapped), so freeing
// now_garbage is fine.
unsafe { guard.retire_shared(now_garbage) };
// safety: since the value is present now, and we've held a guard from
// the beginning of the search, the value cannot be dropped until after
// we drop our guard.
Some(unsafe { value.deref() })
} else {
removed_node = true;
// remove the BinEntry::TreeNode containing the removed key value pair from the bucket
// also drop the old value stored in the tree node, as it was removed from the map
// safety: `p` and its value are either marked for garbage collection in `remove_tree_node`
// directly, or we will `need_to_untreeify`. In the latter case, we `defer_destroy`
// both `p` and its value below, after storing the linear bin. Thus, everything is
// always marked for garbage collection _after_ it becomes unaccessible by other threads.
let need_to_untreeify = unsafe {
tree_bin.remove_tree_node(p, true, guard, &self.collector)
};
if need_to_untreeify {
let linear_bin = self.untreeify(
tree_bin.first.load(Ordering::SeqCst, guard),
guard,
);
t.store_bin(bini, linear_bin);
// the old bin is now garbage, but its values are not,
// since they are re-used in the linear bin.
// safety: in the same way as for `now_garbage` above, any existing
// references to `bin` must have been obtained before storing the
// linear bin. These references were obtained while holding a
// guard, and are protected until they drop it and decrement
// the reference count. After the store, threads will
// always see the linear bin, so the cannot obtain new references either.
//
// The same holds for `p` and its value, which does not get dropped together
// with `bin` here since `remove_tree_node` indicated that the bin needs to
// be untreeified.
unsafe {
TreeBin::defer_drop_without_values(bin, guard);
guard.retire_shared(p);
guard.retire_shared(current_value);
}
}
None
}
}
};
drop(bin_lock);
}
BinEntry::TreeNode(_) => unreachable!(
"The head of a bin cannot be a TreeNode directly without BinEntry::Tree"
),
}
// NOTE: the Java code checks `bin_count` here because they also
// reach this point if the bin changed while obtaining the lock.
// However, our code doesn't (it uses continue) and making this
// break conditional confuses the compiler about how many times we
// use the `remapping_function`.
debug_assert_ne!(bin_count, 0);
break;
}
if removed_node {
// decrement count
self.add_count(-1, Some(bin_count), guard);
}
new_val.map(|linked| &**linked)
}
/// Removes a key-value pair from the map, and returns the removed value (if any).
///
/// The key may be any borrowed form of the map's key type, but
/// [`Hash`] and [`Ord`] on the borrowed form *must* match those for
/// the key type.
///
/// [`Ord`]: std::cmp::Ord
/// [`Hash`]: std::hash::Hash
///
/// # Examples
///
/// ```
/// use flurry::HashMap;
///
/// let map = HashMap::new();
/// map.pin().insert(1, "a");
/// assert_eq!(map.pin().remove(&1), Some(&"a"));
/// assert_eq!(map.pin().remove(&1), None);
/// ```
pub fn remove<'g, Q>(&'g self, key: &Q, guard: &'g Guard<'_>) -> Option<&'g V>
where
K: Borrow<Q>,
Q: ?Sized + Hash + Ord,
{
// NOTE: _technically_, this method shouldn't require the thread-safety bounds, but a) that
// would require special-casing replace_node for when new_value.is_none(), and b) it's sort
// of useless to call remove on a collection that you know you can never insert into.
self.check_guard(guard);
self.replace_node(key, None, None, guard).map(|(_, v)| v)
}
/// Removes a key from the map, returning the stored key and value if the
/// key was previously in the map.
///
/// The key may be any borrowed form of the map's key type, but
/// [`Hash`] and [`Ord`] on the borrowed form *must* match those for
/// the key type.
///
/// [`Ord`]: std::cmp::Ord
/// [`Hash`]: std::hash::Hash
///
/// # Examples
///
/// ```
/// use flurry::HashMap;
///
/// let map = HashMap::new();
/// let guard = map.guard();
/// map.insert(1, "a", &guard);
/// assert_eq!(map.remove_entry(&1, &guard), Some((&1, &"a")));
/// assert_eq!(map.remove(&1, &guard), None);
/// ```
pub fn remove_entry<'g, Q>(&'g self, key: &Q, guard: &'g Guard<'_>) -> Option<(&'g K, &'g V)>
where
K: Borrow<Q>,
Q: ?Sized + Hash + Ord,
{
self.check_guard(guard);
self.replace_node(key, None, None, guard)
}
/// Replaces node value with `new_value`.
///
/// If an `observed_value` is provided, the replacement only happens if `observed_value` equals
/// the value that is currently associated with the given key.
///
/// If `new_value` is `None`, it removes the key (and its corresponding value) from this map.
///
/// This method does nothing if the key is not in the map.
///
/// Returns the previous key and value associated with the given key.
///
/// The key may be any borrowed form of the map's key type, but
/// [`Hash`] and [`Ord`] on the borrowed form *must* match those for
/// the key type.
///
/// [`Ord`]: std::cmp::Ord
/// [`Hash`]: std::hash::Hash
fn replace_node<'g, Q>(
&'g self,
key: &Q,
new_value: Option<V>,
observed_value: Option<Shared<'g, V>>,
guard: &'g Guard<'_>,
) -> Option<(&'g K, &'g V)>
where
K: Borrow<Q>,
Q: ?Sized + Hash + Ord,
{
let hash = self.hash(key);
let is_remove = new_value.is_none();
let mut old_val = None;
let mut table = self.table.load(Ordering::SeqCst, guard);
loop {
if table.is_null() {
break;
}
// safety: table is a valid pointer.
//
// we are in one of two cases:
//
// 1. if table is the one we read before the loop, then we read it while holding the
// guard, so it won't be dropped until after we drop that guard b/c this thread must
// have been included in the reference count of a retirement.
//
// 2. if table is set by a Moved node (below) through help_transfer, it will _either_
// keep using `table` (which is fine by 1. and 2.), or use the `next_table` raw
// pointer from inside the Moved. to see that if a Moved(t) is _read_, then t must
// still be valid, see the safety comment on Table.next_table.
let t = unsafe { table.deref() };
let n = t.len() as u64;
if n == 0 {
break;
}
let bini = t.bini(hash);
let bin = t.bin(bini, guard);
if bin.is_null() {
break;
}
// safety: bin is a valid pointer.
//
// there are three cases when a bin pointer is invalidated:
//
// 1. if the table was resized, bin is a move entry, and the resize has completed. in
// that case, the table (and all its heads) have already been retired.
// 2. if the table is being resized, bin may be swapped with a move entry. the old bin
// will only be retired after that happens.
// 3. when elements are inserted into or removed from the map, bin may be changed into
// or from a TreeBin from or into a regular, linear bin. the old bin will be
// retired only once that happens.
//
// in all cases, we held the guard when we got the reference to the bin. if any such
// swap happened, it must have happened _after_ we read. since we did the read while
// the current thread was marked as active, we must be included in the reference count,
// and the drop must happen _after_ we decrement the count (i.e drop our guard).
match **unsafe { bin.deref() } {
BinEntry::Moved => {
table = self.help_transfer(table, guard);
continue;
}
BinEntry::Node(ref head) => {
let head_lock = head.lock.lock();
// need to check that this is _still_ the head
if t.bin(bini, guard) != bin {
continue;
}
let mut e = bin;
let mut pred: Shared<'_, BinEntry<K, V>> = Shared::null();
loop {
// safety: either `e` is `bin`, in which case it is valid due to the above,
// or e was obtained from a next pointer. Any next pointer obtained from
// bin is valid at the time we look up bin in the table, at which point
// we held a guard. Since we found the next pointer in a valid map and
// it is not null (as checked above and below), the node it points to was
// present (i.e. not removed) from the map while we were marked as active.
// Thus, e cannot be dropped until we release our guard, so e is also valid
// if it was obtained from a next pointer.
let n = unsafe { e.deref() }.as_node().unwrap();
let next = n.next.load(Ordering::SeqCst, guard);
if n.hash == hash && n.key.borrow() == key {
let ev = n.value.load(Ordering::SeqCst, guard);
// only replace the node if the value is the one we expected at method call
if observed_value.map(|ov| ov == ev).unwrap_or(true) {
// we remember the old value so that we can return it and mark it for deletion below
old_val = Some((&n.key, ev));
// found the node but we have a new value to replace the old one
if let Some(nv) = new_value {
n.value.store(
Shared::boxed(nv, &self.collector),
Ordering::SeqCst,
);
// we are just replacing entry value and we do not want to remove the node
// so we stop iterating here
break;
}
// remove the BinEntry containing the removed key value pair from the bucket
if !pred.is_null() {
// either by changing the pointer of the previous BinEntry, if present
// safety: as above
unsafe { pred.deref() }
.as_node()
.unwrap()
.next
.store(next, Ordering::SeqCst);
} else {
// or by setting the next node as the first BinEntry if there is no previous entry
t.store_bin(bini, next);
}
// in either case, mark the BinEntry as garbage, since it was just removed
// safety: as for val below / in put
unsafe { guard.retire_shared(e) };
}
// since the key was found and only one node exists per key, we can break here
break;
}
pred = e;
if next.is_null() {
break;
} else {
e = next;
}
}
drop(head_lock);
}
BinEntry::Tree(ref tree_bin) => {
let bin_lock = tree_bin.lock.lock();
// need to check that this is _still_ the head
if t.bin(bini, guard) != bin {
continue;
}
let root = tree_bin.root.load(Ordering::SeqCst, guard);
if root.is_null() {
// we are in the correct bin for the given key's hash and the bin is not
// `Moved`, but it is empty. This means there is no node for the given
// key that could be replaced
// TODO: Is this even reachable?
// The Java code has `NULL` checks for this, but in theory it should not be possible to
// encounter a tree that has no root when we have its lock. It should always have at
// least `UNTREEIFY_THRESHOLD` nodes. If it is indeed impossible we should replace
// this with an assertion instead.
break;
}
let p = TreeNode::find_tree_node(root, hash, key, guard);
if p.is_null() {
// similarly to the above, there now are entries in this bin, but none of
// them matches the given key
break;
}
// safety: the TreeBin was read our guard, at which point the tree
// structure was valid. Since our guard marks the current thread as active,
// the TreeNodes remain valid for at least as long as we hold onto the
// guard.
// Structurally, TreeNodes always point to TreeNodes, so this is sound.
let n = &unsafe { TreeNode::get_tree_node(p) }.node;
let pv = n.value.load(Ordering::SeqCst, guard);
// only replace the node if the value is the one we expected at method call
if observed_value.map(|ov| ov == pv).unwrap_or(true) {
// we remember the old value so that we can return it and mark it for deletion below
old_val = Some((&n.key, pv));
if let Some(nv) = new_value {
// found the node but we have a new value to replace the old one
n.value
.store(Shared::boxed(nv, &self.collector), Ordering::SeqCst);
} else {
// drop `p` without its value, since the old value is dropped
// in the check on `old_val` below
// safety: `p` is either marked for garbage collection in `remove_tree_node` directly,
// or we will `need_to_untreeify`. In the latter case, we `defer_destroy` `p` below,
// after storing the linear bin. The value stored in `p` is `defer_destroy`ed from within
// `old_val` at the end of the method. Thus, everything is always marked for garbage
// collection _after_ it becomes unaccessible by other threads.
let need_to_untreeify = unsafe {
tree_bin.remove_tree_node(p, false, guard, &self.collector)
};
if need_to_untreeify {
let linear_bin = self
.untreeify(tree_bin.first.load(Ordering::SeqCst, guard), guard);
t.store_bin(bini, linear_bin);
// the old bin is now garbage, but its values are not,
// since they get re-used in the linear bin
// safety: same as in put
unsafe {
TreeBin::defer_drop_without_values(bin, guard);
guard.retire_shared(p);
}
}
}
}
drop(bin_lock);
}
BinEntry::TreeNode(_) => unreachable!(
"The head of a bin cannot be a TreeNode directly without BinEntry::Tree"
),
}
if let Some((key, val)) = old_val {
if is_remove {
self.add_count(-1, None, guard);
}
// safety: need to guarantee that the old value is no longer
// reachable. more specifically, no thread that executes _after_
// this line can ever get a reference to val.
//
// here are the possible cases:
//
// - another thread already has a reference to now_garbage.
// they must have read it before the call to swap while
// marked as active (holding a guard), and are included in
// the reference count. therefore t won't be freed until _after_
// it decrements the reference count, which can only happen
// when that thread drops its guard, and with it, any reference
// to the value.
// - another thread is about to get a reference to this value.
// they execute _after_ the swap, and therefore do _not_ get a
// reference to now_garbage (they get `value` instead). there are
// no other ways to get to a value except through its Node's
// `value` field (which is what we swapped), so freeing
// now_garbage is fine.
unsafe { guard.retire_shared(val) };
// safety: the lifetime of the reference is bound to the guard
// supplied which means that the memory will not be freed
// until at least after the guard goes out of scope
return unsafe { val.as_ref() }.map(move |v| (key, &**v));
}
break;
}
None
}
/// Retains only the elements specified by the predicate.
///
/// In other words, remove all pairs `(k, v)` such that `f(&k,&v)` returns `false`.
///
/// # Examples
///
/// ```
/// use flurry::HashMap;
///
/// let map = HashMap::new();
///
/// for i in 0..8 {
/// map.pin().insert(i, i*10);
/// }
/// map.pin().retain(|&k, _| k % 2 == 0);
/// assert_eq!(map.pin().len(), 4);
/// ```
///
/// # Notes
///
/// If `f` returns `false` for a given key/value pair, but the value for that pair is concurrently
/// modified before the removal takes place, the entry will not be removed.
/// If you want the removal to happen even in the case of concurrent modification, use [`HashMap::retain_force`].
pub fn retain<F>(&self, mut f: F, guard: &Guard<'_>)
where
F: FnMut(&K, &V) -> bool,
{
self.check_guard(guard);
let mut iter = self.iter(guard);
while let Some((k, v)) = iter.next_internal() {
// safety: flurry does not drop or move until after guard drop
let value = unsafe { v.deref() };
if !f(k, value) {
self.replace_node(k, None, Some(v), guard);
}
}
}
/// Retains only the elements specified by the predicate.
///
/// In other words, remove all pairs `(k, v)` such that `f(&k,&v)` returns `false`.
///
/// This method always deletes any key/value pair that `f` returns `false` for, even if the
/// value is updated concurrently. If you do not want that behavior, use [`HashMap::retain`].
///
/// # Examples
///
/// ```
/// use flurry::HashMap;
///
/// let map = HashMap::new();
///
/// for i in 0..8 {
/// map.pin().insert(i, i*10);
/// }
/// map.pin().retain_force(|&k, _| k % 2 == 0);
/// assert_eq!(map.pin().len(), 4);
/// ```
pub fn retain_force<F>(&self, mut f: F, guard: &Guard<'_>)
where
F: FnMut(&K, &V) -> bool,
{
self.check_guard(guard);
// removed selected keys
for (k, v) in self.iter(guard) {
if !f(k, v) {
self.replace_node(k, None, None, guard);
}
}
}
}
impl<K, V, S> HashMap<K, V, S>
where
K: Clone + Ord,
{
/// Replaces all linked nodes in the bin at the given index unless the table
/// is too small, in which case a resize is initiated instead.
fn treeify_bin<'g>(&'g self, tab: &Table<K, V>, index: usize, guard: &'g Guard<'_>) {
let n = tab.len();
if n < MIN_TREEIFY_CAPACITY {
self.try_presize(n << 1, guard);
} else {
let bin = tab.bin(index, guard);
if bin.is_null() {
return;
}
// safety: we loaded `bin` while holding a guard.
// if the bin was replaced since then, the old bin still
// won't be dropped until after we release our guard.
match **unsafe { bin.deref() } {
BinEntry::Node(ref node) => {
let lock = node.lock.lock();
// check if `bin` is still the head
if tab.bin(index, guard) != bin {
return;
}
let mut e = bin;
let mut head = Shared::null();
let mut tail = Shared::null();
while !e.is_null() {
// safety: either `e` is `bin`, in which case it is valid due to the above,
// or e was obtained from a next pointer. Any next pointer obtained from
// bin is valid at the time we look up bin in the table, at which point
// we held a guard. Since we found the next pointer in a valid map and
// it is not null (as checked above and below), the node it points to was
// present (i.e. not removed) from the map while we were marked as active.
// Thus, e cannot be dropped until we release our guard, so e is also valid
// if it was obtained from a next pointer.
let e_deref = unsafe { e.deref() }.as_node().unwrap();
// NOTE: cloning the value uses a load with Ordering::Relaxed, but
// write access is synchronized through the bin lock
let new_tree_node = TreeNode::new(
e_deref.hash,
e_deref.key.clone(),
e_deref.value.clone(),
Atomic::null(),
Atomic::null(),
);
new_tree_node.prev.store(tail, Ordering::Relaxed);
let new_tree_node =
Shared::boxed(BinEntry::TreeNode(new_tree_node), &self.collector);
if tail.is_null() {
// this was the first TreeNode, so it becomes the head
head = new_tree_node;
} else {
// safety: if `tail` is not `null`, we have just created
// it in the last iteration, thus the pointer is valid
unsafe { tail.deref() }
.as_tree_node()
.unwrap()
.node
.next
.store(new_tree_node, Ordering::Relaxed);
}
tail = new_tree_node;
e = e_deref.next.load(Ordering::SeqCst, guard);
}
// safety: we have just created `head` and its `next` nodes using `Shared::boxed`
// and have never shared them
let head_bin = unsafe { BinEntry::Tree(TreeBin::new(head, guard)) };
tab.store_bin(index, Shared::boxed(head_bin, &self.collector));
drop(lock);
// make sure the old bin entries get dropped
e = bin;
while !e.is_null() {
// safety: we just replaced the bin containing this BinEntry, making it
// unreachable for other threads since subsequent loads will see the new
// bin. Threads with existing references to `e` must have obtained them
// while holding guards. Thus, `e` will only be dropped after these threads
// release their guard, at which point they can no longer hold their reference
// to `e`. Any loads after this point will see the new bin.
// The BinEntry pointers are valid to deref for the same reason as above.
//
// NOTE: we do not drop the value, since it gets moved to the new TreeNode
unsafe {
guard.retire_shared(e);
e = e
.deref()
.as_node()
.unwrap()
.next
.load(Ordering::SeqCst, guard);
}
}
}
BinEntry::Moved | BinEntry::Tree(_) => {
// The bin we wanted to treeify has changed under us. This is possible because
// the call to `treeify_bin` does not happen inside the critical section of its
// callers (while they are holding the lock). To see why, consider the
// implications for the cases we match here:
//
// BinEntry::Moved:
// One thread inserts a new entry and passes the `TREEIFY_THRESHOLD`, but a
// different thread executes a move of that bin. If we _always_ forced
// treeification to happen after the insert while still holding the lock, the
// move would have to wait for the bin lock and would then move the treeified
// bin. It is very likely that the move will split the bin in question into two
// smaller bins, both below the threshold, and has to untreeify the bin again
// (since the bin we inserted to _just_ passed the threshold right before the
// move).
// If we instead try to treeify after the releasing the lock, and due to
// scheduling the move happens first, it is fine for us as the first thread to
// see the `Moved` when we re-check here and just not treeify the bin. If either
// of the two bins in the new table (after the bin is moved) is still large
// enough to be above the `TREEIFY_THRESHOLD`, it will still get treeified in
// the _new_ table with the next insert.
// BinEntry::Tree(_):
// In the same scenario of trying to treeify _outside_ of the critical section,
// if there is one insert passing the threshold there may then be another insert
// before the first insert actually gets to do the treeification (due to
// scheduling). This second insert might also get to treeifying the bin (it will
// try because it sees a regular bin and the number of elements in the bin is
// still above the threshold). When the first thread resumes and re-checks here,
// the bin is already treeified and so it is again fine to not treeify it here.
// Of course there is a tradeoff here where the second insert would already have
// happend into a tree bin if we forced the first thread to treeify while still
// holding the lock. However, the second thread would then also have to wait for
// the lock before executing its insert.
//
// With the above reasoning, we choose to minimize the time any thread holds the
// lock and allow other threads to possibly mutate the bin we want to treeify
// before we get to do just that. If we encounter such a situation, we don't
// need to perform any action on the bin anymore, since either it has already
// been treeified or it was moved to a new table.
}
BinEntry::TreeNode(_) => unreachable!("TreeNode cannot be the head of a bin"),
}
}
}
/// Returns a list of non-TreeNodes replacing those in the given list. Does
/// _not_ clean up old TreeNodes, as they may still be reachable.
fn untreeify<'g>(
&self,
bin: Shared<'g, BinEntry<K, V>>,
guard: &'g Guard<'_>,
) -> Shared<'g, BinEntry<K, V>> {
let mut head = Shared::null();
let mut tail: Shared<'_, BinEntry<K, V>> = Shared::null();
let mut q = bin;
while !q.is_null() {
// safety: we only untreeify sequences of TreeNodes which either
// - were just created (e.g. in transfer) and are thus valid, or
// - are read from a TreeBin loaded from the map. In this case,
// the bin gets loaded under our guard and at that point all
// of its nodes (its `first` and all `next` nodes) are valid.
// As `q` is not `null` (checked above), this means that `q`
// remains a valid pointer at least until our guard is dropped.
let q_deref = unsafe { q.deref() }.as_tree_node().unwrap();
// NOTE: cloning the value uses a load with Ordering::Relaxed, but
// write access is synchronized through the bin lock
let new_node = Shared::boxed(
BinEntry::Node(Node::new(
q_deref.node.hash,
q_deref.node.key.clone(),
q_deref.node.value.clone(),
)),
&self.collector,
);
if tail.is_null() {
head = new_node;
} else {
// safety: if `tail` is not `null`, we have just created it
// in the last iteration, thus the pointer is valid
unsafe { tail.deref() }
.as_node()
.unwrap()
.next
.store(new_node, Ordering::Relaxed);
}
tail = new_node;
q = q_deref.node.next.load(Ordering::Relaxed, guard);
}
head
}
}
impl<K, V, S> PartialEq for HashMap<K, V, S>
where
K: Ord + Hash,
V: PartialEq,
S: BuildHasher,
{
fn eq(&self, other: &Self) -> bool {
if self.len() != other.len() {
return false;
}
self.guarded_eq(other, &self.guard(), &other.guard())
}
}
impl<K, V, S> Eq for HashMap<K, V, S>
where
K: Ord + Hash,
V: Eq,
S: BuildHasher,
{
}
impl<K, V, S> fmt::Debug for HashMap<K, V, S>
where
K: Debug,
V: Debug,
{
fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
let guard = self.collector.enter();
f.debug_map().entries(self.iter(&guard)).finish()
}
}
impl<K, V, S> Drop for HashMap<K, V, S> {
fn drop(&mut self) {
// safety: we have &mut self _and_ all references we have returned are bound to the
// lifetime of their borrow of self, so there cannot be any outstanding references to
// anything in the map.
//
// NOTE: we _could_ relax the bounds in all the methods that return `&'g ...` to not also
// bound `&self` by `'g`, but if we did that, we would need to use a regular `Guard`
// here rather than an unprotected one.
let guard = unsafe { Guard::unprotected() };
assert!(self.next_table.load(Ordering::SeqCst, &guard).is_null());
let table = self.table.swap(Shared::null(), Ordering::SeqCst, &guard);
if table.is_null() {
// table was never allocated!
return;
}
// safety: same as above + we own the table
let mut table = unsafe { table.into_box() };
table.drop_bins();
}
}
impl<K, V, S> Extend<(K, V)> for &HashMap<K, V, S>
where
K: Sync + Send + Clone + Hash + Ord,
V: Sync + Send,
S: BuildHasher,
{
fn extend<T: IntoIterator<Item = (K, V)>>(&mut self, iter: T) {
// from `hashbrown::HashMap::extend`:
// Keys may be already present or show multiple times in the iterator.
// Reserve the entire hint lower bound if the map is empty.
// Otherwise reserve half the hint (rounded up), so the map
// will only resize twice in the worst case.
let iter = iter.into_iter();
let reserve = if self.is_empty() {
iter.size_hint().0
} else {
(iter.size_hint().0 + 1) / 2
};
let guard = self.collector.enter();
self.reserve(reserve, &guard);
(*self).put_all(iter, &guard);
}
}
impl<'a, K, V, S> Extend<(&'a K, &'a V)> for &HashMap<K, V, S>
where
K: Sync + Send + Copy + Hash + Ord,
V: Sync + Send + Copy,
S: BuildHasher,
{
fn extend<T: IntoIterator<Item = (&'a K, &'a V)>>(&mut self, iter: T) {
self.extend(iter.into_iter().map(|(&key, &value)| (key, value)));
}
}
impl<K, V, S> FromIterator<(K, V)> for HashMap<K, V, S>
where
K: Sync + Send + Clone + Hash + Ord,
V: Sync + Send,
S: BuildHasher + Default,
{
fn from_iter<T: IntoIterator<Item = (K, V)>>(iter: T) -> Self {
let mut iter = iter.into_iter();
if let Some((key, value)) = iter.next() {
// safety: we own `map`, so it's not concurrently accessed by
// anyone else at this point.
let guard = unsafe { Guard::unprotected() };
let (lower, _) = iter.size_hint();
let map = HashMap::with_capacity_and_hasher(lower.saturating_add(1), S::default());
map.put(key, value, false, &guard);
map.put_all(iter, &guard);
map
} else {
Self::default()
}
}
}
impl<'a, K, V, S> FromIterator<(&'a K, &'a V)> for HashMap<K, V, S>
where
K: Sync + Send + Copy + Hash + Ord,
V: Sync + Send + Copy,
S: BuildHasher + Default,
{
fn from_iter<T: IntoIterator<Item = (&'a K, &'a V)>>(iter: T) -> Self {
iter.into_iter().map(|(&k, &v)| (k, v)).collect()
}
}
impl<'a, K, V, S> FromIterator<&'a (K, V)> for HashMap<K, V, S>
where
K: Sync + Send + Copy + Hash + Ord,
V: Sync + Send + Copy,
S: BuildHasher + Default,
{
fn from_iter<T: IntoIterator<Item = &'a (K, V)>>(iter: T) -> Self {
iter.into_iter().map(|&(k, v)| (k, v)).collect()
}
}
impl<K, V, S> Clone for HashMap<K, V, S>
where
K: Sync + Send + Clone + Hash + Ord,
V: Sync + Send + Clone,
S: BuildHasher + Clone,
{
fn clone(&self) -> HashMap<K, V, S> {
let cloned_map = Self::with_capacity_and_hasher(self.len(), self.build_hasher.clone())
.with_collector(self.collector.clone());
{
let guard = self.collector.enter();
let cloned_guard = cloned_map.collector.enter();
for (k, v) in self.iter(&guard) {
cloned_map.insert(k.clone(), v.clone(), &cloned_guard);
}
}
cloned_map
}
}
#[cfg(not(miri))]
#[inline]
/// Returns the number of physical CPUs in the machine (_O(1)_).
fn num_cpus() -> usize {
NCPU_INITIALIZER.call_once(|| NCPU.store(num_cpus::get_physical(), Ordering::Relaxed));
NCPU.load(Ordering::Relaxed)
}
#[cfg(miri)]
#[inline]
const fn num_cpus() -> usize {
1
}
#[test]
fn capacity() {
let map = HashMap::<usize, usize>::new();
let guard = map.guard();
assert_eq!(map.capacity(&guard), 0);
// The table has not yet been allocated
map.insert(42, 0, &guard);
assert_eq!(map.capacity(&guard), 16);
// The table has been allocated and has default capacity
for i in 0..16 {
map.insert(i, 42, &guard);
}
assert_eq!(map.capacity(&guard), 32);
// The table has been resized once (and it's capacity doubled),
// since we inserted more elements than it can hold
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn reserve() {
let map = HashMap::<usize, usize>::new();
let guard = map.guard();
map.insert(42, 0, &guard);
map.reserve(32, &guard);
let capacity = map.capacity(&guard);
assert!(capacity >= 16 + 32);
}
#[test]
fn reserve_uninit() {
let map = HashMap::<usize, usize>::new();
let guard = map.guard();
map.reserve(32, &guard);
let capacity = map.capacity(&guard);
assert!(capacity >= 32);
}
#[test]
fn resize_stamp_negative() {
let resize_stamp = HashMap::<usize, usize>::resize_stamp(1);
assert!(resize_stamp << RESIZE_STAMP_SHIFT < 0);
let resize_stamp = HashMap::<usize, usize>::resize_stamp(MAXIMUM_CAPACITY);
assert!(resize_stamp << RESIZE_STAMP_SHIFT < 0);
}
}
/// It's kind of stupid, but apparently there is no way to write a regular `#[test]` that is _not_
/// supposed to compile without pulling in `compiletest` as a dependency. See rust-lang/rust#12335.
/// But it _is_ possible to write `compile_test` tests as doctests, sooooo:
///
/// # No references outlive the map.
///
/// Note that these have to be _separate_ tests, otherwise you could have, say, `get` break the
/// contract, but `insert` continue to uphold it, and then the test would still fail to compile
/// (and so pass).
///
/// ```compile_fail
/// let guard = map.pin();
/// let map = super::HashMap::default();
/// let r = map.insert((), (), &guard);
/// drop(map);
/// drop(r);
/// ```
/// ```compile_fail
/// let guard = map.pin();
/// let map = super::HashMap::default();
/// let r = map.get(&(), &guard);
/// drop(map);
/// drop(r);
/// ```
/// ```compile_fail
/// let guard = map.pin();
/// let map = super::HashMap::default();
/// let r = map.remove(&(), &guard);
/// drop(map);
/// drop(r);
/// ```
/// ```compile_fail
/// let guard = map.pin();
/// let map = super::HashMap::default();
/// let r = map.iter(&guard).next();
/// drop(map);
/// drop(r);
/// ```
/// ```compile_fail
/// let guard = map.pin();
/// let map = super::HashMap::default();
/// let r = map.keys(&guard).next();
/// drop(map);
/// drop(r);
/// ```
/// ```compile_fail
/// let guard = map.pin();
/// let map = super::HashMap::default();
/// let r = map.values(&guard).next();
/// drop(map);
/// drop(r);
/// ```
///
/// # No references outlive the guard.
///
/// ```compile_fail
/// let guard = map.pin();
/// let map = super::HashMap::default();
/// let r = map.insert((), (), &guard);
/// drop(guard);
/// drop(r);
/// ```
/// ```compile_fail
/// let guard = map.pin();
/// let map = super::HashMap::default();
/// let r = map.get(&(), &guard);
/// drop(guard);
/// drop(r);
/// ```
/// ```compile_fail
/// let guard = map.pin();
/// let map = super::HashMap::default();
/// let r = map.remove(&(), &guard);
/// drop(guard);
/// drop(r);
/// ```
/// ```compile_fail
/// let guard = map.pin();
/// let map = super::HashMap::default();
/// let r = map.iter(&guard).next();
/// drop(guard);
/// drop(r);
/// ```
/// ```compile_fail
/// let guard = map.pin();
/// let map = super::HashMap::default();
/// let r = map.keys(&guard).next();
/// drop(guard);
/// drop(r);
/// ```
/// ```compile_fail
/// let guard = map.pin();
/// let map = super::HashMap::default();
/// let r = map.values(&guard).next();
/// drop(guard);
/// drop(r);
/// ```
///
/// # Keys and values do not have be static
///
/// ```
/// let x = String::from("foo");
/// let map: flurry::HashMap<_, _> = std::iter::once((&x, &x)).collect();
/// ```
/// ```
/// let x = String::from("foo");
/// let map: flurry::HashMap<_, _> = flurry::HashMap::new();
/// map.insert(&x, &x, &map.guard());
/// ```
///
/// # get() key can be non-static
///
/// ```
/// let x = String::from("foo");
/// let map: flurry::HashMap<_, _> = flurry::HashMap::new();
/// map.insert(x.clone(), x.clone(), &map.guard());
/// map.get(&x, &map.guard());
/// ```
#[allow(dead_code)]
struct CompileFailTests;
#[test]
fn replace_empty() {
let map = HashMap::<usize, usize>::new();
{
let guard = map.guard();
assert_eq!(map.len(), 0);
let old = map.replace_node(&42, None, None, &guard);
assert_eq!(map.len(), 0);
assert!(old.is_none());
}
}
#[test]
fn replace_existing() {
let map = HashMap::<usize, usize>::new();
{
let guard = map.guard();
map.insert(42, 42, &guard);
assert_eq!(map.len(), 1);
let old = map.replace_node(&42, Some(10), None, &guard);
assert_eq!(old, Some((&42, &42)));
assert_eq!(*map.get(&42, &guard).unwrap(), 10);
assert_eq!(map.len(), 1);
}
}
#[test]
fn no_replacement_return_val() {
// NOTE: this test also serves as a leak test for the injected value
let map = HashMap::<usize, String>::new();
{
let guard = map.guard();
map.insert(42, String::from("hello"), &guard);
assert_eq!(
map.put(42, String::from("world"), true, &guard),
PutResult::Exists {
current: &String::from("hello"),
not_inserted: Box::new(map.collector.link_value(String::from("world"))),
}
);
}
}
// TODO
// #[test]
// fn replace_existing_observed_value_matching() {
// let map = HashMap::<usize, usize>::new();
// {
// let guard = map.guard();
// map.insert(42, 42, &guard);
// assert_eq!(map.len(), 1);
// let observed_value = Shared::from(map.get(&42, &guard).unwrap() as *const _);
// let old = map.replace_node(&42, Some(10), Some(observed_value), &guard);
// assert_eq!(map.len(), 1);
// assert_eq!(old, Some((&42, &42)));
// assert_eq!(*map.get(&42, &guard).unwrap(), 10);
// }
// }
#[test]
fn replace_existing_observed_value_non_matching() {
let map = HashMap::<usize, usize>::new();
{
let guard = map.guard();
map.insert(42, 42, &guard);
assert_eq!(map.len(), 1);
let old = map.replace_node(&42, Some(10), Some(Shared::null()), &guard);
assert_eq!(map.len(), 1);
assert!(old.is_none());
assert_eq!(*map.get(&42, &guard).unwrap(), 42);
}
}
#[test]
fn replace_twice() {
let map = HashMap::<usize, usize>::new();
{
let guard = map.guard();
map.insert(42, 42, &guard);
assert_eq!(map.len(), 1);
let old = map.replace_node(&42, Some(43), None, &guard);
assert_eq!(map.len(), 1);
assert_eq!(old, Some((&42, &42)));
assert_eq!(*map.get(&42, &guard).unwrap(), 43);
let old = map.replace_node(&42, Some(44), None, &guard);
assert_eq!(map.len(), 1);
assert_eq!(old, Some((&42, &43)));
assert_eq!(*map.get(&42, &guard).unwrap(), 44);
}
}
#[cfg(test)]
mod tree_bins {
use super::*;
use std::hash::Hasher;
// Tests for the tree bin optimization.
// Includes testing that bins are actually treeified and untreeified, and that, when tree bins
// are untreeified, the associated values remain in the map.
#[derive(Default)]
struct ZeroHasher;
struct ZeroHashBuilder;
impl Hasher for ZeroHasher {
fn finish(&self) -> u64 {
0
}
fn write(&mut self, _: &[u8]) {}
}
impl BuildHasher for ZeroHashBuilder {
type Hasher = ZeroHasher;
fn build_hasher(&self) -> ZeroHasher {
ZeroHasher
}
}
#[test]
#[cfg_attr(miri, ignore)]
fn concurrent_tree_bin() {
let map = HashMap::<usize, usize, _>::with_hasher(ZeroHashBuilder);
// first, ensure that we have a tree bin
{
let guard = &map.guard();
// Force creation of a tree bin by inserting enough values that hash to 0
for i in 0..10 {
map.insert(i, i, guard);
}
// Ensure the bin was correctly treeified
let t = map.table.load(Ordering::Relaxed, guard);
let t = unsafe { t.deref() };
let bini = t.bini(0);
let bin = t.bin(bini, guard);
match unsafe { &**bin.deref() } {
BinEntry::Tree(_) => {} // pass
BinEntry::Moved => panic!("bin was not correctly treeified -- is Moved"),
BinEntry::Node(_) => panic!("bin was not correctly treeified -- is Node"),
BinEntry::TreeNode(_) => panic!("bin was not correctly treeified -- is TreeNode"),
}
let _ = guard;
}
// then, spin up lots of reading and writing threads on a range of keys
const NUM_WRITERS: usize = 5;
const NUM_READERS: usize = 20;
const NUM_REPEATS: usize = 1000;
const NUM_KEYS: usize = 1000;
use rand::{
distributions::{Distribution, Uniform},
thread_rng,
};
let uniform = Uniform::new(0, NUM_KEYS);
let m = std::sync::Arc::new(map);
let mut handles = Vec::with_capacity(2 * NUM_WRITERS + NUM_READERS);
for _ in 0..NUM_READERS {
// ...and a reading thread
let map = m.clone();
handles.push(std::thread::spawn(move || {
let guard = &map.guard();
let mut trng = thread_rng();
for _ in 0..NUM_REPEATS {
let key = uniform.sample(&mut trng);
if let Some(v) = map.get(&key, guard) {
criterion::black_box(v);
}
}
}));
}
for i in 0..NUM_WRITERS {
// NUM_WRITERS times, create a writing thread...
let map = m.clone();
handles.push(std::thread::spawn(move || {
let guard = &map.guard();
let mut trng = thread_rng();
for _ in 0..NUM_REPEATS {
let key = uniform.sample(&mut trng);
map.insert(key, i, guard);
}
}));
// ...a removing thread.
let map = m.clone();
handles.push(std::thread::spawn(move || {
let guard = &map.guard();
let mut trng = thread_rng();
for _ in 0..NUM_REPEATS {
let key = uniform.sample(&mut trng);
if let Some(v) = map.remove(&key, guard) {
criterion::black_box(v);
}
}
}));
}
// in the end, join all threads
for handle in handles {
handle.join().unwrap();
}
}
#[test]
fn untreeify_shared_values_remove() {
test_tree_bin_remove(|i, map, guard| {
assert_eq!(map.remove(&i, guard), Some(&i));
});
}
#[test]
fn untreeify_shared_values_compute_if_present() {
test_tree_bin_remove(|i, map, guard| {
assert_eq!(map.compute_if_present(&i, |_, _| None, guard), None);
});
}
fn test_tree_bin_remove<F>(f: F)
where
F: Fn(usize, &HashMap<usize, usize, ZeroHashBuilder>, &Guard<'_>),
{
let map = HashMap::<usize, usize, _>::with_hasher(ZeroHashBuilder);
{
let guard = &map.guard();
// Force creation of a tree bin by inserting enough values that hash to 0
for i in 0..10 {
map.insert(i, i, guard);
}
// Ensure the bin was correctly treeified
let t = map.table.load(Ordering::Relaxed, guard);
let t = unsafe { t.deref() };
let bini = t.bini(0);
let bin = t.bin(bini, guard);
match unsafe { &**bin.deref() } {
BinEntry::Tree(_) => {} // pass
BinEntry::Moved => panic!("bin was not correctly treeified -- is Moved"),
BinEntry::Node(_) => panic!("bin was not correctly treeified -- is Node"),
BinEntry::TreeNode(_) => panic!("bin was not correctly treeified -- is TreeNode"),
}
// Delete keys to force untreeifying the bin
for i in 0..9 {
f(i, &map, guard);
}
let _ = guard;
}
assert_eq!(map.len(), 1);
{
// Ensure the bin was correctly untreeified
let guard = &map.guard();
let t = map.table.load(Ordering::Relaxed, guard);
let t = unsafe { t.deref() };
let bini = t.bini(0);
let bin = t.bin(bini, guard);
match unsafe { &**bin.deref() } {
BinEntry::Tree(_) => panic!("bin was not correctly untreeified -- is Tree"),
BinEntry::Moved => panic!("bin was not correctly untreeified -- is Moved"),
BinEntry::Node(_) => {} // pass
BinEntry::TreeNode(_) => panic!("bin was not correctly untreeified -- is TreeNode"),
}
}
// Create some guards to more reliably trigger garbage collection
for _ in 0..10 {
let _ = map.guard();
}
// Access a value that should still be in the map
let guard = &map.guard();
assert_eq!(map.get(&9, guard), Some(&9));
}
#[test]
#[should_panic]
fn disallow_evil() {
let map: HashMap<_, _> = HashMap::default();
map.insert(42, String::from("hello"), &map.guard());
let evil = seize::Collector::new();
let guard = evil.enter();
let oops = map.get(&42, &guard);
map.remove(&42, &map.guard());
// at this point, the default collector is allowed to free `"hello"`
// since no guard from `map`s collector is active.
// `oops` is tied to the lifetime of a Guard that is not a part of
// the same collector, and so can now be dangling.
// but we can still access it!
assert_eq!(oops.unwrap(), "hello");
}
}