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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//
+// 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).
+//
+// Snow-white is an addition to the original algorithm. A snow-white node
+// has reference count zero and is just waiting for deletion.
+//
+// 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.
+
+// Incremental cycle collection
+//
+// Beyond the simple state machine required to implement incremental
+// collection, the CC needs to be able to compensate for things the browser
+// is doing during the collection. There are two kinds of problems. For each
+// of these, there are two cases to deal with: purple-buffered C++ objects
+// and JS objects.
+
+// The first problem is that an object in the CC's graph can become garbage.
+// This is bad because the CC touches the objects in its graph at every
+// stage of its operation.
+//
+// All cycle collected C++ objects that die during a cycle collection
+// will end up actually getting deleted by the SnowWhiteKiller. Before
+// the SWK deletes an object, it checks if an ICC is running, and if so,
+// if the object is in the graph. If it is, the CC clears mPointer and
+// mParticipant so it does not point to the raw object any more. Because
+// objects could die any time the CC returns to the mutator, any time the CC
+// accesses a PtrInfo it must perform a null check on mParticipant to
+// ensure the object has not gone away.
+//
+// JS objects don't always run finalizers, so the CC can't remove them from
+// the graph when they die. Fortunately, JS objects can only die during a GC,
+// so if a GC is begun during an ICC, the browser synchronously finishes off
+// the ICC, which clears the entire CC graph. If the GC and CC are scheduled
+// properly, this should be rare.
+//
+// The second problem is that objects in the graph can be changed, say by
+// being addrefed or released, or by having a field updated, after the object
+// has been added to the graph. The problem is that ICC can miss a newly
+// created reference to an object, and end up unlinking an object that is
+// actually alive.
+//
+// The basic idea of the solution, from "An on-the-fly Reference Counting
+// Garbage Collector for Java" by Levanoni and Petrank, is to notice if an
+// object has had an additional reference to it created during the collection,
+// and if so, don't collect it during the current collection. This avoids having
+// to rerun the scan as in Bacon & Rajan 2001.
+//
+// For cycle collected C++ objects, we modify AddRef to place the object in
+// the purple buffer, in addition to Release. Then, in the CC, we treat any
+// objects in the purple buffer as being alive, after graph building has
+// completed. Because they are in the purple buffer, they will be suspected
+// in the next CC, so there's no danger of leaks. This is imprecise, because
+// we will treat as live an object that has been Released but not AddRefed
+// during graph building, but that's probably rare enough that the additional
+// bookkeeping overhead is not worthwhile.
+//
+// For JS objects, the cycle collector is only looking at gray objects. If a
+// gray object is touched during ICC, it will be made black by UnmarkGray.
+// Thus, if a JS object has become black during the ICC, we treat it as live.
+// Merged JS zones have to be handled specially: we scan all zone globals.
+// If any are black, we treat the zone as being black.
+
+// Safety
+//
+// An XPCOM object is either scan-safe or scan-unsafe, purple-safe or
+// purple-unsafe.
+//
+// An nsISupports object is scan-safe if:
+//
+// - It can be QI'ed to |nsXPCOMCycleCollectionParticipant|, though
+// this operation loses ISupports identity (like nsIClassInfo).
+// - Additionally, the operation |traverse| on the resulting
+// nsXPCOMCycleCollectionParticipant does not cause *any* refcount
+// adjustment to occur (no AddRef / Release calls).
+//
+// A non-nsISupports ("native") object is scan-safe by explicitly
+// providing its nsCycleCollectionParticipant.
+//
+// An object is purple-safe if it satisfies the following properties:
+//
+// - The object is scan-safe.
+//
+// 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. The easiest way to ensure that an
+// object is purple-safe is to use nsCycleCollectingAutoRefCnt.
+//
+// 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 the purple-safety of the roots that call |suspect| to
+// hold, such that we will clear the pointer from the purple buffer
+// entry to the object 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.
+//
+// We *do* call |Root| and |Unroot| 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"
+
+#include "mozilla/ArrayUtils.h"
+#include "mozilla/AutoRestore.h"
+#include "mozilla/CycleCollectedJSContext.h"
+#include "mozilla/CycleCollectedJSRuntime.h"
+#include "mozilla/DebugOnly.h"
+#include "mozilla/HashFunctions.h"
+#include "mozilla/HashTable.h"
+#include "mozilla/HoldDropJSObjects.h"
+/* This must occur *after* base/process_util.h to avoid typedefs conflicts. */
+#include <stdint.h>
+#include <stdio.h>
+
+#include <utility>
+
+#include "js/SliceBudget.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/AutoGlobalTimelineMarker.h"
+#include "mozilla/Likely.h"
+#include "mozilla/LinkedList.h"
+#include "mozilla/MemoryReporting.h"
+#include "mozilla/MruCache.h"
+#include "mozilla/PoisonIOInterposer.h"
+#include "mozilla/ProfilerLabels.h"
+#include "mozilla/SegmentedVector.h"
+#include "mozilla/Telemetry.h"
+#include "mozilla/ThreadLocal.h"
+#include "mozilla/UniquePtr.h"
+#include "nsCycleCollectionNoteRootCallback.h"
+#include "nsCycleCollectionParticipant.h"
+#include "nsCycleCollector.h"
+#include "nsDeque.h"
+#include "nsDumpUtils.h"
+#include "nsExceptionHandler.h"
+#include "nsIConsoleService.h"
+#include "nsICycleCollectorListener.h"
+#include "nsIFile.h"
+#include "nsIMemoryReporter.h"
+#include "nsISerialEventTarget.h"
+#include "nsPrintfCString.h"
+#include "nsTArray.h"
+#include "nsThreadUtils.h"
+#include "nsXULAppAPI.h"
+#include "prenv.h"
+#include "xpcpublic.h"
+
+using namespace mozilla;
+
+struct NurseryPurpleBufferEntry {
+ void* mPtr;
+ nsCycleCollectionParticipant* mParticipant;
+ nsCycleCollectingAutoRefCnt* mRefCnt;
+};
+
+#define NURSERY_PURPLE_BUFFER_SIZE 2048
+bool gNurseryPurpleBufferEnabled = true;
+NurseryPurpleBufferEntry gNurseryPurpleBufferEntry[NURSERY_PURPLE_BUFFER_SIZE];
+uint32_t gNurseryPurpleBufferEntryCount = 0;
+
+void ClearNurseryPurpleBuffer();
+
+static void SuspectUsingNurseryPurpleBuffer(
+ void* aPtr, nsCycleCollectionParticipant* aCp,
+ nsCycleCollectingAutoRefCnt* aRefCnt) {
+ MOZ_ASSERT(NS_IsMainThread(), "Wrong thread!");
+ MOZ_ASSERT(gNurseryPurpleBufferEnabled);
+ if (gNurseryPurpleBufferEntryCount == NURSERY_PURPLE_BUFFER_SIZE) {
+ ClearNurseryPurpleBuffer();
+ }
+
+ gNurseryPurpleBufferEntry[gNurseryPurpleBufferEntryCount] = {aPtr, aCp,
+ aRefCnt};
+ ++gNurseryPurpleBufferEntryCount;
+}
+
+// #define COLLECT_TIME_DEBUG
+
+// Enable assertions that are useful for diagnosing errors in graph
+// construction.
+// #define DEBUG_CC_GRAPH
+
+#define DEFAULT_SHUTDOWN_COLLECTIONS 5
+
+// One to do the freeing, then another to detect there is no more work to do.
+#define NORMAL_SHUTDOWN_COLLECTIONS 2
+
+// Cycle collector environment variables
+//
+// MOZ_CC_LOG_ALL: If defined, always log cycle collector heaps.
+//
+// MOZ_CC_LOG_SHUTDOWN: If defined, log cycle collector heaps at shutdown.
+//
+// MOZ_CC_LOG_SHUTDOWN_SKIP: If set to a non-negative integer value n, then
+// skip logging for the first n shutdown CCs. This implies MOZ_CC_LOG_SHUTDOWN.
+// The first log or two are much larger than the rest, so it can be useful to
+// reduce the total size of logs if you know already that the initial logs
+// aren't interesting.
+//
+// MOZ_CC_LOG_THREAD: If set to "main", only automatically log main thread
+// CCs. If set to "worker", only automatically log worker CCs. If set to "all",
+// log either. The default value is "all". This must be used with either
+// MOZ_CC_LOG_ALL or MOZ_CC_LOG_SHUTDOWN for it to do anything.
+//
+// MOZ_CC_LOG_PROCESS: If set to "main", only automatically log main process
+// CCs. If set to "content", only automatically log tab CCs. If set to "all",
+// log everything. The default value is "all". This must be used with either
+// MOZ_CC_LOG_ALL or MOZ_CC_LOG_SHUTDOWN for it to do anything.
+//
+// MOZ_CC_ALL_TRACES: If set to "all", any cycle collector
+// logging done will be WantAllTraces, which disables
+// various cycle collector optimizations to give a fuller picture of
+// the heap. If set to "shutdown", only shutdown logging will be WantAllTraces.
+// The default is none.
+//
+// MOZ_CC_RUN_DURING_SHUTDOWN: In non-DEBUG or builds, if this is set,
+// run cycle collections at shutdown.
+//
+// MOZ_CC_LOG_DIRECTORY: The directory in which logs are placed (such as
+// logs from MOZ_CC_LOG_ALL and MOZ_CC_LOG_SHUTDOWN, or other uses
+// of nsICycleCollectorListener)
+
+// Various parameters of this collector can be tuned using environment
+// variables.
+
+struct nsCycleCollectorParams {
+ bool mLogAll;
+ bool mLogShutdown;
+ bool mAllTracesAll;
+ bool mAllTracesShutdown;
+ bool mLogThisThread;
+ int32_t mLogShutdownSkip = 0;
+
+ nsCycleCollectorParams()
+ : mLogAll(PR_GetEnv("MOZ_CC_LOG_ALL") != nullptr),
+ mLogShutdown(PR_GetEnv("MOZ_CC_LOG_SHUTDOWN") != nullptr),
+ mAllTracesAll(false),
+ mAllTracesShutdown(false) {
+ if (const char* lssEnv = PR_GetEnv("MOZ_CC_LOG_SHUTDOWN_SKIP")) {
+ mLogShutdown = true;
+ nsDependentCString lssString(lssEnv);
+ nsresult rv;
+ int32_t lss = lssString.ToInteger(&rv);
+ if (NS_SUCCEEDED(rv) && lss >= 0) {
+ mLogShutdownSkip = lss;
+ }
+ }
+
+ const char* logThreadEnv = PR_GetEnv("MOZ_CC_LOG_THREAD");
+ bool threadLogging = true;
+ if (logThreadEnv && !!strcmp(logThreadEnv, "all")) {
+ if (NS_IsMainThread()) {
+ threadLogging = !strcmp(logThreadEnv, "main");
+ } else {
+ threadLogging = !strcmp(logThreadEnv, "worker");
+ }
+ }
+
+ const char* logProcessEnv = PR_GetEnv("MOZ_CC_LOG_PROCESS");
+ bool processLogging = true;
+ if (logProcessEnv && !!strcmp(logProcessEnv, "all")) {
+ switch (XRE_GetProcessType()) {
+ case GeckoProcessType_Default:
+ processLogging = !strcmp(logProcessEnv, "main");
+ break;
+ case GeckoProcessType_Content:
+ processLogging = !strcmp(logProcessEnv, "content");
+ break;
+ default:
+ processLogging = false;
+ break;
+ }
+ }
+ mLogThisThread = threadLogging && processLogging;
+
+ const char* allTracesEnv = PR_GetEnv("MOZ_CC_ALL_TRACES");
+ if (allTracesEnv) {
+ if (!strcmp(allTracesEnv, "all")) {
+ mAllTracesAll = true;
+ } else if (!strcmp(allTracesEnv, "shutdown")) {
+ mAllTracesShutdown = true;
+ }
+ }
+ }
+
+ // aShutdownCount is how many shutdown CCs we've started.
+ // For non-shutdown CCs, we'll pass in 0.
+ // For the first shutdown CC, we'll pass in 1.
+ bool LogThisCC(int32_t aShutdownCount) {
+ if (mLogAll) {
+ return mLogThisThread;
+ }
+ if (aShutdownCount == 0 || !mLogShutdown) {
+ return false;
+ }
+ if (aShutdownCount <= mLogShutdownSkip) {
+ return false;
+ }
+ return mLogThisThread;
+ }
+
+ bool AllTracesThisCC(bool aIsShutdown) {
+ return mAllTracesAll || (aIsShutdown && mAllTracesShutdown);
+ }
+};
+
+#ifdef COLLECT_TIME_DEBUG
+class TimeLog {
+ public:
+ TimeLog() : mLastCheckpoint(TimeStamp::Now()) {}
+
+ void Checkpoint(const char* aEvent) {
+ TimeStamp now = TimeStamp::Now();
+ double dur = (now - mLastCheckpoint).ToMilliseconds();
+ if (dur >= 0.5) {
+ printf("cc: %s took %.1fms\n", aEvent, dur);
+ }
+ mLastCheckpoint = now;
+ }
+
+ private:
+ TimeStamp mLastCheckpoint;
+};
+#else
+class TimeLog {
+ public:
+ TimeLog() = default;
+ void Checkpoint(const char* aEvent) {}
+};
+#endif
+
+////////////////////////////////////////////////////////////////////////
+// Base types
+////////////////////////////////////////////////////////////////////////
+
+class 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 = nullptr;
+ mSentinelAndBlocks[1].block = nullptr;
+ }
+
+ ~EdgePool() {
+ MOZ_ASSERT(!mSentinelAndBlocks[0].block && !mSentinelAndBlocks[1].block,
+ "Didn't call Clear()?");
+ }
+
+ void Clear() {
+ EdgeBlock* b = EdgeBlocks();
+ while (b) {
+ EdgeBlock* next = b->Next();
+ delete b;
+ b = next;
+ }
+
+ mSentinelAndBlocks[0].block = nullptr;
+ mSentinelAndBlocks[1].block = nullptr;
+ }
+
+#ifdef DEBUG
+ bool IsEmpty() {
+ return !mSentinelAndBlocks[0].block && !mSentinelAndBlocks[1].block;
+ }
+#endif
+
+ private:
+ struct EdgeBlock;
+ union PtrInfoOrBlock {
+ // Use a union to avoid reinterpret_cast and the ensuing
+ // potential aliasing bugs.
+ PtrInfo* ptrInfo;
+ EdgeBlock* block;
+ };
+ struct EdgeBlock {
+ enum { EdgeBlockSize = 16 * 1024 };
+
+ PtrInfoOrBlock mPointers[EdgeBlockSize];
+ EdgeBlock() {
+ mPointers[EdgeBlockSize - 2].block = nullptr; // sentinel
+ mPointers[EdgeBlockSize - 1].block = nullptr; // next block pointer
+ }
+ EdgeBlock*& Next() { return mPointers[EdgeBlockSize - 1].block; }
+ PtrInfoOrBlock* Start() { return &mPointers[0]; }
+ PtrInfoOrBlock* End() { return &mPointers[EdgeBlockSize - 2]; }
+ };
+
+ // Store the null sentinel so that we can have valid iterators
+ // before adding any edges and without adding any blocks.
+ PtrInfoOrBlock mSentinelAndBlocks[2];
+
+ EdgeBlock*& EdgeBlocks() { return mSentinelAndBlocks[1].block; }
+ EdgeBlock* EdgeBlocks() const { return mSentinelAndBlocks[1].block; }
+
+ public:
+ class Iterator {
+ public:
+ Iterator() : mPointer(nullptr) {}
+ explicit Iterator(PtrInfoOrBlock* aPointer) : mPointer(aPointer) {}
+ Iterator(const Iterator& aOther) = default;
+
+ Iterator& operator++() {
+ if (!mPointer->ptrInfo) {
+ // 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) {
+ // 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;
+ }
+
+#ifdef DEBUG_CC_GRAPH
+ bool Initialized() const { return mPointer != nullptr; }
+#endif
+
+ private:
+ PtrInfoOrBlock* mPointer;
+ };
+
+ class Builder;
+ friend class Builder;
+ class Builder {
+ public:
+ explicit Builder(EdgePool& aPool)
+ : mCurrent(&aPool.mSentinelAndBlocks[0]),
+ mBlockEnd(&aPool.mSentinelAndBlocks[0]),
+ mNextBlockPtr(&aPool.EdgeBlocks()) {}
+
+ Iterator Mark() { return Iterator(mCurrent); }
+
+ void Add(PtrInfo* aEdge) {
+ if (mCurrent == mBlockEnd) {
+ EdgeBlock* b = new EdgeBlock();
+ *mNextBlockPtr = b;
+ mCurrent = b->Start();
+ mBlockEnd = b->End();
+ mNextBlockPtr = &b->Next();
+ }
+ (mCurrent++)->ptrInfo = aEdge;
+ }
+
+ private:
+ // mBlockEnd points to space for null sentinel
+ PtrInfoOrBlock* mCurrent;
+ PtrInfoOrBlock* mBlockEnd;
+ EdgeBlock** mNextBlockPtr;
+ };
+
+ size_t SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const {
+ size_t n = 0;
+ EdgeBlock* b = EdgeBlocks();
+ while (b) {
+ n += aMallocSizeOf(b);
+ b = b->Next();
+ }
+ return n;
+ }
+};
+
+#ifdef DEBUG_CC_GRAPH
+# define CC_GRAPH_ASSERT(b) MOZ_ASSERT(b)
+#else
+# define CC_GRAPH_ASSERT(b)
+#endif
+
+#define CC_TELEMETRY(_name, _value) \
+ do { \
+ if (NS_IsMainThread()) { \
+ Telemetry::Accumulate(Telemetry::CYCLE_COLLECTOR##_name, _value); \
+ } else { \
+ Telemetry::Accumulate(Telemetry::CYCLE_COLLECTOR_WORKER##_name, _value); \
+ } \
+ } while (0)
+
+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.
+class PtrInfo final {
+ public:
+ // mParticipant knows a more concrete type.
+ void* mPointer;
+ nsCycleCollectionParticipant* mParticipant;
+ uint32_t mColor : 2;
+ uint32_t mInternalRefs : 30;
+ uint32_t mRefCount;
+
+ private:
+ EdgePool::Iterator mFirstChild;
+
+ static const uint32_t kInitialRefCount = UINT32_MAX - 1;
+
+ public:
+ PtrInfo(void* aPointer, nsCycleCollectionParticipant* aParticipant)
+ : mPointer(aPointer),
+ mParticipant(aParticipant),
+ mColor(grey),
+ mInternalRefs(0),
+ mRefCount(kInitialRefCount),
+ mFirstChild() {
+ MOZ_ASSERT(aParticipant);
+
+ // We initialize mRefCount to a large non-zero value so
+ // that it doesn't look like a JS object to the cycle collector
+ // in the case where the object dies before being traversed.
+ MOZ_ASSERT(!IsGrayJS() && !IsBlackJS());
+ }
+
+ // Allow NodePool::NodeBlock's constructor to compile.
+ PtrInfo()
+ : mPointer{nullptr},
+ mParticipant{nullptr},
+ mColor{0},
+ mInternalRefs{0},
+ mRefCount{0} {
+ MOZ_ASSERT_UNREACHABLE("should never be called");
+ }
+
+ bool IsGrayJS() const { return mRefCount == 0; }
+
+ bool IsBlackJS() const { return mRefCount == UINT32_MAX; }
+
+ bool WasTraversed() const { return mRefCount != kInitialRefCount; }
+
+ EdgePool::Iterator FirstChild() const {
+ CC_GRAPH_ASSERT(mFirstChild.Initialized());
+ return mFirstChild;
+ }
+
+ // this PtrInfo must be part of a NodePool
+ EdgePool::Iterator LastChild() const {
+ CC_GRAPH_ASSERT((this + 1)->mFirstChild.Initialized());
+ return (this + 1)->mFirstChild;
+ }
+
+ void SetFirstChild(EdgePool::Iterator aFirstChild) {
+ CC_GRAPH_ASSERT(aFirstChild.Initialized());
+ mFirstChild = aFirstChild;
+ }
+
+ // this PtrInfo must be part of a NodePool
+ void SetLastChild(EdgePool::Iterator aLastChild) {
+ CC_GRAPH_ASSERT(aLastChild.Initialized());
+ (this + 1)->mFirstChild = aLastChild;
+ }
+
+ void AnnotatedReleaseAssert(bool aCondition, const char* aMessage);
+};
+
+void PtrInfo::AnnotatedReleaseAssert(bool aCondition, const char* aMessage) {
+ if (aCondition) {
+ return;
+ }
+
+ const char* piName = "Unknown";
+ if (mParticipant) {
+ piName = mParticipant->ClassName();
+ }
+ nsPrintfCString msg("%s, for class %s", aMessage, piName);
+ NS_WARNING(msg.get());
+ CrashReporter::AnnotateCrashReport(CrashReporter::Annotation::CycleCollector,
+ msg);
+
+ MOZ_CRASH();
+}
+
+/**
+ * A structure designed to be used like a linked list of PtrInfo, except
+ * it allocates many PtrInfos at a time.
+ */
+class NodePool {
+ private:
+ // The -2 allows us to use |NodeBlockSize + 1| for |mEntries|, and fit
+ // |mNext|, all without causing slop.
+ enum { NodeBlockSize = 4 * 1024 - 2 };
+
+ struct NodeBlock {
+ // We create and destroy NodeBlock using moz_xmalloc/free rather than new
+ // and delete to avoid calling its constructor and destructor.
+ NodeBlock() : mNext{nullptr} {
+ MOZ_ASSERT_UNREACHABLE("should never be called");
+
+ // Ensure NodeBlock is the right size (see the comment on NodeBlockSize
+ // above).
+ static_assert(
+ sizeof(NodeBlock) == 81904 || // 32-bit; equals 19.996 x 4 KiB pages
+ sizeof(NodeBlock) ==
+ 131048, // 64-bit; equals 31.994 x 4 KiB pages
+ "ill-sized NodeBlock");
+ }
+ ~NodeBlock() { MOZ_ASSERT_UNREACHABLE("should never be called"); }
+
+ NodeBlock* mNext;
+ PtrInfo mEntries[NodeBlockSize + 1]; // +1 to store last child of last node
+ };
+
+ public:
+ NodePool() : mBlocks(nullptr), mLast(nullptr) {}
+
+ ~NodePool() { MOZ_ASSERT(!mBlocks, "Didn't call Clear()?"); }
+
+ void Clear() {
+ NodeBlock* b = mBlocks;
+ while (b) {
+ NodeBlock* n = b->mNext;
+ free(b);
+ b = n;
+ }
+
+ mBlocks = nullptr;
+ mLast = nullptr;
+ }
+
+#ifdef DEBUG
+ bool IsEmpty() { return !mBlocks && !mLast; }
+#endif
+
+ class Builder;
+ friend class Builder;
+ class Builder {
+ public:
+ explicit Builder(NodePool& aPool)
+ : mNextBlock(&aPool.mBlocks), mNext(aPool.mLast), mBlockEnd(nullptr) {
+ MOZ_ASSERT(!aPool.mBlocks && !aPool.mLast, "pool not empty");
+ }
+ PtrInfo* Add(void* aPointer, nsCycleCollectionParticipant* aParticipant) {
+ if (mNext == mBlockEnd) {
+ NodeBlock* block = static_cast<NodeBlock*>(malloc(sizeof(NodeBlock)));
+ if (!block) {
+ return nullptr;
+ }
+
+ *mNextBlock = block;
+ mNext = block->mEntries;
+ mBlockEnd = block->mEntries + NodeBlockSize;
+ block->mNext = nullptr;
+ mNextBlock = &block->mNext;
+ }
+ return new (mozilla::KnownNotNull, mNext++)
+ PtrInfo(aPointer, aParticipant);
+ }
+
+ private:
+ NodeBlock** mNextBlock;
+ PtrInfo*& mNext;
+ PtrInfo* mBlockEnd;
+ };
+
+ class Enumerator;
+ friend class Enumerator;
+ class Enumerator {
+ public:
+ explicit Enumerator(NodePool& aPool)
+ : mFirstBlock(aPool.mBlocks),
+ mCurBlock(nullptr),
+ mNext(nullptr),
+ mBlockEnd(nullptr),
+ mLast(aPool.mLast) {}
+
+ bool IsDone() const { return mNext == mLast; }
+
+ bool AtBlockEnd() const { return mNext == mBlockEnd; }
+
+ PtrInfo* GetNext() {
+ MOZ_ASSERT(!IsDone(), "calling GetNext when done");
+ if (mNext == mBlockEnd) {
+ NodeBlock* nextBlock = mCurBlock ? mCurBlock->mNext : mFirstBlock;
+ mNext = nextBlock->mEntries;
+ mBlockEnd = mNext + NodeBlockSize;
+ mCurBlock = nextBlock;
+ }
+ return mNext++;
+ }
+
+ private:
+ // mFirstBlock is a reference to allow an Enumerator to be constructed
+ // for an empty graph.
+ NodeBlock*& mFirstBlock;
+ NodeBlock* 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;
+ PtrInfo* mBlockEnd;
+ PtrInfo*& mLast;
+ };
+
+ size_t SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const {
+ // We don't measure the things pointed to by mEntries[] because those
+ // pointers are non-owning.
+ size_t n = 0;
+ NodeBlock* b = mBlocks;
+ while (b) {
+ n += aMallocSizeOf(b);
+ b = b->mNext;
+ }
+ return n;
+ }
+
+ private:
+ NodeBlock* mBlocks;
+ PtrInfo* mLast;
+};
+
+struct PtrToNodeHashPolicy {
+ using Key = PtrInfo*;
+ using Lookup = void*;
+
+ static js::HashNumber hash(const Lookup& aLookup) {
+ return mozilla::HashGeneric(aLookup);
+ }
+
+ static bool match(const Key& aKey, const Lookup& aLookup) {
+ return aKey->mPointer == aLookup;
+ }
+};
+
+struct WeakMapping {
+ // map and key will be null if the corresponding objects are GC marked
+ PtrInfo* mMap;
+ PtrInfo* mKey;
+ PtrInfo* mKeyDelegate;
+ PtrInfo* mVal;
+};
+
+class CCGraphBuilder;
+
+struct CCGraph {
+ NodePool mNodes;
+ EdgePool mEdges;
+ nsTArray<WeakMapping> mWeakMaps;
+ uint32_t mRootCount;
+
+ private:
+ friend CCGraphBuilder;
+
+ mozilla::HashSet<PtrInfo*, PtrToNodeHashPolicy> mPtrInfoMap;
+
+ bool mOutOfMemory;
+
+ static const uint32_t kInitialMapLength = 16384;
+
+ public:
+ CCGraph()
+ : mRootCount(0), mPtrInfoMap(kInitialMapLength), mOutOfMemory(false) {}
+
+ ~CCGraph() = default;
+
+ void Init() { MOZ_ASSERT(IsEmpty(), "Failed to call CCGraph::Clear"); }
+
+ void Clear() {
+ mNodes.Clear();
+ mEdges.Clear();
+ mWeakMaps.Clear();
+ mRootCount = 0;
+ mPtrInfoMap.clearAndCompact();
+ mOutOfMemory = false;
+ }
+
+#ifdef DEBUG
+ bool IsEmpty() {
+ return mNodes.IsEmpty() && mEdges.IsEmpty() && mWeakMaps.IsEmpty() &&
+ mRootCount == 0 && mPtrInfoMap.empty();
+ }
+#endif
+
+ PtrInfo* FindNode(void* aPtr);
+ void RemoveObjectFromMap(void* aObject);
+
+ uint32_t MapCount() const { return mPtrInfoMap.count(); }
+
+ size_t SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const {
+ size_t n = 0;
+
+ n += mNodes.SizeOfExcludingThis(aMallocSizeOf);
+ n += mEdges.SizeOfExcludingThis(aMallocSizeOf);
+
+ // We don't measure what the WeakMappings point to, because the
+ // pointers are non-owning.
+ n += mWeakMaps.ShallowSizeOfExcludingThis(aMallocSizeOf);
+
+ n += mPtrInfoMap.shallowSizeOfExcludingThis(aMallocSizeOf);
+
+ return n;
+ }
+};
+
+PtrInfo* CCGraph::FindNode(void* aPtr) {
+ auto p = mPtrInfoMap.lookup(aPtr);
+ return p ? *p : nullptr;
+}
+
+void CCGraph::RemoveObjectFromMap(void* aObj) {
+ auto p = mPtrInfoMap.lookup(aObj);
+ if (p) {
+ PtrInfo* pinfo = *p;
+ pinfo->mPointer = nullptr;
+ pinfo->mParticipant = nullptr;
+ mPtrInfoMap.remove(p);
+ }
+}
+
+static nsISupports* CanonicalizeXPCOMParticipant(nsISupports* aIn) {
+ nsISupports* out = nullptr;
+ aIn->QueryInterface(NS_GET_IID(nsCycleCollectionISupports),
+ reinterpret_cast<void**>(&out));
+ return out;
+}
+
+struct nsPurpleBufferEntry {
+ nsPurpleBufferEntry(void* aObject, nsCycleCollectingAutoRefCnt* aRefCnt,
+ nsCycleCollectionParticipant* aParticipant)
+ : mObject(aObject), mRefCnt(aRefCnt), mParticipant(aParticipant) {}
+
+ nsPurpleBufferEntry(nsPurpleBufferEntry&& aOther)
+ : mObject(nullptr), mRefCnt(nullptr), mParticipant(nullptr) {
+ Swap(aOther);
+ }
+
+ void Swap(nsPurpleBufferEntry& aOther) {
+ std::swap(mObject, aOther.mObject);
+ std::swap(mRefCnt, aOther.mRefCnt);
+ std::swap(mParticipant, aOther.mParticipant);
+ }
+
+ void Clear() {
+ mRefCnt->RemoveFromPurpleBuffer();
+ mRefCnt = nullptr;
+ mObject = nullptr;
+ mParticipant = nullptr;
+ }
+
+ ~nsPurpleBufferEntry() {
+ if (mRefCnt) {
+ mRefCnt->RemoveFromPurpleBuffer();
+ }
+ }
+
+ void* mObject;
+ nsCycleCollectingAutoRefCnt* mRefCnt;
+ nsCycleCollectionParticipant* mParticipant; // nullptr for nsISupports
+};
+
+class nsCycleCollector;
+
+struct nsPurpleBuffer {
+ private:
+ uint32_t mCount;
+
+ // Try to match the size of a jemalloc bucket, to minimize slop bytes.
+ // - On 32-bit platforms sizeof(nsPurpleBufferEntry) is 12, so mEntries'
+ // Segment is 16,372 bytes.
+ // - On 64-bit platforms sizeof(nsPurpleBufferEntry) is 24, so mEntries'
+ // Segment is 32,760 bytes.
+ static const uint32_t kEntriesPerSegment = 1365;
+ static const size_t kSegmentSize =
+ sizeof(nsPurpleBufferEntry) * kEntriesPerSegment;
+ typedef SegmentedVector<nsPurpleBufferEntry, kSegmentSize,
+ InfallibleAllocPolicy>
+ PurpleBufferVector;
+ PurpleBufferVector mEntries;
+
+ public:
+ nsPurpleBuffer() : mCount(0) {
+ static_assert(
+ sizeof(PurpleBufferVector::Segment) == 16372 || // 32-bit
+ sizeof(PurpleBufferVector::Segment) == 32760 || // 64-bit
+ sizeof(PurpleBufferVector::Segment) == 32744, // 64-bit Windows
+ "ill-sized nsPurpleBuffer::mEntries");
+ }
+
+ ~nsPurpleBuffer() = default;
+
+ // This method compacts mEntries.
+ template <class PurpleVisitor>
+ void VisitEntries(PurpleVisitor& aVisitor) {
+ Maybe<AutoRestore<bool>> ar;
+ if (NS_IsMainThread()) {
+ ar.emplace(gNurseryPurpleBufferEnabled);
+ gNurseryPurpleBufferEnabled = false;
+ ClearNurseryPurpleBuffer();
+ }
+
+ if (mEntries.IsEmpty()) {
+ return;
+ }
+
+ uint32_t oldLength = mEntries.Length();
+ uint32_t keptLength = 0;
+ auto revIter = mEntries.IterFromLast();
+ auto iter = mEntries.Iter();
+ // After iteration this points to the first empty entry.
+ auto firstEmptyIter = mEntries.Iter();
+ auto iterFromLastEntry = mEntries.IterFromLast();
+ for (; !iter.Done(); iter.Next()) {
+ nsPurpleBufferEntry& e = iter.Get();
+ if (e.mObject) {
+ if (!aVisitor.Visit(*this, &e)) {
+ return;
+ }
+ }
+
+ // Visit call above may have cleared the entry, or the entry was empty
+ // already.
+ if (!e.mObject) {
+ // Try to find a non-empty entry from the end of the vector.
+ for (; !revIter.Done(); revIter.Prev()) {
+ nsPurpleBufferEntry& otherEntry = revIter.Get();
+ if (&e == &otherEntry) {
+ break;
+ }
+ if (otherEntry.mObject) {
+ if (!aVisitor.Visit(*this, &otherEntry)) {
+ return;
+ }
+ // Visit may have cleared otherEntry.
+ if (otherEntry.mObject) {
+ e.Swap(otherEntry);
+ revIter.Prev(); // We've swapped this now empty entry.
+ break;
+ }
+ }
+ }
+ }
+
+ // Entry is non-empty even after the Visit call, ensure it is kept
+ // in mEntries.
+ if (e.mObject) {
+ firstEmptyIter.Next();
+ ++keptLength;
+ }
+
+ if (&e == &revIter.Get()) {
+ break;
+ }
+ }
+
+ // There were some empty entries.
+ if (oldLength != keptLength) {
+ // While visiting entries, some new ones were possibly added. This can
+ // happen during CanSkip. Move all such new entries to be after other
+ // entries. Note, we don't call Visit on newly added entries!
+ if (&iterFromLastEntry.Get() != &mEntries.GetLast()) {
+ iterFromLastEntry.Next(); // Now pointing to the first added entry.
+ auto& iterForNewEntries = iterFromLastEntry;
+ while (!iterForNewEntries.Done()) {
+ MOZ_ASSERT(!firstEmptyIter.Done());
+ MOZ_ASSERT(!firstEmptyIter.Get().mObject);
+ firstEmptyIter.Get().Swap(iterForNewEntries.Get());
+ firstEmptyIter.Next();
+ iterForNewEntries.Next();
+ }
+ }
+
+ mEntries.PopLastN(oldLength - keptLength);
+ }
+ }
+
+ void FreeBlocks() {
+ mCount = 0;
+ mEntries.Clear();
+ }
+
+ void SelectPointers(CCGraphBuilder& aBuilder);
+
+ // RemoveSkippable removes entries from the purple buffer synchronously
+ // (1) if !aAsyncSnowWhiteFreeing and nsPurpleBufferEntry::mRefCnt is 0 or
+ // (2) if nsXPCOMCycleCollectionParticipant::CanSkip() for the obj or
+ // (3) if nsPurpleBufferEntry::mRefCnt->IsPurple() is false.
+ // (4) If aRemoveChildlessNodes 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(nsCycleCollector* aCollector, js::SliceBudget& aBudget,
+ bool aRemoveChildlessNodes, bool aAsyncSnowWhiteFreeing,
+ CC_ForgetSkippableCallback aCb);
+
+ MOZ_ALWAYS_INLINE void Put(void* aObject, nsCycleCollectionParticipant* aCp,
+ nsCycleCollectingAutoRefCnt* aRefCnt) {
+ nsPurpleBufferEntry entry(aObject, aRefCnt, aCp);
+ Unused << mEntries.Append(std::move(entry));
+ MOZ_ASSERT(!entry.mRefCnt, "Move didn't work!");
+ ++mCount;
+ }
+
+ void Remove(nsPurpleBufferEntry* aEntry) {
+ MOZ_ASSERT(mCount != 0, "must have entries");
+ --mCount;
+ aEntry->Clear();
+ }
+
+ uint32_t Count() const { return mCount; }
+
+ size_t SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const {
+ return mEntries.SizeOfExcludingThis(aMallocSizeOf);
+ }
+};
+
+static bool AddPurpleRoot(CCGraphBuilder& aBuilder, void* aRoot,
+ nsCycleCollectionParticipant* aParti);
+
+struct SelectPointersVisitor {
+ explicit SelectPointersVisitor(CCGraphBuilder& aBuilder)
+ : mBuilder(aBuilder) {}
+
+ bool Visit(nsPurpleBuffer& aBuffer, nsPurpleBufferEntry* aEntry) {
+ MOZ_ASSERT(aEntry->mObject, "Null object in purple buffer");
+ MOZ_ASSERT(aEntry->mRefCnt->get() != 0,
+ "SelectPointersVisitor: snow-white object in the purple buffer");
+ if (!aEntry->mRefCnt->IsPurple() ||
+ AddPurpleRoot(mBuilder, aEntry->mObject, aEntry->mParticipant)) {
+ aBuffer.Remove(aEntry);
+ }
+ return true;
+ }
+
+ private:
+ CCGraphBuilder& mBuilder;
+};
+
+void nsPurpleBuffer::SelectPointers(CCGraphBuilder& aBuilder) {
+ SelectPointersVisitor visitor(aBuilder);
+ VisitEntries(visitor);
+
+ MOZ_ASSERT(mCount == 0, "AddPurpleRoot failed");
+ if (mCount == 0) {
+ FreeBlocks();
+ }
+}
+
+enum ccPhase {
+ IdlePhase,
+ GraphBuildingPhase,
+ ScanAndCollectWhitePhase,
+ CleanupPhase
+};
+
+enum ccIsManual { CCIsNotManual = false, CCIsManual = true };
+
+////////////////////////////////////////////////////////////////////////
+// Top level structure for the cycle collector.
+////////////////////////////////////////////////////////////////////////
+
+using js::SliceBudget;
+
+class JSPurpleBuffer;
+
+class nsCycleCollector : public nsIMemoryReporter {
+ public:
+ NS_DECL_ISUPPORTS
+ NS_DECL_NSIMEMORYREPORTER
+
+ private:
+ bool mActivelyCollecting;
+ bool mFreeingSnowWhite;
+ // mScanInProgress should be false when we're collecting white objects.
+ bool mScanInProgress;
+ CycleCollectorResults mResults;
+ TimeStamp mCollectionStart;
+
+ CycleCollectedJSRuntime* mCCJSRuntime;
+
+ ccPhase mIncrementalPhase;
+ int32_t mShutdownCount = 0;
+ CCGraph mGraph;
+ UniquePtr<CCGraphBuilder> mBuilder;
+ RefPtr<nsCycleCollectorLogger> mLogger;
+
+#ifdef DEBUG
+ nsISerialEventTarget* mEventTarget;
+#endif
+
+ nsCycleCollectorParams mParams;
+
+ uint32_t mWhiteNodeCount;
+
+ CC_BeforeUnlinkCallback mBeforeUnlinkCB;
+ CC_ForgetSkippableCallback mForgetSkippableCB;
+
+ nsPurpleBuffer mPurpleBuf;
+
+ uint32_t mUnmergedNeeded;
+ uint32_t mMergedInARow;
+
+ RefPtr<JSPurpleBuffer> mJSPurpleBuffer;
+
+ private:
+ virtual ~nsCycleCollector();
+
+ public:
+ nsCycleCollector();
+
+ void SetCCJSRuntime(CycleCollectedJSRuntime* aCCRuntime);
+ void ClearCCJSRuntime();
+
+ void SetBeforeUnlinkCallback(CC_BeforeUnlinkCallback aBeforeUnlinkCB) {
+ CheckThreadSafety();
+ mBeforeUnlinkCB = aBeforeUnlinkCB;
+ }
+
+ void SetForgetSkippableCallback(
+ CC_ForgetSkippableCallback aForgetSkippableCB) {
+ CheckThreadSafety();
+ mForgetSkippableCB = aForgetSkippableCB;
+ }
+
+ void Suspect(void* aPtr, nsCycleCollectionParticipant* aCp,
+ nsCycleCollectingAutoRefCnt* aRefCnt);
+ void SuspectNurseryEntries();
+ uint32_t SuspectedCount();
+ void ForgetSkippable(js::SliceBudget& aBudget, bool aRemoveChildlessNodes,
+ bool aAsyncSnowWhiteFreeing);
+ bool FreeSnowWhite(bool aUntilNoSWInPurpleBuffer);
+ bool FreeSnowWhiteWithBudget(js::SliceBudget& aBudget);
+
+ // This method assumes its argument is already canonicalized.
+ void RemoveObjectFromGraph(void* aPtr);
+
+ void PrepareForGarbageCollection();
+ void FinishAnyCurrentCollection(CCReason aReason);
+
+ bool Collect(CCReason aReason, ccIsManual aIsManual, SliceBudget& aBudget,
+ nsICycleCollectorListener* aManualListener,
+ bool aPreferShorterSlices = false);
+ MOZ_CAN_RUN_SCRIPT
+ void Shutdown(bool aDoCollect);
+
+ bool IsIdle() const { return mIncrementalPhase == IdlePhase; }
+
+ void SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf,
+ size_t* aObjectSize, size_t* aGraphSize,
+ size_t* aPurpleBufferSize) const;
+
+ JSPurpleBuffer* GetJSPurpleBuffer();
+
+ CycleCollectedJSRuntime* Runtime() { return mCCJSRuntime; }
+
+ private:
+ void CheckThreadSafety();
+ MOZ_CAN_RUN_SCRIPT
+ void ShutdownCollect();
+
+ void FixGrayBits(bool aIsShutdown, TimeLog& aTimeLog);
+ bool IsIncrementalGCInProgress();
+ void FinishAnyIncrementalGCInProgress();
+ bool ShouldMergeZones(ccIsManual aIsManual);
+
+ void BeginCollection(CCReason aReason, ccIsManual aIsManual,
+ nsICycleCollectorListener* aManualListener);
+ void MarkRoots(SliceBudget& aBudget);
+ void ScanRoots(bool aFullySynchGraphBuild);
+ void ScanIncrementalRoots();
+ void ScanWhiteNodes(bool aFullySynchGraphBuild);
+ void ScanBlackNodes();
+ void ScanWeakMaps();
+
+ // returns whether anything was collected
+ bool CollectWhite();
+
+ void CleanupAfterCollection();
+};
+
+NS_IMPL_ISUPPORTS(nsCycleCollector, nsIMemoryReporter)
+
+/**
+ * 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<PtrInfo>& aQueue);
+
+ void CheckedPush(nsDeque<PtrInfo>& aQueue, PtrInfo* aPi) {
+ if (!aPi) {
+ MOZ_CRASH();
+ }
+ if (!aQueue.Push(aPi, fallible)) {
+ mVisitor.Failed();
+ }
+ }
+
+ public:
+ void Walk(PtrInfo* aPi);
+ void WalkFromRoots(CCGraph& aGraph);
+ // copy-constructing the visitor should be cheap, and less
+ // indirection than using a reference
+ explicit GraphWalker(const Visitor aVisitor) : mVisitor(aVisitor) {}
+};
+
+////////////////////////////////////////////////////////////////////////
+// The static collector struct
+////////////////////////////////////////////////////////////////////////
+
+struct CollectorData {
+ RefPtr<nsCycleCollector> mCollector;
+ CycleCollectedJSContext* mContext;
+};
+
+static MOZ_THREAD_LOCAL(CollectorData*) sCollectorData;
+
+////////////////////////////////////////////////////////////////////////
+// Utility functions
+////////////////////////////////////////////////////////////////////////
+
+static inline void ToParticipant(nsISupports* aPtr,
+ nsXPCOMCycleCollectionParticipant** aCp) {
+ // 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.
+ *aCp = nullptr;
+ CallQueryInterface(aPtr, aCp);
+}
+
+static void ToParticipant(void* aParti, nsCycleCollectionParticipant** aCp) {
+ // If the participant is null, this is an nsISupports participant,
+ // so we must QI to get the real participant.
+
+ if (!*aCp) {
+ nsISupports* nsparti = static_cast<nsISupports*>(aParti);
+ MOZ_ASSERT(CanonicalizeXPCOMParticipant(nsparti) == nsparti);
+ nsXPCOMCycleCollectionParticipant* xcp;
+ ToParticipant(nsparti, &xcp);
+ *aCp = xcp;
+ }
+}
+
+template <class Visitor>
+MOZ_NEVER_INLINE void GraphWalker<Visitor>::Walk(PtrInfo* aPi) {
+ nsDeque<PtrInfo> queue;
+ CheckedPush(queue, aPi);
+ DoWalk(queue);
+}
+
+template <class Visitor>
+MOZ_NEVER_INLINE void GraphWalker<Visitor>::WalkFromRoots(CCGraph& aGraph) {
+ nsDeque<PtrInfo> queue;
+ NodePool::Enumerator etor(aGraph.mNodes);
+ for (uint32_t i = 0; i < aGraph.mRootCount; ++i) {
+ CheckedPush(queue, etor.GetNext());
+ }
+ DoWalk(queue);
+}
+
+template <class Visitor>
+MOZ_NEVER_INLINE void GraphWalker<Visitor>::DoWalk(nsDeque<PtrInfo>& 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 = aQueue.PopFront();
+
+ if (pi->WasTraversed() && mVisitor.ShouldVisitNode(pi)) {
+ mVisitor.VisitNode(pi);
+ for (EdgePool::Iterator child = pi->FirstChild(),
+ child_end = pi->LastChild();
+ child != child_end; ++child) {
+ CheckedPush(aQueue, *child);
+ }
+ }
+ }
+}
+
+struct CCGraphDescriber : public LinkedListElement<CCGraphDescriber> {
+ CCGraphDescriber() : mAddress("0x"), mCnt(0), mType(eUnknown) {}
+
+ enum Type {
+ eRefCountedObject,
+ eGCedObject,
+ eGCMarkedObject,
+ eEdge,
+ eRoot,
+ eGarbage,
+ eUnknown
+ };
+
+ nsCString mAddress;
+ nsCString mName;
+ nsCString mCompartmentOrToAddress;
+ uint32_t mCnt;
+ Type mType;
+};
+
+class LogStringMessageAsync : public DiscardableRunnable {
+ public:
+ explicit LogStringMessageAsync(const nsAString& aMsg)
+ : mozilla::DiscardableRunnable("LogStringMessageAsync"), mMsg(aMsg) {}
+
+ NS_IMETHOD Run() override {
+ nsCOMPtr<nsIConsoleService> cs =
+ do_GetService(NS_CONSOLESERVICE_CONTRACTID);
+ if (cs) {
+ cs->LogStringMessage(mMsg.get());
+ }
+ return NS_OK;
+ }
+
+ private:
+ nsString mMsg;
+};
+
+class nsCycleCollectorLogSinkToFile final : public nsICycleCollectorLogSink {
+ public:
+ NS_DECL_ISUPPORTS
+
+ nsCycleCollectorLogSinkToFile()
+ : mProcessIdentifier(base::GetCurrentProcId()),
+ mGCLog("gc-edges"),
+ mCCLog("cc-edges") {}
+
+ NS_IMETHOD GetFilenameIdentifier(nsAString& aIdentifier) override {
+ aIdentifier = mFilenameIdentifier;
+ return NS_OK;
+ }
+
+ NS_IMETHOD SetFilenameIdentifier(const nsAString& aIdentifier) override {
+ mFilenameIdentifier = aIdentifier;
+ return NS_OK;
+ }
+
+ NS_IMETHOD GetProcessIdentifier(int32_t* aIdentifier) override {
+ *aIdentifier = mProcessIdentifier;
+ return NS_OK;
+ }
+
+ NS_IMETHOD SetProcessIdentifier(int32_t aIdentifier) override {
+ mProcessIdentifier = aIdentifier;
+ return NS_OK;
+ }
+
+ NS_IMETHOD GetGcLog(nsIFile** aPath) override {
+ NS_IF_ADDREF(*aPath = mGCLog.mFile);
+ return NS_OK;
+ }
+
+ NS_IMETHOD GetCcLog(nsIFile** aPath) override {
+ NS_IF_ADDREF(*aPath = mCCLog.mFile);
+ return NS_OK;
+ }
+
+ NS_IMETHOD Open(FILE** aGCLog, FILE** aCCLog) override {
+ nsresult rv;
+
+ if (mGCLog.mStream || mCCLog.mStream) {
+ return NS_ERROR_UNEXPECTED;
+ }
+
+ rv = OpenLog(&mGCLog);
+ NS_ENSURE_SUCCESS(rv, rv);
+ *aGCLog = mGCLog.mStream;
+
+ rv = OpenLog(&mCCLog);
+ NS_ENSURE_SUCCESS(rv, rv);
+ *aCCLog = mCCLog.mStream;
+
+ return NS_OK;
+ }
+
+ NS_IMETHOD CloseGCLog() override {
+ if (!mGCLog.mStream) {
+ return NS_ERROR_UNEXPECTED;
+ }
+ CloseLog(&mGCLog, u"Garbage"_ns);
+ return NS_OK;
+ }
+
+ NS_IMETHOD CloseCCLog() override {
+ if (!mCCLog.mStream) {
+ return NS_ERROR_UNEXPECTED;
+ }
+ CloseLog(&mCCLog, u"Cycle"_ns);
+ return NS_OK;
+ }
+
+ private:
+ ~nsCycleCollectorLogSinkToFile() {
+ if (mGCLog.mStream) {
+ MozillaUnRegisterDebugFILE(mGCLog.mStream);
+ fclose(mGCLog.mStream);
+ }
+ if (mCCLog.mStream) {
+ MozillaUnRegisterDebugFILE(mCCLog.mStream);
+ fclose(mCCLog.mStream);
+ }
+ }
+
+ struct FileInfo {
+ const char* const mPrefix;
+ nsCOMPtr<nsIFile> mFile;
+ FILE* mStream;
+
+ explicit FileInfo(const char* aPrefix)
+ : mPrefix(aPrefix), mStream(nullptr) {}
+ };
+
+ /**
+ * Create a new file named something like aPrefix.$PID.$IDENTIFIER.log in
+ * $MOZ_CC_LOG_DIRECTORY or in the system's temp directory. No existing
+ * file will be overwritten; if aPrefix.$PID.$IDENTIFIER.log exists, we'll
+ * try a file named something like aPrefix.$PID.$IDENTIFIER-1.log, and so
+ * on.
+ */
+ already_AddRefed<nsIFile> CreateTempFile(const char* aPrefix) {
+ nsPrintfCString filename("%s.%d%s%s.log", aPrefix, mProcessIdentifier,
+ mFilenameIdentifier.IsEmpty() ? "" : ".",
+ NS_ConvertUTF16toUTF8(mFilenameIdentifier).get());
+
+ // Get the log directory either from $MOZ_CC_LOG_DIRECTORY or from
+ // the fallback directories in OpenTempFile. We don't use an nsCOMPtr
+ // here because OpenTempFile uses an in/out param and getter_AddRefs
+ // wouldn't work.
+ nsIFile* logFile = nullptr;
+ if (char* env = PR_GetEnv("MOZ_CC_LOG_DIRECTORY")) {
+ NS_NewNativeLocalFile(nsCString(env), /* followLinks = */ true, &logFile);
+ }
+
+ // On Android or B2G, this function will open a file named
+ // aFilename under a memory-reporting-specific folder
+ // (/data/local/tmp/memory-reports). Otherwise, it will open a
+ // file named aFilename under "NS_OS_TEMP_DIR".
+ nsresult rv =
+ nsDumpUtils::OpenTempFile(filename, &logFile, "memory-reports"_ns);
+ if (NS_FAILED(rv)) {
+ NS_IF_RELEASE(logFile);
+ return nullptr;
+ }
+
+ return dont_AddRef(logFile);
+ }
+
+ nsresult OpenLog(FileInfo* aLog) {
+ // Initially create the log in a file starting with "incomplete-".
+ // We'll move the file and strip off the "incomplete-" once the dump
+ // completes. (We do this because we don't want scripts which poll
+ // the filesystem looking for GC/CC dumps to grab a file before we're
+ // finished writing to it.)
+ nsAutoCString incomplete;
+ incomplete += "incomplete-";
+ incomplete += aLog->mPrefix;
+ MOZ_ASSERT(!aLog->mFile);
+ aLog->mFile = CreateTempFile(incomplete.get());
+ if (NS_WARN_IF(!aLog->mFile)) {
+ return NS_ERROR_UNEXPECTED;
+ }
+
+ MOZ_ASSERT(!aLog->mStream);
+ nsresult rv = aLog->mFile->OpenANSIFileDesc("w", &aLog->mStream);
+ if (NS_WARN_IF(NS_FAILED(rv))) {
+ return NS_ERROR_UNEXPECTED;
+ }
+ MozillaRegisterDebugFILE(aLog->mStream);
+ return NS_OK;
+ }
+
+ nsresult CloseLog(FileInfo* aLog, const nsAString& aCollectorKind) {
+ MOZ_ASSERT(aLog->mStream);
+ MOZ_ASSERT(aLog->mFile);
+
+ MozillaUnRegisterDebugFILE(aLog->mStream);
+ fclose(aLog->mStream);
+ aLog->mStream = nullptr;
+
+ // Strip off "incomplete-".
+ nsCOMPtr<nsIFile> logFileFinalDestination = CreateTempFile(aLog->mPrefix);
+ if (NS_WARN_IF(!logFileFinalDestination)) {
+ return NS_ERROR_UNEXPECTED;
+ }
+
+ nsAutoString logFileFinalDestinationName;
+ logFileFinalDestination->GetLeafName(logFileFinalDestinationName);
+ if (NS_WARN_IF(logFileFinalDestinationName.IsEmpty())) {
+ return NS_ERROR_UNEXPECTED;
+ }
+
+ aLog->mFile->MoveTo(/* directory */ nullptr, logFileFinalDestinationName);
+
+ // Save the file path.
+ aLog->mFile = logFileFinalDestination;
+
+ // Log to the error console.
+ nsAutoString logPath;
+ logFileFinalDestination->GetPath(logPath);
+ nsAutoString msg =
+ aCollectorKind + u" Collector log dumped to "_ns + logPath;
+
+ // We don't want any JS to run between ScanRoots and CollectWhite calls,
+ // and since ScanRoots calls this method, better to log the message
+ // asynchronously.
+ RefPtr<LogStringMessageAsync> log = new LogStringMessageAsync(msg);
+ NS_DispatchToCurrentThread(log);
+ return NS_OK;
+ }
+
+ int32_t mProcessIdentifier;
+ nsString mFilenameIdentifier;
+ FileInfo mGCLog;
+ FileInfo mCCLog;
+};
+
+NS_IMPL_ISUPPORTS(nsCycleCollectorLogSinkToFile, nsICycleCollectorLogSink)
+
+class nsCycleCollectorLogger final : public nsICycleCollectorListener {
+ ~nsCycleCollectorLogger() { ClearDescribers(); }
+
+ public:
+ nsCycleCollectorLogger()
+ : mLogSink(nsCycleCollector_createLogSink()),
+ mWantAllTraces(false),
+ mDisableLog(false),
+ mWantAfterProcessing(false),
+ mCCLog(nullptr) {}
+
+ NS_DECL_ISUPPORTS
+
+ void SetAllTraces() { mWantAllTraces = true; }
+
+ bool IsAllTraces() { return mWantAllTraces; }
+
+ NS_IMETHOD AllTraces(nsICycleCollectorListener** aListener) override {
+ SetAllTraces();
+ NS_ADDREF(*aListener = this);
+ return NS_OK;
+ }
+
+ NS_IMETHOD GetWantAllTraces(bool* aAllTraces) override {
+ *aAllTraces = mWantAllTraces;
+ return NS_OK;
+ }
+
+ NS_IMETHOD GetDisableLog(bool* aDisableLog) override {
+ *aDisableLog = mDisableLog;
+ return NS_OK;
+ }
+
+ NS_IMETHOD SetDisableLog(bool aDisableLog) override {
+ mDisableLog = aDisableLog;
+ return NS_OK;
+ }
+
+ NS_IMETHOD GetWantAfterProcessing(bool* aWantAfterProcessing) override {
+ *aWantAfterProcessing = mWantAfterProcessing;
+ return NS_OK;
+ }
+
+ NS_IMETHOD SetWantAfterProcessing(bool aWantAfterProcessing) override {
+ mWantAfterProcessing = aWantAfterProcessing;
+ return NS_OK;
+ }
+
+ NS_IMETHOD GetLogSink(nsICycleCollectorLogSink** aLogSink) override {
+ NS_ADDREF(*aLogSink = mLogSink);
+ return NS_OK;
+ }
+
+ NS_IMETHOD SetLogSink(nsICycleCollectorLogSink* aLogSink) override {
+ if (!aLogSink) {
+ return NS_ERROR_INVALID_ARG;
+ }
+ mLogSink = aLogSink;
+ return NS_OK;
+ }
+
+ nsresult Begin() {
+ nsresult rv;
+
+ mCurrentAddress.AssignLiteral("0x");
+ ClearDescribers();
+ if (mDisableLog) {
+ return NS_OK;
+ }
+
+ FILE* gcLog;
+ rv = mLogSink->Open(&gcLog, &mCCLog);
+ NS_ENSURE_SUCCESS(rv, rv);
+ // Dump the JS heap.
+ CollectorData* data = sCollectorData.get();
+ if (data && data->mContext) {
+ data->mContext->Runtime()->DumpJSHeap(gcLog);
+ }
+ rv = mLogSink->CloseGCLog();
+ NS_ENSURE_SUCCESS(rv, rv);
+
+ fprintf(mCCLog, "# WantAllTraces=%s\n", mWantAllTraces ? "true" : "false");
+ return NS_OK;
+ }
+ void NoteRefCountedObject(uint64_t aAddress, uint32_t aRefCount,
+ const char* aObjectDescription) {
+ if (!mDisableLog) {
+ fprintf(mCCLog, "%p [rc=%u] %s\n", (void*)aAddress, aRefCount,
+ aObjectDescription);
+ }
+ if (mWantAfterProcessing) {
+ CCGraphDescriber* d = new CCGraphDescriber();
+ mDescribers.insertBack(d);
+ mCurrentAddress.AssignLiteral("0x");
+ mCurrentAddress.AppendInt(aAddress, 16);
+ d->mType = CCGraphDescriber::eRefCountedObject;
+ d->mAddress = mCurrentAddress;
+ d->mCnt = aRefCount;
+ d->mName.Append(aObjectDescription);
+ }
+ }
+ void NoteGCedObject(uint64_t aAddress, bool aMarked,
+ const char* aObjectDescription,
+ uint64_t aCompartmentAddress) {
+ if (!mDisableLog) {
+ fprintf(mCCLog, "%p [gc%s] %s\n", (void*)aAddress,
+ aMarked ? ".marked" : "", aObjectDescription);
+ }
+ if (mWantAfterProcessing) {
+ CCGraphDescriber* d = new CCGraphDescriber();
+ mDescribers.insertBack(d);
+ mCurrentAddress.AssignLiteral("0x");
+ mCurrentAddress.AppendInt(aAddress, 16);
+ d->mType = aMarked ? CCGraphDescriber::eGCMarkedObject
+ : CCGraphDescriber::eGCedObject;
+ d->mAddress = mCurrentAddress;
+ d->mName.Append(aObjectDescription);
+ if (aCompartmentAddress) {
+ d->mCompartmentOrToAddress.AssignLiteral("0x");
+ d->mCompartmentOrToAddress.AppendInt(aCompartmentAddress, 16);
+ } else {
+ d->mCompartmentOrToAddress.SetIsVoid(true);
+ }
+ }
+ }
+ void NoteEdge(uint64_t aToAddress, const char* aEdgeName) {
+ if (!mDisableLog) {
+ fprintf(mCCLog, "> %p %s\n", (void*)aToAddress, aEdgeName);
+ }
+ if (mWantAfterProcessing) {
+ CCGraphDescriber* d = new CCGraphDescriber();
+ mDescribers.insertBack(d);
+ d->mType = CCGraphDescriber::eEdge;
+ d->mAddress = mCurrentAddress;
+ d->mCompartmentOrToAddress.AssignLiteral("0x");
+ d->mCompartmentOrToAddress.AppendInt(aToAddress, 16);
+ d->mName.Append(aEdgeName);
+ }
+ }
+ void NoteWeakMapEntry(uint64_t aMap, uint64_t aKey, uint64_t aKeyDelegate,
+ uint64_t aValue) {
+ if (!mDisableLog) {
+ fprintf(mCCLog, "WeakMapEntry map=%p key=%p keyDelegate=%p value=%p\n",
+ (void*)aMap, (void*)aKey, (void*)aKeyDelegate, (void*)aValue);
+ }
+ // We don't support after-processing for weak map entries.
+ }
+ void NoteIncrementalRoot(uint64_t aAddress) {
+ if (!mDisableLog) {
+ fprintf(mCCLog, "IncrementalRoot %p\n", (void*)aAddress);
+ }
+ // We don't support after-processing for incremental roots.
+ }
+ void BeginResults() {
+ if (!mDisableLog) {
+ fputs("==========\n", mCCLog);
+ }
+ }
+ void DescribeRoot(uint64_t aAddress, uint32_t aKnownEdges) {
+ if (!mDisableLog) {
+ fprintf(mCCLog, "%p [known=%u]\n", (void*)aAddress, aKnownEdges);
+ }
+ if (mWantAfterProcessing) {
+ CCGraphDescriber* d = new CCGraphDescriber();
+ mDescribers.insertBack(d);
+ d->mType = CCGraphDescriber::eRoot;
+ d->mAddress.AppendInt(aAddress, 16);
+ d->mCnt = aKnownEdges;
+ }
+ }
+ void DescribeGarbage(uint64_t aAddress) {
+ if (!mDisableLog) {
+ fprintf(mCCLog, "%p [garbage]\n", (void*)aAddress);
+ }
+ if (mWantAfterProcessing) {
+ CCGraphDescriber* d = new CCGraphDescriber();
+ mDescribers.insertBack(d);
+ d->mType = CCGraphDescriber::eGarbage;
+ d->mAddress.AppendInt(aAddress, 16);
+ }
+ }
+ void End() {
+ if (!mDisableLog) {
+ mCCLog = nullptr;
+ Unused << NS_WARN_IF(NS_FAILED(mLogSink->CloseCCLog()));
+ }
+ }
+ NS_IMETHOD ProcessNext(nsICycleCollectorHandler* aHandler,
+ bool* aCanContinue) override {
+ if (NS_WARN_IF(!aHandler) || NS_WARN_IF(!mWantAfterProcessing)) {
+ return NS_ERROR_UNEXPECTED;
+ }
+ CCGraphDescriber* d = mDescribers.popFirst();
+ if (d) {
+ 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, d->mCompartmentOrToAddress);
+ break;
+ case CCGraphDescriber::eEdge:
+ aHandler->NoteEdge(d->mAddress, d->mCompartmentOrToAddress, d->mName);
+ break;
+ case CCGraphDescriber::eRoot:
+ aHandler->DescribeRoot(d->mAddress, d->mCnt);
+ break;
+ case CCGraphDescriber::eGarbage:
+ aHandler->DescribeGarbage(d->mAddress);
+ break;
+ case CCGraphDescriber::eUnknown:
+ MOZ_ASSERT_UNREACHABLE("CCGraphDescriber::eUnknown");
+ break;
+ }
+ delete d;
+ }
+ if (!(*aCanContinue = !mDescribers.isEmpty())) {
+ mCurrentAddress.AssignLiteral("0x");
+ }
+ return NS_OK;
+ }
+ NS_IMETHOD AsLogger(nsCycleCollectorLogger** aRetVal) override {
+ RefPtr<nsCycleCollectorLogger> rval = this;
+ rval.forget(aRetVal);
+ return NS_OK;
+ }
+
+ private:
+ void ClearDescribers() {
+ CCGraphDescriber* d;
+ while ((d = mDescribers.popFirst())) {
+ delete d;
+ }
+ }
+
+ nsCOMPtr<nsICycleCollectorLogSink> mLogSink;
+ bool mWantAllTraces;
+ bool mDisableLog;
+ bool mWantAfterProcessing;
+ nsCString mCurrentAddress;
+ mozilla::LinkedList<CCGraphDescriber> mDescribers;
+ FILE* mCCLog;
+};
+
+NS_IMPL_ISUPPORTS(nsCycleCollectorLogger, nsICycleCollectorListener)
+
+already_AddRefed<nsICycleCollectorListener> nsCycleCollector_createLogger() {
+ nsCOMPtr<nsICycleCollectorListener> logger = new nsCycleCollectorLogger();
+ return logger.forget();
+}
+
+static bool GCThingIsGrayCCThing(JS::GCCellPtr thing) {
+ return JS::IsCCTraceKind(thing.kind()) && JS::GCThingIsMarkedGrayInCC(thing);
+}
+
+static bool ValueIsGrayCCThing(const JS::Value& value) {
+ return JS::IsCCTraceKind(value.traceKind()) &&
+ JS::GCThingIsMarkedGray(value.toGCCellPtr());
+}
+
+////////////////////////////////////////////////////////////////////////
+// Bacon & Rajan's |MarkRoots| routine.
+////////////////////////////////////////////////////////////////////////
+
+class CCGraphBuilder final : public nsCycleCollectionTraversalCallback,
+ public nsCycleCollectionNoteRootCallback {
+ private:
+ CCGraph& mGraph;
+ CycleCollectorResults& mResults;
+ NodePool::Builder mNodeBuilder;
+ EdgePool::Builder mEdgeBuilder;
+ MOZ_INIT_OUTSIDE_CTOR PtrInfo* mCurrPi;
+ nsCycleCollectionParticipant* mJSParticipant;
+ nsCycleCollectionParticipant* mJSZoneParticipant;
+ nsCString mNextEdgeName;
+ RefPtr<nsCycleCollectorLogger> mLogger;
+ bool mMergeZones;
+ UniquePtr<NodePool::Enumerator> mCurrNode;
+ uint32_t mNoteChildCount;
+
+ struct PtrInfoCache : public MruCache<void*, PtrInfo*, PtrInfoCache, 491> {
+ static HashNumber Hash(const void* aKey) { return HashGeneric(aKey); }
+ static bool Match(const void* aKey, const PtrInfo* aVal) {
+ return aVal->mPointer == aKey;
+ }
+ };
+
+ PtrInfoCache mGraphCache;
+
+ public:
+ CCGraphBuilder(CCGraph& aGraph, CycleCollectorResults& aResults,
+ CycleCollectedJSRuntime* aCCRuntime,
+ nsCycleCollectorLogger* aLogger, bool aMergeZones);
+ virtual ~CCGraphBuilder();
+
+ bool WantAllTraces() const {
+ return nsCycleCollectionNoteRootCallback::WantAllTraces();
+ }
+
+ bool AddPurpleRoot(void* aRoot, nsCycleCollectionParticipant* aParti);
+
+ // This is called when all roots have been added to the graph, to prepare for
+ // BuildGraph().
+ void DoneAddingRoots();
+
+ // Do some work traversing nodes in the graph. Returns true if this graph
+ // building is finished.
+ bool BuildGraph(SliceBudget& aBudget);
+
+ void RemoveCachedEntry(void* aPtr) { mGraphCache.Remove(aPtr); }
+
+ private:
+ PtrInfo* AddNode(void* aPtr, nsCycleCollectionParticipant* aParticipant);
+ PtrInfo* AddWeakMapNode(JS::GCCellPtr aThing);
+ PtrInfo* AddWeakMapNode(JSObject* aObject);
+
+ void SetFirstChild() { mCurrPi->SetFirstChild(mEdgeBuilder.Mark()); }
+
+ void SetLastChild() { mCurrPi->SetLastChild(mEdgeBuilder.Mark()); }
+
+ public:
+ // nsCycleCollectionNoteRootCallback methods.
+ NS_IMETHOD_(void)
+ NoteXPCOMRoot(nsISupports* aRoot,
+ nsCycleCollectionParticipant* aParticipant) override;
+ NS_IMETHOD_(void) NoteJSRoot(JSObject* aRoot) override;
+ NS_IMETHOD_(void)
+ NoteNativeRoot(void* aRoot,
+ nsCycleCollectionParticipant* aParticipant) override;
+ NS_IMETHOD_(void)
+ NoteWeakMapping(JSObject* aMap, JS::GCCellPtr aKey, JSObject* aKdelegate,
+ JS::GCCellPtr aVal) override;
+ // This is used to create synthetic non-refcounted references to
+ // nsXPCWrappedJS from their wrapped JS objects. No map is needed, because
+ // the SubjectToFinalization list is like a known-black weak map, and
+ // no delegate is needed because the keys are all unwrapped objects.
+ NS_IMETHOD_(void)
+ NoteWeakMapping(JSObject* aKey, nsISupports* aVal,
+ nsCycleCollectionParticipant* aValParticipant) override;
+
+ // nsCycleCollectionTraversalCallback methods.
+ NS_IMETHOD_(void)
+ DescribeRefCountedNode(nsrefcnt aRefCount, const char* aObjName) override;
+ NS_IMETHOD_(void)
+ DescribeGCedNode(bool aIsMarked, const char* aObjName,
+ uint64_t aCompartmentAddress) override;
+
+ NS_IMETHOD_(void) NoteXPCOMChild(nsISupports* aChild) override;
+ NS_IMETHOD_(void) NoteJSChild(JS::GCCellPtr aThing) override;
+ NS_IMETHOD_(void)
+ NoteNativeChild(void* aChild,
+ nsCycleCollectionParticipant* aParticipant) override;
+ NS_IMETHOD_(void) NoteNextEdgeName(const char* aName) override;
+
+ private:
+ NS_IMETHOD_(void)
+ NoteRoot(void* aRoot, nsCycleCollectionParticipant* aParticipant) {
+ MOZ_ASSERT(aRoot);
+ MOZ_ASSERT(aParticipant);
+
+ if (!aParticipant->CanSkipInCC(aRoot) || MOZ_UNLIKELY(WantAllTraces())) {
+ AddNode(aRoot, aParticipant);
+ }
+ }
+
+ NS_IMETHOD_(void)
+ NoteChild(void* aChild, nsCycleCollectionParticipant* aCp,
+ nsCString& aEdgeName) {
+ PtrInfo* childPi = AddNode(aChild, aCp);
+ if (!childPi) {
+ return;
+ }
+ mEdgeBuilder.Add(childPi);
+ if (mLogger) {
+ mLogger->NoteEdge((uint64_t)aChild, aEdgeName.get());
+ }
+ ++childPi->mInternalRefs;
+ }
+
+ JS::Zone* MergeZone(JS::GCCellPtr aGcthing) {
+ if (!mMergeZones) {
+ return nullptr;
+ }
+ JS::Zone* zone = JS::GetTenuredGCThingZone(aGcthing);
+ if (js::IsSystemZone(zone)) {
+ return nullptr;
+ }
+ return zone;
+ }
+};
+
+CCGraphBuilder::CCGraphBuilder(CCGraph& aGraph, CycleCollectorResults& aResults,
+ CycleCollectedJSRuntime* aCCRuntime,
+ nsCycleCollectorLogger* aLogger,
+ bool aMergeZones)
+ : mGraph(aGraph),
+ mResults(aResults),
+ mNodeBuilder(aGraph.mNodes),
+ mEdgeBuilder(aGraph.mEdges),
+ mJSParticipant(nullptr),
+ mJSZoneParticipant(nullptr),
+ mLogger(aLogger),
+ mMergeZones(aMergeZones),
+ mNoteChildCount(0) {
+ // 4096 is an allocation bucket size.
+ static_assert(sizeof(CCGraphBuilder) <= 4096,
+ "Don't create too large CCGraphBuilder objects");
+
+ if (aCCRuntime) {
+ mJSParticipant = aCCRuntime->GCThingParticipant();
+ mJSZoneParticipant = aCCRuntime->ZoneParticipant();
+ }
+
+ if (mLogger) {
+ mFlags |= nsCycleCollectionTraversalCallback::WANT_DEBUG_INFO;
+ if (mLogger->IsAllTraces()) {
+ mFlags |= nsCycleCollectionTraversalCallback::WANT_ALL_TRACES;
+ mWantAllTraces = true; // for nsCycleCollectionNoteRootCallback
+ }
+ }
+
+ mMergeZones = mMergeZones && MOZ_LIKELY(!WantAllTraces());
+
+ MOZ_ASSERT(nsCycleCollectionNoteRootCallback::WantAllTraces() ==
+ nsCycleCollectionTraversalCallback::WantAllTraces());
+}
+
+CCGraphBuilder::~CCGraphBuilder() = default;
+
+PtrInfo* CCGraphBuilder::AddNode(void* aPtr,
+ nsCycleCollectionParticipant* aParticipant) {
+ if (mGraph.mOutOfMemory) {
+ return nullptr;
+ }
+
+ PtrInfoCache::Entry cached = mGraphCache.Lookup(aPtr);
+ if (cached) {
+#ifdef DEBUG
+ if (cached.Data()->mParticipant != aParticipant) {
+ auto* parti1 = cached.Data()->mParticipant;
+ auto* parti2 = aParticipant;
+ NS_WARNING(
+ nsPrintfCString("cached participant: %s; AddNode participant: %s\n",
+ parti1 ? parti1->ClassName() : "null",
+ parti2 ? parti2->ClassName() : "null")
+ .get());
+ }
+#endif
+ MOZ_ASSERT(cached.Data()->mParticipant == aParticipant,
+ "nsCycleCollectionParticipant shouldn't change!");
+ return cached.Data();
+ }
+
+ PtrInfo* result;
+ auto p = mGraph.mPtrInfoMap.lookupForAdd(aPtr);
+ if (!p) {
+ // New entry
+ result = mNodeBuilder.Add(aPtr, aParticipant);
+ if (!result) {
+ return nullptr;
+ }
+
+ if (!mGraph.mPtrInfoMap.add(p, result)) {
+ // `result` leaks here, but we can't free it because it's
+ // pool-allocated within NodePool.
+ mGraph.mOutOfMemory = true;
+ MOZ_ASSERT(false, "OOM while building cycle collector graph");
+ return nullptr;
+ }
+
+ } else {
+ result = *p;
+ MOZ_ASSERT(result->mParticipant == aParticipant,
+ "nsCycleCollectionParticipant shouldn't change!");
+ }
+
+ cached.Set(result);
+
+ return result;
+}
+
+bool CCGraphBuilder::AddPurpleRoot(void* aRoot,
+ nsCycleCollectionParticipant* aParti) {
+ ToParticipant(aRoot, &aParti);
+
+ if (WantAllTraces() || !aParti->CanSkipInCC(aRoot)) {
+ PtrInfo* pinfo = AddNode(aRoot, aParti);
+ if (!pinfo) {
+ return false;
+ }
+ }
+
+ return true;
+}
+
+void CCGraphBuilder::DoneAddingRoots() {
+ // We've finished adding roots, and everything in the graph is a root.
+ mGraph.mRootCount = mGraph.MapCount();
+
+ mCurrNode = MakeUnique<NodePool::Enumerator>(mGraph.mNodes);
+}
+
+MOZ_NEVER_INLINE bool CCGraphBuilder::BuildGraph(SliceBudget& aBudget) {
+ MOZ_ASSERT(mCurrNode);
+
+ while (!aBudget.isOverBudget() && !mCurrNode->IsDone()) {
+ mNoteChildCount = 0;
+
+ PtrInfo* pi = mCurrNode->GetNext();
+ if (!pi) {
+ MOZ_CRASH();
+ }
+
+ mCurrPi = pi;
+
+ // We need to call SetFirstChild() even on deleted nodes, to set their
+ // firstChild() that may be read by a prior non-deleted neighbor.
+ SetFirstChild();
+
+ if (pi->mParticipant) {
+ nsresult rv = pi->mParticipant->TraverseNativeAndJS(pi->mPointer, *this);
+ MOZ_RELEASE_ASSERT(!NS_FAILED(rv),
+ "Cycle collector Traverse method failed");
+ }
+
+ if (mCurrNode->AtBlockEnd()) {
+ SetLastChild();
+ }
+
+ aBudget.step(mNoteChildCount + 1);
+ }
+
+ if (!mCurrNode->IsDone()) {
+ return false;
+ }
+
+ if (mGraph.mRootCount > 0) {
+ SetLastChild();
+ }
+
+ mCurrNode = nullptr;
+
+ return true;
+}
+
+NS_IMETHODIMP_(void)
+CCGraphBuilder::NoteXPCOMRoot(nsISupports* aRoot,
+ nsCycleCollectionParticipant* aParticipant) {
+ MOZ_ASSERT(aRoot == CanonicalizeXPCOMParticipant(aRoot));
+
+#ifdef DEBUG
+ nsXPCOMCycleCollectionParticipant* cp;
+ ToParticipant(aRoot, &cp);
+ MOZ_ASSERT(aParticipant == cp);
+#endif
+
+ NoteRoot(aRoot, aParticipant);
+}
+
+NS_IMETHODIMP_(void)
+CCGraphBuilder::NoteJSRoot(JSObject* aRoot) {
+ if (JS::Zone* zone = MergeZone(JS::GCCellPtr(aRoot))) {
+ NoteRoot(zone, mJSZoneParticipant);
+ } else {
+ NoteRoot(aRoot, mJSParticipant);
+ }
+}
+
+NS_IMETHODIMP_(void)
+CCGraphBuilder::NoteNativeRoot(void* aRoot,
+ nsCycleCollectionParticipant* aParticipant) {
+ NoteRoot(aRoot, aParticipant);
+}
+
+NS_IMETHODIMP_(void)
+CCGraphBuilder::DescribeRefCountedNode(nsrefcnt aRefCount,
+ const char* aObjName) {
+ mCurrPi->AnnotatedReleaseAssert(aRefCount != 0,
+ "CCed refcounted object has zero refcount");
+ mCurrPi->AnnotatedReleaseAssert(
+ aRefCount != UINT32_MAX,
+ "CCed refcounted object has overflowing refcount");
+
+ mResults.mVisitedRefCounted++;
+
+ if (mLogger) {
+ mLogger->NoteRefCountedObject((uint64_t)mCurrPi->mPointer, aRefCount,
+ aObjName);
+ }
+
+ mCurrPi->mRefCount = aRefCount;
+}
+
+NS_IMETHODIMP_(void)
+CCGraphBuilder::DescribeGCedNode(bool aIsMarked, const char* aObjName,
+ uint64_t aCompartmentAddress) {
+ uint32_t refCount = aIsMarked ? UINT32_MAX : 0;
+ mResults.mVisitedGCed++;
+
+ if (mLogger) {
+ mLogger->NoteGCedObject((uint64_t)mCurrPi->mPointer, aIsMarked, aObjName,
+ aCompartmentAddress);
+ }
+
+ mCurrPi->mRefCount = refCount;
+}
+
+NS_IMETHODIMP_(void)
+CCGraphBuilder::NoteXPCOMChild(nsISupports* aChild) {
+ nsCString edgeName;
+ if (WantDebugInfo()) {
+ edgeName.Assign(mNextEdgeName);
+ mNextEdgeName.Truncate();
+ }
+ if (!aChild || !(aChild = CanonicalizeXPCOMParticipant(aChild))) {
+ return;
+ }
+
+ ++mNoteChildCount;
+
+ nsXPCOMCycleCollectionParticipant* cp;
+ ToParticipant(aChild, &cp);
+ if (cp && (!cp->CanSkipThis(aChild) || WantAllTraces())) {
+ NoteChild(aChild, cp, edgeName);
+ }
+}
+
+NS_IMETHODIMP_(void)
+CCGraphBuilder::NoteNativeChild(void* aChild,
+ nsCycleCollectionParticipant* aParticipant) {
+ nsCString edgeName;
+ if (WantDebugInfo()) {
+ edgeName.Assign(mNextEdgeName);
+ mNextEdgeName.Truncate();
+ }
+ if (!aChild) {
+ return;
+ }
+
+ ++mNoteChildCount;
+
+ MOZ_ASSERT(aParticipant, "Need a nsCycleCollectionParticipant!");
+ if (!aParticipant->CanSkipThis(aChild) || WantAllTraces()) {
+ NoteChild(aChild, aParticipant, edgeName);
+ }
+}
+
+NS_IMETHODIMP_(void)
+CCGraphBuilder::NoteJSChild(JS::GCCellPtr aChild) {
+ if (!aChild) {
+ return;
+ }
+
+ ++mNoteChildCount;
+
+ nsCString edgeName;
+ if (MOZ_UNLIKELY(WantDebugInfo())) {
+ edgeName.Assign(mNextEdgeName);
+ mNextEdgeName.Truncate();
+ }
+
+ if (GCThingIsGrayCCThing(aChild) || MOZ_UNLIKELY(WantAllTraces())) {
+ if (JS::Zone* zone = MergeZone(aChild)) {
+ NoteChild(zone, mJSZoneParticipant, edgeName);
+ } else {
+ NoteChild(aChild.asCell(), mJSParticipant, edgeName);
+ }
+ }
+}
+
+NS_IMETHODIMP_(void)
+CCGraphBuilder::NoteNextEdgeName(const char* aName) {
+ if (WantDebugInfo()) {
+ mNextEdgeName = aName;
+ }
+}
+
+PtrInfo* CCGraphBuilder::AddWeakMapNode(JS::GCCellPtr aNode) {
+ MOZ_ASSERT(aNode, "Weak map node should be non-null.");
+
+ if (!GCThingIsGrayCCThing(aNode) && !WantAllTraces()) {
+ return nullptr;
+ }
+
+ if (JS::Zone* zone = MergeZone(aNode)) {
+ return AddNode(zone, mJSZoneParticipant);
+ }
+ return AddNode(aNode.asCell(), mJSParticipant);
+}
+
+PtrInfo* CCGraphBuilder::AddWeakMapNode(JSObject* aObject) {
+ return AddWeakMapNode(JS::GCCellPtr(aObject));
+}
+
+NS_IMETHODIMP_(void)
+CCGraphBuilder::NoteWeakMapping(JSObject* aMap, JS::GCCellPtr aKey,
+ JSObject* aKdelegate, JS::GCCellPtr aVal) {
+ // Don't try to optimize away the entry here, as we've already attempted to
+ // do that in TraceWeakMapping in nsXPConnect.
+ WeakMapping* mapping = mGraph.mWeakMaps.AppendElement();
+ mapping->mMap = aMap ? AddWeakMapNode(aMap) : nullptr;
+ mapping->mKey = aKey ? AddWeakMapNode(aKey) : nullptr;
+ mapping->mKeyDelegate =
+ aKdelegate ? AddWeakMapNode(aKdelegate) : mapping->mKey;
+ mapping->mVal = aVal ? AddWeakMapNode(aVal) : nullptr;
+
+ if (mLogger) {
+ mLogger->NoteWeakMapEntry((uint64_t)aMap, aKey ? aKey.unsafeAsInteger() : 0,
+ (uint64_t)aKdelegate,
+ aVal ? aVal.unsafeAsInteger() : 0);
+ }
+}
+
+NS_IMETHODIMP_(void)
+CCGraphBuilder::NoteWeakMapping(JSObject* aKey, nsISupports* aVal,
+ nsCycleCollectionParticipant* aValParticipant) {
+ MOZ_ASSERT(aKey, "Don't call NoteWeakMapping with a null key");
+ MOZ_ASSERT(aVal, "Don't call NoteWeakMapping with a null value");
+ WeakMapping* mapping = mGraph.mWeakMaps.AppendElement();
+ mapping->mMap = nullptr;
+ mapping->mKey = AddWeakMapNode(aKey);
+ mapping->mKeyDelegate = mapping->mKey;
+ MOZ_ASSERT(js::UncheckedUnwrapWithoutExpose(aKey) == aKey);
+ mapping->mVal = AddNode(aVal, aValParticipant);
+
+ if (mLogger) {
+ mLogger->NoteWeakMapEntry(0, (uint64_t)aKey, 0, (uint64_t)aVal);
+ }
+}
+
+static bool AddPurpleRoot(CCGraphBuilder& aBuilder, void* aRoot,
+ nsCycleCollectionParticipant* aParti) {
+ return aBuilder.AddPurpleRoot(aRoot, aParti);
+}
+
+// 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 CCGraphBuilder.
+ NS_IMETHOD_(void) NoteXPCOMChild(nsISupports* aChild) override;
+ NS_IMETHOD_(void)
+ NoteNativeChild(void* aChild, nsCycleCollectionParticipant* aHelper) override;
+ NS_IMETHOD_(void) NoteJSChild(JS::GCCellPtr aThing) override;
+
+ NS_IMETHOD_(void)
+ NoteWeakMapping(JSObject* aKey, nsISupports* aVal,
+ nsCycleCollectionParticipant* aValParticipant) override {}
+
+ NS_IMETHOD_(void)
+ DescribeRefCountedNode(nsrefcnt aRefcount, const char* aObjname) override {}
+ NS_IMETHOD_(void)
+ DescribeGCedNode(bool aIsMarked, const char* aObjname,
+ uint64_t aCompartmentAddress) override {}
+ NS_IMETHOD_(void) NoteNextEdgeName(const char* aName) override {}
+ bool MayHaveChild() { return mMayHaveChild; }
+
+ private:
+ bool mMayHaveChild;
+};
+
+NS_IMETHODIMP_(void)
+ChildFinder::NoteXPCOMChild(nsISupports* aChild) {
+ if (!aChild || !(aChild = CanonicalizeXPCOMParticipant(aChild))) {
+ return;
+ }
+ nsXPCOMCycleCollectionParticipant* cp;
+ ToParticipant(aChild, &cp);
+ if (cp && !cp->CanSkip(aChild, true)) {
+ mMayHaveChild = true;
+ }
+}
+
+NS_IMETHODIMP_(void)
+ChildFinder::NoteNativeChild(void* aChild,
+ nsCycleCollectionParticipant* aHelper) {
+ if (!aChild) {
+ return;
+ }
+ MOZ_ASSERT(aHelper, "Native child must have a participant");
+ if (!aHelper->CanSkip(aChild, true)) {
+ mMayHaveChild = true;
+ }
+}
+
+NS_IMETHODIMP_(void)
+ChildFinder::NoteJSChild(JS::GCCellPtr aChild) {
+ if (aChild && JS::GCThingIsMarkedGray(aChild)) {
+ mMayHaveChild = true;
+ }
+}
+
+static bool MayHaveChild(void* aObj, nsCycleCollectionParticipant* aCp) {
+ ChildFinder cf;
+ aCp->TraverseNativeAndJS(aObj, cf);
+ return cf.MayHaveChild();
+}
+
+// JSPurpleBuffer keeps references to GCThings which might affect the
+// next cycle collection. It is owned only by itself and during unlink its
+// self reference is broken down and the object ends up killing itself.
+// If GC happens before CC, references to GCthings and the self reference are
+// removed.
+class JSPurpleBuffer {
+ ~JSPurpleBuffer() {
+ MOZ_ASSERT(mValues.IsEmpty());
+ MOZ_ASSERT(mObjects.IsEmpty());
+ }
+
+ public:
+ explicit JSPurpleBuffer(RefPtr<JSPurpleBuffer>& aReferenceToThis)
+ : mReferenceToThis(aReferenceToThis),
+ mValues(kSegmentSize),
+ mObjects(kSegmentSize) {
+ mReferenceToThis = this;
+ mozilla::HoldJSObjects(this);
+ }
+
+ void Destroy() {
+ RefPtr<JSPurpleBuffer> referenceToThis;
+ mReferenceToThis.swap(referenceToThis);
+ mValues.Clear();
+ mObjects.Clear();
+ mozilla::DropJSObjects(this);
+ }
+
+ NS_INLINE_DECL_CYCLE_COLLECTING_NATIVE_REFCOUNTING(JSPurpleBuffer)
+ NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_NATIVE_CLASS(JSPurpleBuffer)
+
+ RefPtr<JSPurpleBuffer>& mReferenceToThis;
+
+ // These are raw pointers instead of Heap<T> because we only need Heap<T> for
+ // pointers which may point into the nursery. The purple buffer never contains
+ // pointers to the nursery because nursery gcthings can never be gray and only
+ // gray things can be inserted into the purple buffer.
+ static const size_t kSegmentSize = 512;
+ SegmentedVector<JS::Value, kSegmentSize, InfallibleAllocPolicy> mValues;
+ SegmentedVector<JSObject*, kSegmentSize, InfallibleAllocPolicy> mObjects;
+};
+
+NS_IMPL_CYCLE_COLLECTION_CLASS(JSPurpleBuffer)
+
+NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(JSPurpleBuffer)
+ tmp->Destroy();
+NS_IMPL_CYCLE_COLLECTION_UNLINK_END
+
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(JSPurpleBuffer)
+ CycleCollectionNoteChild(cb, tmp, "self");
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
+
+#define NS_TRACE_SEGMENTED_ARRAY(_field, _type) \
+ { \
+ for (auto iter = tmp->_field.Iter(); !iter.Done(); iter.Next()) { \
+ js::gc::CallTraceCallbackOnNonHeap<_type, TraceCallbacks>( \
+ &iter.Get(), aCallbacks, #_field, aClosure); \
+ } \
+ }
+
+NS_IMPL_CYCLE_COLLECTION_TRACE_BEGIN(JSPurpleBuffer)
+ NS_TRACE_SEGMENTED_ARRAY(mValues, JS::Value)
+ NS_TRACE_SEGMENTED_ARRAY(mObjects, JSObject*)
+NS_IMPL_CYCLE_COLLECTION_TRACE_END
+
+class SnowWhiteKiller : public TraceCallbacks {
+ struct SnowWhiteObject {
+ void* mPointer;
+ nsCycleCollectionParticipant* mParticipant;
+ nsCycleCollectingAutoRefCnt* mRefCnt;
+ };
+
+ // Segments are 4 KiB on 32-bit and 8 KiB on 64-bit.
+ static const size_t kSegmentSize = sizeof(void*) * 1024;
+ typedef SegmentedVector<SnowWhiteObject, kSegmentSize, InfallibleAllocPolicy>
+ ObjectsVector;
+
+ public:
+ SnowWhiteKiller(nsCycleCollector* aCollector, js::SliceBudget* aBudget)
+ : mCollector(aCollector),
+ mObjects(kSegmentSize),
+ mBudget(aBudget),
+ mSawSnowWhiteObjects(false) {
+ MOZ_ASSERT(mCollector, "Calling SnowWhiteKiller after nsCC went away");
+ }
+
+ explicit SnowWhiteKiller(nsCycleCollector* aCollector)
+ : SnowWhiteKiller(aCollector, nullptr) {}
+
+ ~SnowWhiteKiller() {
+ for (auto iter = mObjects.Iter(); !iter.Done(); iter.Next()) {
+ SnowWhiteObject& o = iter.Get();
+ MaybeKillObject(o);
+ }
+ }
+
+ private:
+ void MaybeKillObject(SnowWhiteObject& aObject) {
+ if (!aObject.mRefCnt->get() && !aObject.mRefCnt->IsInPurpleBuffer()) {
+ mCollector->RemoveObjectFromGraph(aObject.mPointer);
+ aObject.mRefCnt->stabilizeForDeletion();
+ {
+ JS::AutoEnterCycleCollection autocc(mCollector->Runtime()->Runtime());
+ aObject.mParticipant->Trace(aObject.mPointer, *this, nullptr);
+ }
+ aObject.mParticipant->DeleteCycleCollectable(aObject.mPointer);
+ }
+ }
+
+ public:
+ bool Visit(nsPurpleBuffer& aBuffer, nsPurpleBufferEntry* aEntry) {
+ if (mBudget) {
+ if (mBudget->isOverBudget()) {
+ return false;
+ }
+ mBudget->step();
+ }
+
+ MOZ_ASSERT(aEntry->mObject, "Null object in purple buffer");
+ if (!aEntry->mRefCnt->get()) {
+ mSawSnowWhiteObjects = true;
+ void* o = aEntry->mObject;
+ nsCycleCollectionParticipant* cp = aEntry->mParticipant;
+ ToParticipant(o, &cp);
+ SnowWhiteObject swo = {o, cp, aEntry->mRefCnt};
+ if (!mBudget) {
+ mObjects.InfallibleAppend(swo);
+ }
+ aBuffer.Remove(aEntry);
+ if (mBudget) {
+ MaybeKillObject(swo);
+ }
+ }
+ return true;
+ }
+
+ bool HasSnowWhiteObjects() const { return !mObjects.IsEmpty(); }
+
+ bool SawSnowWhiteObjects() const { return mSawSnowWhiteObjects; }
+
+ virtual void Trace(JS::Heap<JS::Value>* aValue, const char* aName,
+ void* aClosure) const override {
+ const JS::Value& val = aValue->unbarrieredGet();
+ if (val.isGCThing() && ValueIsGrayCCThing(val)) {
+ MOZ_ASSERT(!js::gc::IsInsideNursery(val.toGCThing()));
+ mCollector->GetJSPurpleBuffer()->mValues.InfallibleAppend(val);
+ }
+ }
+
+ virtual void Trace(JS::Heap<jsid>* aId, const char* aName,
+ void* aClosure) const override {}
+
+ void AppendJSObjectToPurpleBuffer(JSObject* obj) const {
+ if (obj && JS::ObjectIsMarkedGray(obj)) {
+ MOZ_ASSERT(JS::ObjectIsTenured(obj));
+ mCollector->GetJSPurpleBuffer()->mObjects.InfallibleAppend(obj);
+ }
+ }
+
+ virtual void Trace(JS::Heap<JSObject*>* aObject, const char* aName,
+ void* aClosure) const override {
+ AppendJSObjectToPurpleBuffer(aObject->unbarrieredGet());
+ }
+
+ virtual void Trace(nsWrapperCache* aWrapperCache, const char* aName,
+ void* aClosure) const override {
+ AppendJSObjectToPurpleBuffer(aWrapperCache->GetWrapperPreserveColor());
+ }
+
+ virtual void Trace(JS::TenuredHeap<JSObject*>* aObject, const char* aName,
+ void* aClosure) const override {
+ AppendJSObjectToPurpleBuffer(aObject->unbarrieredGetPtr());
+ }
+
+ virtual void Trace(JS::Heap<JSString*>* aString, const char* aName,
+ void* aClosure) const override {}
+
+ virtual void Trace(JS::Heap<JSScript*>* aScript, const char* aName,
+ void* aClosure) const override {}
+
+ virtual void Trace(JS::Heap<JSFunction*>* aFunction, const char* aName,
+ void* aClosure) const override {}
+
+ private:
+ RefPtr<nsCycleCollector> mCollector;
+ ObjectsVector mObjects;
+ js::SliceBudget* mBudget;
+ bool mSawSnowWhiteObjects;
+};
+
+class RemoveSkippableVisitor : public SnowWhiteKiller {
+ public:
+ RemoveSkippableVisitor(nsCycleCollector* aCollector, js::SliceBudget& aBudget,
+ bool aRemoveChildlessNodes,
+ bool aAsyncSnowWhiteFreeing,
+ CC_ForgetSkippableCallback aCb)
+ : SnowWhiteKiller(aCollector),
+ mBudget(aBudget),
+ mRemoveChildlessNodes(aRemoveChildlessNodes),
+ mAsyncSnowWhiteFreeing(aAsyncSnowWhiteFreeing),
+ mDispatchedDeferredDeletion(false),
+ mCallback(aCb) {}
+
+ ~RemoveSkippableVisitor() {
+ // Note, we must call the callback before SnowWhiteKiller calls
+ // DeleteCycleCollectable!
+ if (mCallback) {
+ mCallback();
+ }
+ if (HasSnowWhiteObjects()) {
+ // Effectively a continuation.
+ nsCycleCollector_dispatchDeferredDeletion(true);
+ }
+ }
+
+ bool Visit(nsPurpleBuffer& aBuffer, nsPurpleBufferEntry* aEntry) {
+ if (mBudget.isOverBudget()) {
+ return false;
+ }
+
+ // CanSkip calls can be a bit slow, so increase the likelihood that
+ // isOverBudget actually checks whether we're over the time budget.
+ mBudget.step(5);
+ MOZ_ASSERT(aEntry->mObject, "null mObject in purple buffer");
+ if (!aEntry->mRefCnt->get()) {
+ if (!mAsyncSnowWhiteFreeing) {
+ SnowWhiteKiller::Visit(aBuffer, aEntry);
+ } else if (!mDispatchedDeferredDeletion) {
+ mDispatchedDeferredDeletion = true;
+ nsCycleCollector_dispatchDeferredDeletion(false);
+ }
+ return true;
+ }
+ void* o = aEntry->mObject;
+ nsCycleCollectionParticipant* cp = aEntry->mParticipant;
+ ToParticipant(o, &cp);
+ if (aEntry->mRefCnt->IsPurple() && !cp->CanSkip(o, false) &&
+ (!mRemoveChildlessNodes || MayHaveChild(o, cp))) {
+ return true;
+ }
+ aBuffer.Remove(aEntry);
+ return true;
+ }
+
+ private:
+ js::SliceBudget& mBudget;
+ bool mRemoveChildlessNodes;
+ bool mAsyncSnowWhiteFreeing;
+ bool mDispatchedDeferredDeletion;
+ CC_ForgetSkippableCallback mCallback;
+};
+
+void nsPurpleBuffer::RemoveSkippable(nsCycleCollector* aCollector,
+ js::SliceBudget& aBudget,
+ bool aRemoveChildlessNodes,
+ bool aAsyncSnowWhiteFreeing,
+ CC_ForgetSkippableCallback aCb) {
+ RemoveSkippableVisitor visitor(aCollector, aBudget, aRemoveChildlessNodes,
+ aAsyncSnowWhiteFreeing, aCb);
+ VisitEntries(visitor);
+}
+
+bool nsCycleCollector::FreeSnowWhite(bool aUntilNoSWInPurpleBuffer) {
+ CheckThreadSafety();
+
+ if (mFreeingSnowWhite) {
+ return false;
+ }
+
+ AUTO_PROFILER_LABEL_CATEGORY_PAIR(GCCC_FreeSnowWhite);
+
+ AutoRestore<bool> ar(mFreeingSnowWhite);
+ mFreeingSnowWhite = true;
+
+ bool hadSnowWhiteObjects = false;
+ do {
+ SnowWhiteKiller visitor(this);
+ mPurpleBuf.VisitEntries(visitor);
+ hadSnowWhiteObjects = hadSnowWhiteObjects || visitor.HasSnowWhiteObjects();
+ if (!visitor.HasSnowWhiteObjects()) {
+ break;
+ }
+ } while (aUntilNoSWInPurpleBuffer);
+ return hadSnowWhiteObjects;
+}
+
+bool nsCycleCollector::FreeSnowWhiteWithBudget(js::SliceBudget& aBudget) {
+ CheckThreadSafety();
+
+ if (mFreeingSnowWhite) {
+ return false;
+ }
+
+ AUTO_PROFILER_LABEL_CATEGORY_PAIR(GCCC_FreeSnowWhite);
+ AutoRestore<bool> ar(mFreeingSnowWhite);
+ mFreeingSnowWhite = true;
+
+ SnowWhiteKiller visitor(this, &aBudget);
+ mPurpleBuf.VisitEntries(visitor);
+ return visitor.SawSnowWhiteObjects();
+ ;
+}
+
+void nsCycleCollector::ForgetSkippable(js::SliceBudget& aBudget,
+ bool aRemoveChildlessNodes,
+ bool aAsyncSnowWhiteFreeing) {
+ CheckThreadSafety();
+
+ if (mFreeingSnowWhite) {
+ return;
+ }
+
+ mozilla::Maybe<mozilla::AutoGlobalTimelineMarker> marker;
+ if (NS_IsMainThread()) {
+ marker.emplace("nsCycleCollector::ForgetSkippable",
+ MarkerStackRequest::NO_STACK);
+ }
+
+ // If we remove things from the purple buffer during graph building, we may
+ // lose track of an object that was mutated during graph building.
+ MOZ_ASSERT(IsIdle());
+
+ if (mCCJSRuntime) {
+ mCCJSRuntime->PrepareForForgetSkippable();
+ }
+ MOZ_ASSERT(
+ !mScanInProgress,
+ "Don't forget skippable or free snow-white while scan is in progress.");
+ mPurpleBuf.RemoveSkippable(this, aBudget, aRemoveChildlessNodes,
+ aAsyncSnowWhiteFreeing, mForgetSkippableCB);
+}
+
+MOZ_NEVER_INLINE void nsCycleCollector::MarkRoots(SliceBudget& aBudget) {
+ JS::AutoAssertNoGC nogc;
+ TimeLog timeLog;
+ AutoRestore<bool> ar(mScanInProgress);
+ MOZ_RELEASE_ASSERT(!mScanInProgress);
+ mScanInProgress = true;
+ MOZ_ASSERT(mIncrementalPhase == GraphBuildingPhase);
+
+ AUTO_PROFILER_LABEL_CATEGORY_PAIR(GCCC_BuildGraph);
+ JS::AutoEnterCycleCollection autocc(Runtime()->Runtime());
+ bool doneBuilding = mBuilder->BuildGraph(aBudget);
+
+ if (!doneBuilding) {
+ timeLog.Checkpoint("MarkRoots()");
+ return;
+ }
+
+ mBuilder = nullptr;
+ mIncrementalPhase = ScanAndCollectWhitePhase;
+ timeLog.Checkpoint("MarkRoots()");
+}
+
+////////////////////////////////////////////////////////////////////////
+// Bacon & Rajan's |ScanRoots| routine.
+////////////////////////////////////////////////////////////////////////
+
+struct ScanBlackVisitor {
+ ScanBlackVisitor(uint32_t& aWhiteNodeCount, bool& aFailed)
+ : mWhiteNodeCount(aWhiteNodeCount), mFailed(aFailed) {}
+
+ bool ShouldVisitNode(PtrInfo const* aPi) { return aPi->mColor != black; }
+
+ MOZ_NEVER_INLINE void VisitNode(PtrInfo* aPi) {
+ if (aPi->mColor == white) {
+ --mWhiteNodeCount;
+ }
+ aPi->mColor = black;
+ }
+
+ void Failed() { mFailed = true; }
+
+ private:
+ uint32_t& mWhiteNodeCount;
+ bool& mFailed;
+};
+
+static void FloodBlackNode(uint32_t& aWhiteNodeCount, bool& aFailed,
+ PtrInfo* aPi) {
+ GraphWalker<ScanBlackVisitor>(ScanBlackVisitor(aWhiteNodeCount, aFailed))
+ .Walk(aPi);
+ MOZ_ASSERT(aPi->mColor == black || !aPi->WasTraversed(),
+ "FloodBlackNode should make aPi black");
+}
+
+// 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;
+ bool failed = false;
+ do {
+ anyChanged = false;
+ for (uint32_t i = 0; i < mGraph.mWeakMaps.Length(); i++) {
+ WeakMapping* wm = &mGraph.mWeakMaps[i];
+
+ // If any of these are null, the original object was marked black.
+ uint32_t mColor = wm->mMap ? wm->mMap->mColor : black;
+ uint32_t kColor = wm->mKey ? wm->mKey->mColor : black;
+ uint32_t kdColor = wm->mKeyDelegate ? wm->mKeyDelegate->mColor : black;
+ uint32_t vColor = wm->mVal ? wm->mVal->mColor : black;
+
+ MOZ_ASSERT(mColor != grey, "Uncolored weak map");
+ MOZ_ASSERT(kColor != grey, "Uncolored weak map key");
+ MOZ_ASSERT(kdColor != grey, "Uncolored weak map key delegate");
+ MOZ_ASSERT(vColor != grey, "Uncolored weak map value");
+
+ if (mColor == black && kColor != black && kdColor == black) {
+ FloodBlackNode(mWhiteNodeCount, failed, wm->mKey);
+ anyChanged = true;
+ }
+
+ if (mColor == black && kColor == black && vColor != black) {
+ FloodBlackNode(mWhiteNodeCount, failed, wm->mVal);
+ anyChanged = true;
+ }
+ }
+ } while (anyChanged);
+
+ if (failed) {
+ MOZ_ASSERT(false, "Ran out of memory in ScanWeakMaps");
+ CC_TELEMETRY(_OOM, true);
+ }
+}
+
+// Flood black from any objects in the purple buffer that are in the CC graph.
+class PurpleScanBlackVisitor {
+ public:
+ PurpleScanBlackVisitor(CCGraph& aGraph, nsCycleCollectorLogger* aLogger,
+ uint32_t& aCount, bool& aFailed)
+ : mGraph(aGraph), mLogger(aLogger), mCount(aCount), mFailed(aFailed) {}
+
+ bool Visit(nsPurpleBuffer& aBuffer, nsPurpleBufferEntry* aEntry) {
+ MOZ_ASSERT(aEntry->mObject,
+ "Entries with null mObject shouldn't be in the purple buffer.");
+ MOZ_ASSERT(aEntry->mRefCnt->get() != 0,
+ "Snow-white objects shouldn't be in the purple buffer.");
+
+ void* obj = aEntry->mObject;
+
+ MOZ_ASSERT(
+ aEntry->mParticipant ||
+ CanonicalizeXPCOMParticipant(static_cast<nsISupports*>(obj)) == obj,
+ "Suspect nsISupports pointer must be canonical");
+
+ PtrInfo* pi = mGraph.FindNode(obj);
+ if (!pi) {
+ return true;
+ }
+ MOZ_ASSERT(pi->mParticipant,
+ "No dead objects should be in the purple buffer.");
+ if (MOZ_UNLIKELY(mLogger)) {
+ mLogger->NoteIncrementalRoot((uint64_t)pi->mPointer);
+ }
+ if (pi->mColor == black) {
+ return true;
+ }
+ FloodBlackNode(mCount, mFailed, pi);
+ return true;
+ }
+
+ private:
+ CCGraph& mGraph;
+ RefPtr<nsCycleCollectorLogger> mLogger;
+ uint32_t& mCount;
+ bool& mFailed;
+};
+
+// Objects that have been stored somewhere since the start of incremental graph
+// building must be treated as live for this cycle collection, because we may
+// not have accurate information about who holds references to them.
+void nsCycleCollector::ScanIncrementalRoots() {
+ TimeLog timeLog;
+
+ // Reference counted objects:
+ // We cleared the purple buffer at the start of the current ICC, so if a
+ // refcounted object is purple, it may have been AddRef'd during the current
+ // ICC. (It may also have only been released.) If that is the case, we cannot
+ // be sure that the set of things pointing to the object in the CC graph
+ // is accurate. Therefore, for safety, we treat any purple objects as being
+ // live during the current CC. We don't remove anything from the purple
+ // buffer here, so these objects will be suspected and freed in the next CC
+ // if they are garbage.
+ bool failed = false;
+ PurpleScanBlackVisitor purpleScanBlackVisitor(mGraph, mLogger,
+ mWhiteNodeCount, failed);
+ mPurpleBuf.VisitEntries(purpleScanBlackVisitor);
+ timeLog.Checkpoint("ScanIncrementalRoots::fix purple");
+
+ bool hasJSRuntime = !!mCCJSRuntime;
+ nsCycleCollectionParticipant* jsParticipant =
+ hasJSRuntime ? mCCJSRuntime->GCThingParticipant() : nullptr;
+ nsCycleCollectionParticipant* zoneParticipant =
+ hasJSRuntime ? mCCJSRuntime->ZoneParticipant() : nullptr;
+ bool hasLogger = !!mLogger;
+
+ NodePool::Enumerator etor(mGraph.mNodes);
+ while (!etor.IsDone()) {
+ PtrInfo* pi = etor.GetNext();
+
+ // As an optimization, if an object has already been determined to be live,
+ // don't consider it further. We can't do this if there is a listener,
+ // because the listener wants to know the complete set of incremental roots.
+ if (pi->mColor == black && MOZ_LIKELY(!hasLogger)) {
+ continue;
+ }
+
+ // Garbage collected objects:
+ // If a GCed object was added to the graph with a refcount of zero, and is
+ // now marked black by the GC, it was probably gray before and was exposed
+ // to active JS, so it may have been stored somewhere, so it needs to be
+ // treated as live.
+ if (pi->IsGrayJS() && MOZ_LIKELY(hasJSRuntime)) {
+ // If the object is still marked gray by the GC, nothing could have gotten
+ // hold of it, so it isn't an incremental root.
+ if (pi->mParticipant == jsParticipant) {
+ JS::GCCellPtr ptr(pi->mPointer, JS::GCThingTraceKind(pi->mPointer));
+ if (GCThingIsGrayCCThing(ptr)) {
+ continue;
+ }
+ } else if (pi->mParticipant == zoneParticipant) {
+ JS::Zone* zone = static_cast<JS::Zone*>(pi->mPointer);
+ if (js::ZoneGlobalsAreAllGray(zone)) {
+ continue;
+ }
+ } else {
+ MOZ_ASSERT(false, "Non-JS thing with 0 refcount? Treating as live.");
+ }
+ } else if (!pi->mParticipant && pi->WasTraversed()) {
+ // Dead traversed refcounted objects:
+ // If the object was traversed, it must have been alive at the start of
+ // the CC, and thus had a positive refcount. It is dead now, so its
+ // refcount must have decreased at some point during the CC. Therefore,
+ // it would be in the purple buffer if it wasn't dead, so treat it as an
+ // incremental root.
+ //
+ // This should not cause leaks because as the object died it should have
+ // released anything it held onto, which will add them to the purple
+ // buffer, which will cause them to be considered in the next CC.
+ } else {
+ continue;
+ }
+
+ // At this point, pi must be an incremental root.
+
+ // If there's a listener, tell it about this root. We don't bother with the
+ // optimization of skipping the Walk() if pi is black: it will just return
+ // without doing anything and there's no need to make this case faster.
+ if (MOZ_UNLIKELY(hasLogger) && pi->mPointer) {
+ // Dead objects aren't logged. See bug 1031370.
+ mLogger->NoteIncrementalRoot((uint64_t)pi->mPointer);
+ }
+
+ FloodBlackNode(mWhiteNodeCount, failed, pi);
+ }
+
+ timeLog.Checkpoint("ScanIncrementalRoots::fix nodes");
+
+ if (failed) {
+ NS_ASSERTION(false, "Ran out of memory in ScanIncrementalRoots");
+ CC_TELEMETRY(_OOM, true);
+ }
+}
+
+// Mark nodes white and make sure their refcounts are ok.
+// No nodes are marked black during this pass to ensure that refcount
+// checking is run on all nodes not marked black by ScanIncrementalRoots.
+void nsCycleCollector::ScanWhiteNodes(bool aFullySynchGraphBuild) {
+ NodePool::Enumerator nodeEnum(mGraph.mNodes);
+ while (!nodeEnum.IsDone()) {
+ PtrInfo* pi = nodeEnum.GetNext();
+ if (pi->mColor == black) {
+ // Incremental roots can be in a nonsensical state, so don't
+ // check them. This will miss checking nodes that are merely
+ // reachable from incremental roots.
+ MOZ_ASSERT(!aFullySynchGraphBuild,
+ "In a synch CC, no nodes should be marked black early on.");
+ continue;
+ }
+ MOZ_ASSERT(pi->mColor == grey);
+
+ if (!pi->WasTraversed()) {
+ // This node was deleted before it was traversed, so there's no reason
+ // to look at it.
+ MOZ_ASSERT(!pi->mParticipant,
+ "Live nodes should all have been traversed");
+ continue;
+ }
+
+ if (pi->mInternalRefs == pi->mRefCount || pi->IsGrayJS()) {
+ pi->mColor = white;
+ ++mWhiteNodeCount;
+ continue;
+ }
+
+ pi->AnnotatedReleaseAssert(
+ pi->mInternalRefs <= pi->mRefCount,
+ "More references to an object than its refcount");
+
+ // This node will get marked black in the next pass.
+ }
+}
+
+// Any remaining grey nodes that haven't already been deleted must be alive,
+// so mark them and their children black. Any nodes that are black must have
+// already had their children marked black, so there's no need to look at them
+// again. This pass may turn some white nodes to black.
+void nsCycleCollector::ScanBlackNodes() {
+ bool failed = false;
+ NodePool::Enumerator nodeEnum(mGraph.mNodes);
+ while (!nodeEnum.IsDone()) {
+ PtrInfo* pi = nodeEnum.GetNext();
+ if (pi->mColor == grey && pi->WasTraversed()) {
+ FloodBlackNode(mWhiteNodeCount, failed, pi);
+ }
+ }
+
+ if (failed) {
+ NS_ASSERTION(false, "Ran out of memory in ScanBlackNodes");
+ CC_TELEMETRY(_OOM, true);
+ }
+}
+
+void nsCycleCollector::ScanRoots(bool aFullySynchGraphBuild) {
+ JS::AutoAssertNoGC nogc;
+ AutoRestore<bool> ar(mScanInProgress);
+ MOZ_RELEASE_ASSERT(!mScanInProgress);
+ mScanInProgress = true;
+ mWhiteNodeCount = 0;
+ MOZ_ASSERT(mIncrementalPhase == ScanAndCollectWhitePhase);
+
+ JS::AutoEnterCycleCollection autocc(Runtime()->Runtime());
+
+ if (!aFullySynchGraphBuild) {
+ ScanIncrementalRoots();
+ }
+
+ TimeLog timeLog;
+ ScanWhiteNodes(aFullySynchGraphBuild);
+ timeLog.Checkpoint("ScanRoots::ScanWhiteNodes");
+
+ ScanBlackNodes();
+ timeLog.Checkpoint("ScanRoots::ScanBlackNodes");
+
+ // Scanning weak maps must be done last.
+ ScanWeakMaps();
+ timeLog.Checkpoint("ScanRoots::ScanWeakMaps");
+
+ if (mLogger) {
+ mLogger->BeginResults();
+
+ NodePool::Enumerator etor(mGraph.mNodes);
+ while (!etor.IsDone()) {
+ PtrInfo* pi = etor.GetNext();
+ if (!pi->WasTraversed()) {
+ continue;
+ }
+ switch (pi->mColor) {
+ case black:
+ if (!pi->IsGrayJS() && !pi->IsBlackJS() &&
+ pi->mInternalRefs != pi->mRefCount) {
+ mLogger->DescribeRoot((uint64_t)pi->mPointer, pi->mInternalRefs);
+ }
+ break;
+ case white:
+ mLogger->DescribeGarbage((uint64_t)pi->mPointer);
+ break;
+ case grey:
+ MOZ_ASSERT(false, "All traversed objects should be black or white");
+ break;
+ }
+ }
+
+ mLogger->End();
+ mLogger = nullptr;
+ timeLog.Checkpoint("ScanRoots::listener");
+ }
+}
+
+////////////////////////////////////////////////////////////////////////
+// Bacon & Rajan's |CollectWhite| routine, somewhat modified.
+////////////////////////////////////////////////////////////////////////
+
+bool nsCycleCollector::CollectWhite() {
+ // 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.
+
+ // Segments are 4 KiB on 32-bit and 8 KiB on 64-bit.
+ static const size_t kSegmentSize = sizeof(void*) * 1024;
+ SegmentedVector<PtrInfo*, kSegmentSize, InfallibleAllocPolicy> whiteNodes(
+ kSegmentSize);
+ TimeLog timeLog;
+
+ MOZ_ASSERT(mIncrementalPhase == ScanAndCollectWhitePhase);
+
+ uint32_t numWhiteNodes = 0;
+ uint32_t numWhiteGCed = 0;
+ uint32_t numWhiteJSZones = 0;
+
+ {
+ JS::AutoAssertNoGC nogc;
+ bool hasJSRuntime = !!mCCJSRuntime;
+ nsCycleCollectionParticipant* zoneParticipant =
+ hasJSRuntime ? mCCJSRuntime->ZoneParticipant() : nullptr;
+
+ NodePool::Enumerator etor(mGraph.mNodes);
+ while (!etor.IsDone()) {
+ PtrInfo* pinfo = etor.GetNext();
+ if (pinfo->mColor == white && pinfo->mParticipant) {
+ if (pinfo->IsGrayJS()) {
+ MOZ_ASSERT(mCCJSRuntime);
+ ++numWhiteGCed;
+ JS::Zone* zone;
+ if (MOZ_UNLIKELY(pinfo->mParticipant == zoneParticipant)) {
+ ++numWhiteJSZones;
+ zone = static_cast<JS::Zone*>(pinfo->mPointer);
+ } else {
+ JS::GCCellPtr ptr(pinfo->mPointer,
+ JS::GCThingTraceKind(pinfo->mPointer));
+ zone = JS::GetTenuredGCThingZone(ptr);
+ }
+ mCCJSRuntime->AddZoneWaitingForGC(zone);
+ } else {
+ whiteNodes.InfallibleAppend(pinfo);
+ pinfo->mParticipant->Root(pinfo->mPointer);
+ ++numWhiteNodes;
+ }
+ }
+ }
+ }
+
+ mResults.mFreedRefCounted += numWhiteNodes;
+ mResults.mFreedGCed += numWhiteGCed;
+ mResults.mFreedJSZones += numWhiteJSZones;
+
+ timeLog.Checkpoint("CollectWhite::Root");
+
+ if (mBeforeUnlinkCB) {
+ mBeforeUnlinkCB();
+ timeLog.Checkpoint("CollectWhite::BeforeUnlinkCB");
+ }
+
+ // Unlink() can trigger a GC, so do not touch any JS or anything
+ // else not in whiteNodes after here.
+
+ for (auto iter = whiteNodes.Iter(); !iter.Done(); iter.Next()) {
+ PtrInfo* pinfo = iter.Get();
+ MOZ_ASSERT(pinfo->mParticipant,
+ "Unlink shouldn't see objects removed from graph.");
+ pinfo->mParticipant->Unlink(pinfo->mPointer);
+#ifdef DEBUG
+ if (mCCJSRuntime) {
+ mCCJSRuntime->AssertNoObjectsToTrace(pinfo->mPointer);
+ }
+#endif
+ }
+ timeLog.Checkpoint("CollectWhite::Unlink");
+
+ JS::AutoAssertNoGC nogc;
+ for (auto iter = whiteNodes.Iter(); !iter.Done(); iter.Next()) {
+ PtrInfo* pinfo = iter.Get();
+ MOZ_ASSERT(pinfo->mParticipant,
+ "Unroot shouldn't see objects removed from graph.");
+ pinfo->mParticipant->Unroot(pinfo->mPointer);
+ }
+ timeLog.Checkpoint("CollectWhite::Unroot");
+
+ nsCycleCollector_dispatchDeferredDeletion(false, true);
+ timeLog.Checkpoint("CollectWhite::dispatchDeferredDeletion");
+
+ mIncrementalPhase = CleanupPhase;
+
+ return numWhiteNodes > 0 || numWhiteGCed > 0 || numWhiteJSZones > 0;
+}
+
+////////////////////////
+// Memory reporting
+////////////////////////
+
+MOZ_DEFINE_MALLOC_SIZE_OF(CycleCollectorMallocSizeOf)
+
+NS_IMETHODIMP
+nsCycleCollector::CollectReports(nsIHandleReportCallback* aHandleReport,
+ nsISupports* aData, bool aAnonymize) {
+ size_t objectSize, graphSize, purpleBufferSize;
+ SizeOfIncludingThis(CycleCollectorMallocSizeOf, &objectSize, &graphSize,
+ &purpleBufferSize);
+
+ if (objectSize > 0) {
+ MOZ_COLLECT_REPORT("explicit/cycle-collector/collector-object", KIND_HEAP,
+ UNITS_BYTES, objectSize,
+ "Memory used for the cycle collector object itself.");
+ }
+
+ if (graphSize > 0) {
+ MOZ_COLLECT_REPORT(
+ "explicit/cycle-collector/graph", KIND_HEAP, UNITS_BYTES, graphSize,
+ "Memory used for the cycle collector's graph. This should be zero when "
+ "the collector is idle.");
+ }
+
+ if (purpleBufferSize > 0) {
+ MOZ_COLLECT_REPORT("explicit/cycle-collector/purple-buffer", KIND_HEAP,
+ UNITS_BYTES, purpleBufferSize,
+ "Memory used for the cycle collector's purple buffer.");
+ }
+
+ return NS_OK;
+};
+
+////////////////////////////////////////////////////////////////////////
+// Collector implementation
+////////////////////////////////////////////////////////////////////////
+
+nsCycleCollector::nsCycleCollector()
+ : mActivelyCollecting(false),
+ mFreeingSnowWhite(false),
+ mScanInProgress(false),
+ mCCJSRuntime(nullptr),
+ mIncrementalPhase(IdlePhase),
+#ifdef DEBUG
+ mEventTarget(GetCurrentSerialEventTarget()),
+#endif
+ mWhiteNodeCount(0),
+ mBeforeUnlinkCB(nullptr),
+ mForgetSkippableCB(nullptr),
+ mUnmergedNeeded(0),
+ mMergedInARow(0) {
+}
+
+nsCycleCollector::~nsCycleCollector() {
+ MOZ_ASSERT(!mJSPurpleBuffer, "Didn't call JSPurpleBuffer::Destroy?");
+
+ UnregisterWeakMemoryReporter(this);
+}
+
+void nsCycleCollector::SetCCJSRuntime(CycleCollectedJSRuntime* aCCRuntime) {
+ MOZ_RELEASE_ASSERT(
+ !mCCJSRuntime,
+ "Multiple registrations of CycleCollectedJSRuntime in cycle collector");
+ mCCJSRuntime = aCCRuntime;
+
+ if (!NS_IsMainThread()) {
+ return;
+ }
+
+ // We can't register as a reporter in nsCycleCollector() because that runs
+ // before the memory reporter manager is initialized. So we do it here
+ // instead.
+ RegisterWeakMemoryReporter(this);
+}
+
+void nsCycleCollector::ClearCCJSRuntime() {
+ MOZ_RELEASE_ASSERT(mCCJSRuntime,
+ "Clearing CycleCollectedJSRuntime in cycle collector "
+ "before a runtime was registered");
+ mCCJSRuntime = nullptr;
+}
+
+#ifdef DEBUG
+static bool HasParticipant(void* aPtr, nsCycleCollectionParticipant* aParti) {
+ if (aParti) {
+ return true;
+ }
+
+ nsXPCOMCycleCollectionParticipant* xcp;
+ ToParticipant(static_cast<nsISupports*>(aPtr), &xcp);
+ return xcp != nullptr;
+}
+#endif
+
+MOZ_ALWAYS_INLINE void nsCycleCollector::Suspect(
+ void* aPtr, nsCycleCollectionParticipant* aParti,
+ nsCycleCollectingAutoRefCnt* aRefCnt) {
+ CheckThreadSafety();
+
+ // Don't call AddRef or Release of a CCed object in a Traverse() method.
+ MOZ_ASSERT(!mScanInProgress,
+ "Attempted to call Suspect() while a scan was in progress");
+
+ if (MOZ_UNLIKELY(mScanInProgress)) {
+ return;
+ }
+
+ MOZ_ASSERT(aPtr, "Don't suspect null pointers");
+
+ MOZ_ASSERT(HasParticipant(aPtr, aParti),
+ "Suspected nsISupports pointer must QI to "
+ "nsXPCOMCycleCollectionParticipant");
+
+ MOZ_ASSERT(aParti || CanonicalizeXPCOMParticipant(
+ static_cast<nsISupports*>(aPtr)) == aPtr,
+ "Suspect nsISupports pointer must be canonical");
+
+ mPurpleBuf.Put(aPtr, aParti, aRefCnt);
+}
+
+void nsCycleCollector::SuspectNurseryEntries() {
+ MOZ_ASSERT(NS_IsMainThread(), "Wrong thread!");
+ while (gNurseryPurpleBufferEntryCount) {
+ NurseryPurpleBufferEntry& entry =
+ gNurseryPurpleBufferEntry[--gNurseryPurpleBufferEntryCount];
+ mPurpleBuf.Put(entry.mPtr, entry.mParticipant, entry.mRefCnt);
+ }
+}
+
+void nsCycleCollector::CheckThreadSafety() {
+#ifdef DEBUG
+ MOZ_ASSERT(mEventTarget->IsOnCurrentThread());
+#endif
+}
+
+// The cycle collector uses the mark bitmap to discover what JS objects are
+// 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 should only
+// be true when UnmarkGray has run out of stack. We also force GCs on shutdown
+// to collect cycles involving both DOM and JS, and in WantAllTraces CCs to
+// prevent hijinks from ForgetSkippable and compartmental GCs.
+void nsCycleCollector::FixGrayBits(bool aIsShutdown, TimeLog& aTimeLog) {
+ CheckThreadSafety();
+
+ if (!mCCJSRuntime) {
+ return;
+ }
+
+ // If we're not forcing a GC anyways due to shutdown or an all traces CC,
+ // check to see if we still need to do one to fix the gray bits.
+ if (!(aIsShutdown || (mLogger && mLogger->IsAllTraces()))) {
+ mCCJSRuntime->FixWeakMappingGrayBits();
+ aTimeLog.Checkpoint("FixWeakMappingGrayBits");
+
+ bool needGC = !mCCJSRuntime->AreGCGrayBitsValid();
+ // Only do a telemetry ping for non-shutdown CCs.
+ CC_TELEMETRY(_NEED_GC, needGC);
+ if (!needGC) {
+ return;
+ }
+ }
+
+ mResults.mForcedGC = true;
+
+ uint32_t count = 0;
+ do {
+ if (aIsShutdown) {
+ mCCJSRuntime->GarbageCollect(JS::GCOptions::Shutdown,
+ JS::GCReason::SHUTDOWN_CC);
+ } else {
+ mCCJSRuntime->GarbageCollect(JS::GCOptions::Normal,
+ JS::GCReason::CC_FORCED);
+ }
+
+ mCCJSRuntime->FixWeakMappingGrayBits();
+
+ // It's possible that FixWeakMappingGrayBits will hit OOM when unmarking
+ // gray and we will have to go round again. The second time there should not
+ // be any weak mappings to fix up so the loop body should run at most twice.
+ MOZ_RELEASE_ASSERT(count < 2);
+ count++;
+ } while (!mCCJSRuntime->AreGCGrayBitsValid());
+
+ aTimeLog.Checkpoint("FixGrayBits");
+}
+
+bool nsCycleCollector::IsIncrementalGCInProgress() {
+ return mCCJSRuntime && JS::IsIncrementalGCInProgress(mCCJSRuntime->Runtime());
+}
+
+void nsCycleCollector::FinishAnyIncrementalGCInProgress() {
+ if (IsIncrementalGCInProgress()) {
+ NS_WARNING("Finishing incremental GC in progress during CC");
+ JSContext* cx = CycleCollectedJSContext::Get()->Context();
+ JS::PrepareForIncrementalGC(cx);
+ JS::FinishIncrementalGC(cx, JS::GCReason::CC_FORCED);
+ }
+}
+
+void nsCycleCollector::CleanupAfterCollection() {
+ TimeLog timeLog;
+ MOZ_ASSERT(mIncrementalPhase == CleanupPhase);
+ MOZ_RELEASE_ASSERT(!mScanInProgress);
+ mGraph.Clear();
+ timeLog.Checkpoint("CleanupAfterCollection::mGraph.Clear()");
+
+ uint32_t interval =
+ (uint32_t)((TimeStamp::Now() - mCollectionStart).ToMilliseconds());
+#ifdef COLLECT_TIME_DEBUG
+ printf("cc: total cycle collector time was %ums in %u slices\n", interval,
+ mResults.mNumSlices);
+ printf(
+ "cc: visited %u ref counted and %u GCed objects, freed %d ref counted "
+ "and %d GCed objects",
+ mResults.mVisitedRefCounted, mResults.mVisitedGCed,
+ mResults.mFreedRefCounted, mResults.mFreedGCed);
+ uint32_t numVisited = mResults.mVisitedRefCounted + mResults.mVisitedGCed;
+ if (numVisited > 1000) {
+ uint32_t numFreed = mResults.mFreedRefCounted + mResults.mFreedGCed;
+ printf(" (%d%%)", 100 * numFreed / numVisited);
+ }
+ printf(".\ncc: \n");
+#endif
+
+ CC_TELEMETRY(, interval);
+ CC_TELEMETRY(_VISITED_REF_COUNTED, mResults.mVisitedRefCounted);
+ CC_TELEMETRY(_VISITED_GCED, mResults.mVisitedGCed);
+ CC_TELEMETRY(_COLLECTED, mWhiteNodeCount);
+ timeLog.Checkpoint("CleanupAfterCollection::telemetry");
+
+ if (mCCJSRuntime) {
+ mCCJSRuntime->FinalizeDeferredThings(
+ mResults.mAnyManual ? CycleCollectedJSRuntime::FinalizeNow
+ : CycleCollectedJSRuntime::FinalizeIncrementally);
+ mCCJSRuntime->EndCycleCollectionCallback(mResults);
+ timeLog.Checkpoint("CleanupAfterCollection::EndCycleCollectionCallback()");
+ }
+ mIncrementalPhase = IdlePhase;
+}
+
+void nsCycleCollector::ShutdownCollect() {
+ FinishAnyIncrementalGCInProgress();
+ CycleCollectedJSContext* ccJSContext = CycleCollectedJSContext::Get();
+ JS::ShutdownAsyncTasks(ccJSContext->Context());
+
+ SliceBudget unlimitedBudget = SliceBudget::unlimited();
+ uint32_t i;
+ bool collectedAny = true;
+ for (i = 0; i < DEFAULT_SHUTDOWN_COLLECTIONS && collectedAny; ++i) {
+ collectedAny = Collect(CCReason::SHUTDOWN, ccIsManual::CCIsManual,
+ unlimitedBudget, nullptr);
+ // Run any remaining tasks that may have been enqueued via RunInStableState
+ // or DispatchToMicroTask. These can hold alive CCed objects, and we want to
+ // clear them out before we run the CC again or finish shutting down.
+ ccJSContext->PerformMicroTaskCheckPoint(true);
+ ccJSContext->ProcessStableStateQueue();
+ }
+ NS_WARNING_ASSERTION(i < NORMAL_SHUTDOWN_COLLECTIONS, "Extra shutdown CC");
+}
+
+static void PrintPhase(const char* aPhase) {
+#ifdef DEBUG_PHASES
+ printf("cc: begin %s on %s\n", aPhase,
+ NS_IsMainThread() ? "mainthread" : "worker");
+#endif
+}
+
+bool nsCycleCollector::Collect(CCReason aReason, ccIsManual aIsManual,
+ SliceBudget& aBudget,
+ nsICycleCollectorListener* aManualListener,
+ bool aPreferShorterSlices) {
+ AUTO_PROFILER_LABEL_RELEVANT_FOR_JS("Incremental CC", GCCC);
+
+ CheckThreadSafety();
+
+ // This can legitimately happen in a few cases. See bug 383651.
+ if (mActivelyCollecting || mFreeingSnowWhite) {
+ return false;
+ }
+ mActivelyCollecting = true;
+
+ MOZ_ASSERT(!IsIncrementalGCInProgress());
+
+ mozilla::Maybe<mozilla::AutoGlobalTimelineMarker> marker;
+ if (NS_IsMainThread()) {
+ marker.emplace("nsCycleCollector::Collect", MarkerStackRequest::NO_STACK);
+ }
+
+ bool startedIdle = IsIdle();
+ bool collectedAny = false;
+
+ // If the CC started idle, it will call BeginCollection, which
+ // will do FreeSnowWhite, so it doesn't need to be done here.
+ if (!startedIdle) {
+ TimeLog timeLog;
+ FreeSnowWhite(true);
+ timeLog.Checkpoint("Collect::FreeSnowWhite");
+ }
+
+ if (aIsManual == ccIsManual::CCIsManual) {
+ mResults.mAnyManual = true;
+ }
+
+ ++mResults.mNumSlices;
+
+ bool continueSlice = aBudget.isUnlimited() || !aPreferShorterSlices;
+ do {
+ switch (mIncrementalPhase) {
+ case IdlePhase:
+ PrintPhase("BeginCollection");
+ BeginCollection(aReason, aIsManual, aManualListener);
+ break;
+ case GraphBuildingPhase:
+ PrintPhase("MarkRoots");
+ MarkRoots(aBudget);
+
+ // Only continue this slice if we're running synchronously or the
+ // next phase will probably be short, to reduce the max pause for this
+ // collection.
+ // (There's no need to check if we've finished graph building, because
+ // if we haven't, we've already exceeded our budget, and will finish
+ // this slice anyways.)
+ continueSlice = aBudget.isUnlimited() ||
+ (mResults.mNumSlices < 3 && !aPreferShorterSlices);
+ break;
+ case ScanAndCollectWhitePhase:
+ // We do ScanRoots and CollectWhite in a single slice to ensure
+ // that we won't unlink a live object if a weak reference is
+ // promoted to a strong reference after ScanRoots has finished.
+ // See bug 926533.
+ {
+ AUTO_PROFILER_LABEL_CATEGORY_PAIR(GCCC_ScanRoots);
+ PrintPhase("ScanRoots");
+ ScanRoots(startedIdle);
+ }
+ {
+ AUTO_PROFILER_LABEL_CATEGORY_PAIR(GCCC_CollectWhite);
+ PrintPhase("CollectWhite");
+ collectedAny = CollectWhite();
+ }
+ break;
+ case CleanupPhase:
+ PrintPhase("CleanupAfterCollection");
+ CleanupAfterCollection();
+ continueSlice = false;
+ break;
+ }
+ if (continueSlice) {
+ aBudget.stepAndForceCheck();
+ continueSlice = !aBudget.isOverBudget();
+ }
+ } while (continueSlice);
+
+ // Clear mActivelyCollecting here to ensure that a recursive call to
+ // Collect() does something.
+ mActivelyCollecting = false;
+
+ if (aIsManual && !startedIdle) {
+ // We were in the middle of an incremental CC (using its own listener).
+ // Somebody has forced a CC, so after having finished out the current CC,
+ // run the CC again using the new listener.
+ MOZ_ASSERT(IsIdle());
+ if (Collect(aReason, ccIsManual::CCIsManual, aBudget, aManualListener)) {
+ collectedAny = true;
+ }
+ }
+
+ MOZ_ASSERT_IF(aIsManual == CCIsManual, IsIdle());
+
+ return collectedAny;
+}
+
+// Any JS objects we have in the graph could die when we GC, but we
+// don't want to abandon the current CC, because the graph contains
+// information about purple roots. So we synchronously finish off
+// the current CC.
+void nsCycleCollector::PrepareForGarbageCollection() {
+ if (IsIdle()) {
+ MOZ_ASSERT(mGraph.IsEmpty(), "Non-empty graph when idle");
+ MOZ_ASSERT(!mBuilder, "Non-null builder when idle");
+ if (mJSPurpleBuffer) {
+ mJSPurpleBuffer->Destroy();
+ }
+ return;
+ }
+
+ FinishAnyCurrentCollection(CCReason::GC_WAITING);
+}
+
+void nsCycleCollector::FinishAnyCurrentCollection(CCReason aReason) {
+ if (IsIdle()) {
+ return;
+ }
+
+ SliceBudget unlimitedBudget = SliceBudget::unlimited();
+ PrintPhase("FinishAnyCurrentCollection");
+ // Use CCIsNotManual because we only want to finish the CC in progress.
+ Collect(aReason, ccIsManual::CCIsNotManual, unlimitedBudget, nullptr);
+
+ // It is only okay for Collect() to have failed to finish the
+ // current CC if we're reentering the CC at some point past
+ // graph building. We need to be past the point where the CC will
+ // look at JS objects so that it is safe to GC.
+ MOZ_ASSERT(IsIdle() || (mActivelyCollecting &&
+ mIncrementalPhase != GraphBuildingPhase),
+ "Reentered CC during graph building");
+}
+
+// Don't merge too many times in a row, and do at least a minimum
+// number of unmerged CCs in a row.
+static const uint32_t kMinConsecutiveUnmerged = 3;
+static const uint32_t kMaxConsecutiveMerged = 3;
+
+bool nsCycleCollector::ShouldMergeZones(ccIsManual aIsManual) {
+ if (!mCCJSRuntime) {
+ return false;
+ }
+
+ MOZ_ASSERT(mUnmergedNeeded <= kMinConsecutiveUnmerged);
+ MOZ_ASSERT(mMergedInARow <= kMaxConsecutiveMerged);
+
+ if (mMergedInARow == kMaxConsecutiveMerged) {
+ MOZ_ASSERT(mUnmergedNeeded == 0);
+ mUnmergedNeeded = kMinConsecutiveUnmerged;
+ }
+
+ if (mUnmergedNeeded > 0) {
+ mUnmergedNeeded--;
+ mMergedInARow = 0;
+ return false;
+ }
+
+ if (aIsManual == CCIsNotManual && mCCJSRuntime->UsefulToMergeZones()) {
+ mMergedInARow++;
+ return true;
+ } else {
+ mMergedInARow = 0;
+ return false;
+ }
+}
+
+void nsCycleCollector::BeginCollection(
+ CCReason aReason, ccIsManual aIsManual,
+ nsICycleCollectorListener* aManualListener) {
+ TimeLog timeLog;
+ MOZ_ASSERT(IsIdle());
+ MOZ_RELEASE_ASSERT(!mScanInProgress);
+
+ mCollectionStart = TimeStamp::Now();
+
+ if (mCCJSRuntime) {
+ mCCJSRuntime->BeginCycleCollectionCallback(aReason);
+ timeLog.Checkpoint("BeginCycleCollectionCallback()");
+ }
+
+ bool isShutdown = (aReason == CCReason::SHUTDOWN);
+ if (isShutdown) {
+ mShutdownCount += 1;
+ }
+
+ // Set up the listener for this CC.
+ MOZ_ASSERT_IF(isShutdown, !aManualListener);
+ MOZ_ASSERT(!mLogger, "Forgot to clear a previous listener?");
+
+ if (aManualListener) {
+ aManualListener->AsLogger(getter_AddRefs(mLogger));
+ }
+
+ aManualListener = nullptr;
+ if (!mLogger && mParams.LogThisCC(mShutdownCount)) {
+ mLogger = new nsCycleCollectorLogger();
+ if (mParams.AllTracesThisCC(isShutdown)) {
+ mLogger->SetAllTraces();
+ }
+ }
+
+ // BeginCycleCollectionCallback() might have started an IGC, and we need
+ // to finish it before we run FixGrayBits.
+ FinishAnyIncrementalGCInProgress();
+ timeLog.Checkpoint("Pre-FixGrayBits finish IGC");
+
+ FixGrayBits(isShutdown, timeLog);
+ if (mCCJSRuntime) {
+ mCCJSRuntime->CheckGrayBits();
+ }
+
+ FreeSnowWhite(true);
+ timeLog.Checkpoint("BeginCollection FreeSnowWhite");
+
+ if (mLogger && NS_FAILED(mLogger->Begin())) {
+ mLogger = nullptr;
+ }
+
+ // FreeSnowWhite could potentially have started an IGC, which we need
+ // to finish before we look at any JS roots.
+ FinishAnyIncrementalGCInProgress();
+ timeLog.Checkpoint("Post-FreeSnowWhite finish IGC");
+
+ // Set up the data structures for building the graph.
+ JS::AutoAssertNoGC nogc;
+ JS::AutoEnterCycleCollection autocc(mCCJSRuntime->Runtime());
+ mGraph.Init();
+ mResults.Init();
+ mResults.mSuspectedAtCCStart = SuspectedCount();
+ mResults.mAnyManual = aIsManual;
+ bool mergeZones = ShouldMergeZones(aIsManual);
+ mResults.mMergedZones = mergeZones;
+
+ MOZ_ASSERT(!mBuilder, "Forgot to clear mBuilder");
+ mBuilder = MakeUnique<CCGraphBuilder>(mGraph, mResults, mCCJSRuntime, mLogger,
+ mergeZones);
+ timeLog.Checkpoint("BeginCollection prepare graph builder");
+
+ if (mCCJSRuntime) {
+ mCCJSRuntime->TraverseRoots(*mBuilder);
+ timeLog.Checkpoint("mJSContext->TraverseRoots()");
+ }
+
+ AutoRestore<bool> ar(mScanInProgress);
+ MOZ_RELEASE_ASSERT(!mScanInProgress);
+ mScanInProgress = true;
+ mPurpleBuf.SelectPointers(*mBuilder);
+ timeLog.Checkpoint("SelectPointers()");
+
+ mBuilder->DoneAddingRoots();
+ mIncrementalPhase = GraphBuildingPhase;
+}
+
+uint32_t nsCycleCollector::SuspectedCount() {
+ CheckThreadSafety();
+ if (NS_IsMainThread()) {
+ return gNurseryPurpleBufferEntryCount + mPurpleBuf.Count();
+ }
+
+ return mPurpleBuf.Count();
+}
+
+void nsCycleCollector::Shutdown(bool aDoCollect) {
+ CheckThreadSafety();
+
+ if (NS_IsMainThread()) {
+ gNurseryPurpleBufferEnabled = false;
+ }
+
+ // Always delete snow white objects.
+ FreeSnowWhite(true);
+
+ if (aDoCollect) {
+ ShutdownCollect();
+ }
+
+ if (mJSPurpleBuffer) {
+ mJSPurpleBuffer->Destroy();
+ }
+}
+
+void nsCycleCollector::RemoveObjectFromGraph(void* aObj) {
+ if (IsIdle()) {
+ return;
+ }
+
+ mGraph.RemoveObjectFromMap(aObj);
+ if (mBuilder) {
+ mBuilder->RemoveCachedEntry(aObj);
+ }
+}
+
+void nsCycleCollector::SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf,
+ size_t* aObjectSize,
+ size_t* aGraphSize,
+ size_t* aPurpleBufferSize) const {
+ *aObjectSize = aMallocSizeOf(this);
+
+ *aGraphSize = mGraph.SizeOfExcludingThis(aMallocSizeOf);
+
+ *aPurpleBufferSize = mPurpleBuf.SizeOfExcludingThis(aMallocSizeOf);
+
+ // These fields are deliberately not measured:
+ // - mCCJSRuntime: because it's non-owning and measured by JS reporters.
+ // - mParams: because it only contains scalars.
+}
+
+JSPurpleBuffer* nsCycleCollector::GetJSPurpleBuffer() {
+ if (!mJSPurpleBuffer) {
+ // The Release call here confuses the GC analysis.
+ JS::AutoSuppressGCAnalysis nogc;
+ // JSPurpleBuffer keeps itself alive, but we need to create it in such way
+ // that it ends up in the normal purple buffer. That happens when
+ // nsRefPtr goes out of the scope and calls Release.
+ RefPtr<JSPurpleBuffer> pb = new JSPurpleBuffer(mJSPurpleBuffer);
+ }
+ return mJSPurpleBuffer;
+}
+
+////////////////////////////////////////////////////////////////////////
+// Module public API (exported in nsCycleCollector.h)
+// Just functions that redirect into the singleton, once it's built.
+////////////////////////////////////////////////////////////////////////
+
+void nsCycleCollector_registerJSContext(CycleCollectedJSContext* aCx) {
+ CollectorData* data = sCollectorData.get();
+
+ // We should have started the cycle collector by now.
+ MOZ_ASSERT(data);
+ MOZ_ASSERT(data->mCollector);
+ // But we shouldn't already have a context.
+ MOZ_ASSERT(!data->mContext);
+
+ data->mContext = aCx;
+ data->mCollector->SetCCJSRuntime(aCx->Runtime());
+}
+
+void nsCycleCollector_forgetJSContext() {
+ CollectorData* data = sCollectorData.get();
+
+ // We should have started the cycle collector by now.
+ MOZ_ASSERT(data);
+ // And we shouldn't have already forgotten our context.
+ MOZ_ASSERT(data->mContext);
+
+ // But it may have shutdown already.
+ if (data->mCollector) {
+ data->mCollector->ClearCCJSRuntime();
+ data->mContext = nullptr;
+ } else {
+ data->mContext = nullptr;
+ delete data;
+ sCollectorData.set(nullptr);
+ }
+}
+
+/* static */
+CycleCollectedJSContext* CycleCollectedJSContext::Get() {
+ CollectorData* data = sCollectorData.get();
+ if (data) {
+ return data->mContext;
+ }
+ return nullptr;
+}
+
+MOZ_NEVER_INLINE static void SuspectAfterShutdown(
+ void* aPtr, nsCycleCollectionParticipant* aCp,
+ nsCycleCollectingAutoRefCnt* aRefCnt, bool* aShouldDelete) {
+ if (aRefCnt->get() == 0) {
+ if (!aShouldDelete) {
+ // The CC is shut down, so we can't be in the middle of an ICC.
+ ToParticipant(aPtr, &aCp);
+ aRefCnt->stabilizeForDeletion();
+ aCp->DeleteCycleCollectable(aPtr);
+ } else {
+ *aShouldDelete = true;
+ }
+ } else {
+ // Make sure we'll get called again.
+ aRefCnt->RemoveFromPurpleBuffer();
+ }
+}
+
+void NS_CycleCollectorSuspect3(void* aPtr, nsCycleCollectionParticipant* aCp,
+ nsCycleCollectingAutoRefCnt* aRefCnt,
+ bool* aShouldDelete) {
+ CollectorData* data = sCollectorData.get();
+
+ // This assertion will happen if you AddRef or Release a cycle collected
+ // object on a thread that does not have an active cycle collector.
+ // This can happen in a few situations:
+ // 1. We never cycle collect on this thread. (The cycle collector is only
+ // run on the main thread and DOM worker threads.)
+ // 2. The cycle collector hasn't been initialized on this thread yet.
+ // 3. The cycle collector has already been shut down on this thread.
+ MOZ_DIAGNOSTIC_ASSERT(
+ data,
+ "Cycle collected object used on a thread without a cycle collector.");
+
+ if (MOZ_LIKELY(data->mCollector)) {
+ data->mCollector->Suspect(aPtr, aCp, aRefCnt);
+ return;
+ }
+ SuspectAfterShutdown(aPtr, aCp, aRefCnt, aShouldDelete);
+}
+
+void ClearNurseryPurpleBuffer() {
+ MOZ_ASSERT(NS_IsMainThread(), "Wrong thread!");
+ CollectorData* data = sCollectorData.get();
+ MOZ_ASSERT(data);
+ MOZ_ASSERT(data->mCollector);
+ data->mCollector->SuspectNurseryEntries();
+}
+
+void NS_CycleCollectorSuspectUsingNursery(void* aPtr,
+ nsCycleCollectionParticipant* aCp,
+ nsCycleCollectingAutoRefCnt* aRefCnt,
+ bool* aShouldDelete) {
+ MOZ_ASSERT(NS_IsMainThread(), "Wrong thread!");
+ if (!gNurseryPurpleBufferEnabled) {
+ NS_CycleCollectorSuspect3(aPtr, aCp, aRefCnt, aShouldDelete);
+ return;
+ }
+
+ SuspectUsingNurseryPurpleBuffer(aPtr, aCp, aRefCnt);
+}
+
+uint32_t nsCycleCollector_suspectedCount() {
+ CollectorData* data = sCollectorData.get();
+
+ // We should have started the cycle collector by now.
+ MOZ_ASSERT(data);
+
+ if (!data->mCollector) {
+ return 0;
+ }
+
+ return data->mCollector->SuspectedCount();
+}
+
+bool nsCycleCollector_init() {
+#ifdef DEBUG
+ static bool sInitialized;
+
+ MOZ_ASSERT(NS_IsMainThread(), "Wrong thread!");
+ MOZ_ASSERT(!sInitialized, "Called twice!?");
+ sInitialized = true;
+#endif
+
+ return sCollectorData.init();
+}
+
+void nsCycleCollector_startup() {
+ if (sCollectorData.get()) {
+ MOZ_CRASH();
+ }
+
+ CollectorData* data = new CollectorData;
+ data->mCollector = new nsCycleCollector();
+ data->mContext = nullptr;
+
+ sCollectorData.set(data);
+}
+
+void nsCycleCollector_setBeforeUnlinkCallback(CC_BeforeUnlinkCallback aCB) {
+ CollectorData* data = sCollectorData.get();
+
+ // We should have started the cycle collector by now.
+ MOZ_ASSERT(data);
+ MOZ_ASSERT(data->mCollector);
+
+ data->mCollector->SetBeforeUnlinkCallback(aCB);
+}
+
+void nsCycleCollector_setForgetSkippableCallback(
+ CC_ForgetSkippableCallback aCB) {
+ CollectorData* data = sCollectorData.get();
+
+ // We should have started the cycle collector by now.
+ MOZ_ASSERT(data);
+ MOZ_ASSERT(data->mCollector);
+
+ data->mCollector->SetForgetSkippableCallback(aCB);
+}
+
+void nsCycleCollector_forgetSkippable(js::SliceBudget& aBudget,
+ bool aRemoveChildlessNodes,
+ bool aAsyncSnowWhiteFreeing) {
+ CollectorData* data = sCollectorData.get();
+
+ // We should have started the cycle collector by now.
+ MOZ_ASSERT(data);
+ MOZ_ASSERT(data->mCollector);
+
+ TimeLog timeLog;
+ data->mCollector->ForgetSkippable(aBudget, aRemoveChildlessNodes,
+ aAsyncSnowWhiteFreeing);
+ timeLog.Checkpoint("ForgetSkippable()");
+}
+
+void nsCycleCollector_dispatchDeferredDeletion(bool aContinuation,
+ bool aPurge) {
+ CycleCollectedJSRuntime* rt = CycleCollectedJSRuntime::Get();
+ if (rt) {
+ rt->DispatchDeferredDeletion(aContinuation, aPurge);
+ }
+}
+
+bool nsCycleCollector_doDeferredDeletion() {
+ CollectorData* data = sCollectorData.get();
+
+ // We should have started the cycle collector by now.
+ MOZ_ASSERT(data);
+ MOZ_ASSERT(data->mCollector);
+ MOZ_ASSERT(data->mContext);
+
+ return data->mCollector->FreeSnowWhite(false);
+}
+
+bool nsCycleCollector_doDeferredDeletionWithBudget(js::SliceBudget& aBudget) {
+ CollectorData* data = sCollectorData.get();
+
+ // We should have started the cycle collector by now.
+ MOZ_ASSERT(data);
+ MOZ_ASSERT(data->mCollector);
+ MOZ_ASSERT(data->mContext);
+
+ return data->mCollector->FreeSnowWhiteWithBudget(aBudget);
+}
+
+already_AddRefed<nsICycleCollectorLogSink> nsCycleCollector_createLogSink() {
+ nsCOMPtr<nsICycleCollectorLogSink> sink = new nsCycleCollectorLogSinkToFile();
+ return sink.forget();
+}
+
+bool nsCycleCollector_collect(CCReason aReason,
+ nsICycleCollectorListener* aManualListener) {
+ CollectorData* data = sCollectorData.get();
+
+ // We should have started the cycle collector by now.
+ MOZ_ASSERT(data);
+ MOZ_ASSERT(data->mCollector);
+
+ AUTO_PROFILER_LABEL("nsCycleCollector_collect", GCCC);
+
+ SliceBudget unlimitedBudget = SliceBudget::unlimited();
+ return data->mCollector->Collect(aReason, ccIsManual::CCIsManual,
+ unlimitedBudget, aManualListener);
+}
+
+void nsCycleCollector_collectSlice(SliceBudget& budget, CCReason aReason,
+ bool aPreferShorterSlices) {
+ CollectorData* data = sCollectorData.get();
+
+ // We should have started the cycle collector by now.
+ MOZ_ASSERT(data);
+ MOZ_ASSERT(data->mCollector);
+
+ AUTO_PROFILER_LABEL("nsCycleCollector_collectSlice", GCCC);
+
+ data->mCollector->Collect(aReason, ccIsManual::CCIsNotManual, budget, nullptr,
+ aPreferShorterSlices);
+}
+
+void nsCycleCollector_prepareForGarbageCollection() {
+ CollectorData* data = sCollectorData.get();
+
+ MOZ_ASSERT(data);
+
+ if (!data->mCollector) {
+ return;
+ }
+
+ data->mCollector->PrepareForGarbageCollection();
+}
+
+void nsCycleCollector_finishAnyCurrentCollection() {
+ CollectorData* data = sCollectorData.get();
+
+ MOZ_ASSERT(data);
+
+ if (!data->mCollector) {
+ return;
+ }
+
+ data->mCollector->FinishAnyCurrentCollection(CCReason::API);
+}
+
+void nsCycleCollector_shutdown(bool aDoCollect) {
+ CollectorData* data = sCollectorData.get();
+
+ if (data) {
+ MOZ_ASSERT(data->mCollector);
+ AUTO_PROFILER_LABEL("nsCycleCollector_shutdown", OTHER);
+
+ {
+ RefPtr<nsCycleCollector> collector = data->mCollector;
+ collector->Shutdown(aDoCollect);
+ data->mCollector = nullptr;
+ }
+
+ if (!data->mContext) {
+ delete data;
+ sCollectorData.set(nullptr);
+ }
+ }
+}