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gecko-dev/xpcom/base/nsCycleCollector.cpp

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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/* vim: set cindent tabstop=4 expandtab shiftwidth=4: */
/* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is mozilla.org code.
*
* The Initial Developer of the Original Code is
* The Mozilla Foundation.
* Portions created by the Initial Developer are Copyright (C) 2006
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* L. David Baron <dbaron@dbaron.org>, Mozilla Corporation
*
* Alternatively, the contents of this file may be used under the terms of
* either of the GNU General Public License Version 2 or later (the "GPL"),
* or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
//
// This file implements a garbage-cycle collector based on the paper
//
// Concurrent Cycle Collection in Reference Counted Systems
// Bacon & Rajan (2001), ECOOP 2001 / Springer LNCS vol 2072
//
// We are not using the concurrent or acyclic cases of that paper; so
// the green, red and orange colors are not used.
//
// The collector is based on tracking pointers of four colors:
//
// Black nodes are definitely live. If we ever determine a node is
// black, it's ok to forget about, drop from our records.
//
// White nodes are definitely garbage cycles. Once we finish with our
// scanning, we unlink all the white nodes and expect that by
// unlinking them they will self-destruct (since a garbage cycle is
// only keeping itself alive with internal links, by definition).
//
// Grey nodes are being scanned. Nodes that turn grey will turn
// either black if we determine that they're live, or white if we
// determine that they're a garbage cycle. After the main collection
// algorithm there should be no grey nodes.
//
// Purple nodes are *candidates* for being scanned. They are nodes we
// haven't begun scanning yet because they're not old enough, or we're
// still partway through the algorithm.
//
// XPCOM objects participating in garbage-cycle collection are obliged
// to inform us when they ought to turn purple; that is, when their
// refcount transitions from N+1 -> N, for nonzero N. Furthermore we
// require that *after* an XPCOM object has informed us of turning
// purple, they will tell us when they either transition back to being
// black (incremented refcount) or are ultimately deleted.
// Safety:
//
// An XPCOM object is either scan-safe or scan-unsafe, purple-safe or
// purple-unsafe.
//
// An object is scan-safe if:
//
// - It can be QI'ed to |nsXPCOMCycleCollectionParticipant|, though this
// operation loses ISupports identity (like nsIClassInfo).
// - The operation |traverse| on the resulting
// nsXPCOMCycleCollectionParticipant does not cause *any* refcount
// adjustment to occur (no AddRef / Release calls).
//
// An object is purple-safe if it satisfies the following properties:
//
// - The object is scan-safe.
// - If the object calls |nsCycleCollector::suspect(this)|,
// it will eventually call |nsCycleCollector::forget(this)|,
// exactly once per call to |suspect|, before being destroyed.
//
// When we receive a pointer |ptr| via
// |nsCycleCollector::suspect(ptr)|, we assume it is purple-safe. We
// can check the scan-safety, but have no way to ensure the
// purple-safety; objects must obey, or else the entire system falls
// apart. Don't involve an object in this scheme if you can't
// guarantee its purple-safety.
//
// When we have a scannable set of purple nodes ready, we begin
// our walks. During the walks, the nodes we |traverse| should only
// feed us more scan-safe nodes, and should not adjust the refcounts
// of those nodes.
//
// We do not |AddRef| or |Release| any objects during scanning. We
// rely on purple-safety of the roots that call |suspect| and
// |forget| to hold, such that we will forget about a purple pointer
// before it is destroyed. The pointers that are merely scan-safe,
// we hold only for the duration of scanning, and there should be no
// objects released from the scan-safe set during the scan (there
// should be no threads involved).
//
// We *do* call |AddRef| and |Release| on every white object, on
// either side of the calls to |Unlink|. This keeps the set of white
// objects alive during the unlinking.
//
#if !defined(__MINGW32__)
#ifdef WIN32
#include <crtdbg.h>
#include <errno.h>
#endif
#endif
#include "base/process_util.h"
/* This must occur *after* base/process_util.h to avoid typedefs conflicts. */
#include "mozilla/Util.h"
#include "nsCycleCollectionParticipant.h"
#include "nsCycleCollectorUtils.h"
#include "nsIProgrammingLanguage.h"
#include "nsBaseHashtable.h"
#include "nsHashKeys.h"
#include "nsDeque.h"
#include "nsCycleCollector.h"
#include "nsThreadUtils.h"
#include "prenv.h"
#include "prprf.h"
#include "plstr.h"
#include "nsPrintfCString.h"
#include "nsTArray.h"
#include "nsIObserverService.h"
#include "nsIConsoleService.h"
#include "nsServiceManagerUtils.h"
#include "nsThreadUtils.h"
#include "nsTArray.h"
#include "mozilla/Services.h"
#include "nsICycleCollectorListener.h"
#include "nsIXPConnect.h"
#include "nsIJSRuntimeService.h"
#include "nsIMemoryReporter.h"
#include "xpcpublic.h"
#include "nsXPCOMPrivate.h"
#include "sampler.h"
#include <stdio.h>
#include <string.h>
#ifdef WIN32
#include <io.h>
#include <process.h>
#endif
#ifdef XP_WIN
#include <windows.h>
#endif
#include "mozilla/Mutex.h"
#include "mozilla/CondVar.h"
#include "mozilla/Telemetry.h"
using namespace mozilla;
//#define COLLECT_TIME_DEBUG
#ifdef DEBUG_CC
#define IF_DEBUG_CC_PARAM(_p) , _p
#define IF_DEBUG_CC_ONLY_PARAM(_p) _p
#else
#define IF_DEBUG_CC_PARAM(_p)
#define IF_DEBUG_CC_ONLY_PARAM(_p)
#endif
#define DEFAULT_SHUTDOWN_COLLECTIONS 5
#ifdef DEBUG_CC
#define SHUTDOWN_COLLECTIONS(params) params.mShutdownCollections
#else
#define SHUTDOWN_COLLECTIONS(params) DEFAULT_SHUTDOWN_COLLECTIONS
#endif
#if defined(XP_WIN)
// Defined in nsThreadManager.cpp.
extern DWORD gTLSThreadIDIndex;
#elif defined(NS_TLS)
// Defined in nsThreadManager.cpp.
extern NS_TLS mozilla::threads::ID gTLSThreadID;
#else
PRThread* gCycleCollectorThread = nsnull;
#endif
// If true, always log cycle collector graphs.
const bool gAlwaysLogCCGraphs = false;
MOZ_NEVER_INLINE void
CC_AbortIfNull(void *ptr)
{
if (!ptr)
MOZ_Assert("ptr was null", __FILE__, __LINE__);
}
// Various parameters of this collector can be tuned using environment
// variables.
struct nsCycleCollectorParams
{
bool mDoNothing;
bool mLogGraphs;
#ifdef DEBUG_CC
bool mReportStats;
bool mHookMalloc;
bool mLogPointers;
PRUint32 mShutdownCollections;
#endif
nsCycleCollectorParams() :
#ifdef DEBUG_CC
mDoNothing (PR_GetEnv("XPCOM_CC_DO_NOTHING") != NULL),
mLogGraphs (gAlwaysLogCCGraphs ||
PR_GetEnv("XPCOM_CC_DRAW_GRAPHS") != NULL),
mReportStats (PR_GetEnv("XPCOM_CC_REPORT_STATS") != NULL),
mHookMalloc (PR_GetEnv("XPCOM_CC_HOOK_MALLOC") != NULL),
mLogPointers (PR_GetEnv("XPCOM_CC_LOG_POINTERS") != NULL),
mShutdownCollections(DEFAULT_SHUTDOWN_COLLECTIONS)
#else
mDoNothing (false),
mLogGraphs (gAlwaysLogCCGraphs)
#endif
{
#ifdef DEBUG_CC
char *s = PR_GetEnv("XPCOM_CC_SHUTDOWN_COLLECTIONS");
if (s)
PR_sscanf(s, "%d", &mShutdownCollections);
#endif
}
};
#ifdef DEBUG_CC
// Various operations involving the collector are recorded in a
// statistics table. These are for diagnostics.
struct nsCycleCollectorStats
{
PRUint32 mFailedQI;
PRUint32 mSuccessfulQI;
PRUint32 mVisitedNode;
PRUint32 mWalkedGraph;
PRUint32 mCollectedBytes;
PRUint32 mFreeCalls;
PRUint32 mFreedBytes;
PRUint32 mSetColorGrey;
PRUint32 mSetColorBlack;
PRUint32 mSetColorWhite;
PRUint32 mFailedUnlink;
PRUint32 mCollectedNode;
PRUint32 mSuspectNode;
PRUint32 mForgetNode;
PRUint32 mFreedWhilePurple;
PRUint32 mCollection;
nsCycleCollectorStats()
{
memset(this, 0, sizeof(nsCycleCollectorStats));
}
void Dump()
{
fprintf(stderr, "\f\n");
#define DUMP(entry) fprintf(stderr, "%30.30s: %-20.20d\n", #entry, entry)
DUMP(mFailedQI);
DUMP(mSuccessfulQI);
DUMP(mVisitedNode);
DUMP(mWalkedGraph);
DUMP(mCollectedBytes);
DUMP(mFreeCalls);
DUMP(mFreedBytes);
DUMP(mSetColorGrey);
DUMP(mSetColorBlack);
DUMP(mSetColorWhite);
DUMP(mFailedUnlink);
DUMP(mCollectedNode);
DUMP(mSuspectNode);
DUMP(mForgetNode);
DUMP(mFreedWhilePurple);
DUMP(mCollection);
#undef DUMP
}
};
#endif
#ifdef DEBUG_CC
static bool nsCycleCollector_shouldSuppress(nsISupports *s);
static void InitMemHook(void);
#endif
#ifdef COLLECT_TIME_DEBUG
class TimeLog
{
public:
TimeLog() : mLastCheckpoint(TimeStamp::Now()) {}
void
Checkpoint(const char* aEvent)
{
TimeStamp now = TimeStamp::Now();
PRUint32 dur = (PRUint32) ((now - mLastCheckpoint).ToMilliseconds());
if (dur > 0) {
printf("cc: %s took %dms\n", aEvent, dur);
}
mLastCheckpoint = now;
}
private:
TimeStamp mLastCheckpoint;
};
#else
class TimeLog
{
public:
TimeLog() {}
void Checkpoint(const char* aEvent) {}
};
#endif
////////////////////////////////////////////////////////////////////////
// Base types
////////////////////////////////////////////////////////////////////////
struct PtrInfo;
class EdgePool
{
public:
// EdgePool allocates arrays of void*, primarily to hold PtrInfo*.
// However, at the end of a block, the last two pointers are a null
// and then a void** pointing to the next block. This allows
// EdgePool::Iterators to be a single word but still capable of crossing
// block boundaries.
EdgePool()
{
mSentinelAndBlocks[0].block = nsnull;
mSentinelAndBlocks[1].block = nsnull;
mNumBlocks = 0;
}
~EdgePool()
{
NS_ASSERTION(!mSentinelAndBlocks[0].block &&
!mSentinelAndBlocks[1].block,
"Didn't call Clear()?");
}
void Clear()
{
Block *b = Blocks();
while (b) {
Block *next = b->Next();
delete b;
NS_ASSERTION(mNumBlocks > 0,
"Expected EdgePool mNumBlocks to be positive.");
mNumBlocks--;
b = next;
}
mSentinelAndBlocks[0].block = nsnull;
mSentinelAndBlocks[1].block = nsnull;
}
private:
struct Block;
union PtrInfoOrBlock {
// Use a union to avoid reinterpret_cast and the ensuing
// potential aliasing bugs.
PtrInfo *ptrInfo;
Block *block;
};
struct Block {
enum { BlockSize = 16 * 1024 };
PtrInfoOrBlock mPointers[BlockSize];
Block() {
mPointers[BlockSize - 2].block = nsnull; // sentinel
mPointers[BlockSize - 1].block = nsnull; // next block pointer
}
Block*& Next()
{ return mPointers[BlockSize - 1].block; }
PtrInfoOrBlock* Start()
{ return &mPointers[0]; }
PtrInfoOrBlock* End()
{ return &mPointers[BlockSize - 2]; }
};
// Store the null sentinel so that we can have valid iterators
// before adding any edges and without adding any blocks.
PtrInfoOrBlock mSentinelAndBlocks[2];
PRUint32 mNumBlocks;
Block*& Blocks() { return mSentinelAndBlocks[1].block; }
public:
class Iterator
{
public:
Iterator() : mPointer(nsnull) {}
Iterator(PtrInfoOrBlock *aPointer) : mPointer(aPointer) {}
Iterator(const Iterator& aOther) : mPointer(aOther.mPointer) {}
Iterator& operator++()
{
if (mPointer->ptrInfo == nsnull) {
// Null pointer is a sentinel for link to the next block.
mPointer = (mPointer + 1)->block->mPointers;
}
++mPointer;
return *this;
}
PtrInfo* operator*() const
{
if (mPointer->ptrInfo == nsnull) {
// Null pointer is a sentinel for link to the next block.
return (mPointer + 1)->block->mPointers->ptrInfo;
}
return mPointer->ptrInfo;
}
bool operator==(const Iterator& aOther) const
{ return mPointer == aOther.mPointer; }
bool operator!=(const Iterator& aOther) const
{ return mPointer != aOther.mPointer; }
private:
PtrInfoOrBlock *mPointer;
};
class Builder;
friend class Builder;
class Builder {
public:
Builder(EdgePool &aPool)
: mCurrent(&aPool.mSentinelAndBlocks[0]),
mBlockEnd(&aPool.mSentinelAndBlocks[0]),
mNextBlockPtr(&aPool.Blocks()),
mNumBlocks(aPool.mNumBlocks)
{
}
Iterator Mark() { return Iterator(mCurrent); }
void Add(PtrInfo* aEdge) {
if (mCurrent == mBlockEnd) {
Block *b = new Block();
if (!b) {
// This means we just won't collect (some) cycles.
NS_NOTREACHED("out of memory, ignoring edges");
return;
}
*mNextBlockPtr = b;
mCurrent = b->Start();
mBlockEnd = b->End();
mNextBlockPtr = &b->Next();
mNumBlocks++;
}
(mCurrent++)->ptrInfo = aEdge;
}
private:
// mBlockEnd points to space for null sentinel
PtrInfoOrBlock *mCurrent, *mBlockEnd;
Block **mNextBlockPtr;
PRUint32 &mNumBlocks;
};
size_t BlocksSize() const {
return sizeof(Block) * mNumBlocks;
}
};
#ifdef DEBUG_CC
struct ReversedEdge {
PtrInfo *mTarget;
nsCString *mEdgeName;
ReversedEdge *mNext;
};
#endif
enum NodeColor { black, white, grey };
// This structure should be kept as small as possible; we may expect
// hundreds of thousands of them to be allocated and touched
// repeatedly during each cycle collection.
struct PtrInfo
{
void *mPointer;
nsCycleCollectionParticipant *mParticipant;
PRUint32 mColor : 2;
PRUint32 mInternalRefs : 30;
PRUint32 mRefCount;
private:
EdgePool::Iterator mFirstChild;
public:
#ifdef DEBUG_CC
size_t mBytes;
char *mName;
PRUint32 mLangID;
// For finding roots in ExplainLiveExpectedGarbage (when there are
// missing calls to suspect or failures to unlink).
PRUint32 mSCCIndex; // strongly connected component
// For finding roots in ExplainLiveExpectedGarbage (when nodes
// expected to be garbage are black).
ReversedEdge* mReversedEdges; // linked list
PtrInfo* mShortestPathToExpectedGarbage;
nsCString* mShortestPathToExpectedGarbageEdgeName;
nsTArray<nsCString> mEdgeNames;
#endif
PtrInfo(void *aPointer, nsCycleCollectionParticipant *aParticipant
IF_DEBUG_CC_PARAM(PRUint32 aLangID)
)
: mPointer(aPointer),
mParticipant(aParticipant),
mColor(grey),
mInternalRefs(0),
mRefCount(0),
mFirstChild()
#ifdef DEBUG_CC
, mBytes(0),
mName(nsnull),
mLangID(aLangID),
mSCCIndex(0),
mReversedEdges(nsnull),
mShortestPathToExpectedGarbage(nsnull),
mShortestPathToExpectedGarbageEdgeName(nsnull)
#endif
{
}
#ifdef DEBUG_CC
void Destroy() {
PL_strfree(mName);
mEdgeNames.~nsTArray<nsCString>();
}
#endif
// Allow NodePool::Block's constructor to compile.
PtrInfo() {
NS_NOTREACHED("should never be called");
}
EdgePool::Iterator FirstChild()
{
return mFirstChild;
}
// this PtrInfo must be part of a NodePool
EdgePool::Iterator LastChild()
{
return (this + 1)->mFirstChild;
}
void SetFirstChild(EdgePool::Iterator aFirstChild)
{
mFirstChild = aFirstChild;
}
// this PtrInfo must be part of a NodePool
void SetLastChild(EdgePool::Iterator aLastChild)
{
(this + 1)->mFirstChild = aLastChild;
}
};
/**
* A structure designed to be used like a linked list of PtrInfo, except
* that allocates the PtrInfo 32K-at-a-time.
*/
class NodePool
{
private:
enum { BlockSize = 8 * 1024 }; // could be int template parameter
struct Block {
// We create and destroy Block using NS_Alloc/NS_Free rather
// than new and delete to avoid calling its constructor and
// destructor.
Block() { NS_NOTREACHED("should never be called"); }
~Block() { NS_NOTREACHED("should never be called"); }
Block* mNext;
PtrInfo mEntries[BlockSize + 1]; // +1 to store last child of last node
};
public:
NodePool()
: mBlocks(nsnull),
mLast(nsnull),
mNumBlocks(0)
{
}
~NodePool()
{
NS_ASSERTION(!mBlocks, "Didn't call Clear()?");
}
void Clear()
{
#ifdef DEBUG_CC
{
Enumerator queue(*this);
while (!queue.IsDone()) {
queue.GetNext()->Destroy();
}
}
#endif
Block *b = mBlocks;
while (b) {
Block *n = b->mNext;
NS_Free(b);
NS_ASSERTION(mNumBlocks > 0,
"Expected NodePool mNumBlocks to be positive.");
mNumBlocks--;
b = n;
}
mBlocks = nsnull;
mLast = nsnull;
}
class Builder;
friend class Builder;
class Builder {
public:
Builder(NodePool& aPool)
: mNextBlock(&aPool.mBlocks),
mNext(aPool.mLast),
mBlockEnd(nsnull),
mNumBlocks(aPool.mNumBlocks)
{
NS_ASSERTION(aPool.mBlocks == nsnull && aPool.mLast == nsnull,
"pool not empty");
}
PtrInfo *Add(void *aPointer, nsCycleCollectionParticipant *aParticipant
IF_DEBUG_CC_PARAM(PRUint32 aLangID)
)
{
if (mNext == mBlockEnd) {
Block *block;
if (!(*mNextBlock = block =
static_cast<Block*>(NS_Alloc(sizeof(Block)))))
return nsnull;
mNext = block->mEntries;
mBlockEnd = block->mEntries + BlockSize;
block->mNext = nsnull;
mNextBlock = &block->mNext;
mNumBlocks++;
}
return new (mNext++) PtrInfo(aPointer, aParticipant
IF_DEBUG_CC_PARAM(aLangID)
);
}
private:
Block **mNextBlock;
PtrInfo *&mNext;
PtrInfo *mBlockEnd;
PRUint32 &mNumBlocks;
};
class Enumerator;
friend class Enumerator;
class Enumerator {
public:
Enumerator(NodePool& aPool)
: mFirstBlock(aPool.mBlocks),
mCurBlock(nsnull),
mNext(nsnull),
mBlockEnd(nsnull),
mLast(aPool.mLast)
{
}
bool IsDone() const
{
return mNext == mLast;
}
bool AtBlockEnd() const
{
return mNext == mBlockEnd;
}
PtrInfo* GetNext()
{
NS_ASSERTION(!IsDone(), "calling GetNext when done");
if (mNext == mBlockEnd) {
Block *nextBlock = mCurBlock ? mCurBlock->mNext : mFirstBlock;
mNext = nextBlock->mEntries;
mBlockEnd = mNext + BlockSize;
mCurBlock = nextBlock;
}
return mNext++;
}
private:
Block *mFirstBlock, *mCurBlock;
// mNext is the next value we want to return, unless mNext == mBlockEnd
// NB: mLast is a reference to allow enumerating while building!
PtrInfo *mNext, *mBlockEnd, *&mLast;
};
size_t BlocksSize() const {
return sizeof(Block) * mNumBlocks;
}
private:
Block *mBlocks;
PtrInfo *mLast;
PRUint32 mNumBlocks;
};
struct WeakMapping
{
// map and key will be null if the corresponding objects are GC marked
PtrInfo *mMap;
PtrInfo *mKey;
PtrInfo *mVal;
};
class GCGraphBuilder;
struct GCGraph
{
NodePool mNodes;
EdgePool mEdges;
nsTArray<WeakMapping> mWeakMaps;
PRUint32 mRootCount;
#ifdef DEBUG_CC
ReversedEdge *mReversedEdges;
#endif
GCGraph() : mRootCount(0) {
}
~GCGraph() {
}
size_t BlocksSize() const {
return mNodes.BlocksSize() + mEdges.BlocksSize();
}
};
// XXX Would be nice to have an nsHashSet<KeyType> API that has
// Add/Remove/Has rather than PutEntry/RemoveEntry/GetEntry.
typedef nsTHashtable<nsPtrHashKey<const void> > PointerSet;
static inline void
ToParticipant(nsISupports *s, nsXPCOMCycleCollectionParticipant **cp);
struct nsPurpleBuffer
{
private:
struct Block {
Block *mNext;
nsPurpleBufferEntry mEntries[255];
Block() : mNext(nsnull) {}
};
public:
// This class wraps a linked list of the elements in the purple
// buffer.
nsCycleCollectorParams &mParams;
PRUint32 mNumBlocksAlloced;
PRUint32 mCount;
Block mFirstBlock;
nsPurpleBufferEntry *mFreeList;
// For objects compiled against Gecko 1.9 and 1.9.1.
PointerSet mCompatObjects;
#ifdef DEBUG_CC
PointerSet mNormalObjects; // duplicates our blocks
nsCycleCollectorStats &mStats;
#endif
#ifdef DEBUG_CC
nsPurpleBuffer(nsCycleCollectorParams &params,
nsCycleCollectorStats &stats)
: mParams(params),
mStats(stats)
{
InitBlocks();
mNormalObjects.Init();
mCompatObjects.Init();
}
#else
nsPurpleBuffer(nsCycleCollectorParams &params)
: mParams(params)
{
InitBlocks();
mCompatObjects.Init();
}
#endif
~nsPurpleBuffer()
{
FreeBlocks();
}
void InitBlocks()
{
mNumBlocksAlloced = 0;
mCount = 0;
mFreeList = nsnull;
StartBlock(&mFirstBlock);
}
void StartBlock(Block *aBlock)
{
NS_ABORT_IF_FALSE(!mFreeList, "should not have free list");
// Put all the entries in the block on the free list.
nsPurpleBufferEntry *entries = aBlock->mEntries;
mFreeList = entries;
for (PRUint32 i = 1; i < ArrayLength(aBlock->mEntries); ++i) {
entries[i - 1].mNextInFreeList =
(nsPurpleBufferEntry*)(PRUword(entries + i) | 1);
}
entries[ArrayLength(aBlock->mEntries) - 1].mNextInFreeList =
(nsPurpleBufferEntry*)1;
}
void FreeBlocks()
{
if (mCount > 0)
UnmarkRemainingPurple(&mFirstBlock);
Block *b = mFirstBlock.mNext;
while (b) {
if (mCount > 0)
UnmarkRemainingPurple(b);
Block *next = b->mNext;
delete b;
b = next;
NS_ASSERTION(mNumBlocksAlloced > 0,
"Expected positive mNumBlocksAlloced.");
mNumBlocksAlloced--;
}
mFirstBlock.mNext = nsnull;
}
void UnmarkRemainingPurple(Block *b)
{
for (nsPurpleBufferEntry *e = b->mEntries,
*eEnd = ArrayEnd(b->mEntries);
e != eEnd; ++e) {
if (!(PRUword(e->mObject) & PRUword(1))) {
// This is a real entry (rather than something on the
// free list).
if (e->mObject) {
nsXPCOMCycleCollectionParticipant *cp;
ToParticipant(e->mObject, &cp);
cp->UnmarkIfPurple(e->mObject);
}
if (--mCount == 0)
break;
}
}
}
void SelectPointers(GCGraphBuilder &builder);
// RemoveSkippable removes entries from the purple buffer if
// nsPurpleBufferEntry::mObject is null or if the object's
// nsXPCOMCycleCollectionParticipant::CanSkip() returns true.
// If removeChildlessNodes is true, then any nodes in the purple buffer
// that will have no children in the cycle collector graph will also be
// removed. CanSkip() may be run on these children.
void RemoveSkippable(bool removeChildlessNodes);
#ifdef DEBUG_CC
void NoteAll(GCGraphBuilder &builder);
bool Exists(void *p) const
{
return mNormalObjects.GetEntry(p) || mCompatObjects.GetEntry(p);
}
#endif
nsPurpleBufferEntry* NewEntry()
{
if (!mFreeList) {
Block *b = new Block;
if (!b) {
return nsnull;
}
mNumBlocksAlloced++;
StartBlock(b);
// Add the new block as the second block in the list.
b->mNext = mFirstBlock.mNext;
mFirstBlock.mNext = b;
}
nsPurpleBufferEntry *e = mFreeList;
mFreeList = (nsPurpleBufferEntry*)
(PRUword(mFreeList->mNextInFreeList) & ~PRUword(1));
return e;
}
nsPurpleBufferEntry* Put(nsISupports *p)
{
nsPurpleBufferEntry *e = NewEntry();
if (!e) {
return nsnull;
}
++mCount;
e->mObject = p;
#ifdef DEBUG_CC
mNormalObjects.PutEntry(p);
#endif
// Caller is responsible for filling in result's mRefCnt.
return e;
}
void Remove(nsPurpleBufferEntry *e)
{
NS_ASSERTION(mCount != 0, "must have entries");
#ifdef DEBUG_CC
mNormalObjects.RemoveEntry(e->mObject);
#endif
e->mNextInFreeList =
(nsPurpleBufferEntry*)(PRUword(mFreeList) | PRUword(1));
mFreeList = e;
--mCount;
}
bool PutCompatObject(nsISupports *p)
{
++mCount;
return !!mCompatObjects.PutEntry(p);
}
void RemoveCompatObject(nsISupports *p)
{
--mCount;
mCompatObjects.RemoveEntry(p);
}
PRUint32 Count() const
{
return mCount;
}
size_t BlocksSize() const
{
return sizeof(Block) * mNumBlocksAlloced;
}
};
struct CallbackClosure
{
CallbackClosure(nsPurpleBuffer *aPurpleBuffer, GCGraphBuilder &aBuilder)
: mPurpleBuffer(aPurpleBuffer),
mBuilder(aBuilder)
{
}
nsPurpleBuffer *mPurpleBuffer;
GCGraphBuilder &mBuilder;
};
static bool
AddPurpleRoot(GCGraphBuilder &builder, nsISupports *root);
static PLDHashOperator
selectionCallback(nsPtrHashKey<const void>* key, void* userArg)
{
CallbackClosure *closure = static_cast<CallbackClosure*>(userArg);
if (AddPurpleRoot(closure->mBuilder,
static_cast<nsISupports *>(
const_cast<void*>(key->GetKey()))))
return PL_DHASH_REMOVE;
return PL_DHASH_NEXT;
}
void
nsPurpleBuffer::SelectPointers(GCGraphBuilder &aBuilder)
{
#ifdef DEBUG_CC
// Can't use mCount here, since it may include null entries.
PRUint32 realCount = 0;
for (Block *b = &mFirstBlock; b; b = b->mNext) {
for (nsPurpleBufferEntry *e = b->mEntries,
*eEnd = ArrayEnd(b->mEntries);
e != eEnd; ++e) {
if (!(PRUword(e->mObject) & PRUword(1))) {
if (e->mObject) {
++realCount;
}
}
}
}
NS_ABORT_IF_FALSE(mCompatObjects.Count() + mNormalObjects.Count() ==
realCount,
"count out of sync");
#endif
if (mCompatObjects.Count()) {
mCount -= mCompatObjects.Count();
CallbackClosure closure(this, aBuilder);
mCompatObjects.EnumerateEntries(selectionCallback, &closure);
mCount += mCompatObjects.Count(); // in case of allocation failure
}
// Walk through all the blocks.
for (Block *b = &mFirstBlock; b; b = b->mNext) {
for (nsPurpleBufferEntry *e = b->mEntries,
*eEnd = ArrayEnd(b->mEntries);
e != eEnd; ++e) {
if (!(PRUword(e->mObject) & PRUword(1))) {
// This is a real entry (rather than something on the
// free list).
if (!e->mObject || AddPurpleRoot(aBuilder, e->mObject)) {
Remove(e);
}
}
}
}
NS_WARN_IF_FALSE(mCount == 0, "AddPurpleRoot failed");
if (mCount == 0) {
FreeBlocks();
InitBlocks();
}
}
////////////////////////////////////////////////////////////////////////
// Implement the LanguageRuntime interface for C++/XPCOM
////////////////////////////////////////////////////////////////////////
struct nsCycleCollectionXPCOMRuntime :
public nsCycleCollectionLanguageRuntime
{
nsresult BeginCycleCollection(nsCycleCollectionTraversalCallback &cb,
bool explainLiveExpectedGarbage)
{
return NS_OK;
}
nsresult FinishTraverse()
{
return NS_OK;
}
nsresult FinishCycleCollection()
{
return NS_OK;
}
inline nsCycleCollectionParticipant *ToParticipant(void *p);
#ifdef DEBUG_CC
virtual void PrintAllReferencesTo(void *p) {}
#endif
};
struct nsCycleCollector
{
bool mCollectionInProgress;
bool mScanInProgress;
bool mFollowupCollection;
nsCycleCollectorResults *mResults;
TimeStamp mCollectionStart;
nsCycleCollectionLanguageRuntime *mRuntimes[nsIProgrammingLanguage::MAX+1];
nsCycleCollectionXPCOMRuntime mXPCOMRuntime;
GCGraph mGraph;
nsCycleCollectorParams mParams;
nsTArray<PtrInfo*> *mWhiteNodes;
PRUint32 mWhiteNodeCount;
// mVisitedRefCounted and mVisitedGCed are only used for telemetry
PRUint32 mVisitedRefCounted;
PRUint32 mVisitedGCed;
nsPurpleBuffer mPurpleBuf;
CC_BeforeUnlinkCallback mBeforeUnlinkCB;
CC_ForgetSkippableCallback mForgetSkippableCB;
void RegisterRuntime(PRUint32 langID,
nsCycleCollectionLanguageRuntime *rt);
void ForgetRuntime(PRUint32 langID);
void SelectPurple(GCGraphBuilder &builder);
void MarkRoots(GCGraphBuilder &builder);
void ScanRoots();
void ScanWeakMaps();
void ForgetSkippable(bool removeChildlessNodes);
// returns whether anything was collected
bool CollectWhite(nsICycleCollectorListener *aListener);
nsCycleCollector();
~nsCycleCollector();
// The first pair of Suspect and Forget functions are only used by
// old XPCOM binary components.
bool Suspect(nsISupports *n);
bool Forget(nsISupports *n);
nsPurpleBufferEntry* Suspect2(nsISupports *n);
bool Forget2(nsPurpleBufferEntry *e);
void Collect(nsCycleCollectorResults *aResults,
PRUint32 aTryCollections,
nsICycleCollectorListener *aListener);
// Prepare for and cleanup after one or more collection(s).
bool PrepareForCollection(nsCycleCollectorResults *aResults,
nsTArray<PtrInfo*> *aWhiteNodes);
void GCIfNeeded(bool aForceGC);
void CleanupAfterCollection();
// Start and finish an individual collection.
bool BeginCollection(nsICycleCollectorListener *aListener);
bool FinishCollection(nsICycleCollectorListener *aListener);
PRUint32 SuspectedCount();
void Shutdown();
void ClearGraph()
{
mGraph.mNodes.Clear();
mGraph.mEdges.Clear();
mGraph.mWeakMaps.Clear();
mGraph.mRootCount = 0;
}
#ifdef DEBUG_CC
nsCycleCollectorStats mStats;
FILE *mPtrLog;
void Allocated(void *n, size_t sz);
void Freed(void *n);
void LogPurpleRemoval(void* aObject);
void ExplainLiveExpectedGarbage();
bool CreateReversedEdges();
void DestroyReversedEdges();
void ShouldBeFreed(nsISupports *n);
void WasFreed(nsISupports *n);
PointerSet mExpectedGarbage;
#endif
};
/**
* GraphWalker is templatized over a Visitor class that must provide
* the following two methods:
*
* bool ShouldVisitNode(PtrInfo const *pi);
* void VisitNode(PtrInfo *pi);
*/
template <class Visitor>
class GraphWalker
{
private:
Visitor mVisitor;
void DoWalk(nsDeque &aQueue);
public:
void Walk(PtrInfo *s0);
void WalkFromRoots(GCGraph &aGraph);
// copy-constructing the visitor should be cheap, and less
// indirection than using a reference
GraphWalker(const Visitor aVisitor) : mVisitor(aVisitor) {}
};
////////////////////////////////////////////////////////////////////////
// The static collector object
////////////////////////////////////////////////////////////////////////
static nsCycleCollector *sCollector = nsnull;
////////////////////////////////////////////////////////////////////////
// Utility functions
////////////////////////////////////////////////////////////////////////
MOZ_NEVER_INLINE static void
Fault(const char *msg, const void *ptr=nsnull)
{
if (ptr)
printf("Fault in cycle collector: %s (ptr: %p)\n", msg, ptr);
else
printf("Fault in cycle collector: %s\n", msg);
NS_RUNTIMEABORT("cycle collector fault");
}
#ifdef DEBUG_CC
static void
Fault(const char *msg, PtrInfo *pi)
{
printf("Fault in cycle collector: %s\n"
" while operating on pointer %p %s\n",
msg, pi->mPointer, pi->mName);
if (pi->mInternalRefs) {
printf(" which has internal references from:\n");
NodePool::Enumerator queue(sCollector->mGraph.mNodes);
while (!queue.IsDone()) {
PtrInfo *ppi = queue.GetNext();
for (EdgePool::Iterator e = ppi->FirstChild(),
e_end = ppi->LastChild();
e != e_end; ++e) {
if (*e == pi) {
printf(" %p %s\n", ppi->mPointer, ppi->mName);
}
}
}
}
Fault(msg, pi->mPointer);
}
#else
static void
Fault(const char *msg, PtrInfo *pi)
{
Fault(msg, pi->mPointer);
}
#endif
static inline void
AbortIfOffMainThreadIfCheckFast()
{
#if defined(XP_WIN) || defined(NS_TLS)
if (!NS_IsMainThread() && !NS_IsCycleCollectorThread()) {
NS_RUNTIMEABORT("Main-thread-only object used off the main thread");
}
#endif
}
static nsISupports *
canonicalize(nsISupports *in)
{
nsISupports* child;
in->QueryInterface(NS_GET_IID(nsCycleCollectionISupports),
reinterpret_cast<void**>(&child));
return child;
}
static inline void
ToParticipant(nsISupports *s, nsXPCOMCycleCollectionParticipant **cp)
{
// We use QI to move from an nsISupports to an
// nsXPCOMCycleCollectionParticipant, which is a per-class singleton helper
// object that implements traversal and unlinking logic for the nsISupports
// in question.
CallQueryInterface(s, cp);
#ifdef DEBUG_CC
if (cp)
++sCollector->mStats.mSuccessfulQI;
else
++sCollector->mStats.mFailedQI;
#endif
}
nsCycleCollectionParticipant *
nsCycleCollectionXPCOMRuntime::ToParticipant(void *p)
{
nsXPCOMCycleCollectionParticipant *cp;
::ToParticipant(static_cast<nsISupports*>(p), &cp);
return cp;
}
template <class Visitor>
MOZ_NEVER_INLINE void
GraphWalker<Visitor>::Walk(PtrInfo *s0)
{
nsDeque queue;
CC_AbortIfNull(s0);
queue.Push(s0);
DoWalk(queue);
}
template <class Visitor>
MOZ_NEVER_INLINE void
GraphWalker<Visitor>::WalkFromRoots(GCGraph& aGraph)
{
nsDeque queue;
NodePool::Enumerator etor(aGraph.mNodes);
for (PRUint32 i = 0; i < aGraph.mRootCount; ++i) {
PtrInfo *pi = etor.GetNext();
CC_AbortIfNull(pi);
queue.Push(pi);
}
DoWalk(queue);
}
template <class Visitor>
MOZ_NEVER_INLINE void
GraphWalker<Visitor>::DoWalk(nsDeque &aQueue)
{
// Use a aQueue to match the breadth-first traversal used when we
// built the graph, for hopefully-better locality.
while (aQueue.GetSize() > 0) {
PtrInfo *pi = static_cast<PtrInfo*>(aQueue.PopFront());
CC_AbortIfNull(pi);
if (mVisitor.ShouldVisitNode(pi)) {
mVisitor.VisitNode(pi);
for (EdgePool::Iterator child = pi->FirstChild(),
child_end = pi->LastChild();
child != child_end; ++child) {
CC_AbortIfNull(*child);
aQueue.Push(*child);
}
}
};
#ifdef DEBUG_CC
sCollector->mStats.mWalkedGraph++;
#endif
}
struct CCGraphDescriber
{
CCGraphDescriber()
: mAddress("0x"), mToAddress("0x"), mCnt(0), mType(eUnknown) {}
enum Type
{
eRefCountedObject,
eGCedObject,
eGCMarkedObject,
eEdge,
eRoot,
eGarbage,
eUnknown
};
nsCString mAddress;
nsCString mToAddress;
nsCString mName;
PRUint32 mCnt;
Type mType;
};
class nsCycleCollectorLogger : public nsICycleCollectorListener
{
public:
nsCycleCollectorLogger() :
mStream(nsnull), mWantAllTraces(false),
mDisableLog(false), mWantAfterProcessing(false),
mNextIndex(0)
{
}
~nsCycleCollectorLogger()
{
if (mStream) {
fclose(mStream);
}
}
NS_DECL_ISUPPORTS
NS_IMETHOD AllTraces(nsICycleCollectorListener** aListener)
{
mWantAllTraces = true;
NS_ADDREF(*aListener = this);
return NS_OK;
}
NS_IMETHOD GetWantAllTraces(bool* aAllTraces)
{
*aAllTraces = mWantAllTraces;
return NS_OK;
}
NS_IMETHOD GetDisableLog(bool* aDisableLog)
{
*aDisableLog = mDisableLog;
return NS_OK;
}
NS_IMETHOD SetDisableLog(bool aDisableLog)
{
mDisableLog = aDisableLog;
return NS_OK;
}
NS_IMETHOD GetWantAfterProcessing(bool* aWantAfterProcessing)
{
*aWantAfterProcessing = mWantAfterProcessing;
return NS_OK;
}
NS_IMETHOD SetWantAfterProcessing(bool aWantAfterProcessing)
{
mWantAfterProcessing = aWantAfterProcessing;
return NS_OK;
}
NS_IMETHOD Begin()
{
mCurrentAddress.AssignLiteral("0x");
mDescribers.Clear();
mNextIndex = 0;
if (mDisableLog) {
return NS_OK;
}
char basename[MAXPATHLEN] = {'\0'};
char ccname[MAXPATHLEN] = {'\0'};
#ifdef XP_WIN
// On Windows, tmpnam returns useless stuff, such as "\\s164.".
// Therefore we need to call the APIs directly.
GetTempPathA(mozilla::ArrayLength(basename), basename);
#else
tmpnam(basename);
char *lastSlash = strrchr(basename, XPCOM_FILE_PATH_SEPARATOR[0]);
if (lastSlash) {
*lastSlash = '\0';
}
#endif
++gLogCounter;
#ifdef DEBUG
// Dump the JS heap.
char gcname[MAXPATHLEN] = {'\0'};
sprintf(gcname, "%s%sgc-edges-%d.%d.log", basename,
XPCOM_FILE_PATH_SEPARATOR,
gLogCounter, base::GetCurrentProcId());
FILE* gcDumpFile = fopen(gcname, "w");
if (!gcDumpFile)
return NS_ERROR_FAILURE;
xpc::DumpJSHeap(gcDumpFile);
fclose(gcDumpFile);
#endif
// Open a file for dumping the CC graph.
sprintf(ccname, "%s%scc-edges-%d.%d.log", basename,
XPCOM_FILE_PATH_SEPARATOR,
gLogCounter, base::GetCurrentProcId());
mStream = fopen(ccname, "w");
if (!mStream)
return NS_ERROR_FAILURE;
nsCOMPtr<nsIConsoleService> cs =
do_GetService(NS_CONSOLESERVICE_CONTRACTID);
if (cs) {
cs->LogStringMessage(NS_ConvertUTF8toUTF16(ccname).get());
#ifdef DEBUG
cs->LogStringMessage(NS_ConvertUTF8toUTF16(gcname).get());
#endif
}
return NS_OK;
}
NS_IMETHOD NoteRefCountedObject(PRUint64 aAddress, PRUint32 refCount,
const char *aObjectDescription)
{
if (!mDisableLog) {
fprintf(mStream, "%p [rc=%u] %s\n", (void*)aAddress, refCount,
aObjectDescription);
}
if (mWantAfterProcessing) {
CCGraphDescriber* d = mDescribers.AppendElement();
NS_ENSURE_TRUE(d, NS_ERROR_OUT_OF_MEMORY);
mCurrentAddress.AssignLiteral("0x");
mCurrentAddress.AppendInt(aAddress, 16);
d->mType = CCGraphDescriber::eRefCountedObject;
d->mAddress = mCurrentAddress;
d->mCnt = refCount;
d->mName.Append(aObjectDescription);
}
return NS_OK;
}
NS_IMETHOD NoteGCedObject(PRUint64 aAddress, bool aMarked,
const char *aObjectDescription)
{
if (!mDisableLog) {
fprintf(mStream, "%p [gc%s] %s\n", (void*)aAddress,
aMarked ? ".marked" : "", aObjectDescription);
}
if (mWantAfterProcessing) {
CCGraphDescriber* d = mDescribers.AppendElement();
NS_ENSURE_TRUE(d, NS_ERROR_OUT_OF_MEMORY);
mCurrentAddress.AssignLiteral("0x");
mCurrentAddress.AppendInt(aAddress, 16);
d->mType = aMarked ? CCGraphDescriber::eGCMarkedObject :
CCGraphDescriber::eGCedObject;
d->mAddress = mCurrentAddress;
d->mName.Append(aObjectDescription);
}
return NS_OK;
}
NS_IMETHOD NoteEdge(PRUint64 aToAddress, const char *aEdgeName)
{
if (!mDisableLog) {
fprintf(mStream, "> %p %s\n", (void*)aToAddress, aEdgeName);
}
if (mWantAfterProcessing) {
CCGraphDescriber* d = mDescribers.AppendElement();
NS_ENSURE_TRUE(d, NS_ERROR_OUT_OF_MEMORY);
d->mType = CCGraphDescriber::eEdge;
d->mAddress = mCurrentAddress;
d->mToAddress.AppendInt(aToAddress, 16);
d->mName.Append(aEdgeName);
}
return NS_OK;
}
NS_IMETHOD BeginResults()
{
if (!mDisableLog) {
fputs("==========\n", mStream);
}
return NS_OK;
}
NS_IMETHOD DescribeRoot(PRUint64 aAddress, PRUint32 aKnownEdges)
{
if (!mDisableLog) {
fprintf(mStream, "%p [known=%u]\n", (void*)aAddress, aKnownEdges);
}
if (mWantAfterProcessing) {
CCGraphDescriber* d = mDescribers.AppendElement();
NS_ENSURE_TRUE(d, NS_ERROR_OUT_OF_MEMORY);
d->mType = CCGraphDescriber::eRoot;
d->mAddress.AppendInt(aAddress, 16);
d->mCnt = aKnownEdges;
}
return NS_OK;
}
NS_IMETHOD DescribeGarbage(PRUint64 aAddress)
{
if (!mDisableLog) {
fprintf(mStream, "%p [garbage]\n", (void*)aAddress);
}
if (mWantAfterProcessing) {
CCGraphDescriber* d = mDescribers.AppendElement();
NS_ENSURE_TRUE(d, NS_ERROR_OUT_OF_MEMORY);
d->mType = CCGraphDescriber::eGarbage;
d->mAddress.AppendInt(aAddress, 16);
}
return NS_OK;
}
NS_IMETHOD End()
{
if (!mDisableLog) {
fclose(mStream);
mStream = nsnull;
}
return NS_OK;
}
NS_IMETHOD ProcessNext(nsICycleCollectorHandler* aHandler,
bool* aCanContinue)
{
NS_ENSURE_STATE(aHandler && mWantAfterProcessing);
if (mNextIndex < mDescribers.Length()) {
CCGraphDescriber& d = mDescribers[mNextIndex++];
switch (d.mType) {
case CCGraphDescriber::eRefCountedObject:
aHandler->NoteRefCountedObject(d.mAddress,
d.mCnt,
d.mName);
break;
case CCGraphDescriber::eGCedObject:
case CCGraphDescriber::eGCMarkedObject:
aHandler->NoteGCedObject(d.mAddress,
d.mType ==
CCGraphDescriber::eGCMarkedObject,
d.mName);
break;
case CCGraphDescriber::eEdge:
aHandler->NoteEdge(d.mAddress,
d.mToAddress,
d.mName);
break;
case CCGraphDescriber::eRoot:
aHandler->DescribeRoot(d.mAddress,
d.mCnt);
break;
case CCGraphDescriber::eGarbage:
aHandler->DescribeGarbage(d.mAddress);
break;
case CCGraphDescriber::eUnknown:
NS_NOTREACHED("CCGraphDescriber::eUnknown");
break;
}
}
if (!(*aCanContinue = mNextIndex < mDescribers.Length())) {
mCurrentAddress.AssignLiteral("0x");
mDescribers.Clear();
mNextIndex = 0;
}
return NS_OK;
}
private:
FILE *mStream;
bool mWantAllTraces;
bool mDisableLog;
bool mWantAfterProcessing;
nsCString mCurrentAddress;
nsTArray<CCGraphDescriber> mDescribers;
PRUint32 mNextIndex;
static PRUint32 gLogCounter;
};
NS_IMPL_ISUPPORTS1(nsCycleCollectorLogger, nsICycleCollectorListener)
PRUint32 nsCycleCollectorLogger::gLogCounter = 0;
nsresult
nsCycleCollectorLoggerConstructor(nsISupports* aOuter,
const nsIID& aIID,
void* *aInstancePtr)
{
NS_ENSURE_TRUE(!aOuter, NS_ERROR_NO_AGGREGATION);
nsISupports *logger = new nsCycleCollectorLogger();
return logger->QueryInterface(aIID, aInstancePtr);
}
////////////////////////////////////////////////////////////////////////
// Bacon & Rajan's |MarkRoots| routine.
////////////////////////////////////////////////////////////////////////
struct PtrToNodeEntry : public PLDHashEntryHdr
{
// The key is mNode->mPointer
PtrInfo *mNode;
};
static bool
PtrToNodeMatchEntry(PLDHashTable *table,
const PLDHashEntryHdr *entry,
const void *key)
{
const PtrToNodeEntry *n = static_cast<const PtrToNodeEntry*>(entry);
return n->mNode->mPointer == key;
}
static PLDHashTableOps PtrNodeOps = {
PL_DHashAllocTable,
PL_DHashFreeTable,
PL_DHashVoidPtrKeyStub,
PtrToNodeMatchEntry,
PL_DHashMoveEntryStub,
PL_DHashClearEntryStub,
PL_DHashFinalizeStub,
nsnull
};
class GCGraphBuilder : public nsCycleCollectionTraversalCallback
{
private:
NodePool::Builder mNodeBuilder;
EdgePool::Builder mEdgeBuilder;
nsTArray<WeakMapping> &mWeakMaps;
PLDHashTable mPtrToNodeMap;
PtrInfo *mCurrPi;
nsCycleCollectionLanguageRuntime **mRuntimes; // weak, from nsCycleCollector
nsCString mNextEdgeName;
nsICycleCollectorListener *mListener;
public:
GCGraphBuilder(GCGraph &aGraph,
nsCycleCollectionLanguageRuntime **aRuntimes,
nsICycleCollectorListener *aListener);
~GCGraphBuilder();
bool Initialized();
PRUint32 Count() const { return mPtrToNodeMap.entryCount; }
#ifdef DEBUG_CC
PtrInfo* AddNode(void *s, nsCycleCollectionParticipant *aParticipant,
PRUint32 aLangID);
#else
PtrInfo* AddNode(void *s, nsCycleCollectionParticipant *aParticipant);
PtrInfo* AddNode(void *s, nsCycleCollectionParticipant *aParticipant,
PRUint32 aLangID)
{
return AddNode(s, aParticipant);
}
#endif
PtrInfo* AddWeakMapNode(void* node);
void Traverse(PtrInfo* aPtrInfo);
void SetLastChild();
// nsCycleCollectionTraversalCallback methods.
NS_IMETHOD_(void) NoteXPCOMRoot(nsISupports *root);
private:
void DescribeNode(PRUint32 refCount,
size_t objSz,
const char *objName)
{
mCurrPi->mRefCount = refCount;
#ifdef DEBUG_CC
mCurrPi->mBytes = objSz;
mCurrPi->mName = PL_strdup(objName);
sCollector->mStats.mVisitedNode++;
#endif
}
NS_IMETHOD_(void) DescribeRefCountedNode(nsrefcnt refCount, size_t objSz,
const char *objName);
NS_IMETHOD_(void) DescribeGCedNode(bool isMarked, size_t objSz,
const char *objName);
NS_IMETHOD_(void) NoteRoot(PRUint32 langID, void *child,
nsCycleCollectionParticipant* participant);
NS_IMETHOD_(void) NoteXPCOMChild(nsISupports *child);
NS_IMETHOD_(void) NoteNativeChild(void *child,
nsCycleCollectionParticipant *participant);
NS_IMETHOD_(void) NoteScriptChild(PRUint32 langID, void *child);
NS_IMETHOD_(void) NoteNextEdgeName(const char* name);
NS_IMETHOD_(void) NoteWeakMapping(void *map, void *key, void *val);
private:
NS_IMETHOD_(void) NoteChild(void *child, nsCycleCollectionParticipant *cp,
PRUint32 langID, nsCString edgeName)
{
PtrInfo *childPi = AddNode(child, cp, langID);
if (!childPi)
return;
mEdgeBuilder.Add(childPi);
#ifdef DEBUG_CC
mCurrPi->mEdgeNames.AppendElement(edgeName);
#endif
if (mListener) {
mListener->NoteEdge((PRUint64)child, edgeName.get());
}
++childPi->mInternalRefs;
}
};
GCGraphBuilder::GCGraphBuilder(GCGraph &aGraph,
nsCycleCollectionLanguageRuntime **aRuntimes,
nsICycleCollectorListener *aListener)
: mNodeBuilder(aGraph.mNodes),
mEdgeBuilder(aGraph.mEdges),
mWeakMaps(aGraph.mWeakMaps),
mRuntimes(aRuntimes),
mListener(aListener)
{
if (!PL_DHashTableInit(&mPtrToNodeMap, &PtrNodeOps, nsnull,
sizeof(PtrToNodeEntry), 32768))
mPtrToNodeMap.ops = nsnull;
PRUint32 flags = 0;
#ifdef DEBUG_CC
flags = nsCycleCollectionTraversalCallback::WANT_DEBUG_INFO |
nsCycleCollectionTraversalCallback::WANT_ALL_TRACES;
#endif
if (!flags && mListener) {
flags = nsCycleCollectionTraversalCallback::WANT_DEBUG_INFO;
bool all = false;
mListener->GetWantAllTraces(&all);
if (all) {
flags |= nsCycleCollectionTraversalCallback::WANT_ALL_TRACES;
}
}
mFlags |= flags;
}
GCGraphBuilder::~GCGraphBuilder()
{
if (mPtrToNodeMap.ops)
PL_DHashTableFinish(&mPtrToNodeMap);
}
bool
GCGraphBuilder::Initialized()
{
return !!mPtrToNodeMap.ops;
}
PtrInfo*
GCGraphBuilder::AddNode(void *s, nsCycleCollectionParticipant *aParticipant
IF_DEBUG_CC_PARAM(PRUint32 aLangID)
)
{
PtrToNodeEntry *e = static_cast<PtrToNodeEntry*>(PL_DHashTableOperate(&mPtrToNodeMap, s, PL_DHASH_ADD));
if (!e)
return nsnull;
PtrInfo *result;
if (!e->mNode) {
// New entry.
result = mNodeBuilder.Add(s, aParticipant
IF_DEBUG_CC_PARAM(aLangID)
);
if (!result) {
PL_DHashTableRawRemove(&mPtrToNodeMap, e);
return nsnull;
}
e->mNode = result;
} else {
result = e->mNode;
NS_ASSERTION(result->mParticipant == aParticipant,
"nsCycleCollectionParticipant shouldn't change!");
}
return result;
}
MOZ_NEVER_INLINE void
GCGraphBuilder::Traverse(PtrInfo* aPtrInfo)
{
mCurrPi = aPtrInfo;
#ifdef DEBUG_CC
if (!mCurrPi->mParticipant) {
Fault("unknown pointer during walk", aPtrInfo);
return;
}
#endif
mCurrPi->SetFirstChild(mEdgeBuilder.Mark());
nsresult rv = aPtrInfo->mParticipant->Traverse(aPtrInfo->mPointer, *this);
if (NS_FAILED(rv)) {
Fault("script pointer traversal failed", aPtrInfo);
}
}
void
GCGraphBuilder::SetLastChild()
{
mCurrPi->SetLastChild(mEdgeBuilder.Mark());
}
NS_IMETHODIMP_(void)
GCGraphBuilder::NoteXPCOMRoot(nsISupports *root)
{
root = canonicalize(root);
NS_ASSERTION(root,
"Don't add objects that don't participate in collection!");
#ifdef DEBUG_CC
if (nsCycleCollector_shouldSuppress(root))
return;
#endif
nsXPCOMCycleCollectionParticipant *cp;
ToParticipant(root, &cp);
NoteRoot(nsIProgrammingLanguage::CPLUSPLUS, root, cp);
}
NS_IMETHODIMP_(void)
GCGraphBuilder::NoteRoot(PRUint32 langID, void *root,
nsCycleCollectionParticipant* participant)
{
NS_ASSERTION(root, "Don't add a null root!");
if (langID > nsIProgrammingLanguage::MAX || !mRuntimes[langID]) {
Fault("adding root for unregistered language", root);
return;
}
if (!participant->CanSkipInCC(root) || WantAllTraces()) {
AddNode(root, participant, langID);
}
}
NS_IMETHODIMP_(void)
GCGraphBuilder::DescribeRefCountedNode(nsrefcnt refCount, size_t objSz,
const char *objName)
{
if (refCount == 0)
Fault("zero refcount", mCurrPi);
if (refCount == PR_UINT32_MAX)
Fault("overflowing refcount", mCurrPi);
sCollector->mVisitedRefCounted++;
if (mListener) {
mListener->NoteRefCountedObject((PRUint64)mCurrPi->mPointer, refCount,
objName);
}
DescribeNode(refCount, objSz, objName);
}
NS_IMETHODIMP_(void)
GCGraphBuilder::DescribeGCedNode(bool isMarked, size_t objSz,
const char *objName)
{
PRUint32 refCount = isMarked ? PR_UINT32_MAX : 0;
sCollector->mVisitedGCed++;
if (mListener) {
mListener->NoteGCedObject((PRUint64)mCurrPi->mPointer, isMarked,
objName);
}
DescribeNode(refCount, objSz, objName);
}
NS_IMETHODIMP_(void)
GCGraphBuilder::NoteXPCOMChild(nsISupports *child)
{
nsCString edgeName;
if (WantDebugInfo()) {
edgeName.Assign(mNextEdgeName);
mNextEdgeName.Truncate();
}
if (!child || !(child = canonicalize(child)))
return;
#ifdef DEBUG_CC
if (nsCycleCollector_shouldSuppress(child))
return;
#endif
nsXPCOMCycleCollectionParticipant *cp;
ToParticipant(child, &cp);
if (cp && (!cp->CanSkipThis(child) || WantAllTraces())) {
NoteChild(child, cp, nsIProgrammingLanguage::CPLUSPLUS, edgeName);
}
}
NS_IMETHODIMP_(void)
GCGraphBuilder::NoteNativeChild(void *child,
nsCycleCollectionParticipant *participant)
{
nsCString edgeName;
if (WantDebugInfo()) {
edgeName.Assign(mNextEdgeName);
mNextEdgeName.Truncate();
}
if (!child)
return;
NS_ASSERTION(participant, "Need a nsCycleCollectionParticipant!");
NoteChild(child, participant, nsIProgrammingLanguage::CPLUSPLUS, edgeName);
}
NS_IMETHODIMP_(void)
GCGraphBuilder::NoteScriptChild(PRUint32 langID, void *child)
{
nsCString edgeName;
if (WantDebugInfo()) {
edgeName.Assign(mNextEdgeName);
mNextEdgeName.Truncate();
}
if (!child)
return;
if (langID > nsIProgrammingLanguage::MAX) {
Fault("traversing pointer for unknown language", child);
return;
}
if (!mRuntimes[langID]) {
NS_WARNING("Not collecting cycles involving objects for scripting "
"languages that don't participate in cycle collection.");
return;
}
// skip over non-grey JS children
if (langID == nsIProgrammingLanguage::JAVASCRIPT &&
!xpc_GCThingIsGrayCCThing(child) && !WantAllTraces()) {
return;
}
nsCycleCollectionParticipant *cp = mRuntimes[langID]->ToParticipant(child);
if (cp)
NoteChild(child, cp, langID, edgeName);
}
NS_IMETHODIMP_(void)
GCGraphBuilder::NoteNextEdgeName(const char* name)
{
if (WantDebugInfo()) {
mNextEdgeName = name;
}
}
PtrInfo*
GCGraphBuilder::AddWeakMapNode(void *node)
{
nsCycleCollectionParticipant *cp;
NS_ASSERTION(node, "Weak map node should be non-null.");
if (!xpc_GCThingIsGrayCCThing(node) && !WantAllTraces())
return nsnull;
cp = mRuntimes[nsIProgrammingLanguage::JAVASCRIPT]->ToParticipant(node);
NS_ASSERTION(cp, "Javascript runtime participant should be non-null.");
return AddNode(node, cp, nsIProgrammingLanguage::JAVASCRIPT);
}
NS_IMETHODIMP_(void)
GCGraphBuilder::NoteWeakMapping(void *map, void *key, void *val)
{
PtrInfo *valNode = AddWeakMapNode(val);
if (!valNode)
return;
WeakMapping *mapping = mWeakMaps.AppendElement();
mapping->mMap = map ? AddWeakMapNode(map) : nsnull;
mapping->mKey = key ? AddWeakMapNode(key) : nsnull;
mapping->mVal = valNode;
}
// MayHaveChild() will be false after a Traverse if the object does
// not have any children the CC will visit.
class ChildFinder : public nsCycleCollectionTraversalCallback
{
public:
ChildFinder() : mMayHaveChild(false) {}
// The logic of the Note*Child functions must mirror that of their
// respective functions in GCGraphBuilder.
NS_IMETHOD_(void) NoteXPCOMChild(nsISupports *child);
NS_IMETHOD_(void) NoteNativeChild(void *child,
nsCycleCollectionParticipant *helper);
NS_IMETHOD_(void) NoteScriptChild(PRUint32 langID, void *child);
NS_IMETHOD_(void) DescribeRefCountedNode(nsrefcnt refcount,
size_t objsz,
const char *objname) {};
NS_IMETHOD_(void) DescribeGCedNode(bool ismarked,
size_t objsz,
const char *objname) {};
NS_IMETHOD_(void) NoteXPCOMRoot(nsISupports *root) {};
NS_IMETHOD_(void) NoteRoot(PRUint32 langID, void *root,
nsCycleCollectionParticipant* helper) {};
NS_IMETHOD_(void) NoteNextEdgeName(const char* name) {};
NS_IMETHOD_(void) NoteWeakMapping(void *map, void *key, void *val) {};
bool MayHaveChild() {
return mMayHaveChild;
};
private:
bool mMayHaveChild;
};
NS_IMETHODIMP_(void)
ChildFinder::NoteXPCOMChild(nsISupports *child)
{
if (!child || !(child = canonicalize(child)))
return;
nsXPCOMCycleCollectionParticipant *cp;
ToParticipant(child, &cp);
if (cp && !cp->CanSkip(child, true))
mMayHaveChild = true;
};
NS_IMETHODIMP_(void)
ChildFinder::NoteNativeChild(void *child,
nsCycleCollectionParticipant *helper)
{
if (child)
mMayHaveChild = true;
};
NS_IMETHODIMP_(void)
ChildFinder::NoteScriptChild(PRUint32 langID, void *child)
{
if (!child)
return;
if (langID == nsIProgrammingLanguage::JAVASCRIPT &&
!xpc_GCThingIsGrayCCThing(child)) {
return;
}
mMayHaveChild = true;
};
static bool
AddPurpleRoot(GCGraphBuilder &builder, nsISupports *root)
{
root = canonicalize(root);
NS_ASSERTION(root,
"Don't add objects that don't participate in collection!");
nsXPCOMCycleCollectionParticipant *cp;
ToParticipant(root, &cp);
if (builder.WantAllTraces() || !cp->CanSkipInCC(root)) {
PtrInfo *pinfo = builder.AddNode(root, cp,
nsIProgrammingLanguage::CPLUSPLUS);
if (!pinfo) {
return false;
}
}
cp->UnmarkIfPurple(root);
return true;
}
static bool
MayHaveChild(nsISupports *o, nsXPCOMCycleCollectionParticipant* cp)
{
ChildFinder cf;
cp->Traverse(o, cf);
return cf.MayHaveChild();
}
void
nsPurpleBuffer::RemoveSkippable(bool removeChildlessNodes)
{
// Walk through all the blocks.
for (Block *b = &mFirstBlock; b; b = b->mNext) {
for (nsPurpleBufferEntry *e = b->mEntries,
*eEnd = ArrayEnd(b->mEntries);
e != eEnd; ++e) {
if (!(PRUword(e->mObject) & PRUword(1))) {
// This is a real entry (rather than something on the
// free list).
if (e->mObject) {
nsISupports* o = canonicalize(e->mObject);
nsXPCOMCycleCollectionParticipant* cp;
ToParticipant(o, &cp);
if (!cp->CanSkip(o, false) &&
(!removeChildlessNodes || MayHaveChild(o, cp))) {
continue;
}
cp->UnmarkIfPurple(o);
}
Remove(e);
}
}
}
}
#ifdef DEBUG_CC
static PLDHashOperator
noteAllCallback(nsPtrHashKey<const void>* key, void* userArg)
{
GCGraphBuilder *builder = static_cast<GCGraphBuilder*>(userArg);
builder->NoteXPCOMRoot(
static_cast<nsISupports *>(const_cast<void*>(key->GetKey())));
return PL_DHASH_NEXT;
}
void
nsPurpleBuffer::NoteAll(GCGraphBuilder &builder)
{
mCompatObjects.EnumerateEntries(noteAllCallback, &builder);
for (Block *b = &mFirstBlock; b; b = b->mNext) {
for (nsPurpleBufferEntry *e = b->mEntries,
*eEnd = ArrayEnd(b->mEntries);
e != eEnd; ++e) {
if (!(PRUword(e->mObject) & PRUword(1)) && e->mObject) {
builder.NoteXPCOMRoot(e->mObject);
}
}
}
}
#endif
void
nsCycleCollector::SelectPurple(GCGraphBuilder &builder)
{
mPurpleBuf.SelectPointers(builder);
}
void
nsCycleCollector::ForgetSkippable(bool removeChildlessNodes)
{
nsCOMPtr<nsIObserverService> obs = mozilla::services::GetObserverService();
if (obs) {
obs->NotifyObservers(nsnull, "cycle-collector-forget-skippable", nsnull);
}
mPurpleBuf.RemoveSkippable(removeChildlessNodes);
if (mForgetSkippableCB) {
mForgetSkippableCB();
}
}
MOZ_NEVER_INLINE void
nsCycleCollector::MarkRoots(GCGraphBuilder &builder)
{
mGraph.mRootCount = builder.Count();
// read the PtrInfo out of the graph that we are building
NodePool::Enumerator queue(mGraph.mNodes);
while (!queue.IsDone()) {
PtrInfo *pi = queue.GetNext();
CC_AbortIfNull(pi);
builder.Traverse(pi);
if (queue.AtBlockEnd())
builder.SetLastChild();
}
if (mGraph.mRootCount > 0)
builder.SetLastChild();
}
////////////////////////////////////////////////////////////////////////
// Bacon & Rajan's |ScanRoots| routine.
////////////////////////////////////////////////////////////////////////
struct ScanBlackVisitor
{
ScanBlackVisitor(PRUint32 &aWhiteNodeCount)
: mWhiteNodeCount(aWhiteNodeCount)
{
}
bool ShouldVisitNode(PtrInfo const *pi)
{
return pi->mColor != black;
}
MOZ_NEVER_INLINE void VisitNode(PtrInfo *pi)
{
if (pi->mColor == white)
--mWhiteNodeCount;
pi->mColor = black;
#ifdef DEBUG_CC
sCollector->mStats.mSetColorBlack++;
#endif
}
PRUint32 &mWhiteNodeCount;
};
struct scanVisitor
{
scanVisitor(PRUint32 &aWhiteNodeCount) : mWhiteNodeCount(aWhiteNodeCount)
{
}
bool ShouldVisitNode(PtrInfo const *pi)
{
return pi->mColor == grey;
}
MOZ_NEVER_INLINE void VisitNode(PtrInfo *pi)
{
if (pi->mInternalRefs > pi->mRefCount && pi->mRefCount > 0)
Fault("traversed refs exceed refcount", pi);
if (pi->mInternalRefs == pi->mRefCount || pi->mRefCount == 0) {
pi->mColor = white;
++mWhiteNodeCount;
#ifdef DEBUG_CC
sCollector->mStats.mSetColorWhite++;
#endif
} else {
GraphWalker<ScanBlackVisitor>(ScanBlackVisitor(mWhiteNodeCount)).Walk(pi);
NS_ASSERTION(pi->mColor == black,
"Why didn't ScanBlackVisitor make pi black?");
}
}
PRUint32 &mWhiteNodeCount;
};
// Iterate over the WeakMaps. If we mark anything while iterating
// over the WeakMaps, we must iterate over all of the WeakMaps again.
void
nsCycleCollector::ScanWeakMaps()
{
bool anyChanged;
do {
anyChanged = false;
for (PRUint32 i = 0; i < mGraph.mWeakMaps.Length(); i++) {
WeakMapping *wm = &mGraph.mWeakMaps[i];
// If mMap or mKey are null, the original object was marked black.
uint32 mColor = wm->mMap ? wm->mMap->mColor : black;
uint32 kColor = wm->mKey ? wm->mKey->mColor : black;
PtrInfo *v = wm->mVal;
// All non-null weak mapping maps, keys and values are
// roots (in the sense of WalkFromRoots) in the cycle
// collector graph, and thus should have been colored
// either black or white in ScanRoots().
NS_ASSERTION(mColor != grey, "Uncolored weak map");
NS_ASSERTION(kColor != grey, "Uncolored weak map key");
NS_ASSERTION(v->mColor != grey, "Uncolored weak map value");
if (mColor == black && kColor == black && v->mColor != black) {
GraphWalker<ScanBlackVisitor>(ScanBlackVisitor(mWhiteNodeCount)).Walk(v);
anyChanged = true;
}
}
} while (anyChanged);
}
void
nsCycleCollector::ScanRoots()
{
mWhiteNodeCount = 0;
// On the assumption that most nodes will be black, it's
// probably faster to use a GraphWalker than a
// NodePool::Enumerator.
GraphWalker<scanVisitor>(scanVisitor(mWhiteNodeCount)).WalkFromRoots(mGraph);
ScanWeakMaps();
#ifdef DEBUG_CC
// Sanity check: scan should have colored all grey nodes black or
// white. So we ensure we have no grey nodes at this point.
NodePool::Enumerator etor(mGraph.mNodes);
while (!etor.IsDone())
{
PtrInfo *pinfo = etor.GetNext();
if (pinfo->mColor == grey) {
Fault("valid grey node after scanning", pinfo);
}
}
#endif
}
////////////////////////////////////////////////////////////////////////
// Bacon & Rajan's |CollectWhite| routine, somewhat modified.
////////////////////////////////////////////////////////////////////////
bool
nsCycleCollector::CollectWhite(nsICycleCollectorListener *aListener)
{
// Explanation of "somewhat modified": we have no way to collect the
// set of whites "all at once", we have to ask each of them to drop
// their outgoing links and assume this will cause the garbage cycle
// to *mostly* self-destruct (except for the reference we continue
// to hold).
//
// To do this "safely" we must make sure that the white nodes we're
// operating on are stable for the duration of our operation. So we
// make 3 sets of calls to language runtimes:
//
// - Root(whites), which should pin the whites in memory.
// - Unlink(whites), which drops outgoing links on each white.
// - Unroot(whites), which returns the whites to normal GC.
nsresult rv;
TimeLog timeLog;
NS_ASSERTION(mWhiteNodes->IsEmpty(),
"FinishCollection wasn't called?");
mWhiteNodes->SetCapacity(mWhiteNodeCount);
PRUint32 numWhiteGCed = 0;
NodePool::Enumerator etor(mGraph.mNodes);
while (!etor.IsDone())
{
PtrInfo *pinfo = etor.GetNext();
if (pinfo->mColor == white && mWhiteNodes->AppendElement(pinfo)) {
rv = pinfo->mParticipant->Root(pinfo->mPointer);
if (NS_FAILED(rv)) {
Fault("Failed root call while unlinking", pinfo);
mWhiteNodes->RemoveElementAt(mWhiteNodes->Length() - 1);
} else if (pinfo->mRefCount == 0) {
// only JS objects have a refcount of 0
++numWhiteGCed;
}
}
}
PRUint32 count = mWhiteNodes->Length();
NS_ASSERTION(numWhiteGCed <= count,
"More freed GCed nodes than total freed nodes.");
if (mResults) {
mResults->mFreedRefCounted += count - numWhiteGCed;
mResults->mFreedGCed += numWhiteGCed;
}
timeLog.Checkpoint("CollectWhite::Root");
if (mBeforeUnlinkCB) {
mBeforeUnlinkCB();
timeLog.Checkpoint("CollectWhite::BeforeUnlinkCB");
}
#if defined(DEBUG_CC) && !defined(__MINGW32__) && defined(WIN32)
struct _CrtMemState ms1, ms2;
_CrtMemCheckpoint(&ms1);
#endif
if (aListener) {
for (PRUint32 i = 0; i < count; ++i) {
PtrInfo *pinfo = mWhiteNodes->ElementAt(i);
aListener->DescribeGarbage((PRUint64)pinfo->mPointer);
}
aListener->End();
}
for (PRUint32 i = 0; i < count; ++i) {
PtrInfo *pinfo = mWhiteNodes->ElementAt(i);
rv = pinfo->mParticipant->Unlink(pinfo->mPointer);
if (NS_FAILED(rv)) {
Fault("Failed unlink call while unlinking", pinfo);
#ifdef DEBUG_CC
mStats.mFailedUnlink++;
#endif
}
else {
#ifdef DEBUG_CC
++mStats.mCollectedNode;
#endif
}
}
timeLog.Checkpoint("CollectWhite::Unlink");
for (PRUint32 i = 0; i < count; ++i) {
PtrInfo *pinfo = mWhiteNodes->ElementAt(i);
rv = pinfo->mParticipant->Unroot(pinfo->mPointer);
if (NS_FAILED(rv))
Fault("Failed unroot call while unlinking", pinfo);
}
timeLog.Checkpoint("CollectWhite::Unroot");
#if defined(DEBUG_CC) && !defined(__MINGW32__) && defined(WIN32)
_CrtMemCheckpoint(&ms2);
if (ms2.lTotalCount < ms1.lTotalCount)
mStats.mFreedBytes += (ms1.lTotalCount - ms2.lTotalCount);
#endif
return count > 0;
}
#ifdef DEBUG_CC
////////////////////////////////////////////////////////////////////////
// Memory-hooking stuff
// When debugging wild pointers, it sometimes helps to hook malloc and
// free. This stuff is disabled unless you set an environment variable.
////////////////////////////////////////////////////////////////////////
static bool hookedMalloc = false;
#if defined(__GLIBC__) && !defined(__UCLIBC__)
#include <malloc.h>
static void* (*old_memalign_hook)(size_t, size_t, const void *);
static void* (*old_realloc_hook)(void *, size_t, const void *);
static void* (*old_malloc_hook)(size_t, const void *);
static void (*old_free_hook)(void *, const void *);
static void* my_memalign_hook(size_t, size_t, const void *);
static void* my_realloc_hook(void *, size_t, const void *);
static void* my_malloc_hook(size_t, const void *);
static void my_free_hook(void *, const void *);
static inline void
install_old_hooks()
{
__memalign_hook = old_memalign_hook;
__realloc_hook = old_realloc_hook;
__malloc_hook = old_malloc_hook;
__free_hook = old_free_hook;
}
static inline void
save_old_hooks()
{
// Glibc docs recommend re-saving old hooks on
// return from recursive calls. Strangely when
// we do this, we find ourselves in infinite
// recursion.
// old_memalign_hook = __memalign_hook;
// old_realloc_hook = __realloc_hook;
// old_malloc_hook = __malloc_hook;
// old_free_hook = __free_hook;
}
static inline void
install_new_hooks()
{
__memalign_hook = my_memalign_hook;
__realloc_hook = my_realloc_hook;
__malloc_hook = my_malloc_hook;
__free_hook = my_free_hook;
}
static void*
my_realloc_hook(void *ptr, size_t size, const void *caller)
{
void *result;
install_old_hooks();
result = realloc(ptr, size);
save_old_hooks();
if (sCollector) {
sCollector->Freed(ptr);
sCollector->Allocated(result, size);
}
install_new_hooks();
return result;
}
static void*
my_memalign_hook(size_t size, size_t alignment, const void *caller)
{
void *result;
install_old_hooks();
result = memalign(size, alignment);
save_old_hooks();
if (sCollector)
sCollector->Allocated(result, size);
install_new_hooks();
return result;
}
static void
my_free_hook (void *ptr, const void *caller)
{
install_old_hooks();
free(ptr);
save_old_hooks();
if (sCollector)
sCollector->Freed(ptr);
install_new_hooks();
}
static void*
my_malloc_hook (size_t size, const void *caller)
{
void *result;
install_old_hooks();
result = malloc (size);
save_old_hooks();
if (sCollector)
sCollector->Allocated(result, size);
install_new_hooks();
return result;
}
static void
InitMemHook(void)
{
if (!hookedMalloc) {
save_old_hooks();
install_new_hooks();
hookedMalloc = true;
}
}
#elif defined(WIN32)
#ifndef __MINGW32__
static int
AllocHook(int allocType, void *userData, size_t size, int
blockType, long requestNumber, const unsigned char *filename, int
lineNumber)
{
if (allocType == _HOOK_FREE)
sCollector->Freed(userData);
return 1;
}
static void InitMemHook(void)
{
if (!hookedMalloc) {
_CrtSetAllocHook (AllocHook);
hookedMalloc = true;
}
}
#endif // __MINGW32__
#elif 0 // defined(XP_MACOSX)
#include <malloc/malloc.h>
static void (*old_free)(struct _malloc_zone_t *zone, void *ptr);
static void
freehook(struct _malloc_zone_t *zone, void *ptr)
{
if (sCollector)
sCollector->Freed(ptr);
old_free(zone, ptr);
}
static void
InitMemHook(void)
{
if (!hookedMalloc) {
malloc_zone_t *default_zone = malloc_default_zone();
old_free = default_zone->free;
default_zone->free = freehook;
hookedMalloc = true;
}
}
#else
static void
InitMemHook(void)
{
}
#endif // GLIBC / WIN32 / OSX
#endif // DEBUG_CC
////////////////////////////////////////////////////////////////////////
// Collector implementation
////////////////////////////////////////////////////////////////////////
nsCycleCollector::nsCycleCollector() :
mCollectionInProgress(false),
mScanInProgress(false),
mResults(nsnull),
mWhiteNodes(nsnull),
mWhiteNodeCount(0),
mVisitedRefCounted(0),
mVisitedGCed(0),
#ifdef DEBUG_CC
mPurpleBuf(mParams, mStats),
mPtrLog(nsnull),
#else
mPurpleBuf(mParams),
#endif
mBeforeUnlinkCB(nsnull),
mForgetSkippableCB(nsnull)
{
#ifdef DEBUG_CC
mExpectedGarbage.Init();
#endif
memset(mRuntimes, 0, sizeof(mRuntimes));
mRuntimes[nsIProgrammingLanguage::CPLUSPLUS] = &mXPCOMRuntime;
}
nsCycleCollector::~nsCycleCollector()
{
}
void
nsCycleCollector::RegisterRuntime(PRUint32 langID,
nsCycleCollectionLanguageRuntime *rt)
{
if (mParams.mDoNothing)
return;
if (langID > nsIProgrammingLanguage::MAX)
Fault("unknown language runtime in registration");
if (mRuntimes[langID])
Fault("multiple registrations of language runtime", rt);
mRuntimes[langID] = rt;
}
void
nsCycleCollector::ForgetRuntime(PRUint32 langID)
{
if (mParams.mDoNothing)
return;
if (langID > nsIProgrammingLanguage::MAX)
Fault("unknown language runtime in deregistration");
if (! mRuntimes[langID])
Fault("forgetting non-registered language runtime");
mRuntimes[langID] = nsnull;
}
#ifdef DEBUG_CC
class Suppressor :
public nsCycleCollectionTraversalCallback
{
protected:
static char *sSuppressionList;
static bool sInitialized;
bool mSuppressThisNode;
public:
Suppressor()
{
}
bool shouldSuppress(nsISupports *s)
{
if (!sInitialized) {
sSuppressionList = PR_GetEnv("XPCOM_CC_SUPPRESS");
sInitialized = true;
}
if (sSuppressionList == nsnull) {
mSuppressThisNode = false;
} else {
nsresult rv;
nsXPCOMCycleCollectionParticipant *cp;
rv = CallQueryInterface(s, &cp);
if (NS_FAILED(rv)) {
Fault("checking suppression on wrong type of pointer", s);
return true;
}
cp->Traverse(s, *this);
}
return mSuppressThisNode;
}
NS_IMETHOD_(void) DescribeRefCountedNode(nsrefcnt refCount, size_t objSz,
const char *objName)
{
mSuppressThisNode = (PL_strstr(sSuppressionList, objName) != nsnull);
}
NS_IMETHOD_(void) DescribeGCedNode(bool isMarked, size_t objSz,
const char *objName)
{
mSuppressThisNode = (PL_strstr(sSuppressionList, objName) != nsnull);
}
NS_IMETHOD_(void) NoteXPCOMRoot(nsISupports *root) {};
NS_IMETHOD_(void) NoteRoot(PRUint32 langID, void *root,
nsCycleCollectionParticipant* participant) {};
NS_IMETHOD_(void) NoteXPCOMChild(nsISupports *child) {}
NS_IMETHOD_(void) NoteScriptChild(PRUint32 langID, void *child) {}
NS_IMETHOD_(void) NoteNativeChild(void *child,
nsCycleCollectionParticipant *participant) {}
NS_IMETHOD_(void) NoteNextEdgeName(const char* name) {}
NS_IMETHOD_(void) NoteWeakMapping(void *map, void *key, void *val) {}
};
char *Suppressor::sSuppressionList = nsnull;
bool Suppressor::sInitialized = false;
static bool
nsCycleCollector_shouldSuppress(nsISupports *s)
{
Suppressor supp;
return supp.shouldSuppress(s);
}
#endif
#ifdef DEBUG
static bool
nsCycleCollector_isScanSafe(nsISupports *s)
{
if (!s)
return false;
nsXPCOMCycleCollectionParticipant *cp;
ToParticipant(s, &cp);
return cp != nsnull;
}
#endif
bool
nsCycleCollector::Suspect(nsISupports *n)
{
AbortIfOffMainThreadIfCheckFast();
// Re-entering ::Suspect during collection used to be a fault, but
// we are canonicalizing nsISupports pointers using QI, so we will
// see some spurious refcount traffic here.
if (mScanInProgress)
return false;
NS_ASSERTION(nsCycleCollector_isScanSafe(n),
"suspected a non-scansafe pointer");
if (mParams.mDoNothing)
return false;
#ifdef DEBUG_CC
mStats.mSuspectNode++;
if (nsCycleCollector_shouldSuppress(n))
return false;
#ifndef __MINGW32__
if (mParams.mHookMalloc)
InitMemHook();
#endif
if (mParams.mLogPointers) {
if (!mPtrLog)
mPtrLog = fopen("pointer_log", "w");
fprintf(mPtrLog, "S %p\n", static_cast<void*>(n));
}
#endif
return mPurpleBuf.PutCompatObject(n);
}
bool
nsCycleCollector::Forget(nsISupports *n)
{
AbortIfOffMainThreadIfCheckFast();
// Re-entering ::Forget during collection used to be a fault, but
// we are canonicalizing nsISupports pointers using QI, so we will
// see some spurious refcount traffic here.
if (mScanInProgress)
return false;
if (mParams.mDoNothing)
return true; // it's as good as forgotten
#ifdef DEBUG_CC
mStats.mForgetNode++;
#ifndef __MINGW32__
if (mParams.mHookMalloc)
InitMemHook();
#endif
if (mParams.mLogPointers) {
if (!mPtrLog)
mPtrLog = fopen("pointer_log", "w");
fprintf(mPtrLog, "F %p\n", static_cast<void*>(n));
}
#endif
mPurpleBuf.RemoveCompatObject(n);
return true;
}
nsPurpleBufferEntry*
nsCycleCollector::Suspect2(nsISupports *n)
{
AbortIfOffMainThreadIfCheckFast();
// Re-entering ::Suspect during collection used to be a fault, but
// we are canonicalizing nsISupports pointers using QI, so we will
// see some spurious refcount traffic here.
if (mScanInProgress)
return nsnull;
NS_ASSERTION(nsCycleCollector_isScanSafe(n),
"suspected a non-scansafe pointer");
if (mParams.mDoNothing)
return nsnull;
#ifdef DEBUG_CC
mStats.mSuspectNode++;
if (nsCycleCollector_shouldSuppress(n))
return nsnull;
#ifndef __MINGW32__
if (mParams.mHookMalloc)
InitMemHook();
#endif
if (mParams.mLogPointers) {
if (!mPtrLog)
mPtrLog = fopen("pointer_log", "w");
fprintf(mPtrLog, "S %p\n", static_cast<void*>(n));
}
#endif
// Caller is responsible for filling in result's mRefCnt.
return mPurpleBuf.Put(n);
}
bool
nsCycleCollector::Forget2(nsPurpleBufferEntry *e)
{
AbortIfOffMainThreadIfCheckFast();
// Re-entering ::Forget during collection used to be a fault, but
// we are canonicalizing nsISupports pointers using QI, so we will
// see some spurious refcount traffic here.
if (mScanInProgress)
return false;
#ifdef DEBUG_CC
LogPurpleRemoval(e->mObject);
#endif
mPurpleBuf.Remove(e);
return true;
}
#ifdef DEBUG_CC
void
nsCycleCollector_logPurpleRemoval(void* aObject)
{
if (sCollector) {
sCollector->LogPurpleRemoval(aObject);
}
}
void
nsCycleCollector::LogPurpleRemoval(void* aObject)
{
AbortIfOffMainThreadIfCheckFast();
mStats.mForgetNode++;
#ifndef __MINGW32__
if (mParams.mHookMalloc)
InitMemHook();
#endif
if (mParams.mLogPointers) {
if (!mPtrLog)
mPtrLog = fopen("pointer_log", "w");
fprintf(mPtrLog, "F %p\n", aObject);
}
mPurpleBuf.mNormalObjects.RemoveEntry(aObject);
}
void
nsCycleCollector::Allocated(void *n, size_t sz)
{
}
void
nsCycleCollector::Freed(void *n)
{
mStats.mFreeCalls++;
if (!n) {
// Ignore null pointers coming through
return;
}
if (mPurpleBuf.Exists(n)) {
mStats.mForgetNode++;
mStats.mFreedWhilePurple++;
Fault("freed while purple", n);
if (mParams.mLogPointers) {
if (!mPtrLog)
mPtrLog = fopen("pointer_log", "w");
fprintf(mPtrLog, "R %p\n", n);
}
}
}
#endif
// The cycle collector uses the mark bitmap to discover what JS objects
// were reachable only from XPConnect roots that might participate in
// cycles. We ask the JS runtime whether we need to force a GC before
// this CC. It returns true on startup (before the mark bits have been set),
// and also when UnmarkGray has run out of stack. We also force GCs on shut
// down to collect cycles involving both DOM and JS.
void
nsCycleCollector::GCIfNeeded(bool aForceGC)
{
NS_ASSERTION(NS_IsMainThread(),
"nsCycleCollector::GCIfNeeded() must be called on the main thread.");
if (mParams.mDoNothing)
return;
if (!mRuntimes[nsIProgrammingLanguage::JAVASCRIPT])
return;
nsCycleCollectionJSRuntime* rt =
static_cast<nsCycleCollectionJSRuntime*>
(mRuntimes[nsIProgrammingLanguage::JAVASCRIPT]);
if (!aForceGC) {
bool needGC = rt->NeedCollect();
// Only do a telemetry ping for non-shutdown CCs.
Telemetry::Accumulate(Telemetry::CYCLE_COLLECTOR_NEED_GC, needGC);
if (!needGC)
return;
if (mResults)
mResults->mForcedGC = true;
}
TimeLog timeLog;
// rt->Collect() must be called from the main thread,
// because it invokes XPCJSRuntime::GCCallback(cx, JSGC_BEGIN)
// which returns false if not in the main thread.
rt->Collect(js::gcreason::CC_FORCED, nsGCNormal);
timeLog.Checkpoint("GC()");
}
bool
nsCycleCollector::PrepareForCollection(nsCycleCollectorResults *aResults,
nsTArray<PtrInfo*> *aWhiteNodes)
{
#if defined(DEBUG_CC) && !defined(__MINGW32__)
if (!mParams.mDoNothing && mParams.mHookMalloc)
InitMemHook();
#endif
// This can legitimately happen in a few cases. See bug 383651.
if (mCollectionInProgress)
return false;
TimeLog timeLog;
mCollectionStart = TimeStamp::Now();
mVisitedRefCounted = 0;
mVisitedGCed = 0;
mCollectionInProgress = true;
nsCOMPtr<nsIObserverService> obs =
mozilla::services::GetObserverService();
if (obs)
obs->NotifyObservers(nsnull, "cycle-collector-begin", nsnull);
mFollowupCollection = false;
mResults = aResults;
mWhiteNodes = aWhiteNodes;
timeLog.Checkpoint("PrepareForCollection()");
return true;
}
void
nsCycleCollector::CleanupAfterCollection()
{
mWhiteNodes = nsnull;
mCollectionInProgress = false;
#ifdef XP_OS2
// Now that the cycle collector has freed some memory, we can try to
// force the C library to give back as much memory to the system as
// possible.
_heapmin();
#endif
PRUint32 interval = (PRUint32) ((TimeStamp::Now() - mCollectionStart).ToMilliseconds());
#ifdef COLLECT_TIME_DEBUG
printf("cc: total cycle collector time was %ums\n", interval);
if (mResults) {
printf("cc: visited %u ref counted and %u GCed objects, freed %d ref counted and %d GCed objects.\n",
mVisitedRefCounted, mVisitedGCed,
mResults->mFreedRefCounted, mResults->mFreedGCed);
} else {
printf("cc: visited %u ref counted and %u GCed objects, freed %d.\n",
mVisitedRefCounted, mVisitedGCed, mWhiteNodeCount);
}
printf("cc: \n");
#endif
if (mResults) {
mResults->mVisitedRefCounted = mVisitedRefCounted;
mResults->mVisitedGCed = mVisitedGCed;
mResults = nsnull;
}
Telemetry::Accumulate(Telemetry::CYCLE_COLLECTOR, interval);
Telemetry::Accumulate(Telemetry::CYCLE_COLLECTOR_VISITED_REF_COUNTED, mVisitedRefCounted);
Telemetry::Accumulate(Telemetry::CYCLE_COLLECTOR_VISITED_GCED, mVisitedGCed);
Telemetry::Accumulate(Telemetry::CYCLE_COLLECTOR_COLLECTED, mWhiteNodeCount);
#ifdef DEBUG_CC
ExplainLiveExpectedGarbage();
#endif
}
void
nsCycleCollector::Collect(nsCycleCollectorResults *aResults,
PRUint32 aTryCollections,
nsICycleCollectorListener *aListener)
{
nsAutoTArray<PtrInfo*, 4000> whiteNodes;
if (!PrepareForCollection(aResults, &whiteNodes))
return;
PRUint32 totalCollections = 0;
while (aTryCollections > totalCollections) {
// Synchronous cycle collection. Always force a JS GC beforehand.
GCIfNeeded(true);
if (aListener && NS_FAILED(aListener->Begin()))
aListener = nsnull;
if (!(BeginCollection(aListener) &&
FinishCollection(aListener)))
break;
++totalCollections;
}
CleanupAfterCollection();
}
bool
nsCycleCollector::BeginCollection(nsICycleCollectorListener *aListener)
{
// aListener should be Begin()'d before this
TimeLog timeLog;
if (mParams.mDoNothing)
return false;
GCGraphBuilder builder(mGraph, mRuntimes, aListener);
if (!builder.Initialized())
return false;
for (PRUint32 i = 0; i <= nsIProgrammingLanguage::MAX; ++i) {
if (mRuntimes[i])
mRuntimes[i]->BeginCycleCollection(builder, false);
}
timeLog.Checkpoint("mRuntimes[*]->BeginCycleCollection()");
#ifdef DEBUG_CC
PRUint32 purpleStart = builder.Count();
#endif
mScanInProgress = true;
SelectPurple(builder);
#ifdef DEBUG_CC
PRUint32 purpleEnd = builder.Count();
if (purpleStart != purpleEnd) {
#ifndef __MINGW32__
if (mParams.mHookMalloc)
InitMemHook();
#endif
if (mParams.mLogPointers && !mPtrLog)
mPtrLog = fopen("pointer_log", "w");
PRUint32 i = 0;
NodePool::Enumerator queue(mGraph.mNodes);
while (i++ < purpleStart) {
queue.GetNext();
}
while (i++ < purpleEnd) {
mStats.mForgetNode++;
if (mParams.mLogPointers)
fprintf(mPtrLog, "F %p\n", queue.GetNext()->mPointer);
}
}
#endif
timeLog.Checkpoint("SelectPurple()");
if (builder.Count() > 0) {
// The main Bacon & Rajan collection algorithm.
MarkRoots(builder);
timeLog.Checkpoint("MarkRoots()");
ScanRoots();
timeLog.Checkpoint("ScanRoots()");
mScanInProgress = false;
if (aListener) {
aListener->BeginResults();
NodePool::Enumerator etor(mGraph.mNodes);
while (!etor.IsDone()) {
PtrInfo *pi = etor.GetNext();
if (pi->mColor == black &&
pi->mRefCount > 0 && pi->mRefCount < PR_UINT32_MAX &&
pi->mInternalRefs != pi->mRefCount) {
aListener->DescribeRoot((PRUint64)pi->mPointer,
pi->mInternalRefs);
}
}
}
#ifdef DEBUG_CC
if (mFollowupCollection && purpleStart != purpleEnd) {
PRUint32 i = 0;
NodePool::Enumerator queue(mGraph.mNodes);
while (i++ < purpleStart) {
queue.GetNext();
}
while (i++ < purpleEnd) {
PtrInfo *pi = queue.GetNext();
if (pi->mColor == white) {
printf("nsCycleCollector: a later shutdown collection collected the additional\n"
" suspect %p %s\n"
" (which could be fixed by improving traversal)\n",
pi->mPointer, pi->mName);
}
}
}
#endif
for (PRUint32 i = 0; i <= nsIProgrammingLanguage::MAX; ++i) {
if (mRuntimes[i])
mRuntimes[i]->FinishTraverse();
}
timeLog.Checkpoint("mRuntimes[*]->FinishTraverse()");
}
else {
mScanInProgress = false;
}
return true;
}
bool
nsCycleCollector::FinishCollection(nsICycleCollectorListener *aListener)
{
TimeLog timeLog;
bool collected = CollectWhite(aListener);
timeLog.Checkpoint("CollectWhite()");
#ifdef DEBUG_CC
mStats.mCollection++;
if (mParams.mReportStats)
mStats.Dump();
#endif
for (PRUint32 i = 0; i <= nsIProgrammingLanguage::MAX; ++i) {
if (mRuntimes[i])
mRuntimes[i]->FinishCycleCollection();
}
timeLog.Checkpoint("mRuntimes[*]->FinishCycleCollection()");
mFollowupCollection = true;
#ifdef DEBUG_CC
// We wait until after FinishCollection to check the white nodes because
// some objects may outlive CollectWhite but then be freed by
// FinishCycleCollection (like XPConnect's deferred release of native
// objects).
PRUint32 i, count = mWhiteNodes->Length();
for (i = 0; i < count; ++i) {
PtrInfo *pinfo = mWhiteNodes->ElementAt(i);
if (pinfo->mLangID == nsIProgrammingLanguage::CPLUSPLUS &&
mPurpleBuf.Exists(pinfo->mPointer)) {
printf("nsCycleCollector: %s object @%p is still alive after\n"
" calling RootAndUnlinkJSObjects, Unlink, and Unroot on"
" it! This probably\n"
" means the Unlink implementation was insufficient.\n",
pinfo->mName, pinfo->mPointer);
}
}
#endif
mWhiteNodes->Clear();
ClearGraph();
timeLog.Checkpoint("ClearGraph()");
mParams.mDoNothing = false;
return collected;
}
PRUint32
nsCycleCollector::SuspectedCount()
{
return mPurpleBuf.Count();
}
void
nsCycleCollector::Shutdown()
{
// Here we want to run a final collection and then permanently
// disable the collector because the program is shutting down.
nsCOMPtr<nsCycleCollectorLogger> listener;
if (mParams.mLogGraphs) {
listener = new nsCycleCollectorLogger();
}
Collect(nsnull, SHUTDOWN_COLLECTIONS(mParams), listener);
#ifdef DEBUG_CC
GCGraphBuilder builder(mGraph, mRuntimes, nsnull);
mScanInProgress = true;
SelectPurple(builder);
mScanInProgress = false;
if (builder.Count() != 0) {
printf("Might have been able to release more cycles if the cycle collector would "
"run once more at shutdown.\n");
}
ClearGraph();
#endif
mParams.mDoNothing = true;
}
#ifdef DEBUG_CC
static PLDHashOperator
AddExpectedGarbage(nsPtrHashKey<const void> *p, void *arg)
{
GCGraphBuilder *builder = static_cast<GCGraphBuilder*>(arg);
nsISupports *root =
static_cast<nsISupports*>(const_cast<void*>(p->GetKey()));
builder->NoteXPCOMRoot(root);
return PL_DHASH_NEXT;
}
struct SetSCCVisitor
{
SetSCCVisitor(PRUint32 aIndex) : mIndex(aIndex) {}
bool ShouldVisitNode(PtrInfo const *pi) { return pi->mSCCIndex == 0; }
void VisitNode(PtrInfo *pi) { pi->mSCCIndex = mIndex; }
private:
PRUint32 mIndex;
};
struct SetNonRootGreyVisitor
{
bool ShouldVisitNode(PtrInfo const *pi) { return pi->mColor == white; }
void VisitNode(PtrInfo *pi) { pi->mColor = grey; }
};
static void
PrintPathToExpectedGarbage(PtrInfo *pi)
{
printf(" An object expected to be garbage could be "
"reached from it by the path:\n");
for (PtrInfo *path = pi, *prev = nsnull; prev != path;
prev = path,
path = path->mShortestPathToExpectedGarbage) {
if (prev) {
nsCString *edgeName = prev
->mShortestPathToExpectedGarbageEdgeName;
printf(" via %s\n",
edgeName->IsEmpty() ? "<unknown edge>"
: edgeName->get());
}
printf(" %s %p\n", path->mName, path->mPointer);
}
}
void
nsCycleCollector::ExplainLiveExpectedGarbage()
{
if (mScanInProgress || mCollectionInProgress)
Fault("can't explain expected garbage during collection itself");
if (mParams.mDoNothing) {
printf("nsCycleCollector: not explaining expected garbage since\n"
" cycle collection disabled\n");
return;
}
mCollectionInProgress = true;
mScanInProgress = true;
{
GCGraphBuilder builder(mGraph, mRuntimes, nsnull);
// Instead of adding roots from the purple buffer, we add them
// from the list of nodes we were expected to collect.
// Put the expected garbage in *before* calling
// BeginCycleCollection so that we can separate the expected
// garbage from the NoteRoot calls in such a way that something
// that's in both is considered expected garbage.
mExpectedGarbage.EnumerateEntries(&AddExpectedGarbage, &builder);
PRUint32 expectedGarbageCount = builder.Count();
for (PRUint32 i = 0; i <= nsIProgrammingLanguage::MAX; ++i) {
if (mRuntimes[i])
mRuntimes[i]->BeginCycleCollection(builder, true);
}
// But just for extra information, add entries from the purple
// buffer too, since it may give us extra information about
// traversal deficiencies.
mPurpleBuf.NoteAll(builder);
MarkRoots(builder);
ScanRoots();
mScanInProgress = false;
for (PRUint32 i = 0; i <= nsIProgrammingLanguage::MAX; ++i) {
if (mRuntimes[i]) {
mRuntimes[i]->FinishTraverse();
}
}
bool describeExtraRefcounts = false;
bool findCycleRoots = false;
{
NodePool::Enumerator queue(mGraph.mNodes);
PRUint32 i = 0;
while (!queue.IsDone()) {
PtrInfo *pi = queue.GetNext();
if (pi->mColor == white) {
findCycleRoots = true;
}
if (pi->mInternalRefs != pi->mRefCount &&
(i < expectedGarbageCount || i >= mGraph.mRootCount)) {
// This check isn't particularly useful anymore
// given that we need to enter this part for i >=
// mGraph.mRootCount and there are plenty of
// NoteRoot roots.
describeExtraRefcounts = true;
}
++i;
}
}
if ((describeExtraRefcounts || findCycleRoots) &&
CreateReversedEdges()) {
// Note that the external references may have been external
// to a different node in the cycle collection that just
// happened, if that different node was purple and then
// black.
// Use mSCCIndex temporarily to track whether we've reached
// nodes in the breadth-first search.
const PRUint32 INDEX_UNREACHED = 0;
const PRUint32 INDEX_REACHED = 1;
NodePool::Enumerator etor_clear(mGraph.mNodes);
while (!etor_clear.IsDone()) {
PtrInfo *pi = etor_clear.GetNext();
pi->mSCCIndex = INDEX_UNREACHED;
}
nsDeque queue; // for breadth-first search
NodePool::Enumerator etor_roots(mGraph.mNodes);
for (PRUint32 i = 0; i < mGraph.mRootCount; ++i) {
PtrInfo *root_pi = etor_roots.GetNext();
if (i < expectedGarbageCount) {
root_pi->mSCCIndex = INDEX_REACHED;
root_pi->mShortestPathToExpectedGarbage = root_pi;
queue.Push(root_pi);
}
}
while (queue.GetSize() > 0) {
PtrInfo *pi = (PtrInfo*)queue.PopFront();
for (ReversedEdge *e = pi->mReversedEdges; e; e = e->mNext) {
if (e->mTarget->mSCCIndex == INDEX_UNREACHED) {
e->mTarget->mSCCIndex = INDEX_REACHED;
PtrInfo *target = e->mTarget;
if (!target->mShortestPathToExpectedGarbage) {
target->mShortestPathToExpectedGarbage = pi;
target->mShortestPathToExpectedGarbageEdgeName =
e->mEdgeName;
}
queue.Push(target);
}
}
if (pi->mRefCount == PR_UINT32_MAX ||
(pi->mInternalRefs != pi->mRefCount && pi->mRefCount > 0)) {
if (pi->mRefCount == PR_UINT32_MAX) {
printf("nsCycleCollector: %s %p was not collected due "
"to \n"
" external references\n",
pi->mName, pi->mPointer);
}
else {
printf("nsCycleCollector: %s %p was not collected due "
"to %d\n"
" external references (%d total - %d known)\n",
pi->mName, pi->mPointer,
pi->mRefCount - pi->mInternalRefs,
pi->mRefCount, pi->mInternalRefs);
}
PrintPathToExpectedGarbage(pi);
if (pi->mRefCount == PR_UINT32_MAX) {
printf(" The known references to it were from:\n");
}
else {
printf(" The %d known references to it were from:\n",
pi->mInternalRefs);
}
for (ReversedEdge *e = pi->mReversedEdges;
e; e = e->mNext) {
printf(" %s %p",
e->mTarget->mName, e->mTarget->mPointer);
if (!e->mEdgeName->IsEmpty()) {
printf(" via %s", e->mEdgeName->get());
}
printf("\n");
}
mRuntimes[pi->mLangID]->PrintAllReferencesTo(pi->mPointer);
}
}
if (findCycleRoots) {
// NOTE: This code changes the white nodes that are not
// roots to gray.
// Put the nodes in post-order traversal order from a
// depth-first search.
nsDeque DFSPostOrder;
{
// Use mSCCIndex temporarily to track the DFS numbering:
const PRUint32 INDEX_UNREACHED = 0;
const PRUint32 INDEX_TRAVERSING = 1;
const PRUint32 INDEX_NUMBERED = 2;
NodePool::Enumerator etor_clear(mGraph.mNodes);
while (!etor_clear.IsDone()) {
PtrInfo *pi = etor_clear.GetNext();
pi->mSCCIndex = INDEX_UNREACHED;
}
nsDeque stack;
NodePool::Enumerator etor_roots(mGraph.mNodes);
for (PRUint32 i = 0; i < mGraph.mRootCount; ++i) {
PtrInfo *root_pi = etor_roots.GetNext();
stack.Push(root_pi);
}
while (stack.GetSize() > 0) {
PtrInfo *pi = (PtrInfo*)stack.Peek();
if (pi->mSCCIndex == INDEX_UNREACHED) {
pi->mSCCIndex = INDEX_TRAVERSING;
for (EdgePool::Iterator child = pi->FirstChild(),
child_end = pi->LastChild();
child != child_end; ++child) {
stack.Push(*child);
}
} else {
stack.Pop();
// Somebody else might have numbered it already
// (since this is depth-first, not breadth-first).
// This happens if a node is pushed on the stack
// a second time while it is on the stack in
// UNREACHED state.
if (pi->mSCCIndex == INDEX_TRAVERSING) {
pi->mSCCIndex = INDEX_NUMBERED;
DFSPostOrder.Push(pi);
}
}
}
}
// Put the nodes into strongly-connected components.
{
NodePool::Enumerator etor_clear(mGraph.mNodes);
while (!etor_clear.IsDone()) {
PtrInfo *pi = etor_clear.GetNext();
pi->mSCCIndex = 0;
}
PRUint32 currentSCC = 1;
while (DFSPostOrder.GetSize() > 0) {
GraphWalker<SetSCCVisitor>(SetSCCVisitor(currentSCC)).Walk((PtrInfo*)DFSPostOrder.PopFront());
++currentSCC;
}
}
// Mark any white nodes reachable from other components as
// grey.
{
NodePool::Enumerator queue(mGraph.mNodes);
while (!queue.IsDone()) {
PtrInfo *pi = queue.GetNext();
if (pi->mColor != white)
continue;
for (EdgePool::Iterator child = pi->FirstChild(),
child_end = pi->LastChild();
child != child_end; ++child) {
if ((*child)->mSCCIndex != pi->mSCCIndex) {
GraphWalker<SetNonRootGreyVisitor>(SetNonRootGreyVisitor()).Walk(*child);
}
}
}
}
{
NodePool::Enumerator queue(mGraph.mNodes);
while (!queue.IsDone()) {
PtrInfo *pi = queue.GetNext();
if (pi->mColor == white) {
if (pi->mLangID ==
nsIProgrammingLanguage::CPLUSPLUS &&
mPurpleBuf.Exists(pi->mPointer)) {
printf(
"nsCycleCollector: %s %p in component %d\n"
" which was reference counted during the root/unlink/unroot phase of the\n"
" last collection was not collected due to failure to unlink (see other\n"
" warnings) or deficiency in traverse that causes cycles referenced only\n"
" from other cycles to require multiple rounds of cycle collection in which\n"
" this object was likely the reachable object\n",
pi->mName, pi->mPointer, pi->mSCCIndex);
} else {
printf(
"nsCycleCollector: %s %p in component %d\n"
" was not collected due to missing call to suspect, failure to unlink (see\n"
" other warnings), or deficiency in traverse that causes cycles referenced\n"
" only from other cycles to require multiple rounds of cycle collection\n",
pi->mName, pi->mPointer, pi->mSCCIndex);
}
if (pi->mShortestPathToExpectedGarbage)
PrintPathToExpectedGarbage(pi);
}
}
}
}
DestroyReversedEdges();
}
}
ClearGraph();
mCollectionInProgress = false;
for (PRUint32 i = 0; i <= nsIProgrammingLanguage::MAX; ++i) {
if (mRuntimes[i])
mRuntimes[i]->FinishCycleCollection();
}
}
bool
nsCycleCollector::CreateReversedEdges()
{
// Count the edges in the graph.
PRUint32 edgeCount = 0;
NodePool::Enumerator countQueue(mGraph.mNodes);
while (!countQueue.IsDone()) {
PtrInfo *pi = countQueue.GetNext();
for (EdgePool::Iterator e = pi->FirstChild(), e_end = pi->LastChild();
e != e_end; ++e, ++edgeCount) {
}
}
// Allocate a pool to hold all of the edges.
mGraph.mReversedEdges = new ReversedEdge[edgeCount];
if (mGraph.mReversedEdges == nsnull) {
NS_NOTREACHED("allocation failure creating reversed edges");
return false;
}
// Fill in the reversed edges by scanning all forward edges.
ReversedEdge *current = mGraph.mReversedEdges;
NodePool::Enumerator buildQueue(mGraph.mNodes);
while (!buildQueue.IsDone()) {
PtrInfo *pi = buildQueue.GetNext();
PRInt32 i = 0;
for (EdgePool::Iterator e = pi->FirstChild(), e_end = pi->LastChild();
e != e_end; ++e) {
current->mTarget = pi;
current->mEdgeName = &pi->mEdgeNames[i];
current->mNext = (*e)->mReversedEdges;
(*e)->mReversedEdges = current;
++current;
++i;
}
}
NS_ASSERTION(current - mGraph.mReversedEdges == ptrdiff_t(edgeCount),
"misallocation");
return true;
}
void
nsCycleCollector::DestroyReversedEdges()
{
NodePool::Enumerator queue(mGraph.mNodes);
while (!queue.IsDone()) {
PtrInfo *pi = queue.GetNext();
pi->mReversedEdges = nsnull;
}
delete mGraph.mReversedEdges;
mGraph.mReversedEdges = nsnull;
}
void
nsCycleCollector::ShouldBeFreed(nsISupports *n)
{
if (n) {
mExpectedGarbage.PutEntry(n);
}
}
void
nsCycleCollector::WasFreed(nsISupports *n)
{
if (n) {
mExpectedGarbage.RemoveEntry(n);
}
}
#endif
////////////////////////
// Memory reporter
////////////////////////
static PRInt64
ReportCycleCollectorMem()
{
if (!sCollector)
return 0;
PRInt64 size = sizeof(nsCycleCollector) +
sCollector->mPurpleBuf.BlocksSize() +
sCollector->mGraph.BlocksSize();
if (sCollector->mWhiteNodes)
size += sCollector->mWhiteNodes->Capacity() * sizeof(PtrInfo*);
return size;
}
NS_MEMORY_REPORTER_IMPLEMENT(CycleCollector,
"explicit/cycle-collector",
KIND_HEAP,
UNITS_BYTES,
ReportCycleCollectorMem,
"Memory used by the cycle collector. This "
"includes the cycle collector structure, the "
"purple buffer, the graph, and the white nodes. "
"The latter two are expected to be empty when the "
"cycle collector is idle.")
////////////////////////////////////////////////////////////////////////
// Module public API (exported in nsCycleCollector.h)
// Just functions that redirect into the singleton, once it's built.
////////////////////////////////////////////////////////////////////////
void
nsCycleCollector_registerRuntime(PRUint32 langID,
nsCycleCollectionLanguageRuntime *rt)
{
static bool regMemReport = true;
if (sCollector)
sCollector->RegisterRuntime(langID, rt);
if (regMemReport) {
regMemReport = false;
NS_RegisterMemoryReporter(new NS_MEMORY_REPORTER_NAME(CycleCollector));
}
}
void
nsCycleCollector_forgetRuntime(PRUint32 langID)
{
if (sCollector)
sCollector->ForgetRuntime(langID);
}
bool
NS_CycleCollectorSuspect(nsISupports *n)
{
if (sCollector)
return sCollector->Suspect(n);
return false;
}
bool
NS_CycleCollectorForget(nsISupports *n)
{
return sCollector ? sCollector->Forget(n) : true;
}
nsPurpleBufferEntry*
NS_CycleCollectorSuspect2(nsISupports *n)
{
if (sCollector)
return sCollector->Suspect2(n);
return nsnull;
}
bool
NS_CycleCollectorForget2(nsPurpleBufferEntry *e)
{
return sCollector ? sCollector->Forget2(e) : true;
}
PRUint32
nsCycleCollector_suspectedCount()
{
return sCollector ? sCollector->SuspectedCount() : 0;
}
#ifdef DEBUG
void
nsCycleCollector_DEBUG_shouldBeFreed(nsISupports *n)
{
#ifdef DEBUG_CC
if (sCollector)
sCollector->ShouldBeFreed(n);
#endif
}
void
nsCycleCollector_DEBUG_wasFreed(nsISupports *n)
{
#ifdef DEBUG_CC
if (sCollector)
sCollector->WasFreed(n);
#endif
}
#endif
class nsCycleCollectorRunner : public nsRunnable
{
nsCycleCollector *mCollector;
nsICycleCollectorListener *mListener;
Mutex mLock;
CondVar mRequest;
CondVar mReply;
bool mRunning;
bool mShutdown;
bool mCollected;
nsCycleCollectionJSRuntime *GetJSRuntime()
{
return static_cast<nsCycleCollectionJSRuntime*>
(mCollector->mRuntimes[nsIProgrammingLanguage::JAVASCRIPT]);
}
public:
NS_IMETHOD Run()
{
#ifdef XP_WIN
TlsSetValue(gTLSThreadIDIndex,
(void*) mozilla::threads::CycleCollector);
#elif defined(NS_TLS)
gTLSThreadID = mozilla::threads::CycleCollector;
#else
gCycleCollectorThread = PR_GetCurrentThread();
#endif
NS_ASSERTION(NS_IsCycleCollectorThread() && !NS_IsMainThread(),
"Wrong thread!");
MutexAutoLock autoLock(mLock);
if (mShutdown)
return NS_OK;
mRunning = true;
while (1) {
mRequest.Wait();
if (!mRunning) {
mReply.Notify();
return NS_OK;
}
GetJSRuntime()->NotifyEnterCycleCollectionThread();
mCollected = mCollector->BeginCollection(mListener);
GetJSRuntime()->NotifyLeaveCycleCollectionThread();
mReply.Notify();
}
return NS_OK;
}
nsCycleCollectorRunner(nsCycleCollector *collector)
: mCollector(collector),
mListener(nsnull),
mLock("cycle collector lock"),
mRequest(mLock, "cycle collector request condvar"),
mReply(mLock, "cycle collector reply condvar"),
mRunning(false),
mShutdown(false),
mCollected(false)
{
NS_ASSERTION(NS_IsMainThread(), "Wrong thread!");
}
void Collect(nsCycleCollectorResults *aResults,
nsICycleCollectorListener *aListener)
{
NS_ASSERTION(NS_IsMainThread(), "Wrong thread!");
// On a WantAllTraces CC, force a synchronous global GC to prevent
// hijinks from ForgetSkippable and compartmental GCs.
bool wantAllTraces = false;
if (aListener) {
aListener->GetWantAllTraces(&wantAllTraces);
}
mCollector->GCIfNeeded(wantAllTraces);
MutexAutoLock autoLock(mLock);
if (!mRunning)
return;
nsAutoTArray<PtrInfo*, 4000> whiteNodes;
if (!mCollector->PrepareForCollection(aResults, &whiteNodes))
return;
NS_ASSERTION(!mListener, "Should have cleared this already!");
if (aListener && NS_FAILED(aListener->Begin()))
aListener = nsnull;
mListener = aListener;
if (GetJSRuntime()->NotifyLeaveMainThread()) {
mRequest.Notify();
mReply.Wait();
GetJSRuntime()->NotifyEnterMainThread();
} else {
mCollected = mCollector->BeginCollection(mListener);
}
mListener = nsnull;
if (mCollected) {
mCollector->FinishCollection(aListener);
mCollector->CleanupAfterCollection();
}
}
void Shutdown()
{
NS_ASSERTION(NS_IsMainThread(), "Wrong thread!");
MutexAutoLock autoLock(mLock);
mShutdown = true;
if (!mRunning)
return;
mRunning = false;
mRequest.Notify();
mReply.Wait();
}
};
// Holds a reference.
static nsCycleCollectorRunner* sCollectorRunner;
// Holds a reference.
static nsIThread* sCollectorThread;
nsresult
nsCycleCollector_startup()
{
NS_ASSERTION(NS_IsMainThread(), "Wrong thread!");
NS_ASSERTION(!sCollector, "Forgot to call nsCycleCollector_shutdown?");
sCollector = new nsCycleCollector();
nsRefPtr<nsCycleCollectorRunner> runner =
new nsCycleCollectorRunner(sCollector);
nsCOMPtr<nsIThread> thread;
nsresult rv = NS_NewThread(getter_AddRefs(thread), runner);
NS_ENSURE_SUCCESS(rv, rv);
runner.swap(sCollectorRunner);
thread.swap(sCollectorThread);
return rv;
}
void
nsCycleCollector_setBeforeUnlinkCallback(CC_BeforeUnlinkCallback aCB)
{
if (sCollector) {
sCollector->mBeforeUnlinkCB = aCB;
}
}
void
nsCycleCollector_setForgetSkippableCallback(CC_ForgetSkippableCallback aCB)
{
if (sCollector) {
sCollector->mForgetSkippableCB = aCB;
}
}
void
nsCycleCollector_forgetSkippable(bool aRemoveChildlessNodes)
{
if (sCollector) {
SAMPLE_LABEL("CC", "nsCycleCollector_forgetSkippable");
TimeLog timeLog;
sCollector->ForgetSkippable(aRemoveChildlessNodes);
timeLog.Checkpoint("ForgetSkippable()");
}
}
void
nsCycleCollector_collect(nsCycleCollectorResults *aResults,
nsICycleCollectorListener *aListener)
{
NS_ASSERTION(NS_IsMainThread(), "Wrong thread!");
SAMPLE_LABEL("CC", "nsCycleCollector_collect");
nsCOMPtr<nsICycleCollectorListener> listener(aListener);
if (!aListener && sCollector && sCollector->mParams.mLogGraphs) {
listener = new nsCycleCollectorLogger();
}
if (sCollectorRunner) {
sCollectorRunner->Collect(aResults, listener);
} else if (sCollector) {
sCollector->Collect(aResults, 1, listener);
}
}
void
nsCycleCollector_shutdownThreads()
{
NS_ASSERTION(NS_IsMainThread(), "Wrong thread!");
if (sCollectorRunner) {
nsRefPtr<nsCycleCollectorRunner> runner;
runner.swap(sCollectorRunner);
runner->Shutdown();
}
if (sCollectorThread) {
nsCOMPtr<nsIThread> thread;
thread.swap(sCollectorThread);
thread->Shutdown();
}
}
void
nsCycleCollector_shutdown()
{
NS_ASSERTION(NS_IsMainThread(), "Wrong thread!");
NS_ASSERTION(!sCollectorRunner, "Should have finished before!");
NS_ASSERTION(!sCollectorThread, "Should have finished before!");
if (sCollector) {
SAMPLE_LABEL("CC", "nsCycleCollector_shutdown");
sCollector->Shutdown();
delete sCollector;
sCollector = nsnull;
}
}
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