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Bug 1202526 (part 1) - Add PLDHashTable::RemoveEntry(). r=froydnj.

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This patch also consolidates the shrink handling so it's now entirely within
ShrinkIfAppropriate().
This commit is contained in:
Nicholas Nethercote 2015-09-07 19:20:12 -07:00
parent 0cb3e73aaa
commit de8fceb34d
2 changed files with 25 additions and 10 deletions
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22
xpcom/glue/pldhash.cpp
View File

@ -662,18 +662,22 @@ PLDHashTable::Remove(const void* aKey)
ComputeKeyHash(aKey))
: nullptr;
if (entry) {
// Clear this entry and mark it as "removed".
RawRemove(entry);
// Shrink if alpha is <= .25 and the table isn't too small already.
uint32_t capacity = Capacity();
if (capacity > kMinCapacity &&
mEntryCount <= MinLoad(capacity)) {
(void) ChangeTable(-1);
}
ShrinkIfAppropriate();
}
}
void
PLDHashTable::RemoveEntry(PLDHashEntryHdr* aEntry)
{
#ifdef DEBUG
AutoWriteOp op(mChecker);
#endif
RawRemove(aEntry);
ShrinkIfAppropriate();
}
PLDHashEntryHdr* PL_DHASH_FASTCALL
PL_DHashTableSearch(PLDHashTable* aTable, const void* aKey)
{
@ -709,7 +713,7 @@ PLDHashTable::RawRemove(PLDHashEntryHdr* aEntry)
MOZ_ASSERT(mEntryStore.Get());
NS_ASSERTION(EntryIsLive(aEntry), "EntryIsLive(aEntry)");
MOZ_ASSERT(EntryIsLive(aEntry), "EntryIsLive(aEntry)");
// Load keyHash first in case clearEntry() goofs it.
PLDHashNumber keyHash = aEntry->mKeyHash;

13
xpcom/glue/pldhash.h
View File

@ -350,12 +350,23 @@ public:
// table.Remove(key);
//
// If |key|'s entry is found, it is cleared (via table->mOps->clearEntry).
// The table's capacity may be reduced afterwards.
void Remove(const void* aKey);
// To remove an entry found by a prior search, call:
//
// table.RemoveEntry(entry);
//
// The entry, which must be present and in use, is cleared (via
// table->mOps->clearEntry). The table's capacity may be reduced afterwards.
void RemoveEntry(PLDHashEntryHdr* aEntry);
// Remove an entry already accessed via Search() or Add().
//
// NB: this is a "raw" or low-level method. It does not shrink the table if
// it is underloaded. Don't use it unless you know what you are doing.
// it is underloaded. Don't use it unless necessary and you know what you are
// doing, and if so, please explain in a comment why it is necessary instead
// of RemoveEntry().
void RawRemove(PLDHashEntryHdr* aEntry);
// This function is equivalent to