зеркало из https://github.com/mozilla/gecko-dev.git
Bug 1170934 (part 1) - Remove PLDHashTable::{Init,Fini}(). r=froydnj.
--HG-- extra : rebase_source : 1d1ac910420fbc12c7e2501c74680cce00387c63
This commit is contained in:
Nicholas Nethercote
Родитель
1ec5ee71e9
Коммит
cc64c96ae6
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@ -7,6 +7,7 @@
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/*
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* Double hashing implementation.
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*/
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#include <new>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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@ -38,7 +39,7 @@
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* allowed (and therefore the level is 0 or 1, depending on whether they
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* incremented it).
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*
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* Only Finish() needs to allow this special value.
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* Only the destructor needs to allow this special value.
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*/
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#define IMMUTABLE_RECURSION_LEVEL UINT32_MAX
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@ -192,15 +193,8 @@ MinLoad(uint32_t aCapacity)
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return aCapacity >> 2; // == aCapacity * 0.25
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}
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static inline uint32_t
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MinCapacity(uint32_t aLength)
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{
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return (aLength * 4 + (3 - 1)) / 3; // == ceil(aLength * 4 / 3)
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}
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MOZ_ALWAYS_INLINE void
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PLDHashTable::Init(const PLDHashTableOps* aOps,
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uint32_t aEntrySize, uint32_t aLength)
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static MOZ_ALWAYS_INLINE uint32_t
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HashShift(uint32_t aEntrySize, uint32_t aLength)
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{
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if (aLength > PL_DHASH_MAX_INITIAL_LENGTH) {
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MOZ_CRASH("Initial length is too large");
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@ -208,38 +202,39 @@ PLDHashTable::Init(const PLDHashTableOps* aOps,
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// Compute the smallest capacity allowing |aLength| elements to be inserted
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// without rehashing.
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uint32_t capacity = MinCapacity(aLength);
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uint32_t capacity = (aLength * 4 + (3 - 1)) / 3; // == ceil(aLength * 4 / 3)
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if (capacity < PL_DHASH_MIN_CAPACITY) {
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capacity = PL_DHASH_MIN_CAPACITY;
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}
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// Round up capacity to next power-of-two.
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int log2 = CeilingLog2(capacity);
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capacity = 1u << log2;
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MOZ_ASSERT(capacity <= PL_DHASH_MAX_CAPACITY);
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mOps = aOps;
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mHashShift = PL_DHASH_BITS - log2;
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mEntrySize = aEntrySize;
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mEntryCount = mRemovedCount = 0;
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mGeneration = 0;
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uint32_t nbytes;
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if (!SizeOfEntryStore(capacity, aEntrySize, &nbytes)) {
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MOZ_CRASH("Initial entry store size is too large");
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}
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mEntryStore = nullptr;
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METER(memset(&mStats, 0, sizeof(mStats)));
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#ifdef DEBUG
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mRecursionLevel = 0;
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#endif
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// Compute the hashShift value.
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return PL_DHASH_BITS - log2;
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}
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PLDHashTable::PLDHashTable(const PLDHashTableOps* aOps, uint32_t aEntrySize,
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uint32_t aLength)
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: mOps(aOps)
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, mHashShift(HashShift(aEntrySize, aLength))
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, mEntrySize(aEntrySize)
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, mEntryCount(0)
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, mRemovedCount(0)
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, mGeneration(0)
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, mEntryStore(nullptr)
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#ifdef DEBUG
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, mRecursionLevel(0)
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#endif
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{
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Init(aOps, aEntrySize, aLength);
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METER(memset(&mStats, 0, sizeof(mStats)));
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}
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PLDHashTable&
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@ -250,12 +245,18 @@ PLDHashTable::operator=(PLDHashTable&& aOther)
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}
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// Destruct |this|.
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Finish();
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this->~PLDHashTable();
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// Move pieces over.
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mOps = Move(aOther.mOps);
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// |mOps| and |mEntrySize| are const so we can't assign them. Instead, we
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// require that they are equal. The justification for this is that they're
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// conceptually part of the type -- indeed, if PLDHashTable was a templated
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// type like nsTHashtable, they *would* be part of the type -- so it only
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// makes sense to assign in cases where they match.
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MOZ_RELEASE_ASSERT(mOps == aOther.mOps);
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MOZ_RELEASE_ASSERT(mEntrySize == aOther.mEntrySize);
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// Move non-const pieces over.
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mHashShift = Move(aOther.mHashShift);
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mEntrySize = Move(aOther.mEntrySize);
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mEntryCount = Move(aOther.mEntryCount);
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mRemovedCount = Move(aOther.mRemovedCount);
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mGeneration = Move(aOther.mGeneration);
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@ -313,8 +314,7 @@ PLDHashTable::EntryIsFree(PLDHashEntryHdr* aEntry)
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return aEntry->mKeyHash == 0;
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}
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MOZ_ALWAYS_INLINE void
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PLDHashTable::Finish()
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PLDHashTable::~PLDHashTable()
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{
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if (!mEntryStore) {
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return;
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@ -342,20 +342,15 @@ PLDHashTable::Finish()
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mEntryStore = nullptr;
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}
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PLDHashTable::~PLDHashTable()
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{
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Finish();
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}
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void
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PLDHashTable::ClearAndPrepareForLength(uint32_t aLength)
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{
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// Get these values before the call to Finish() clobbers them.
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// Get these values before the destructor clobbers them.
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const PLDHashTableOps* ops = mOps;
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uint32_t entrySize = mEntrySize;
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Finish();
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Init(ops, entrySize, aLength);
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this->~PLDHashTable();
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new (this) PLDHashTable(ops, entrySize, aLength);
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}
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void
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@ -591,7 +586,7 @@ PLDHashTable::Add(const void* aKey, const mozilla::fallible_t&)
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// Allocate the entry storage if it hasn't already been allocated.
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if (!mEntryStore) {
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uint32_t nbytes;
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// We already checked this in Init(), so it must still be true.
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// We already checked this in the constructor, so it must still be true.
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MOZ_RELEASE_ASSERT(SizeOfEntryStore(CapacityFromHashShift(), mEntrySize,
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&nbytes));
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mEntryStore = (char*)malloc(nbytes);
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@ -162,9 +162,9 @@ typedef size_t (*PLDHashSizeOfEntryExcludingThisFun)(
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class PLDHashTable
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{
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private:
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const PLDHashTableOps* mOps; /* Virtual operations; see below. */
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const PLDHashTableOps* const mOps; /* Virtual operations; see below. */
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int16_t mHashShift; /* multiplicative hash shift */
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uint32_t mEntrySize; /* number of bytes in an entry */
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const uint32_t mEntrySize; /* number of bytes in an entry */
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uint32_t mEntryCount; /* number of entries in table */
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uint32_t mRemovedCount; /* removed entry sentinels in table */
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uint32_t mGeneration; /* entry storage generation number */
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@ -214,7 +214,12 @@ public:
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uint32_t aLength = PL_DHASH_DEFAULT_INITIAL_LENGTH);
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PLDHashTable(PLDHashTable&& aOther)
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: mOps(nullptr)
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// These two fields are |const|. Initialize them here because the
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// move assignment operator cannot modify them.
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: mOps(aOther.mOps)
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, mEntrySize(aOther.mEntrySize)
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// Initialize these two fields because they are required for a safe call
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// to the destructor, which the move assignment operator does.
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, mEntryStore(nullptr)
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#ifdef DEBUG
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, mRecursionLevel(0)
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@ -322,9 +327,6 @@ private:
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PLDHashNumber ComputeKeyHash(const void* aKey);
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void Init(const PLDHashTableOps* aOps, uint32_t aEntrySize, uint32_t aLength);
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void Finish();
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enum SearchReason { ForSearchOrRemove, ForAdd };
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template <SearchReason Reason>
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