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
//! A module for simulating multiple memories within a single memory.
//!
//! The typical way for a canister to have multiple stable structures is by dividing the memory into
//! distinct ranges, dedicating each range to a stable structure. This approach has two problems:
//!
//! 1. The developer needs to put in advance an upper bound on the memory of each stable structure.
//! 2. It wastes the canister's memory allocation. For example, if a canister creates two stable
//! structures A and B, and gives each one of them a 1GiB region of memory, then writing to B will
//! require growing > 1GiB of memory just to be able to write to it.
//!
//! The [`MemoryManager`] in this module solves both of these problems. It simulates having
//! multiple memories, each being able to grow without bound. That way, a developer doesn't need to
//! put an upper bound to how much stable structures can grow, and the canister's memory allocation
//! becomes less wasteful.
//!
//! Example Usage:
//!
//! ```
//! use ic_stable_structures::{DefaultMemoryImpl, Memory};
//! use ic_stable_structures::memory_manager::{MemoryManager, MemoryId};
//!
//! let mem_mgr = MemoryManager::init(DefaultMemoryImpl::default());
//!
//! // Create different memories, each with a unique ID.
//! let memory_0 = mem_mgr.get(MemoryId::new(0));
//! let memory_1 = mem_mgr.get(MemoryId::new(1));
//!
//! // Each memory can be used independently.
//! memory_0.grow(1);
//! memory_0.write(0, &[1, 2, 3]);
//!
//! memory_1.grow(1);
//! memory_1.write(0, &[4, 5, 6]);
//!
//! let mut bytes = vec![0; 3];
//! memory_0.read(0, &mut bytes);
//! assert_eq!(bytes, vec![1, 2, 3]);
//!
//! let mut bytes = vec![0; 3];
//! memory_1.read(0, &mut bytes);
//! assert_eq!(bytes, vec![4, 5, 6]);
//! ```
use crate::{
read_struct,
types::{Address, Bytes},
write, write_struct, Memory, WASM_PAGE_SIZE,
};
use std::cell::RefCell;
use std::cmp::min;
use std::collections::BTreeMap;
use std::rc::Rc;
const MAGIC: &[u8; 3] = b"MGR";
const LAYOUT_VERSION: u8 = 1;
// The maximum number of memories that can be created.
const MAX_NUM_MEMORIES: u8 = 255;
// The maximum number of buckets the memory manager can handle.
// With a bucket size of 128 pages this can support up to 256GiB of memory.
const MAX_NUM_BUCKETS: u64 = 32768;
const BUCKET_SIZE_IN_PAGES: u64 = 128;
// A value used internally to indicate that a bucket is unallocated.
const UNALLOCATED_BUCKET_MARKER: u8 = MAX_NUM_MEMORIES;
// The offset where buckets are in memory.
const BUCKETS_OFFSET_IN_PAGES: u64 = 1;
const BUCKETS_OFFSET_IN_BYTES: u64 = BUCKETS_OFFSET_IN_PAGES * WASM_PAGE_SIZE;
// Reserved bytes in the header for future extensions.
const HEADER_RESERVED_BYTES: usize = 32;
/// A memory manager simulates multiple memories within a single memory.
///
/// The memory manager can return up to 255 unique instances of [`VirtualMemory`], and each can be
/// used independently and can grow up to the bounds of the underlying memory.
///
/// By default, the memory manager divides the memory into "buckets" of 128 pages. Each
/// [`VirtualMemory`] is internally represented as a list of buckets. Buckets of different memories
/// can be interleaved, but the [`VirtualMemory`] interface gives the illusion of a continuous
/// address space.
///
/// Because a [`VirtualMemory`] is a list of buckets, this implies that internally it grows one
/// bucket at a time.
///
/// The first page of the memory is reserved for the memory manager's own state. The layout for
/// this state is as follows:
///
/// # V1 layout
///
/// ```text
/// -------------------------------------------------- <- Address 0
/// Magic "MGR" ↕ 3 bytes
/// --------------------------------------------------
/// Layout version ↕ 1 byte
/// --------------------------------------------------
/// Number of allocated buckets ↕ 2 bytes
/// --------------------------------------------------
/// Bucket size (in pages) = N ↕ 2 bytes
/// --------------------------------------------------
/// Reserved space ↕ 32 bytes
/// --------------------------------------------------
/// Size of memory 0 (in pages) ↕ 8 bytes
/// --------------------------------------------------
/// Size of memory 1 (in pages) ↕ 8 bytes
/// --------------------------------------------------
/// ...
/// --------------------------------------------------
/// Size of memory 254 (in pages) ↕ 8 bytes
/// -------------------------------------------------- <- Bucket allocations
/// Bucket 1 ↕ 1 byte (1 byte indicating which memory owns it)
/// --------------------------------------------------
/// Bucket 2 ↕ 1 byte
/// --------------------------------------------------
/// ...
/// --------------------------------------------------
/// Bucket `MAX_NUM_BUCKETS` ↕ 1 byte
/// --------------------------------------------------
/// Unallocated space ↕ 30'688 bytes
/// -------------------------------------------------- <- Buckets (Page 1)
/// Bucket 1 ↕ N pages
/// -------------------------------------------------- <- Page N + 1
/// Bucket 2 ↕ N pages
/// --------------------------------------------------
/// ...
/// -------------------------------------------------- <- Page ((MAX_NUM_BUCKETS - 1) * N + 1)
/// Bucket MAX_NUM_BUCKETS ↕ N pages
/// ```
pub struct MemoryManager<M: Memory> {
inner: Rc<RefCell<MemoryManagerInner<M>>>,
}
impl<M: Memory> MemoryManager<M> {
/// Initializes a `MemoryManager` with the given memory.
pub fn init(memory: M) -> Self {
Self::init_with_bucket_size(memory, BUCKET_SIZE_IN_PAGES as u16)
}
/// Initializes a `MemoryManager` with the given memory and bucket size in pages.
pub fn init_with_bucket_size(memory: M, bucket_size_in_pages: u16) -> Self {
Self {
inner: Rc::new(RefCell::new(MemoryManagerInner::init(
memory,
bucket_size_in_pages,
))),
}
}
/// Returns the memory associated with the given ID.
pub fn get(&self, id: MemoryId) -> VirtualMemory<M> {
VirtualMemory {
id,
memory_manager: self.inner.clone(),
}
}
/// Returns the underlying memory.
///
/// # Returns
/// - The underlying memory, if there is exactly one strong reference to the memory manager. Please see [`Rc::try_unwrap`](https://doc.rust-lang.org/std/rc/struct.Rc.html#method.try_unwrap) for more details.
/// - None otherwise.
pub fn into_memory(self) -> Option<M> {
Rc::into_inner(self.inner).map(|inner| inner.into_inner().into_memory())
}
}
#[repr(C, packed)]
struct Header {
magic: [u8; 3],
version: u8,
// The number of buckets allocated by the memory manager.
num_allocated_buckets: u16,
// The size of a bucket in Wasm pages.
bucket_size_in_pages: u16,
// Reserved bytes for future extensions
_reserved: [u8; HEADER_RESERVED_BYTES],
// The size of each individual memory that can be created by the memory manager.
memory_sizes_in_pages: [u64; MAX_NUM_MEMORIES as usize],
}
impl Header {
fn size() -> Bytes {
Bytes::new(core::mem::size_of::<Self>() as u64)
}
}
#[derive(Clone)]
pub struct VirtualMemory<M: Memory> {
id: MemoryId,
memory_manager: Rc<RefCell<MemoryManagerInner<M>>>,
}
impl<M: Memory> Memory for VirtualMemory<M> {
fn size(&self) -> u64 {
self.memory_manager.borrow().memory_size(self.id)
}
fn grow(&self, pages: u64) -> i64 {
self.memory_manager.borrow_mut().grow(self.id, pages)
}
fn read(&self, offset: u64, dst: &mut [u8]) {
self.memory_manager.borrow().read(self.id, offset, dst)
}
fn write(&self, offset: u64, src: &[u8]) {
self.memory_manager.borrow().write(self.id, offset, src)
}
}
#[derive(Clone)]
struct MemoryManagerInner<M: Memory> {
memory: M,
// The number of buckets that have been allocated.
allocated_buckets: u16,
bucket_size_in_pages: u16,
// An array storing the size (in pages) of each of the managed memories.
memory_sizes_in_pages: [u64; MAX_NUM_MEMORIES as usize],
// A map mapping each managed memory to the bucket ids that are allocated to it.
memory_buckets: BTreeMap<MemoryId, Vec<BucketId>>,
}
impl<M: Memory> MemoryManagerInner<M> {
fn init(memory: M, bucket_size_in_pages: u16) -> Self {
if memory.size() == 0 {
// Memory is empty. Create a new map.
return Self::new(memory, bucket_size_in_pages);
}
// Check if the magic in the memory corresponds to this object.
let mut dst = vec![0; 3];
memory.read(0, &mut dst);
if dst != MAGIC {
// No memory manager found. Create a new instance.
MemoryManagerInner::new(memory, bucket_size_in_pages)
} else {
// The memory already contains a memory manager. Load it.
MemoryManagerInner::load(memory)
}
}
fn new(memory: M, bucket_size_in_pages: u16) -> Self {
let mem_mgr = Self {
memory,
allocated_buckets: 0,
memory_sizes_in_pages: [0; MAX_NUM_MEMORIES as usize],
memory_buckets: BTreeMap::new(),
bucket_size_in_pages,
};
mem_mgr.save_header();
// Mark all the buckets as unallocated.
write(
&mem_mgr.memory,
bucket_allocations_address(BucketId(0)).get(),
&[UNALLOCATED_BUCKET_MARKER; MAX_NUM_BUCKETS as usize],
);
mem_mgr
}
fn load(memory: M) -> Self {
// Read the header from memory.
let header: Header = read_struct(Address::from(0), &memory);
assert_eq!(&header.magic, MAGIC, "Bad magic.");
assert_eq!(header.version, LAYOUT_VERSION, "Unsupported version.");
let mut buckets = vec![0; MAX_NUM_BUCKETS as usize];
memory.read(bucket_allocations_address(BucketId(0)).get(), &mut buckets);
let mut memory_buckets = BTreeMap::new();
for (bucket_idx, memory) in buckets.into_iter().enumerate() {
if memory != UNALLOCATED_BUCKET_MARKER {
memory_buckets
.entry(MemoryId(memory))
.or_insert_with(Vec::new)
.push(BucketId(bucket_idx as u16));
}
}
Self {
memory,
allocated_buckets: header.num_allocated_buckets,
bucket_size_in_pages: header.bucket_size_in_pages,
memory_sizes_in_pages: header.memory_sizes_in_pages,
memory_buckets,
}
}
fn save_header(&self) {
let header = Header {
magic: *MAGIC,
version: LAYOUT_VERSION,
num_allocated_buckets: self.allocated_buckets,
bucket_size_in_pages: self.bucket_size_in_pages,
_reserved: [0; HEADER_RESERVED_BYTES],
memory_sizes_in_pages: self.memory_sizes_in_pages,
};
write_struct(&header, Address::from(0), &self.memory);
}
// Returns the size of a memory (in pages).
fn memory_size(&self, id: MemoryId) -> u64 {
self.memory_sizes_in_pages[id.0 as usize]
}
// Grows the memory with the given id by the given number of pages.
fn grow(&mut self, id: MemoryId, pages: u64) -> i64 {
// Compute how many additional buckets are needed.
let old_size = self.memory_size(id);
let new_size = old_size + pages;
let current_buckets = self.num_buckets_needed(old_size);
let required_buckets = self.num_buckets_needed(new_size);
let new_buckets_needed = required_buckets - current_buckets;
if new_buckets_needed + self.allocated_buckets as u64 > MAX_NUM_BUCKETS {
// Exceeded the memory that can be managed.
return -1;
}
// Allocate new buckets as needed.
for _ in 0..new_buckets_needed {
let new_bucket_id = BucketId(self.allocated_buckets);
self.memory_buckets
.entry(id)
.or_default()
.push(new_bucket_id);
// Write in stable store that this bucket belongs to the memory with the provided `id`.
write(
&self.memory,
bucket_allocations_address(new_bucket_id).get(),
&[id.0],
);
self.allocated_buckets += 1;
}
// Grow the underlying memory if necessary.
let pages_needed = BUCKETS_OFFSET_IN_PAGES
+ self.bucket_size_in_pages as u64 * self.allocated_buckets as u64;
if pages_needed > self.memory.size() {
let additional_pages_needed = pages_needed - self.memory.size();
let prev_pages = self.memory.grow(additional_pages_needed);
if prev_pages == -1 {
panic!("{id:?}: grow failed");
}
}
// Update the memory with the new size.
self.memory_sizes_in_pages[id.0 as usize] = new_size;
// Update the header and return the old size.
self.save_header();
old_size as i64
}
fn write(&self, id: MemoryId, offset: u64, src: &[u8]) {
if (offset + src.len() as u64) > self.memory_size(id) * WASM_PAGE_SIZE {
panic!("{id:?}: write out of bounds");
}
let mut bytes_written = 0;
for Segment { address, length } in self.bucket_iter(id, offset, src.len()) {
self.memory.write(
address.get(),
&src[bytes_written as usize..(bytes_written + length.get()) as usize],
);
bytes_written += length.get();
}
}
fn read(&self, id: MemoryId, offset: u64, dst: &mut [u8]) {
if (offset + dst.len() as u64) > self.memory_size(id) * WASM_PAGE_SIZE {
panic!("{id:?}: read out of bounds");
}
let mut bytes_read = 0;
for Segment { address, length } in self.bucket_iter(id, offset, dst.len()) {
self.memory.read(
address.get(),
&mut dst[bytes_read as usize..(bytes_read + length.get()) as usize],
);
bytes_read += length.get();
}
}
// Initializes a [`BucketIterator`].
fn bucket_iter(&self, id: MemoryId, offset: u64, length: usize) -> BucketIterator {
// Get the buckets allocated to the given memory id.
let buckets = match self.memory_buckets.get(&id) {
Some(s) => s.as_slice(),
None => &[],
};
BucketIterator {
virtual_segment: Segment {
address: Address::from(offset),
length: Bytes::from(length as u64),
},
buckets,
bucket_size_in_bytes: self.bucket_size_in_bytes(),
}
}
fn bucket_size_in_bytes(&self) -> Bytes {
Bytes::from(self.bucket_size_in_pages as u64 * WASM_PAGE_SIZE)
}
// Returns the number of buckets needed to accommodate the given number of pages.
fn num_buckets_needed(&self, num_pages: u64) -> u64 {
// Ceiling division.
(num_pages + self.bucket_size_in_pages as u64 - 1) / self.bucket_size_in_pages as u64
}
// Returns the underlying memory.
pub fn into_memory(self) -> M {
self.memory
}
}
struct Segment {
address: Address,
length: Bytes,
}
// An iterator that maps a segment of virtual memory to segments of real memory.
//
// A segment in virtual memory can map to multiple segments of real memory. Here's an example:
//
// Virtual Memory
// --------------------------------------------------------
// (A) ---------- SEGMENT ---------- (B)
// --------------------------------------------------------
// ↑ ↑ ↑ ↑
// Bucket 0 Bucket 1 Bucket 2 Bucket 3
//
// The [`VirtualMemory`] is internally divided into fixed-size buckets. In the memory's virtual
// address space, all these buckets are consecutive, but in real memory this may not be the case.
//
// A virtual segment would first be split at the bucket boundaries. The example virtual segment
// above would be split into the following segments:
//
// (A, end of bucket 0)
// (start of bucket 1, end of bucket 1)
// (start of bucket 2, B)
//
// Each of the segments above can then be translated into the real address space by looking up
// the underlying buckets' addresses in real memory.
struct BucketIterator<'a> {
virtual_segment: Segment,
buckets: &'a [BucketId],
bucket_size_in_bytes: Bytes,
}
impl Iterator for BucketIterator<'_> {
type Item = Segment;
fn next(&mut self) -> Option<Self::Item> {
if self.virtual_segment.length == Bytes::from(0u64) {
return None;
}
// Map the virtual segment's address to a real address.
let bucket_idx =
(self.virtual_segment.address.get() / self.bucket_size_in_bytes.get()) as usize;
let bucket_address = self.bucket_address(
*self
.buckets
.get(bucket_idx)
.expect("bucket idx out of bounds"),
);
let real_address = bucket_address
+ Bytes::from(self.virtual_segment.address.get() % self.bucket_size_in_bytes.get());
// Compute how many bytes are in this real segment.
let bytes_in_segment = {
let next_bucket_address = bucket_address + self.bucket_size_in_bytes;
// Write up to either the end of the bucket, or the end of the segment.
min(
Bytes::from(next_bucket_address.get() - real_address.get()),
self.virtual_segment.length,
)
};
// Update the virtual segment to exclude the portion we're about to return.
self.virtual_segment.length -= bytes_in_segment;
self.virtual_segment.address += bytes_in_segment;
Some(Segment {
address: real_address,
length: bytes_in_segment,
})
}
}
impl<'a> BucketIterator<'a> {
// Returns the address of a given bucket.
fn bucket_address(&self, id: BucketId) -> Address {
Address::from(BUCKETS_OFFSET_IN_BYTES) + self.bucket_size_in_bytes * Bytes::from(id.0)
}
}
#[derive(Clone, Copy, Ord, Eq, PartialEq, PartialOrd, Debug)]
pub struct MemoryId(u8);
impl MemoryId {
pub const fn new(id: u8) -> Self {
// Any ID can be used except the special value that's used internally to
// mark a bucket as unallocated.
assert!(id != UNALLOCATED_BUCKET_MARKER);
Self(id)
}
}
// Referring to a bucket.
#[derive(Clone, Copy, Debug, PartialEq)]
struct BucketId(u16);
fn bucket_allocations_address(id: BucketId) -> Address {
Address::from(0) + Header::size() + Bytes::from(id.0)
}
#[cfg(test)]
mod test {
use super::*;
use maplit::btreemap;
use proptest::prelude::*;
const MAX_MEMORY_IN_PAGES: u64 = MAX_NUM_BUCKETS * BUCKET_SIZE_IN_PAGES;
fn make_memory() -> Rc<RefCell<Vec<u8>>> {
Rc::new(RefCell::new(Vec::new()))
}
#[test]
fn can_get_memory() {
let mem_mgr = MemoryManager::init(make_memory());
let memory = mem_mgr.get(MemoryId(0));
assert_eq!(memory.size(), 0);
}
#[test]
fn can_allocate_and_use_memory() {
let mem_mgr = MemoryManager::init(make_memory());
let memory = mem_mgr.get(MemoryId(0));
assert_eq!(memory.grow(1), 0);
assert_eq!(memory.size(), 1);
memory.write(0, &[1, 2, 3]);
let mut bytes = vec![0; 3];
memory.read(0, &mut bytes);
assert_eq!(bytes, vec![1, 2, 3]);
assert_eq!(
mem_mgr.inner.borrow().memory_buckets,
btreemap! {
MemoryId(0) => vec![BucketId(0)]
}
);
}
#[test]
fn can_allocate_and_use_multiple_memories() {
let mem = make_memory();
let mem_mgr = MemoryManager::init(mem.clone());
let memory_0 = mem_mgr.get(MemoryId(0));
let memory_1 = mem_mgr.get(MemoryId(1));
assert_eq!(memory_0.grow(1), 0);
assert_eq!(memory_1.grow(1), 0);
assert_eq!(memory_0.size(), 1);
assert_eq!(memory_1.size(), 1);
assert_eq!(
mem_mgr.inner.borrow().memory_buckets,
btreemap! {
MemoryId(0) => vec![BucketId(0)],
MemoryId(1) => vec![BucketId(1)],
}
);
memory_0.write(0, &[1, 2, 3]);
memory_0.write(0, &[1, 2, 3]);
memory_1.write(0, &[4, 5, 6]);
let mut bytes = vec![0; 3];
memory_0.read(0, &mut bytes);
assert_eq!(bytes, vec![1, 2, 3]);
let mut bytes = vec![0; 3];
memory_1.read(0, &mut bytes);
assert_eq!(bytes, vec![4, 5, 6]);
// + 1 is for the header.
assert_eq!(mem.size(), 2 * BUCKET_SIZE_IN_PAGES + 1);
}
#[test]
fn can_be_reinitialized_from_memory() {
let mem = make_memory();
let mem_mgr = MemoryManager::init(mem.clone());
let memory_0 = mem_mgr.get(MemoryId(0));
let memory_1 = mem_mgr.get(MemoryId(1));
assert_eq!(memory_0.grow(1), 0);
assert_eq!(memory_1.grow(1), 0);
memory_0.write(0, &[1, 2, 3]);
memory_1.write(0, &[4, 5, 6]);
let mem_mgr = MemoryManager::init(mem);
let memory_0 = mem_mgr.get(MemoryId(0));
let memory_1 = mem_mgr.get(MemoryId(1));
let mut bytes = vec![0; 3];
memory_0.read(0, &mut bytes);
assert_eq!(bytes, vec![1, 2, 3]);
memory_1.read(0, &mut bytes);
assert_eq!(bytes, vec![4, 5, 6]);
}
#[test]
fn growing_same_memory_multiple_times_doesnt_increase_underlying_allocation() {
let mem = make_memory();
let mem_mgr = MemoryManager::init(mem.clone());
let memory_0 = mem_mgr.get(MemoryId(0));
// Grow the memory by 1 page. This should increase the underlying allocation
// by `BUCKET_SIZE_IN_PAGES` pages.
assert_eq!(memory_0.grow(1), 0);
assert_eq!(mem.size(), 1 + BUCKET_SIZE_IN_PAGES);
// Grow the memory again. This should NOT increase the underlying allocation.
assert_eq!(memory_0.grow(1), 1);
assert_eq!(memory_0.size(), 2);
assert_eq!(mem.size(), 1 + BUCKET_SIZE_IN_PAGES);
// Grow the memory up to the BUCKET_SIZE_IN_PAGES. This should NOT increase the underlying
// allocation.
assert_eq!(memory_0.grow(BUCKET_SIZE_IN_PAGES - 2), 2);
assert_eq!(memory_0.size(), BUCKET_SIZE_IN_PAGES);
assert_eq!(mem.size(), 1 + BUCKET_SIZE_IN_PAGES);
// Grow the memory by one more page. This should increase the underlying allocation.
assert_eq!(memory_0.grow(1), BUCKET_SIZE_IN_PAGES as i64);
assert_eq!(memory_0.size(), BUCKET_SIZE_IN_PAGES + 1);
assert_eq!(mem.size(), 1 + 2 * BUCKET_SIZE_IN_PAGES);
}
#[test]
fn does_not_grow_memory_unnecessarily() {
let mem = make_memory();
let initial_size = BUCKET_SIZE_IN_PAGES * 2;
// Grow the memory manually before passing it into the memory manager.
mem.grow(initial_size);
let mem_mgr = MemoryManager::init(mem.clone());
let memory_0 = mem_mgr.get(MemoryId(0));
// Grow the memory by 1 page.
assert_eq!(memory_0.grow(1), 0);
assert_eq!(mem.size(), initial_size);
// Grow the memory by BUCKET_SIZE_IN_PAGES more pages, which will cause the underlying
// allocation to increase.
assert_eq!(memory_0.grow(BUCKET_SIZE_IN_PAGES), 1);
assert_eq!(mem.size(), 1 + BUCKET_SIZE_IN_PAGES * 2);
}
#[test]
fn growing_beyond_capacity_fails() {
let mem = make_memory();
let mem_mgr = MemoryManager::init(mem);
let memory_0 = mem_mgr.get(MemoryId(0));
assert_eq!(memory_0.grow(MAX_MEMORY_IN_PAGES + 1), -1);
// Try to grow the memory by MAX_MEMORY_IN_PAGES + 1.
assert_eq!(memory_0.grow(1), 0); // should succeed
assert_eq!(memory_0.grow(MAX_MEMORY_IN_PAGES), -1); // should fail.
}
#[test]
fn can_write_across_bucket_boundaries() {
let mem = make_memory();
let mem_mgr = MemoryManager::init(mem);
let memory_0 = mem_mgr.get(MemoryId(0));
assert_eq!(memory_0.grow(BUCKET_SIZE_IN_PAGES + 1), 0);
memory_0.write(
mem_mgr.inner.borrow().bucket_size_in_bytes().get() - 1,
&[1, 2, 3],
);
let mut bytes = vec![0; 3];
memory_0.read(
mem_mgr.inner.borrow().bucket_size_in_bytes().get() - 1,
&mut bytes,
);
assert_eq!(bytes, vec![1, 2, 3]);
}
#[test]
fn can_write_across_bucket_boundaries_with_interleaving_memories() {
let mem = make_memory();
let mem_mgr = MemoryManager::init(mem);
let memory_0 = mem_mgr.get(MemoryId(0));
let memory_1 = mem_mgr.get(MemoryId(1));
assert_eq!(memory_0.grow(BUCKET_SIZE_IN_PAGES), 0);
assert_eq!(memory_1.grow(1), 0);
assert_eq!(memory_0.grow(1), BUCKET_SIZE_IN_PAGES as i64);
memory_0.write(
mem_mgr.inner.borrow().bucket_size_in_bytes().get() - 1,
&[1, 2, 3],
);
memory_1.write(0, &[4, 5, 6]);
let mut bytes = vec![0; 3];
memory_0.read(WASM_PAGE_SIZE * BUCKET_SIZE_IN_PAGES - 1, &mut bytes);
assert_eq!(bytes, vec![1, 2, 3]);
let mut bytes = vec![0; 3];
memory_1.read(0, &mut bytes);
assert_eq!(bytes, vec![4, 5, 6]);
}
#[test]
#[should_panic]
fn reading_out_of_bounds_should_panic() {
let mem = make_memory();
let mem_mgr = MemoryManager::init(mem);
let memory_0 = mem_mgr.get(MemoryId(0));
let memory_1 = mem_mgr.get(MemoryId(1));
assert_eq!(memory_0.grow(1), 0);
assert_eq!(memory_1.grow(1), 0);
let mut bytes = vec![0; WASM_PAGE_SIZE as usize + 1];
memory_0.read(0, &mut bytes);
}
#[test]
#[should_panic]
fn writing_out_of_bounds_should_panic() {
let mem = make_memory();
let mem_mgr = MemoryManager::init(mem);
let memory_0 = mem_mgr.get(MemoryId(0));
let memory_1 = mem_mgr.get(MemoryId(1));
assert_eq!(memory_0.grow(1), 0);
assert_eq!(memory_1.grow(1), 0);
let bytes = vec![0; WASM_PAGE_SIZE as usize + 1];
memory_0.write(0, &bytes);
}
#[test]
fn reading_zero_bytes_from_empty_memory_should_not_panic() {
let mem = make_memory();
let mem_mgr = MemoryManager::init(mem);
let memory_0 = mem_mgr.get(MemoryId(0));
assert_eq!(memory_0.size(), 0);
let mut bytes = vec![];
memory_0.read(0, &mut bytes);
}
#[test]
fn writing_zero_bytes_to_empty_memory_should_not_panic() {
let mem = make_memory();
let mem_mgr = MemoryManager::init(mem);
let memory_0 = mem_mgr.get(MemoryId(0));
assert_eq!(memory_0.size(), 0);
memory_0.write(0, &[]);
}
#[test]
fn write_and_read_random_bytes() {
let mem = make_memory();
let mem_mgr = MemoryManager::init_with_bucket_size(mem, 1); // very small bucket size.
let memories: Vec<_> = (0..MAX_NUM_MEMORIES)
.map(|id| mem_mgr.get(MemoryId(id)))
.collect();
proptest!(|(
num_memories in 0..255usize,
data in proptest::collection::vec(0..u8::MAX, 0..2*WASM_PAGE_SIZE as usize),
offset in 0..10*WASM_PAGE_SIZE
)| {
for memory in memories.iter().take(num_memories) {
// Write a random blob into the memory, growing the memory as it needs to.
write(memory, offset, &data);
// Verify the blob can be read back.
let mut bytes = vec![0; data.len()];
memory.read(offset, &mut bytes);
assert_eq!(bytes, data);
}
});
}
#[test]
fn init_with_non_default_bucket_size() {
// Choose a bucket size that's different from the default bucket size.
let bucket_size = 256;
assert_ne!(bucket_size, BUCKET_SIZE_IN_PAGES as u16);
// Initialize the memory manager.
let mem = make_memory();
let mem_mgr = MemoryManager::init_with_bucket_size(mem.clone(), bucket_size);
// Do some writes.
let memory_0 = mem_mgr.get(MemoryId(0));
let memory_1 = mem_mgr.get(MemoryId(1));
memory_0.grow(300);
memory_1.grow(100);
memory_0.write(0, &[1; 1000]);
memory_1.write(0, &[2; 1000]);
// Reinitializes the memory manager using the `init` method, without specifying
// the bucket size.
let mem_mgr = MemoryManager::init(mem);
// Assert the bucket size is correct.
assert_eq!(mem_mgr.inner.borrow().bucket_size_in_pages, bucket_size);
// Assert that the data written is correct.
let memory_0 = mem_mgr.get(MemoryId(0));
let memory_1 = mem_mgr.get(MemoryId(1));
assert_eq!(memory_0.size(), 300);
assert_eq!(memory_1.size(), 100);
let mut buf = vec![0; 1000];
memory_0.read(0, &mut buf);
assert_eq!(buf, vec![1; 1000]);
memory_1.read(0, &mut buf);
assert_eq!(buf, vec![2; 1000]);
}
}