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-rw-r--r--xpcom/glue/PLDHashTable.cpp801
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diff --git a/xpcom/glue/PLDHashTable.cpp b/xpcom/glue/PLDHashTable.cpp
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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <new>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include "PLDHashTable.h"
+#include "mozilla/HashFunctions.h"
+#include "mozilla/MathAlgorithms.h"
+#include "mozilla/OperatorNewExtensions.h"
+#include "nsAlgorithm.h"
+#include "mozilla/Likely.h"
+#include "mozilla/MemoryReporting.h"
+#include "mozilla/ChaosMode.h"
+
+using namespace mozilla;
+
+#ifdef DEBUG
+
+class AutoReadOp
+{
+ Checker& mChk;
+public:
+ explicit AutoReadOp(Checker& aChk) : mChk(aChk) { mChk.StartReadOp(); }
+ ~AutoReadOp() { mChk.EndReadOp(); }
+};
+
+class AutoWriteOp
+{
+ Checker& mChk;
+public:
+ explicit AutoWriteOp(Checker& aChk) : mChk(aChk) { mChk.StartWriteOp(); }
+ ~AutoWriteOp() { mChk.EndWriteOp(); }
+};
+
+class AutoIteratorRemovalOp
+{
+ Checker& mChk;
+public:
+ explicit AutoIteratorRemovalOp(Checker& aChk)
+ : mChk(aChk)
+ {
+ mChk.StartIteratorRemovalOp();
+ }
+ ~AutoIteratorRemovalOp() { mChk.EndIteratorRemovalOp(); }
+};
+
+class AutoDestructorOp
+{
+ Checker& mChk;
+public:
+ explicit AutoDestructorOp(Checker& aChk)
+ : mChk(aChk)
+ {
+ mChk.StartDestructorOp();
+ }
+ ~AutoDestructorOp() { mChk.EndDestructorOp(); }
+};
+
+#endif
+
+/* static */ PLDHashNumber
+PLDHashTable::HashStringKey(const void* aKey)
+{
+ return HashString(static_cast<const char*>(aKey));
+}
+
+/* static */ PLDHashNumber
+PLDHashTable::HashVoidPtrKeyStub(const void* aKey)
+{
+ return (PLDHashNumber)(ptrdiff_t)aKey >> 2;
+}
+
+/* static */ bool
+PLDHashTable::MatchEntryStub(const PLDHashEntryHdr* aEntry, const void* aKey)
+{
+ const PLDHashEntryStub* stub = (const PLDHashEntryStub*)aEntry;
+
+ return stub->key == aKey;
+}
+
+/* static */ bool
+PLDHashTable::MatchStringKey(const PLDHashEntryHdr* aEntry, const void* aKey)
+{
+ const PLDHashEntryStub* stub = (const PLDHashEntryStub*)aEntry;
+
+ // XXX tolerate null keys on account of sloppy Mozilla callers.
+ return stub->key == aKey ||
+ (stub->key && aKey &&
+ strcmp((const char*)stub->key, (const char*)aKey) == 0);
+}
+
+/* static */ void
+PLDHashTable::MoveEntryStub(PLDHashTable* aTable,
+ const PLDHashEntryHdr* aFrom,
+ PLDHashEntryHdr* aTo)
+{
+ memcpy(aTo, aFrom, aTable->mEntrySize);
+}
+
+/* static */ void
+PLDHashTable::ClearEntryStub(PLDHashTable* aTable, PLDHashEntryHdr* aEntry)
+{
+ memset(aEntry, 0, aTable->mEntrySize);
+}
+
+static const PLDHashTableOps gStubOps = {
+ PLDHashTable::HashVoidPtrKeyStub,
+ PLDHashTable::MatchEntryStub,
+ PLDHashTable::MoveEntryStub,
+ PLDHashTable::ClearEntryStub,
+ nullptr
+};
+
+/* static */ const PLDHashTableOps*
+PLDHashTable::StubOps()
+{
+ return &gStubOps;
+}
+
+static bool
+SizeOfEntryStore(uint32_t aCapacity, uint32_t aEntrySize, uint32_t* aNbytes)
+{
+ uint64_t nbytes64 = uint64_t(aCapacity) * uint64_t(aEntrySize);
+ *aNbytes = aCapacity * aEntrySize;
+ return uint64_t(*aNbytes) == nbytes64; // returns false on overflow
+}
+
+// Compute max and min load numbers (entry counts). We have a secondary max
+// that allows us to overload a table reasonably if it cannot be grown further
+// (i.e. if ChangeTable() fails). The table slows down drastically if the
+// secondary max is too close to 1, but 0.96875 gives only a slight slowdown
+// while allowing 1.3x more elements.
+static inline uint32_t
+MaxLoad(uint32_t aCapacity)
+{
+ return aCapacity - (aCapacity >> 2); // == aCapacity * 0.75
+}
+static inline uint32_t
+MaxLoadOnGrowthFailure(uint32_t aCapacity)
+{
+ return aCapacity - (aCapacity >> 5); // == aCapacity * 0.96875
+}
+static inline uint32_t
+MinLoad(uint32_t aCapacity)
+{
+ return aCapacity >> 2; // == aCapacity * 0.25
+}
+
+// Compute the minimum capacity (and the Log2 of that capacity) for a table
+// containing |aLength| elements while respecting the following contraints:
+// - table must be at most 75% full;
+// - capacity must be a power of two;
+// - capacity cannot be too small.
+static inline void
+BestCapacity(uint32_t aLength, uint32_t* aCapacityOut,
+ uint32_t* aLog2CapacityOut)
+{
+ // Compute the smallest capacity allowing |aLength| elements to be inserted
+ // without rehashing.
+ uint32_t capacity = (aLength * 4 + (3 - 1)) / 3; // == ceil(aLength * 4 / 3)
+ if (capacity < PLDHashTable::kMinCapacity) {
+ capacity = PLDHashTable::kMinCapacity;
+ }
+
+ // Round up capacity to next power-of-two.
+ uint32_t log2 = CeilingLog2(capacity);
+ capacity = 1u << log2;
+ MOZ_ASSERT(capacity <= PLDHashTable::kMaxCapacity);
+
+ *aCapacityOut = capacity;
+ *aLog2CapacityOut = log2;
+}
+
+/* static */ MOZ_ALWAYS_INLINE uint32_t
+PLDHashTable::HashShift(uint32_t aEntrySize, uint32_t aLength)
+{
+ if (aLength > kMaxInitialLength) {
+ MOZ_CRASH("Initial length is too large");
+ }
+
+ uint32_t capacity, log2;
+ BestCapacity(aLength, &capacity, &log2);
+
+ uint32_t nbytes;
+ if (!SizeOfEntryStore(capacity, aEntrySize, &nbytes)) {
+ MOZ_CRASH("Initial entry store size is too large");
+ }
+
+ // Compute the hashShift value.
+ return kHashBits - log2;
+}
+
+PLDHashTable::PLDHashTable(const PLDHashTableOps* aOps, uint32_t aEntrySize,
+ uint32_t aLength)
+ : mOps(aOps)
+ , mHashShift(HashShift(aEntrySize, aLength))
+ , mEntrySize(aEntrySize)
+ , mEntryCount(0)
+ , mRemovedCount(0)
+ , mEntryStore()
+#ifdef DEBUG
+ , mChecker()
+#endif
+{
+}
+
+PLDHashTable&
+PLDHashTable::operator=(PLDHashTable&& aOther)
+{
+ if (this == &aOther) {
+ return *this;
+ }
+
+ // Destruct |this|.
+ this->~PLDHashTable();
+
+ // |mOps| and |mEntrySize| are const so we can't assign them. Instead, we
+ // require that they are equal. The justification for this is that they're
+ // conceptually part of the type -- indeed, if PLDHashTable was a templated
+ // type like nsTHashtable, they *would* be part of the type -- so it only
+ // makes sense to assign in cases where they match.
+ MOZ_RELEASE_ASSERT(mOps == aOther.mOps);
+ MOZ_RELEASE_ASSERT(mEntrySize == aOther.mEntrySize);
+
+ // Move non-const pieces over.
+ mHashShift = Move(aOther.mHashShift);
+ mEntryCount = Move(aOther.mEntryCount);
+ mRemovedCount = Move(aOther.mRemovedCount);
+ mEntryStore = Move(aOther.mEntryStore);
+#ifdef DEBUG
+ mChecker = Move(aOther.mChecker);
+#endif
+
+ // Clear up |aOther| so its destruction will be a no-op.
+ {
+#ifdef DEBUG
+ AutoDestructorOp op(mChecker);
+#endif
+ aOther.mEntryStore.Set(nullptr);
+ }
+
+ return *this;
+}
+
+PLDHashNumber
+PLDHashTable::Hash1(PLDHashNumber aHash0)
+{
+ return aHash0 >> mHashShift;
+}
+
+// Double hashing needs the second hash code to be relatively prime to table
+// size, so we simply make hash2 odd.
+void
+PLDHashTable::Hash2(PLDHashNumber aHash,
+ uint32_t& aHash2Out, uint32_t& aSizeMaskOut)
+{
+ uint32_t sizeLog2 = kHashBits - mHashShift;
+ aHash2Out = ((aHash << sizeLog2) >> mHashShift) | 1;
+ aSizeMaskOut = (PLDHashNumber(1) << sizeLog2) - 1;
+}
+
+// Reserve mKeyHash 0 for free entries and 1 for removed-entry sentinels. Note
+// that a removed-entry sentinel need be stored only if the removed entry had
+// a colliding entry added after it. Therefore we can use 1 as the collision
+// flag in addition to the removed-entry sentinel value. Multiplicative hash
+// uses the high order bits of mKeyHash, so this least-significant reservation
+// should not hurt the hash function's effectiveness much.
+
+// Match an entry's mKeyHash against an unstored one computed from a key.
+/* static */ bool
+PLDHashTable::MatchEntryKeyhash(PLDHashEntryHdr* aEntry, PLDHashNumber aKeyHash)
+{
+ return (aEntry->mKeyHash & ~kCollisionFlag) == aKeyHash;
+}
+
+// Compute the address of the indexed entry in table.
+PLDHashEntryHdr*
+PLDHashTable::AddressEntry(uint32_t aIndex)
+{
+ return reinterpret_cast<PLDHashEntryHdr*>(
+ mEntryStore.Get() + aIndex * mEntrySize);
+}
+
+PLDHashTable::~PLDHashTable()
+{
+#ifdef DEBUG
+ AutoDestructorOp op(mChecker);
+#endif
+
+ if (!mEntryStore.Get()) {
+ return;
+ }
+
+ // Clear any remaining live entries.
+ char* entryAddr = mEntryStore.Get();
+ char* entryLimit = entryAddr + Capacity() * mEntrySize;
+ while (entryAddr < entryLimit) {
+ PLDHashEntryHdr* entry = (PLDHashEntryHdr*)entryAddr;
+ if (EntryIsLive(entry)) {
+ mOps->clearEntry(this, entry);
+ }
+ entryAddr += mEntrySize;
+ }
+
+ // Entry storage is freed last, by ~EntryStore().
+}
+
+void
+PLDHashTable::ClearAndPrepareForLength(uint32_t aLength)
+{
+ // Get these values before the destructor clobbers them.
+ const PLDHashTableOps* ops = mOps;
+ uint32_t entrySize = mEntrySize;
+
+ this->~PLDHashTable();
+ new (KnownNotNull, this) PLDHashTable(ops, entrySize, aLength);
+}
+
+void
+PLDHashTable::Clear()
+{
+ ClearAndPrepareForLength(kDefaultInitialLength);
+}
+
+// If |Reason| is |ForAdd|, the return value is always non-null and it may be
+// a previously-removed entry. If |Reason| is |ForSearchOrRemove|, the return
+// value is null on a miss, and will never be a previously-removed entry on a
+// hit. This distinction is a bit grotty but this function is hot enough that
+// these differences are worthwhile.
+template <PLDHashTable::SearchReason Reason>
+PLDHashEntryHdr* NS_FASTCALL
+PLDHashTable::SearchTable(const void* aKey, PLDHashNumber aKeyHash)
+{
+ MOZ_ASSERT(mEntryStore.Get());
+ NS_ASSERTION(!(aKeyHash & kCollisionFlag),
+ "!(aKeyHash & kCollisionFlag)");
+
+ // Compute the primary hash address.
+ PLDHashNumber hash1 = Hash1(aKeyHash);
+ PLDHashEntryHdr* entry = AddressEntry(hash1);
+
+ // Miss: return space for a new entry.
+ if (EntryIsFree(entry)) {
+ return (Reason == ForAdd) ? entry : nullptr;
+ }
+
+ // Hit: return entry.
+ PLDHashMatchEntry matchEntry = mOps->matchEntry;
+ if (MatchEntryKeyhash(entry, aKeyHash) &&
+ matchEntry(entry, aKey)) {
+ return entry;
+ }
+
+ // Collision: double hash.
+ PLDHashNumber hash2;
+ uint32_t sizeMask;
+ Hash2(aKeyHash, hash2, sizeMask);
+
+ // Save the first removed entry pointer so Add() can recycle it. (Only used
+ // if Reason==ForAdd.)
+ PLDHashEntryHdr* firstRemoved = nullptr;
+
+ for (;;) {
+ if (Reason == ForAdd) {
+ if (MOZ_UNLIKELY(EntryIsRemoved(entry))) {
+ if (!firstRemoved) {
+ firstRemoved = entry;
+ }
+ } else {
+ entry->mKeyHash |= kCollisionFlag;
+ }
+ }
+
+ hash1 -= hash2;
+ hash1 &= sizeMask;
+
+ entry = AddressEntry(hash1);
+ if (EntryIsFree(entry)) {
+ return (Reason == ForAdd) ? (firstRemoved ? firstRemoved : entry)
+ : nullptr;
+ }
+
+ if (MatchEntryKeyhash(entry, aKeyHash) &&
+ matchEntry(entry, aKey)) {
+ return entry;
+ }
+ }
+
+ // NOTREACHED
+ return nullptr;
+}
+
+// This is a copy of SearchTable(), used by ChangeTable(), hardcoded to
+// 1. assume |Reason| is |ForAdd|,
+// 2. assume that |aKey| will never match an existing entry, and
+// 3. assume that no entries have been removed from the current table
+// structure.
+// Avoiding the need for |aKey| means we can avoid needing a way to map entries
+// to keys, which means callers can use complex key types more easily.
+MOZ_ALWAYS_INLINE PLDHashEntryHdr*
+PLDHashTable::FindFreeEntry(PLDHashNumber aKeyHash)
+{
+ MOZ_ASSERT(mEntryStore.Get());
+ NS_ASSERTION(!(aKeyHash & kCollisionFlag),
+ "!(aKeyHash & kCollisionFlag)");
+
+ // Compute the primary hash address.
+ PLDHashNumber hash1 = Hash1(aKeyHash);
+ PLDHashEntryHdr* entry = AddressEntry(hash1);
+
+ // Miss: return space for a new entry.
+ if (EntryIsFree(entry)) {
+ return entry;
+ }
+
+ // Collision: double hash.
+ PLDHashNumber hash2;
+ uint32_t sizeMask;
+ Hash2(aKeyHash, hash2, sizeMask);
+
+ for (;;) {
+ NS_ASSERTION(!EntryIsRemoved(entry),
+ "!EntryIsRemoved(entry)");
+ entry->mKeyHash |= kCollisionFlag;
+
+ hash1 -= hash2;
+ hash1 &= sizeMask;
+
+ entry = AddressEntry(hash1);
+ if (EntryIsFree(entry)) {
+ return entry;
+ }
+ }
+
+ // NOTREACHED
+}
+
+bool
+PLDHashTable::ChangeTable(int32_t aDeltaLog2)
+{
+ MOZ_ASSERT(mEntryStore.Get());
+
+ // Look, but don't touch, until we succeed in getting new entry store.
+ int32_t oldLog2 = kHashBits - mHashShift;
+ int32_t newLog2 = oldLog2 + aDeltaLog2;
+ uint32_t newCapacity = 1u << newLog2;
+ if (newCapacity > kMaxCapacity) {
+ return false;
+ }
+
+ uint32_t nbytes;
+ if (!SizeOfEntryStore(newCapacity, mEntrySize, &nbytes)) {
+ return false; // overflowed
+ }
+
+ char* newEntryStore = (char*)malloc(nbytes);
+ if (!newEntryStore) {
+ return false;
+ }
+
+ // We can't fail from here on, so update table parameters.
+ mHashShift = kHashBits - newLog2;
+ mRemovedCount = 0;
+
+ // Assign the new entry store to table.
+ memset(newEntryStore, 0, nbytes);
+ char* oldEntryStore;
+ char* oldEntryAddr;
+ oldEntryAddr = oldEntryStore = mEntryStore.Get();
+ mEntryStore.Set(newEntryStore);
+ PLDHashMoveEntry moveEntry = mOps->moveEntry;
+
+ // Copy only live entries, leaving removed ones behind.
+ uint32_t oldCapacity = 1u << oldLog2;
+ for (uint32_t i = 0; i < oldCapacity; ++i) {
+ PLDHashEntryHdr* oldEntry = (PLDHashEntryHdr*)oldEntryAddr;
+ if (EntryIsLive(oldEntry)) {
+ oldEntry->mKeyHash &= ~kCollisionFlag;
+ PLDHashEntryHdr* newEntry = FindFreeEntry(oldEntry->mKeyHash);
+ NS_ASSERTION(EntryIsFree(newEntry), "EntryIsFree(newEntry)");
+ moveEntry(this, oldEntry, newEntry);
+ newEntry->mKeyHash = oldEntry->mKeyHash;
+ }
+ oldEntryAddr += mEntrySize;
+ }
+
+ free(oldEntryStore);
+ return true;
+}
+
+MOZ_ALWAYS_INLINE PLDHashNumber
+PLDHashTable::ComputeKeyHash(const void* aKey)
+{
+ MOZ_ASSERT(mEntryStore.Get());
+
+ PLDHashNumber keyHash = mOps->hashKey(aKey);
+ keyHash *= kGoldenRatio;
+
+ // Avoid 0 and 1 hash codes, they indicate free and removed entries.
+ if (keyHash < 2) {
+ keyHash -= 2;
+ }
+ keyHash &= ~kCollisionFlag;
+
+ return keyHash;
+}
+
+PLDHashEntryHdr*
+PLDHashTable::Search(const void* aKey)
+{
+#ifdef DEBUG
+ AutoReadOp op(mChecker);
+#endif
+
+ PLDHashEntryHdr* entry = mEntryStore.Get()
+ ? SearchTable<ForSearchOrRemove>(aKey,
+ ComputeKeyHash(aKey))
+ : nullptr;
+ return entry;
+}
+
+PLDHashEntryHdr*
+PLDHashTable::Add(const void* aKey, const mozilla::fallible_t&)
+{
+#ifdef DEBUG
+ AutoWriteOp op(mChecker);
+#endif
+
+ // Allocate the entry storage if it hasn't already been allocated.
+ if (!mEntryStore.Get()) {
+ uint32_t nbytes;
+ // We already checked this in the constructor, so it must still be true.
+ MOZ_RELEASE_ASSERT(SizeOfEntryStore(CapacityFromHashShift(), mEntrySize,
+ &nbytes));
+ mEntryStore.Set((char*)malloc(nbytes));
+ if (!mEntryStore.Get()) {
+ return nullptr;
+ }
+ memset(mEntryStore.Get(), 0, nbytes);
+ }
+
+ // If alpha is >= .75, grow or compress the table. If aKey is already in the
+ // table, we may grow once more than necessary, but only if we are on the
+ // edge of being overloaded.
+ uint32_t capacity = Capacity();
+ if (mEntryCount + mRemovedCount >= MaxLoad(capacity)) {
+ // Compress if a quarter or more of all entries are removed.
+ int deltaLog2;
+ if (mRemovedCount >= capacity >> 2) {
+ deltaLog2 = 0;
+ } else {
+ deltaLog2 = 1;
+ }
+
+ // Grow or compress the table. If ChangeTable() fails, allow overloading up
+ // to the secondary max. Once we hit the secondary max, return null.
+ if (!ChangeTable(deltaLog2) &&
+ mEntryCount + mRemovedCount >= MaxLoadOnGrowthFailure(capacity)) {
+ return nullptr;
+ }
+ }
+
+ // Look for entry after possibly growing, so we don't have to add it,
+ // then skip it while growing the table and re-add it after.
+ PLDHashNumber keyHash = ComputeKeyHash(aKey);
+ PLDHashEntryHdr* entry = SearchTable<ForAdd>(aKey, keyHash);
+ if (!EntryIsLive(entry)) {
+ // Initialize the entry, indicating that it's no longer free.
+ if (EntryIsRemoved(entry)) {
+ mRemovedCount--;
+ keyHash |= kCollisionFlag;
+ }
+ if (mOps->initEntry) {
+ mOps->initEntry(entry, aKey);
+ }
+ entry->mKeyHash = keyHash;
+ mEntryCount++;
+ }
+
+ return entry;
+}
+
+PLDHashEntryHdr*
+PLDHashTable::Add(const void* aKey)
+{
+ PLDHashEntryHdr* entry = Add(aKey, fallible);
+ if (!entry) {
+ if (!mEntryStore.Get()) {
+ // We OOM'd while allocating the initial entry storage.
+ uint32_t nbytes;
+ (void) SizeOfEntryStore(CapacityFromHashShift(), mEntrySize, &nbytes);
+ NS_ABORT_OOM(nbytes);
+ } else {
+ // We failed to resize the existing entry storage, either due to OOM or
+ // because we exceeded the maximum table capacity or size; report it as
+ // an OOM. The multiplication by 2 gets us the size we tried to allocate,
+ // which is double the current size.
+ NS_ABORT_OOM(2 * EntrySize() * EntryCount());
+ }
+ }
+ return entry;
+}
+
+void
+PLDHashTable::Remove(const void* aKey)
+{
+#ifdef DEBUG
+ AutoWriteOp op(mChecker);
+#endif
+
+ PLDHashEntryHdr* entry = mEntryStore.Get()
+ ? SearchTable<ForSearchOrRemove>(aKey,
+ ComputeKeyHash(aKey))
+ : nullptr;
+ if (entry) {
+ RawRemove(entry);
+ ShrinkIfAppropriate();
+ }
+}
+
+void
+PLDHashTable::RemoveEntry(PLDHashEntryHdr* aEntry)
+{
+#ifdef DEBUG
+ AutoWriteOp op(mChecker);
+#endif
+
+ RawRemove(aEntry);
+ ShrinkIfAppropriate();
+}
+
+void
+PLDHashTable::RawRemove(PLDHashEntryHdr* aEntry)
+{
+ // Unfortunately, we can only do weak checking here. That's because
+ // RawRemove() can be called legitimately while an Enumerate() call is
+ // active, which doesn't fit well into how Checker's mState variable works.
+ MOZ_ASSERT(mChecker.IsWritable());
+
+ MOZ_ASSERT(mEntryStore.Get());
+
+ MOZ_ASSERT(EntryIsLive(aEntry), "EntryIsLive(aEntry)");
+
+ // Load keyHash first in case clearEntry() goofs it.
+ PLDHashNumber keyHash = aEntry->mKeyHash;
+ mOps->clearEntry(this, aEntry);
+ if (keyHash & kCollisionFlag) {
+ MarkEntryRemoved(aEntry);
+ mRemovedCount++;
+ } else {
+ MarkEntryFree(aEntry);
+ }
+ mEntryCount--;
+}
+
+// Shrink or compress if a quarter or more of all entries are removed, or if the
+// table is underloaded according to the minimum alpha, and is not minimal-size
+// already.
+void
+PLDHashTable::ShrinkIfAppropriate()
+{
+ uint32_t capacity = Capacity();
+ if (mRemovedCount >= capacity >> 2 ||
+ (capacity > kMinCapacity && mEntryCount <= MinLoad(capacity))) {
+ uint32_t log2;
+ BestCapacity(mEntryCount, &capacity, &log2);
+
+ int32_t deltaLog2 = log2 - (kHashBits - mHashShift);
+ MOZ_ASSERT(deltaLog2 <= 0);
+
+ (void) ChangeTable(deltaLog2);
+ }
+}
+
+size_t
+PLDHashTable::ShallowSizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const
+{
+#ifdef DEBUG
+ AutoReadOp op(mChecker);
+#endif
+
+ return aMallocSizeOf(mEntryStore.Get());
+}
+
+size_t
+PLDHashTable::ShallowSizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const
+{
+ return aMallocSizeOf(this) + ShallowSizeOfExcludingThis(aMallocSizeOf);
+}
+
+PLDHashTable::Iterator::Iterator(Iterator&& aOther)
+ : mTable(aOther.mTable)
+ , mStart(aOther.mStart)
+ , mLimit(aOther.mLimit)
+ , mCurrent(aOther.mCurrent)
+ , mNexts(aOther.mNexts)
+ , mNextsLimit(aOther.mNextsLimit)
+ , mHaveRemoved(aOther.mHaveRemoved)
+{
+ // No need to change |mChecker| here.
+ aOther.mTable = nullptr;
+ aOther.mStart = nullptr;
+ aOther.mLimit = nullptr;
+ aOther.mCurrent = nullptr;
+ aOther.mNexts = 0;
+ aOther.mNextsLimit = 0;
+ aOther.mHaveRemoved = false;
+}
+
+PLDHashTable::Iterator::Iterator(PLDHashTable* aTable)
+ : mTable(aTable)
+ , mStart(mTable->mEntryStore.Get())
+ , mLimit(mTable->mEntryStore.Get() + mTable->Capacity() * mTable->mEntrySize)
+ , mCurrent(mTable->mEntryStore.Get())
+ , mNexts(0)
+ , mNextsLimit(mTable->EntryCount())
+ , mHaveRemoved(false)
+{
+#ifdef DEBUG
+ mTable->mChecker.StartReadOp();
+#endif
+
+ if (ChaosMode::isActive(ChaosFeature::HashTableIteration) &&
+ mTable->Capacity() > 0) {
+ // Start iterating at a random entry. It would be even more chaotic to
+ // iterate in fully random order, but that's harder.
+ mCurrent += ChaosMode::randomUint32LessThan(mTable->Capacity()) *
+ mTable->mEntrySize;
+ }
+
+ // Advance to the first live entry, if there is one.
+ if (!Done()) {
+ while (IsOnNonLiveEntry()) {
+ MoveToNextEntry();
+ }
+ }
+}
+
+PLDHashTable::Iterator::~Iterator()
+{
+ if (mTable) {
+ if (mHaveRemoved) {
+ mTable->ShrinkIfAppropriate();
+ }
+#ifdef DEBUG
+ mTable->mChecker.EndReadOp();
+#endif
+ }
+}
+
+MOZ_ALWAYS_INLINE bool
+PLDHashTable::Iterator::IsOnNonLiveEntry() const
+{
+ MOZ_ASSERT(!Done());
+ return !EntryIsLive(reinterpret_cast<PLDHashEntryHdr*>(mCurrent));
+}
+
+MOZ_ALWAYS_INLINE void
+PLDHashTable::Iterator::MoveToNextEntry()
+{
+ mCurrent += mTable->mEntrySize;
+ if (mCurrent == mLimit) {
+ mCurrent = mStart; // Wrap-around. Possible due to Chaos Mode.
+ }
+}
+
+void
+PLDHashTable::Iterator::Next()
+{
+ MOZ_ASSERT(!Done());
+
+ mNexts++;
+
+ // Advance to the next live entry, if there is one.
+ if (!Done()) {
+ do {
+ MoveToNextEntry();
+ } while (IsOnNonLiveEntry());
+ }
+}
+
+void
+PLDHashTable::Iterator::Remove()
+{
+ // This cast is needed for the same reason as the one in the destructor.
+ mTable->RawRemove(Get());
+ mHaveRemoved = true;
+}
+
+#ifdef DEBUG
+void
+PLDHashTable::MarkImmutable()
+{
+ mChecker.SetNonWritable();
+}
+#endif