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
#![doc( html_root_url = "https://docs.rs/spirit/0.1.0/spirit/", test(attr(deny(warnings))) )] #![cfg_attr(feature = "cargo-clippy", allow(type_complexity))] #![forbid(unsafe_code)] #![warn(missing_docs)] //! A helper to create unix daemons. //! //! When writing a service (in the unix terminology, a daemon), there are two parts of the job. One //! is the actual functionality of the service, the part that makes it different than all the other //! services out there. And then there's the very boring part of turning the prototype //! implementation into a well-behaved service and handling all the things expected of all of them. //! //! This crate is supposed to help with the latter. Before using, you should know the following: //! //! * This is an early version and while already (hopefully) useful, it is expected to expand and //! maybe change a bit in future versions. There are certainly parts of functionality I still //! haven't written and expect it to be rough around the edges. //! * It is opinionated ‒ it comes with an idea about how a well-behaved daemon should look like //! and how to integrate that into your application. I simply haven't find a way to make it less //! opinionated yet and this helps to scratch my own itch, so it reflects what I needed. If you //! have use cases that you think should fall within the responsibilities of this crate and are //! not handled, you are of course welcome to open an issue (or even better, a pull request) on //! the repository ‒ it would be great if it scratched not only my own itch. //! * It brings in a lot of dependencies. There will likely be features to turn off the unneeded //! parts, but for now, nobody made them yet. //! * This supports unix-style daemons only *for now*. This is because I have no experience in how //! a service for different OS should look like. However, help in this area would be appreciated //! ‒ being able to write a single code and compile a cross-platform service with all the needed //! plumbing would indeed sound very useful. //! //! # What the crate does and how //! //! To be honest, the crate doesn't bring much (or, maybe mostly none) of novelty functionality to //! the table. It just takes other crates doing something useful and gluing them together to form //! something most daemons want to do. //! //! Composing these things together the crate allows for cutting down on your own boilerplate code //! around configuration handling, signal handling, command line arguments and daemonization. //! //! Using the builder pattern, you create a singleton [`Spirit`] object. That one starts a //! background thread that runs some callbacks configured previous when things happen. //! //! It takes two structs, one for command line arguments (using [StructOpt]) and another for //! configuration (implementing [serde]'s [`Deserialize`], loaded using the [config] crate). It //! enriches both to add common options, like configuration overrides on the command line and //! logging into the configuration. //! //! The background thread listens to certain signals (like `SIGHUP`) using the [signal-hook] crate //! and reloads the configuration when requested. It manages the logging backend to reopen on //! `SIGHUP` and reflect changes to the configuration. //! //! [`Spirit`]: struct.Spirit.html //! [StructOpt]: https://crates.io/crates/structopt //! [serde]: https://crates.io/crates/serde //! [`Deserialize`]: https://docs.rs/serde/*/serde/trait.Deserialize.html //! [config]: https://crates.io/crates/config //! [signal-hook]: https://crates.io/crates/signal-hook //! //! # Helpers //! //! It brings the idea of helpers. A helper is something that plugs a certain functionality into //! the main crate, to cut down on some more specific boiler-plate code. These are usually provided //! by other crates. To list some: //! //! * `spirit-tokio`: Integrates basic tokio primitives ‒ auto-reconfiguration for TCP and UDP //! sockets and starting the runtime. //! //! (Others will come over time) //! //! # Examples //! //! ```rust //! #[macro_use] //! extern crate log; //! #[macro_use] //! extern crate serde_derive; //! extern crate spirit; //! //! use std::time::Duration; //! use std::thread; //! //! use spirit::{Empty, Spirit}; //! //! #[derive(Debug, Default, Deserialize)] //! struct Cfg { //! message: String, //! sleep: u64, //! } //! //! static DEFAULT_CFG: &str = r#" //! message = "hello" //! sleep = 2 //! "#; //! //! fn main() { //! Spirit::<_, Empty, _>::new(Cfg::default()) //! // Provide default values for the configuration //! .config_defaults(DEFAULT_CFG) //! // If the program is passed a directory, load files with these extensions from there //! .config_exts(&["toml", "ini", "json"]) //! .on_terminate(|| debug!("Asked to terminate")) //! .on_config(|cfg| debug!("New config loaded: {:?}", cfg)) //! // Run the closure, logging the error nicely if it happens (note: no error happens //! // here) //! .run(|spirit: &_| { //! while !spirit.is_terminated() { //! let cfg = spirit.config(); // Get a new version of config every round //! thread::sleep(Duration::from_secs(cfg.sleep)); //! info!("{}", cfg.message); //! # spirit.terminate(); // Just to make sure the doc-test terminates //! } //! Ok(()) //! }); //! } //! ``` //! //! More complete examples can be found in the //! [repository](https://github.com/vorner/spirit/tree/master/examples). //! //! # Added configuration and options //! //! ## Command line options //! //! * `daemonize`: When this is set, the program becomes instead of staying in the foreground. It //! closes stdio. //! * `config-override`: Override configuration value. //! * `log`: In addition to the logging in configuration file, also log with the given severity to //! stderr. //! * `log-module`: Override the stderr log level of the given module. //! //! Furthermore, it takes a list of paths ‒ both files and directories. They are loaded as //! configuration files (the directories are examined and files in them ‒ the ones passing a //! [filter](struct.Builder.html#method.config_files) ‒ are also loaded). //! //! ```sh //! ./program --log info --log-module program=trace --config-override ui.message=something //! ``` //! //! ## Configuration options //! //! ### `logging` //! //! It is an array of logging destinations. No matter where the logging is sent to, these options //! are valid for all: //! //! * `level`: The log level to use. Valid options are `OFF`, `ERROR`, `WARN`, `INFO`, `DEBUG` and //! `TRACE`. //! * `per-module`: A map, setting log level overrides for specific modules (logging targets). This //! one is optional. //! * `type`: Specifies the type of logger destination. Some of them allow specifying other //! options. //! //! The allowed types are: //! * `stdout`: The logs are sent to standard output. There are no additional options. //! * `stderr`: The logs are sent to standard error output. There are no additional options. //! * `file`: Logs are written to a file. The file is reopened every time a configuration is //! re-read (therefore every time the application gets `SIGHUP`), which makes it work with //! logrotate. //! - `filename`: The path to the file where to put the logs. //! * `network`: The application connects to a given host and port over TCP and sends logs there. //! - `host`: The hostname (or IP address) to connect to. //! - `port`: The port to use. //! * `syslog`: Sends the logs to syslog. //! //! ### `daemon` //! //! Influences how daemonization is done. //! //! * `user`: The user to become. Either a numeric ID or name (not yet implemented). If not //! present, it doesn't change the user. //! * `group`: Similar as user, but with group. //! * `pid_file`: A pid file to write on startup. If not present, nothing is stored. //! * `workdir`: A working directory it'll switch into. If not set, defaults to `/`. //! //! # Multithreaded applications //! //! As daemonization is done by using `fork`, you should start any threads *after* you initialize //! the `spirit`. Otherwise you'll lose the threads (and further bad things will happen). //! //! # Common patterns //! //! TODO extern crate arc_swap; extern crate chrono; extern crate config; #[macro_use] extern crate failure; extern crate fallible_iterator; extern crate fern; extern crate itertools; extern crate libc; #[macro_use] extern crate log; extern crate log_panics; extern crate log_reroute; extern crate nix; extern crate parking_lot; extern crate serde; #[macro_use] extern crate serde_derive; extern crate signal_hook; // For some reason, this produces a warning about unused on nightly… but it is needed on stable #[allow(unused_imports)] #[macro_use] extern crate structopt; extern crate syslog; pub mod helpers; mod logging; pub mod validation; use std::any::TypeId; use std::borrow::Borrow; use std::collections::{HashMap, HashSet}; use std::env; use std::ffi::OsString; use std::fmt::Debug; use std::fs::OpenOptions; use std::io::Write; use std::iter; use std::marker::PhantomData; use std::os::unix::fs::OpenOptionsExt; use std::os::unix::io::AsRawFd; use std::panic::{self, AssertUnwindSafe}; use std::path::{Path, PathBuf}; use std::process; use std::str::FromStr; use std::sync::atomic::{AtomicBool, Ordering}; use std::sync::Arc; use std::thread; use std::time::Duration; pub use arc_swap::ArcSwap; use arc_swap::Lease; use config::{Config, Environment, File, FileFormat}; use failure::{Error, Fail}; use fallible_iterator::FallibleIterator; use log::LevelFilter; use nix::sys::stat::{self, Mode}; use nix::unistd::{self, ForkResult, Gid, Uid}; use parking_lot::Mutex; use serde::Deserialize; use signal_hook::iterator::Signals; use structopt::clap::App; use structopt::StructOpt; use logging::{LogDestination, Logging}; use validation::{ Error as ValidationError, Level as ValidationLevel, Results as ValidationResults, }; pub use logging::SyslogError; #[derive(Debug, Deserialize, Eq, PartialEq)] #[serde(untagged)] enum SecId { Name(String), Id(u32), #[serde(skip)] Nothing, } impl Default for SecId { fn default() -> Self { SecId::Nothing } } #[derive(Debug, Default, Deserialize, Eq, PartialEq)] #[serde(rename_all = "kebab-case")] struct Daemon { #[serde(default)] user: SecId, #[serde(default)] group: SecId, pid_file: Option<PathBuf>, workdir: Option<PathBuf>, } #[derive(Deserialize)] struct ConfigWrapper<C> { #[serde(flatten)] config: C, #[serde(default)] daemon: Daemon, #[serde(default)] logging: Vec<Logging>, // TODO: Find a way to detect and report unused fields } /// An error returned when the user passes a key-value option without equal sign. /// /// Some internal options take a key-value pairs on the command line. If such option is expected, /// but it doesn't contain the equal sign, this is the used error. #[derive(Debug, Fail)] #[fail(display = "Missing = in map option")] pub struct MissingEquals; // TODO: This one probably needs tests ‒ +- errors, parsing of both allowed and disallowed things, // missing equals… fn key_val<K, V>(opt: &str) -> Result<(K, V), Error> where K: FromStr, K::Err: Fail + 'static, V: FromStr, V::Err: Fail + 'static, { let pos = opt.find('=').ok_or(MissingEquals)?; Ok((opt[..pos].parse()?, opt[pos + 1..].parse()?)) } #[derive(Debug, StructOpt)] struct CommonOpts { /// Override specific config values. #[structopt( short = "C", long = "config-override", parse(try_from_str = "key_val"), raw(number_of_values = "1"), )] config_overrides: Vec<(String, String)>, /// Configuration files or directories to load. #[structopt(parse(from_os_str))] configs: Vec<PathBuf>, /// Daemonize ‒ go to background. #[structopt(short = "d", long = "daemonize")] daemonize: bool, /// Log to stderr with this log level. #[structopt(short = "l", long = "log", raw(number_of_values = "1"))] log: Option<LevelFilter>, /// Log to stderr with overriden levels for specific modules. #[structopt( short = "L", long = "log-module", parse(try_from_str = "key_val"), raw(number_of_values = "1"), )] log_modules: Vec<(String, LevelFilter)>, } #[derive(Debug)] struct OptWrapper<O> { common: CommonOpts, other: O, } // Unfortunately, StructOpt doesn't like flatten with type parameter // (https://github.com/TeXitoi/structopt/issues/128). It is not even trivial to do, since some of // the very important functions are *not* part of the trait. So we do it manually ‒ we take the // type parameter's clap definition and add our own into it. impl<O> StructOpt for OptWrapper<O> where O: Debug + StructOpt, { fn clap<'a, 'b>() -> App<'a, 'b> { CommonOpts::augment_clap(O::clap()) } fn from_clap(matches: &::structopt::clap::ArgMatches) -> Self { OptWrapper { common: StructOpt::from_clap(matches), other: StructOpt::from_clap(matches), } } } /// A wrapper around a fallible function that logs any returned errors, with all the causes and /// optionally the backtrace. pub fn log_errors<R, F: FnOnce() -> Result<R, Error>>(f: F) -> Result<R, Error> { let result = f(); if let Err(ref e) = result { // Note: one of the causes is the error itself for cause in e.iter_chain() { error!("{}", cause); } let bt = format!("{}", e.backtrace()); if !bt.is_empty() { debug!("{}", bt); } } result } /// An error returned whenever the user passes something not a file nor a directory as /// configuration. #[derive(Debug, Fail)] #[fail(display = "_1 is not file nor directory")] pub struct InvalidFileType(PathBuf); /// A struct that may be used when either configuration or command line options are not needed. /// /// When the application doesn't need the configuration (in excess of the automatic part provided /// by this library) or it doesn't need any command line options of its own, this struct can be /// used to plug the type parameter. #[derive( Copy, Clone, Debug, Default, Deserialize, Eq, PartialEq, Hash, Ord, PartialOrd, StructOpt, )] pub struct Empty {} struct Hooks<O, C> { config_filter: Box<FnMut(&Path) -> bool + Send>, config: Vec<Box<FnMut(&Arc<C>) + Send>>, config_validators: Vec<Box<FnMut(&Arc<C>, &mut C, &O) -> ValidationResults + Send>>, sigs: HashMap<libc::c_int, Vec<Box<FnMut() + Send>>>, terminate: Vec<Box<FnMut() + Send>>, } impl<O, C> Default for Hooks<O, C> { fn default() -> Self { let no_filter = Box::new(|_: &_| false); Hooks { config_filter: no_filter, config: Vec::new(), config_validators: Vec::new(), sigs: HashMap::new(), terminate: Vec::new(), } } } /// The main manipulation handle/struct of the library. /// /// This gives access to the runtime control over the behaviour of the spirit library and allows /// accessing current configuration and manipulate the behaviour to some extent. /// /// Note that the functionality of the library is not disturbed by dropping this, you simply lose /// the ability to control the library. /// /// By creating this (with the build pattern), you start a background thread that keeps track of /// signals, reloading configuration and other bookkeeping work. /// /// The passed callbacks are run in the service threads if they are caused by the signals. They, /// however, can be run in any other thread when the controlled actions are invoked manually. /// /// This is supposed to be a singleton (it is not enforced, but having more of them around is /// probably not what you want). /// /// # Warning /// /// Only one callback is allowed to run at any given time. This makes it easier to write the /// callbacks (eg. transitioning between configurations at runtime), but if you ever invoke a /// method that contains callbacks from within a callback, you'll get a deadlock. /// /// # Examples /// /// ```rust /// use spirit::{Empty, Spirit}; /// /// Spirit::<_, Empty, _>::new(Empty {}) /// .on_config(|_new_cfg| { /// // Adapt to new config here /// }) /// .run(|_spirit| { /// // Application runs here /// Ok(()) /// }); /// ``` pub struct Spirit<S, O = Empty, C = Empty> where S: Borrow<ArcSwap<C>> + 'static, { config: S, hooks: Mutex<Hooks<O, C>>, // TODO: Mode selection for directories config_files: Vec<PathBuf>, config_defaults: Option<String>, config_env: Option<String>, config_overrides: HashMap<String, String>, daemonize: bool, extra_logger: Option<Logging>, opts: O, previous_daemon: Mutex<Option<Daemon>>, terminate: AtomicBool, } /// A type alias for a `Spirit` with configuration held inside. /// /// Just to ease up naming the type when passing around the program. pub type SpiritInner<O, C> = Arc<Spirit<Arc<ArcSwap<C>>, O, C>>; impl<O, C> Spirit<Arc<ArcSwap<C>>, O, C> where for<'de> C: Deserialize<'de> + Send + Sync + 'static, O: StructOpt, { /// A constructor for spirit with only inner-accessible configuration. /// /// With this constructor, you can look into the current configuration by calling the /// [`config'](#method.config), but it doesn't store it into a globally accessible storage. /// /// # Examples /// /// ``` /// use spirit::{Empty, Spirit}; /// /// Spirit::<_, Empty, _>::new(Empty {}) /// .run(|spirit| { /// println!("The config is: {:?}", spirit.config()); /// Ok(()) /// }); /// ``` #[cfg_attr(feature = "cargo-clippy", allow(new_ret_no_self))] pub fn new(cfg: C) -> Builder<Arc<ArcSwap<C>>, O, C> { Self::with_config_storage(Arc::new(ArcSwap::new(Arc::new(cfg)))) } } impl<S, O, C> Spirit<S, O, C> where S: Borrow<ArcSwap<C>> + Send + Sync + 'static, for<'de> C: Deserialize<'de> + Send + Sync, O: StructOpt, { /// A constructor with specifying external config storage. /// /// This way the spirit keeps the current config in the provided storage, so it is accessible /// from outside as well as through the [`config`](#method.config) method. pub fn with_config_storage(config: S) -> Builder<S, O, C> { Builder { before_bodies: Vec::new(), body_wrappers: Vec::new(), config, config_default_paths: Vec::new(), config_defaults: None, config_env: None, config_hooks: Vec::new(), config_filter: Box::new(|_| false), config_validators: Vec::new(), opts: PhantomData, sig_hooks: HashMap::new(), singletons: HashSet::new(), terminate_hooks: Vec::new(), } } /// Access the parsed command line. /// /// This gives the access to the type declared when creating `Spirit`. The content doesn't /// change (the command line is parsed just once) and it does not contain the options added by /// Spirit itself. pub fn cmd_opts(&self) -> &O { &self.opts } /// Access to the current configuration. /// /// This returns the *current* version of configuration. Note that you can keep hold of this /// snapshot of configuration (which does not change), but calling this again might give a /// different config. /// /// If you *do* want to hold onto the returned configuration for longer time, upgrade the /// returned `Lease` to `Arc`. /// /// # Examples /// /// ```rust /// extern crate arc_swap; /// extern crate spirit; /// /// use arc_swap::Lease; /// use spirit::{Empty, Spirit}; /// /// let (spirit, _, _) = Spirit::<_, Empty, _>::new(Empty {}) /// .build() /// .unwrap(); /// /// let old_config = Lease::upgrade(&spirit.config()); /// # drop(old_config); /// ``` /// /// # Notes /// /// If created with the [`with_config_storage`](#method.with_config_storage), the current /// configuration is also available through that storage. This allows, for example, having the /// configuration in a global variable, for example. pub fn config(&self) -> Lease<Arc<C>> { self.config.borrow().lease() } fn daemonize(&self, daemon: &Daemon) -> Result<(), Error> { // TODO: Discovering by name // TODO: Tests for this debug!("Preparing to daemonize with {:?}", daemon); stat::umask(Mode::empty()); // No restrictions on write modes let workdir = daemon .workdir .as_ref() .map(|pb| pb as &Path) .unwrap_or_else(|| Path::new("/")); trace!("Changing working directory to {:?}", workdir); env::set_current_dir(workdir)?; if self.daemonize { trace!("Redirecting stdio"); let devnull = OpenOptions::new() .read(true) .write(true) .create(true) .open("/dev/null")?; for fd in &[0, 1, 2] { unistd::dup2(devnull.as_raw_fd(), *fd)?; } trace!("Doing double fork"); if let ForkResult::Parent { .. } = unistd::fork()? { process::exit(0); } unistd::setsid()?; if let ForkResult::Parent { .. } = unistd::fork()? { process::exit(0); } } else { trace!("Not going to background"); } if let Some(ref file) = daemon.pid_file { let mut f = OpenOptions::new() .write(true) .create(true) .truncate(true) .mode(0o644) .open(file)?; writeln!(f, "{}", unistd::getpid())?; } match daemon.group { SecId::Id(id) => unistd::setgid(Gid::from_raw(id))?, SecId::Name(_) => unimplemented!("Discovering group name"), SecId::Nothing => (), } match daemon.user { SecId::Id(id) => unistd::setuid(Uid::from_raw(id))?, SecId::Name(_) => unimplemented!("Discovering user name"), SecId::Nothing => (), } Ok(()) } /// Force reload of configuration. /// /// The configuration gets reloaded either when the process receives `SIGHUP` or when this /// method is called manually. /// /// This is what happens: /// * The configuration is loaded from all places. /// * Validation callbacks are called (all of them). /// * If no validation callback returns an error, success callbacks of the validation results /// are called. Otherwise, abort callbacks are called. /// * Logging is reopened in the new form. /// * The configuration is published into the storage. /// * The `on_config` callbacks are called. /// /// If any step fails, it is aborted and the old configuration is preserved. /// /// # Warning /// /// The Spirit allows to run only one callback at a time (even from multiple threads), to make /// reasoning about configuration transitions and such easier (and to make sure the callbacks /// don't have to by `Sync`). That, however, means that you can't call `config_reload` or /// [`terminate`](#method.terminate) from any callback (that would lead to a deadlock). pub fn config_reload(&self) -> Result<(), Error> { let config = self.load_config()?; // The lock here is across the whole processing, to avoid potential races in logic // processing. This makes writing the hooks correctly easier. let mut hooks = self.hooks.lock(); let old = self.config.borrow().load(); let mut new = config.config; debug!("Creating new logging"); // Prepare the logger first, but don't switch until we know we use the new config. let loggers = logging::create(config.logging.iter().chain(&self.extra_logger))?; debug!("Running config validators"); let mut results = hooks .config_validators .iter_mut() .map(|v| v(&old, &mut new, &self.opts)) .fold(ValidationResults::new(), |mut acc, r| { acc.merge(r); acc }); let new = Arc::new(new); for result in &results { match result.level() { ValidationLevel::Error => { error!(target: "configuration", "{}", result.description()); } ValidationLevel::Warning => { warn!(target: "configuration", "{}", result.description()); } ValidationLevel::Hint => { info!(target: "configuration", "{}", result.description()); } ValidationLevel::Nothing => (), } } if results.max_level() == Some(ValidationLevel::Error) { error!(target: "configuration", "Refusing new configuration due to errors"); for r in &mut results.0 { if let Some(abort) = r.on_abort.as_mut() { abort(); } } return Err(ValidationError.into()); } debug!("Validation successful, installing new config"); for r in &mut results.0 { if let Some(success) = r.on_success.as_mut() { success(); } } debug!("Installing loggers"); // Once everything is validated, switch to the new logging logging::install(loggers); // And to the new config. self.config.borrow().store(Arc::clone(&new)); debug!("Running post-configuration hooks"); for hook in &mut hooks.config { hook(&new); } debug!("Configuration reloaded"); let mut daemon = self.previous_daemon.lock(); if let Some(ref daemon) = *daemon { if daemon != &config.daemon { warn!("Can't change daemon configuration at runtime"); } } else { self.daemonize(&config.daemon)?; } *daemon = Some(config.daemon); Ok(()) } /// Is the application in the shutdown phase? /// /// This can be used if the daemon does some kind of periodic work, every loop it can check if /// the application should shut down. /// /// The other option is to hook into [`on_terminate`](struct.Builder.html#method.on_terminate) /// and shut things down (like drop some futures and make the tokio event loop empty). /// /// # Examples /// /// ```rust /// use std::thread; /// use std::time::Duration; /// /// use spirit::{Empty, Spirit}; /// /// let (spirit, _, _) = Spirit::<_, Empty, _>::new(Empty {}) /// .build() /// .unwrap(); /// /// while !spirit.is_terminated() { /// thread::sleep(Duration::from_millis(100)); /// # spirit.terminate(); /// } /// ``` pub fn is_terminated(&self) -> bool { self.terminate.load(Ordering::Relaxed) } /// Terminate the application in a graceful manner. /// /// The Spirit/application can be terminated either by one of termination signals (`SIGTERM`, /// `SIGQUIT`, `SIGINT`) or by manually calling this method. /// /// The termination does this: /// /// * Calls the `on_terminate` callbacks. /// * Sets the [`is_terminated`](#method.is_terminated) flag is set. /// * Drops all callbacks from spirit. This allows destruction/termination of parts of program /// by dropping remote handles or similar things. /// * The background thread terminates. /// /// # Warning /// /// The Spirit guarantees only one callback runs at a time. That means you can't call this from /// within a callback (it would lead to deadlock). pub fn terminate(&self) { debug!("Running termination hooks"); for hook in &mut self.hooks.lock().terminate { hook(); } self.terminate.store(true, Ordering::Relaxed); *self.hooks.lock() = Hooks::default(); } fn background(&self, signals: &Signals) { debug!("Starting background processing"); for signal in signals.forever() { debug!("Received signal {}", signal); let term = match signal { libc::SIGHUP => { let _ = log_errors(|| self.config_reload()); false } libc::SIGTERM | libc::SIGINT | libc::SIGQUIT => { self.terminate(); true } // Some other signal, only for the hook benefit _ => false, }; if let Some(hooks) = self.hooks.lock().sigs.get_mut(&signal) { for hook in hooks { hook(); } } if term { debug!("Terminating the background thread"); return; } } unreachable!("Signals run forever"); } fn load_config(&self) -> Result<ConfigWrapper<C>, Error> { debug!("Loading configuration"); let mut config = Config::new(); // To avoid problems with trying to parse without any configuration present (it would // complain that it found unit and whatever the config was is expected instead). config.merge(File::from_str("", FileFormat::Toml))?; if let Some(ref defaults) = self.config_defaults { trace!("Loading config defaults"); config.merge(File::from_str(defaults, FileFormat::Toml))?; } for path in &self.config_files { if path.is_file() { trace!("Loading config file {:?}", path); config.merge(File::from(path as &Path))?; } else if path.is_dir() { trace!("Scanning directory {:?}", path); let mut lock = self.hooks.lock(); let mut filter = &mut lock.config_filter; // Take all the file entries passing the config file filter, handling errors on the // way. let mut files = fallible_iterator::convert(path.read_dir()?) .and_then(|entry| -> Result<Option<PathBuf>, std::io::Error> { let path = entry.path(); let meta = path.symlink_metadata()?; if meta.is_file() && (filter)(&path) { Ok(Some(path)) } else { trace!("Skipping {:?}", path); Ok(None) } }).filter_map(|path| path) .collect::<Vec<_>>()?; // Traverse them sorted. files.sort(); for file in files { trace!("Loading config file {:?}", file); config.merge(File::from(file))?; } } else { bail!(InvalidFileType(path.to_owned())); } } if let Some(env_prefix) = self.config_env.as_ref() { trace!("Loading config from environment {}", env_prefix); config.merge(Environment::with_prefix(env_prefix))?; } for (ref key, ref value) in &self.config_overrides { trace!("Config override {} => {}", key, value); config.set(*key, *value as &str)?; } Ok(config.try_into()?) } } trait Body<Param>: Send { fn run(&mut self, Param) -> Result<(), Error>; } impl<F: FnOnce(Param) -> Result<(), Error> + Send, Param> Body<Param> for Option<F> { fn run(&mut self, param: Param) -> Result<(), Error> { (self.take().expect("Body called multiple times"))(param) } } /// A workaround type for `Box<FnOnce() -> Result<(), Error>`. /// /// Since it is not possible to use the aforementioned type in any meaningful way in Rust yet, this /// works around the problem. The type has a [`run`](#method.run) method which does the same thing. /// /// This is passed as parameter to the [`body_wrapper`](struct.Builder.html#method.body_wrapper). /// /// It is also returned as part of the [`build`](struct.Builder.html#method.build)'s result. pub struct InnerBody(Box<Body<()>>); impl InnerBody { /// Run the body. pub fn run(mut self) -> Result<(), Error> { self.0.run(()) } } /// A wrapper around a body. /// /// These are essentially boxed closures submitted by /// [`body_wrapper`](struct.Builder.html#method.body_wrapper) (or all of them folded together), but /// in a form that is usable (in contrast to `Box<FnOnce(InnerBody) -> Result(), Error>`). It /// is part of the return value of [`build`](struct.Builder.html#method.build) and the caller /// should call it eventually. pub struct WrapBody(Box<Body<InnerBody>>); impl WrapBody { /// Call the closure inside. pub fn run(mut self, inner: InnerBody) -> Result<(), Error> { self.0.run(inner) } } type Wrapper<S, O, C> = Box<for<'a> Body<(&'a Arc<Spirit<S, O, C>>, InnerBody)>>; type SpiritBody<S, O, C> = Box<for<'a> Body<&'a Arc<Spirit<S, O, C>>>>; /// The builder of [`Spirit`](struct.Spirit.html). /// /// This is returned by the [`Spirit::new`](struct.Spirit.html#new). pub struct Builder<S, O = Empty, C = Empty> where S: Borrow<ArcSwap<C>> + Sync + Send + 'static, { before_bodies: Vec<SpiritBody<S, O, C>>, body_wrappers: Vec<Wrapper<S, O, C>>, config: S, config_default_paths: Vec<PathBuf>, config_defaults: Option<String>, config_env: Option<String>, config_hooks: Vec<Box<FnMut(&Arc<C>) + Send>>, config_filter: Box<FnMut(&Path) -> bool + Send>, config_validators: Vec<Box<FnMut(&Arc<C>, &mut C, &O) -> ValidationResults + Send>>, opts: PhantomData<O>, sig_hooks: HashMap<libc::c_int, Vec<Box<FnMut() + Send>>>, singletons: HashSet<TypeId>, terminate_hooks: Vec<Box<FnMut() + Send>>, } impl<S, O, C> Builder<S, O, C> where S: Borrow<ArcSwap<C>> + Sync + Send + 'static, for<'de> C: Deserialize<'de> + Send + Sync + 'static, O: Debug + StructOpt + Sync + Send + 'static, { /// Add a closure run before the main body. /// /// The [`run`](#method.run) will first execute all closures submitted through this method /// before running the real body. They are run in the order of submissions. /// /// The purpose of this is mostly integration with helpers ‒ they often need some last minute /// preparation. /// /// In case of using only build, the bodies are composed into one object and returned as part /// of the result (the inner body). /// /// # Errors /// /// If any of the before-bodies in the chain return an error, the processing ends there and the /// error is returned right away. /// /// # Examples /// /// ``` /// # use spirit::{Empty, Spirit}; /// Spirit::<_, Empty, _>::new(Empty {}) /// .before_body(|_spirit| { /// println!("Run first"); /// Ok(()) /// }).run(|_spirit| { /// println!("Run second"); /// Ok(()) /// }); /// ``` pub fn before_body<B>(mut self, body: B) -> Self where B: FnOnce(&Arc<Spirit<S, O, C>>) -> Result<(), Error> + Send + 'static, { self.before_bodies.push(Box::new(Some(body))); self } /// Wrap the body run by the [`run`](#method.run) into this closure. /// /// The inner body is passed as an object with a [`run`](struct.InnerBody.html#method.run) /// method, not as a closure, due to a limitation around boxed `FnOnce`. /// /// It is expected the wrapper executes the inner body as part of itself and propagates any /// returned error. /// /// In case of multiple wrappers, the ones submitted later on are placed inside the sooner /// ones ‒ the first one is the outermost. /// /// In case of using only [`build`](#method.build), all the wrappers composed together are /// returned as part of the result. /// /// # Examples /// /// ```rust /// # use spirit::{Empty, Spirit}; /// Spirit::<_, Empty, _>::new(Empty {}) /// .body_wrapper(|_spirit, inner| { /// println!("Run first"); /// inner.run()?; /// println!("Run third"); /// Ok(()) /// }).run(|_spirit| { /// println!("Run second"); /// Ok(()) /// }); /// ``` pub fn body_wrapper<W>(mut self, wrapper: W) -> Self where W: FnOnce(&Arc<Spirit<S, O, C>>, InnerBody) -> Result<(), Error> + Send + 'static, { let wrapper = move |(spirit, inner): (&_, _)| wrapper(spirit, inner); self.body_wrappers.push(Box::new(Some(wrapper))); self } /// Finish building the Spirit. /// /// This transitions from the configuration phase of Spirit to actually creating it and /// launching it. /// /// This starts listening for signals, loads the configuration for the first time and starts /// the background thread. /// /// This version returns the spirit (or error) and error handling is up to the caller. If you /// want spirit to take care of nice error logging (even for your application's top level /// errors), use [`run`](#method.run). /// /// # Result /// /// On success, this returns three things: /// /// * The `spirit` handle, allowing to manipulate it (shutdown, read configuration, ...) /// * The before-body hooks (see [`before_body`](#method.before_body). /// * The body wrappers ([`body_wrapper`](#method.body_wrapper)). /// /// The two latter ones are often set by helpers, so you should not ignore them. /// /// # Warning /// /// If asked to go to background, this uses `fork`. Therefore, start any threads after you call /// `build` (or from within [`run`](#method.run)), or you'll lose them ‒ only the thread doing /// fork is preserved across it. // TODO: The new return value pub fn build(self) -> Result<(Arc<Spirit<S, O, C>>, InnerBody, WrapBody), Error> { let mut logger = Logging { destination: LogDestination::StdErr, level: LevelFilter::Warn, per_module: HashMap::new(), }; log_reroute::init()?; logging::install(logging::create(iter::once(&logger)).unwrap()); debug!("Building the spirit"); log_panics::init(); let opts = OptWrapper::<O>::from_args(); if let Some(level) = opts.common.log { logger.level = level; logger.per_module = opts.common.log_modules.iter().cloned().collect(); logging::install(logging::create(iter::once(&logger))?); } let config_files = if opts.common.configs.is_empty() { self.config_default_paths } else { opts.common.configs }; let interesting_signals = self .sig_hooks .keys() .chain(&[libc::SIGHUP, libc::SIGTERM, libc::SIGQUIT, libc::SIGINT]) .cloned() .collect::<HashSet<_>>(); // Eliminate duplicates let log_modules = opts.common.log_modules; let extra_logger = opts.common.log.map(|level| Logging { destination: LogDestination::StdErr, level, per_module: log_modules.into_iter().collect(), }); let spirit = Spirit { config: self.config, config_files, config_defaults: self.config_defaults, config_env: self.config_env, config_overrides: opts.common.config_overrides.into_iter().collect(), daemonize: opts.common.daemonize, extra_logger, hooks: Mutex::new(Hooks { config: self.config_hooks, config_filter: self.config_filter, config_validators: self.config_validators, sigs: self.sig_hooks, terminate: self.terminate_hooks, }), opts: opts.other, previous_daemon: Mutex::new(None), terminate: AtomicBool::new(false), }; spirit.config_reload()?; let signals = Signals::new(interesting_signals)?; let spirit = Arc::new(spirit); let spirit_bg = Arc::clone(&spirit); thread::Builder::new() .name("spirit".to_owned()) .spawn(move || { loop { // Note: we run a bunch of callbacks inside the service thread. We restart the // thread if it fails. let run = AssertUnwindSafe(|| spirit_bg.background(&signals)); if panic::catch_unwind(run).is_err() { // FIXME: Something better than this to prevent looping? thread::sleep(Duration::from_secs(1)); info!("Restarting the spirit service thread after a panic"); } else { // Willingly terminated break; } } }).unwrap(); // Could fail only if the name contained \0 debug!( "Building bodies from {} before-bodies and {} wrappers", self.before_bodies.len(), self.body_wrappers.len() ); let spirit_body = Arc::clone(&spirit); let bodies = self.before_bodies; let inner = move |()| { for mut body in bodies { body.run(&spirit_body)?; } Ok(()) }; let body_wrappers = self.body_wrappers; let inner = InnerBody(Box::new(Some(inner))); let spirit_body = Arc::clone(&spirit); let mut wrapped = WrapBody(Box::new(Some(|inner: InnerBody| inner.run()))); for mut wrapper in body_wrappers.into_iter().rev() { // TODO: Can we get rid of this clone? let spirit = Arc::clone(&spirit_body); let applied = move |inner: InnerBody| wrapper.run((&spirit, inner)); wrapped = WrapBody(Box::new(Some(applied))); } Ok((spirit, inner, wrapped)) } /// Build the spirit and run the application, handling all relevant errors. /// /// In case an error happens (either when creating the Spirit, or returned by the callback), /// the errors are logged (either to the place where logs are sent to in configuration, or to /// stderr if the error happens before logging is initialized ‒ for example if configuration /// can't be read). The application then terminates with failure exit code. /// /// It first wraps all the calls in the provided wrappers /// ([`body_wrapper`](#method.body_wrapper)) and runs the before body hooks /// ([`before_body`](#method.before_body)) before starting the real body provided as parameter. /// These are usually provided by helpers. /// /// ```rust /// use std::thread; /// use std::time::Duration; /// /// use spirit::{Empty, Spirit}; /// /// Spirit::<_, Empty, _>::new(Empty {}) /// .run(|spirit| { /// while !spirit.is_terminated() { /// // Some reasonable work here /// thread::sleep(Duration::from_millis(100)); /// # spirit.terminate(); /// } /// /// Ok(()) /// }); /// ``` pub fn run<B: FnOnce(&Arc<Spirit<S, O, C>>) -> Result<(), Error> + Send + 'static>( self, body: B, ) { let result = log_errors(|| { let (_spirit, inner, wrapped) = self.before_body(body).build()?; debug!("Running bodies"); wrapped.run(inner) }); if result.is_err() { process::exit(1); } } /// Sets the configuration paths in case the user doesn't provide any. /// /// This replaces any previously set default paths. If none are specified and the user doesn't /// specify any either, no config is loaded (but it is not an error, simply the defaults will /// be used, if available). pub fn config_default_paths<P, I>(self, paths: I) -> Self where I: IntoIterator<Item = P>, P: Into<PathBuf>, { let paths = paths.into_iter().map(Into::into).collect(); Self { config_default_paths: paths, ..self } } /// Specifies the default configuration. /// /// This „loads“ the lowest layer of the configuration from the passed string. The expected /// format is TOML. pub fn config_defaults<D: Into<String>>(self, config: D) -> Self { Self { config_defaults: Some(config.into()), ..self } } /// Enables loading configuration from environment variables. /// /// If this is used, after loading the normal configuration files, the environment of the /// process is examined. Variables with the provided prefix are merged into the configuration. /// /// # Examples /// /// ```rust /// extern crate failure; /// #[macro_use] /// extern crate serde_derive; /// extern crate spirit; /// /// use failure::Error; /// use spirit::{Empty, Spirit}; /// /// #[derive(Default, Deserialize)] /// struct Cfg { /// message: String, /// } /// /// const DEFAULT_CFG: &str = r#" /// message = "Hello" /// "#; /// /// fn main() { /// Spirit::<_, Empty, _>::new(Cfg::default()) /// .config_defaults(DEFAULT_CFG) /// .config_env("HELLO") /// .run(|spirit| -> Result<(), Error> { /// println!("{}", spirit.config().message); /// Ok(()) /// }); /// } /// ``` /// /// If run like this, it'll print `Hi`. The environment takes precedence ‒ even if there was /// configuration file and it set the `message`, the `Hi` here would win. /// /// ```sh /// HELLO_MESSAGE="Hi" ./hello /// ``` pub fn config_env<E: Into<String>>(self, env: E) -> Self { Self { config_env: Some(env.into()), ..self } } /// Configures a config dir filter for a single extension. /// /// Sets the config directory filter (see [`config_filter`](#method.config_filter)) to one /// matching this single extension. pub fn config_ext<E: Into<OsString>>(self, ext: E) -> Self { let ext = ext.into(); Self { config_filter: Box::new(move |path| path.extension() == Some(&ext)), ..self } } /// Configures a config dir filter for multiple extensions. /// /// Sets the config directory filter (see [`config_filter`](#method.config_filter)) to one /// matching files with any of the provided extensions. pub fn config_exts<I, E>(self, exts: I) -> Self where I: IntoIterator<Item = E>, E: Into<OsString>, { let exts = exts.into_iter().map(Into::into).collect::<HashSet<_>>(); Self { config_filter: Box::new(move |path| { path.extension() .map(|ext| exts.contains(ext)) .unwrap_or(false) }), ..self } } /// Sets a configuration dir filter. /// /// If the user passes a directory path instead of a file path, the directory is traversed /// (every time the configuration is reloaded, so if files are added or removed, it is /// reflected) and files passing this filter are merged into the configuration, in the /// lexicographical order of their file names. /// /// There's ever only one filter and the default one passes no files (therefore, directories /// are ignored by default). /// /// The filter has no effect on files, only on loading directories. Only files directly in the /// directory are loaded ‒ subdirectories are not traversed. /// /// For more convenient ways to set the filter, see [`config_ext`](#method.config_ext) and /// [`config_exts`](#method.config_exts). pub fn config_filter<F: FnMut(&Path) -> bool + Send + 'static>(self, filter: F) -> Self { Self { config_filter: Box::new(filter), ..self } } /// Adds another config validator to the chain. /// /// The validators are there to check, possibly modify and possibly refuse a newly loaded /// configuration. /// /// The callback is passed three parameters: /// /// * The old configuration. /// * The new configuration (possible to modify). /// * The command line options. /// /// They are run in order of being set. Each one can pass arbitrary number of results, where a /// result can carry a message (of different severities) that ends up in logs and actions to be /// taken if the validation succeeds or fails. /// /// If none of the validator returns an error-level message, the validation passes. After it is /// determined if the configuration passed, either all the success or failure actions are run. /// /// # The actions /// /// Sometimes, the only way to validate a piece of config is to try it out ‒ like when you want /// to open a listening socket, you don't know if the port is free. But you can't activate and /// apply just yet, because something further down the configuration might still fail. /// /// So, you open the socket (or create an error result) and store it into the success action to /// apply it later on. If something fails, the action is dropped and the socket closed. /// /// The failure action lets you roll back (if it isn't done by simply dropping the thing). /// /// If the validation and application steps can be separated (you can check if something is OK /// by just „looking“ at it ‒ like with a regular expression and using it can't fail), you /// don't have to use them, just use verification and [`on_config`](#method.on_config) /// separately. /// /// TODO: Threads, deadlocks /// /// # Examples /// /// TODO pub fn config_validator<R, F>(self, mut f: F) -> Self where F: FnMut(&Arc<C>, &mut C, &O) -> R + Send + 'static, R: Into<ValidationResults>, { let wrapper = move |old: &Arc<C>, new: &mut C, opts: &O| f(old, new, opts).into(); let mut validators = self.config_validators; validators.push(Box::new(wrapper)); Self { config_validators: validators, ..self } } /// Adds a callback for notification about new configurations. /// /// The callback is called once a new configuration is loaded and successfully validated. /// /// TODO: Threads, deadlocks pub fn on_config<F: FnMut(&Arc<C>) + Send + 'static>(self, hook: F) -> Self { let mut hooks = self.config_hooks; hooks.push(Box::new(hook)); Self { config_hooks: hooks, ..self } } /// Adds a callback for reacting to a signal. /// /// The [`Spirit`](struct.Spirit.html) reacts to some signals itself, in its own service /// thread. However, it is also possible to hook into any signals directly (well, any except /// the ones that are [off limits](https://docs.rs/signal-hook/*/signal_hook/constant.FORBIDDEN.html)). /// /// These are not run inside the real signal handler, but are delayed and run in the service /// thread. Therefore, restrictions about async-signal-safety don't apply to the hook. /// /// TODO: Threads, deadlocks pub fn on_signal<F: FnMut() + Send + 'static>(self, signal: libc::c_int, hook: F) -> Self { let mut hooks = self.sig_hooks; hooks .entry(signal) .or_insert_with(Vec::new) .push(Box::new(hook)); Self { sig_hooks: hooks, ..self } } /// Adds a callback executed once the [`Spirit`](struct.Spirit.html) decides to terminate. /// /// This is called either when someone calls [`terminate`](struct.Spirit.html#method.terminate) /// or when a termination signal is received. /// /// Note that there are ways the application may terminate without calling these hooks ‒ for /// example terminating the main thread, or aborting. /// /// TODO: Threads, deadlocks pub fn on_terminate<F: FnMut() + Send + 'static>(self, hook: F) -> Self { let mut hooks = self.terminate_hooks; hooks.push(Box::new(hook)); Self { terminate_hooks: hooks, ..self } } }