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Bug 1488413 - To improve performance, CycleCollector could use a cache on top of the graph's hashtable, r=mccr8

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--HG--
extra : rebase_source : 8f67777644346549a3df3c4e97433378dc70a177
This commit is contained in:
Olli Pettay 2018-09-04 23:22:37 +03:00
parent 4454f01d19
commit e8a92b84f1
1 changed files with 61 additions and 0 deletions
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61
xpcom/base/nsCycleCollector.cpp
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@ -157,6 +157,7 @@
#include "mozilla/CycleCollectedJSContext.h"
#include "mozilla/CycleCollectedJSRuntime.h"
#include "mozilla/DebugOnly.h"
#include "mozilla/HashFunctions.h"
#include "mozilla/HashTable.h"
#include "mozilla/HoldDropJSObjects.h"
/* This must occur *after* base/process_util.h to avoid typedefs conflicts. */
@ -164,6 +165,7 @@
#include "mozilla/MemoryReporting.h"
#include "mozilla/Move.h"
#include "mozilla/SegmentedVector.h"
#include "mozilla/Variant.h"
#include "nsCycleCollectionParticipant.h"
#include "nsCycleCollectionNoteRootCallback.h"
@ -2092,6 +2094,43 @@ private:
nsAutoPtr<NodePool::Enumerator> mCurrNode;
uint32_t mNoteChildCount;
class GraphCache
{
public:
// This either returns a pointer if present, or an index, if it isn't.
Variant<PtrInfo*, uint32_t> GetEntryOrIndex(void* aPtr)
{
uint32_t hash = mozilla::HashGeneric(aPtr);
uint32_t index = hash % kCacheSize;
PtrInfo* result = mCache[index];
if (result && result->mPointer == aPtr) {
return AsVariant(result);
}
return AsVariant(index);
}
void Add(uint32_t aIndex, PtrInfo* aPtrInfo)
{
mCache[aIndex] = aPtrInfo;
}
void Remove(void* aPtr)
{
uint32_t hash = mozilla::HashGeneric(aPtr);
uint32_t index = hash % kCacheSize;
PtrInfo* pinfo = mCache[index];
if (pinfo && pinfo->mPointer == aPtr) {
mCache[index] = nullptr;
}
}
private:
const static uint32_t kCacheSize = 491;
PtrInfo* mCache[kCacheSize] = {0};
};
GraphCache mGraphCache;
public:
CCGraphBuilder(CCGraph& aGraph,
CycleCollectorResults& aResults,
@ -2113,6 +2152,10 @@ public:
// Do some work traversing nodes in the graph. Returns true if this graph building is finished.
bool BuildGraph(SliceBudget& aBudget);
void RemoveCachedEntry(void* aPtr)
{
mGraphCache.Remove(aPtr);
}
private:
PtrInfo* AddNode(void* aPtr, nsCycleCollectionParticipant* aParticipant);
PtrInfo* AddWeakMapNode(JS::GCCellPtr aThing);
@ -2210,6 +2253,10 @@ CCGraphBuilder::CCGraphBuilder(CCGraph& aGraph,
, mMergeZones(aMergeZones)
, mNoteChildCount(0)
{
// 4096 is an allocation bucket size.
static_assert(sizeof(CCGraphBuilder) <= 4096,
"Don't create too large CCGraphBuilder objects");
if (aCCRuntime) {
mJSParticipant = aCCRuntime->GCThingParticipant();
mJSZoneParticipant = aCCRuntime->ZoneParticipant();
@ -2240,6 +2287,15 @@ CCGraphBuilder::AddNode(void* aPtr, nsCycleCollectionParticipant* aParticipant)
return nullptr;
}
Variant<PtrInfo*, uint32_t> cacheVariant = mGraphCache.GetEntryOrIndex(aPtr);
if (cacheVariant.is<PtrInfo*>()) {
MOZ_ASSERT(cacheVariant.as<PtrInfo*>()->mParticipant == aParticipant,
"nsCycleCollectionParticipant shouldn't change!");
return cacheVariant.as<PtrInfo*>();
}
MOZ_ASSERT(cacheVariant.is<uint32_t>());
PtrInfo* result;
auto p = mGraph.mPtrInfoMap.lookupForAdd(aPtr);
if (!p) {
@ -2263,6 +2319,8 @@ CCGraphBuilder::AddNode(void* aPtr, nsCycleCollectionParticipant* aParticipant)
"nsCycleCollectionParticipant shouldn't change!");
}
mGraphCache.Add(cacheVariant.as<uint32_t>(), result);
return result;
}
@ -4044,6 +4102,9 @@ nsCycleCollector::RemoveObjectFromGraph(void* aObj)
}
mGraph.RemoveObjectFromMap(aObj);
if (mBuilder) {
mBuilder->RemoveCachedEntry(aObj);
}
}
void