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-rw-r--r--memory/replace/dmd/DMD.cpp1888
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diff --git a/memory/replace/dmd/DMD.cpp b/memory/replace/dmd/DMD.cpp
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+++ b/memory/replace/dmd/DMD.cpp
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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/. */
+
+#include <ctype.h>
+#include <errno.h>
+#include <limits.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#if !defined(MOZ_PROFILING)
+# error "DMD requires MOZ_PROFILING"
+#endif
+
+#ifdef XP_WIN
+# include <windows.h>
+# include <process.h>
+#else
+# include <pthread.h>
+# include <sys/types.h>
+# include <unistd.h>
+#endif
+
+#ifdef ANDROID
+# include <android/log.h>
+#endif
+
+#include "nscore.h"
+
+#include "mozilla/Assertions.h"
+#include "mozilla/FastBernoulliTrial.h"
+#include "mozilla/HashFunctions.h"
+#include "mozilla/HashTable.h"
+#include "mozilla/IntegerPrintfMacros.h"
+#include "mozilla/JSONWriter.h"
+#include "mozilla/Likely.h"
+#include "mozilla/MemoryReporting.h"
+#include "mozilla/PodOperations.h"
+#include "mozilla/StackWalk.h"
+#include "mozilla/ThreadLocal.h"
+
+// CodeAddressService is defined entirely in the header, so this does not make
+// DMD depend on XPCOM's object file.
+#include "CodeAddressService.h"
+
+// replace_malloc.h needs to be included before replace_malloc_bridge.h,
+// which DMD.h includes, so DMD.h needs to be included after replace_malloc.h.
+#include "replace_malloc.h"
+#include "DMD.h"
+
+namespace mozilla {
+namespace dmd {
+
+class DMDBridge : public ReplaceMallocBridge {
+ virtual DMDFuncs* GetDMDFuncs() override;
+};
+
+static DMDBridge* gDMDBridge;
+static DMDFuncs gDMDFuncs;
+
+DMDFuncs* DMDBridge::GetDMDFuncs() { return &gDMDFuncs; }
+
+MOZ_FORMAT_PRINTF(1, 2)
+inline void StatusMsg(const char* aFmt, ...) {
+ va_list ap;
+ va_start(ap, aFmt);
+ gDMDFuncs.StatusMsg(aFmt, ap);
+ va_end(ap);
+}
+
+//---------------------------------------------------------------------------
+// Utilities
+//---------------------------------------------------------------------------
+
+#ifndef DISALLOW_COPY_AND_ASSIGN
+# define DISALLOW_COPY_AND_ASSIGN(T) \
+ T(const T&); \
+ void operator=(const T&)
+#endif
+
+static malloc_table_t gMallocTable;
+
+// This provides infallible allocations (they abort on OOM). We use it for all
+// of DMD's own allocations, which fall into the following three cases.
+//
+// - Direct allocations (the easy case).
+//
+// - Indirect allocations in mozilla::{Vector,HashSet,HashMap} -- this class
+// serves as their AllocPolicy.
+//
+// - Other indirect allocations (e.g. MozStackWalk) -- see the comments on
+// Thread::mBlockIntercepts and in replace_malloc for how these work.
+//
+// It would be nice if we could use the InfallibleAllocPolicy from mozalloc,
+// but DMD cannot use mozalloc.
+//
+class InfallibleAllocPolicy {
+ static void ExitOnFailure(const void* aP);
+
+ public:
+ template <typename T>
+ static T* maybe_pod_malloc(size_t aNumElems) {
+ if (aNumElems & mozilla::tl::MulOverflowMask<sizeof(T)>::value)
+ return nullptr;
+ return (T*)gMallocTable.malloc(aNumElems * sizeof(T));
+ }
+
+ template <typename T>
+ static T* maybe_pod_calloc(size_t aNumElems) {
+ return (T*)gMallocTable.calloc(aNumElems, sizeof(T));
+ }
+
+ template <typename T>
+ static T* maybe_pod_realloc(T* aPtr, size_t aOldSize, size_t aNewSize) {
+ if (aNewSize & mozilla::tl::MulOverflowMask<sizeof(T)>::value)
+ return nullptr;
+ return (T*)gMallocTable.realloc(aPtr, aNewSize * sizeof(T));
+ }
+
+ static void* malloc_(size_t aSize) {
+ void* p = gMallocTable.malloc(aSize);
+ ExitOnFailure(p);
+ return p;
+ }
+
+ template <typename T>
+ static T* pod_malloc(size_t aNumElems) {
+ T* p = maybe_pod_malloc<T>(aNumElems);
+ ExitOnFailure(p);
+ return p;
+ }
+
+ static void* calloc_(size_t aCount, size_t aSize) {
+ void* p = gMallocTable.calloc(aCount, aSize);
+ ExitOnFailure(p);
+ return p;
+ }
+
+ template <typename T>
+ static T* pod_calloc(size_t aNumElems) {
+ T* p = maybe_pod_calloc<T>(aNumElems);
+ ExitOnFailure(p);
+ return p;
+ }
+
+ static void* realloc_(void* aPtr, size_t aNewSize) {
+ void* p = gMallocTable.realloc(aPtr, aNewSize);
+ ExitOnFailure(p);
+ return p;
+ }
+
+ template <typename T>
+ static T* pod_realloc(T* aPtr, size_t aOldSize, size_t aNewSize) {
+ T* p = maybe_pod_realloc(aPtr, aOldSize, aNewSize);
+ ExitOnFailure(p);
+ return p;
+ }
+
+ static void* memalign_(size_t aAlignment, size_t aSize) {
+ void* p = gMallocTable.memalign(aAlignment, aSize);
+ ExitOnFailure(p);
+ return p;
+ }
+
+ template <typename T>
+ static void free_(T* aPtr, size_t aSize = 0) {
+ gMallocTable.free(aPtr);
+ }
+
+ static char* strdup_(const char* aStr) {
+ char* s = (char*)InfallibleAllocPolicy::malloc_(strlen(aStr) + 1);
+ strcpy(s, aStr);
+ return s;
+ }
+
+ template <class T>
+ static T* new_() {
+ void* mem = malloc_(sizeof(T));
+ return new (mem) T;
+ }
+
+ template <class T, typename P1>
+ static T* new_(const P1& aP1) {
+ void* mem = malloc_(sizeof(T));
+ return new (mem) T(aP1);
+ }
+
+ template <class T>
+ static void delete_(T* aPtr) {
+ if (aPtr) {
+ aPtr->~T();
+ InfallibleAllocPolicy::free_(aPtr);
+ }
+ }
+
+ static void reportAllocOverflow() { ExitOnFailure(nullptr); }
+ bool checkSimulatedOOM() const { return true; }
+};
+
+// This is only needed because of the |const void*| vs |void*| arg mismatch.
+static size_t MallocSizeOf(const void* aPtr) {
+ return gMallocTable.malloc_usable_size(const_cast<void*>(aPtr));
+}
+
+void DMDFuncs::StatusMsg(const char* aFmt, va_list aAp) {
+#ifdef ANDROID
+ __android_log_vprint(ANDROID_LOG_INFO, "DMD", aFmt, aAp);
+#else
+ // The +64 is easily enough for the "DMD[<pid>] " prefix and the NUL.
+ size_t size = strlen(aFmt) + 64;
+ char* fmt = (char*)InfallibleAllocPolicy::malloc_(size);
+ snprintf(fmt, size, "DMD[%d] %s", getpid(), aFmt);
+ vfprintf(stderr, fmt, aAp);
+ InfallibleAllocPolicy::free_(fmt);
+#endif
+}
+
+/* static */
+void InfallibleAllocPolicy::ExitOnFailure(const void* aP) {
+ if (!aP) {
+ MOZ_CRASH("DMD out of memory; aborting");
+ }
+}
+
+static double Percent(size_t part, size_t whole) {
+ return (whole == 0) ? 0 : 100 * (double)part / whole;
+}
+
+// Commifies the number.
+static char* Show(size_t n, char* buf, size_t buflen) {
+ int nc = 0, i = 0, lasti = buflen - 2;
+ buf[lasti + 1] = '\0';
+ if (n == 0) {
+ buf[lasti - i] = '0';
+ i++;
+ } else {
+ while (n > 0) {
+ if (((i - nc) % 3) == 0 && i != 0) {
+ buf[lasti - i] = ',';
+ i++;
+ nc++;
+ }
+ buf[lasti - i] = static_cast<char>((n % 10) + '0');
+ i++;
+ n /= 10;
+ }
+ }
+ int firstCharIndex = lasti - i + 1;
+
+ MOZ_ASSERT(firstCharIndex >= 0);
+ return &buf[firstCharIndex];
+}
+
+//---------------------------------------------------------------------------
+// Options (Part 1)
+//---------------------------------------------------------------------------
+
+class Options {
+ template <typename T>
+ struct NumOption {
+ const T mDefault;
+ const T mMax;
+ T mActual;
+ NumOption(T aDefault, T aMax)
+ : mDefault(aDefault), mMax(aMax), mActual(aDefault) {}
+ };
+
+ // DMD has several modes. These modes affect what data is recorded and
+ // written to the output file, and the written data affects the
+ // post-processing that dmd.py can do.
+ //
+ // Users specify the mode as soon as DMD starts. This leads to minimal memory
+ // usage and log file size. It has the disadvantage that is inflexible -- if
+ // you want to change modes you have to re-run DMD. But in practice changing
+ // modes seems to be rare, so it's not much of a problem.
+ //
+ // An alternative possibility would be to always record and output *all* the
+ // information needed for all modes. This would let you choose the mode when
+ // running dmd.py, and so you could do multiple kinds of profiling on a
+ // single DMD run. But if you are only interested in one of the simpler
+ // modes, you'd pay the price of (a) increased memory usage and (b) *very*
+ // large log files.
+ //
+ // Finally, another alternative possibility would be to do mode selection
+ // partly at DMD startup or recording, and then partly in dmd.py. This would
+ // give some extra flexibility at moderate memory and file size cost. But
+ // certain mode pairs wouldn't work, which would be confusing.
+ //
+ enum class Mode {
+ // For each live block, this mode outputs: size (usable and slop) and
+ // (possibly) and allocation stack. This mode is good for live heap
+ // profiling.
+ Live,
+
+ // Like "Live", but for each live block it also outputs: zero or more
+ // report stacks. This mode is good for identifying where memory reporters
+ // should be added. This is the default mode.
+ DarkMatter,
+
+ // Like "Live", but also outputs the same data for dead blocks. This mode
+ // does cumulative heap profiling, which is good for identifying where large
+ // amounts of short-lived allocations ("heap churn") occur.
+ Cumulative,
+
+ // Like "Live", but this mode also outputs for each live block the address
+ // of the block and the values contained in the blocks. This mode is useful
+ // for investigating leaks, by helping to figure out which blocks refer to
+ // other blocks. This mode force-enables full stacks coverage.
+ Scan
+ };
+
+ // With full stacks, every heap block gets a stack trace recorded for it.
+ // This is complete but slow.
+ //
+ // With partial stacks, not all heap blocks will get a stack trace recorded.
+ // A Bernoulli trial (see mfbt/FastBernoulliTrial.h for details) is performed
+ // for each heap block to decide if it gets one. Because bigger heap blocks
+ // are more likely to get a stack trace, even though most heap *blocks* won't
+ // get a stack trace, most heap *bytes* will.
+ enum class Stacks { Full, Partial };
+
+ char* mDMDEnvVar; // a saved copy, for later printing
+
+ Mode mMode;
+ Stacks mStacks;
+ bool mShowDumpStats;
+
+ void BadArg(const char* aArg);
+ static const char* ValueIfMatch(const char* aArg, const char* aOptionName);
+ static bool GetLong(const char* aArg, const char* aOptionName, long aMin,
+ long aMax, long* aValue);
+ static bool GetBool(const char* aArg, const char* aOptionName, bool* aValue);
+
+ public:
+ explicit Options(const char* aDMDEnvVar);
+
+ bool IsLiveMode() const { return mMode == Mode::Live; }
+ bool IsDarkMatterMode() const { return mMode == Mode::DarkMatter; }
+ bool IsCumulativeMode() const { return mMode == Mode::Cumulative; }
+ bool IsScanMode() const { return mMode == Mode::Scan; }
+
+ const char* ModeString() const;
+
+ const char* DMDEnvVar() const { return mDMDEnvVar; }
+
+ bool DoFullStacks() const { return mStacks == Stacks::Full; }
+ size_t ShowDumpStats() const { return mShowDumpStats; }
+};
+
+static Options* gOptions;
+
+//---------------------------------------------------------------------------
+// The global lock
+//---------------------------------------------------------------------------
+
+// MutexBase implements the platform-specific parts of a mutex.
+
+#ifdef XP_WIN
+
+class MutexBase {
+ CRITICAL_SECTION mCS;
+
+ DISALLOW_COPY_AND_ASSIGN(MutexBase);
+
+ public:
+ MutexBase() { InitializeCriticalSection(&mCS); }
+ ~MutexBase() { DeleteCriticalSection(&mCS); }
+
+ void Lock() { EnterCriticalSection(&mCS); }
+ void Unlock() { LeaveCriticalSection(&mCS); }
+};
+
+#else
+
+class MutexBase {
+ pthread_mutex_t mMutex;
+
+ MutexBase(const MutexBase&) = delete;
+
+ const MutexBase& operator=(const MutexBase&) = delete;
+
+ public:
+ MutexBase() { pthread_mutex_init(&mMutex, nullptr); }
+
+ void Lock() { pthread_mutex_lock(&mMutex); }
+ void Unlock() { pthread_mutex_unlock(&mMutex); }
+};
+
+#endif
+
+class Mutex : private MutexBase {
+ bool mIsLocked;
+
+ Mutex(const Mutex&) = delete;
+
+ const Mutex& operator=(const Mutex&) = delete;
+
+ public:
+ Mutex() : mIsLocked(false) {}
+
+ void Lock() {
+ MutexBase::Lock();
+ MOZ_ASSERT(!mIsLocked);
+ mIsLocked = true;
+ }
+
+ void Unlock() {
+ MOZ_ASSERT(mIsLocked);
+ mIsLocked = false;
+ MutexBase::Unlock();
+ }
+
+ bool IsLocked() { return mIsLocked; }
+};
+
+// This lock must be held while manipulating global state such as
+// gStackTraceTable, gLiveBlockTable, gDeadBlockTable. Note that gOptions is
+// *not* protected by this lock because it is only written to by Options(),
+// which is only invoked at start-up and in ResetEverything(), which is only
+// used by SmokeDMD.cpp.
+static Mutex* gStateLock = nullptr;
+
+class AutoLockState {
+ AutoLockState(const AutoLockState&) = delete;
+
+ const AutoLockState& operator=(const AutoLockState&) = delete;
+
+ public:
+ AutoLockState() { gStateLock->Lock(); }
+ ~AutoLockState() { gStateLock->Unlock(); }
+};
+
+class AutoUnlockState {
+ AutoUnlockState(const AutoUnlockState&) = delete;
+
+ const AutoUnlockState& operator=(const AutoUnlockState&) = delete;
+
+ public:
+ AutoUnlockState() { gStateLock->Unlock(); }
+ ~AutoUnlockState() { gStateLock->Lock(); }
+};
+
+//---------------------------------------------------------------------------
+// Per-thread blocking of intercepts
+//---------------------------------------------------------------------------
+
+// On MacOS, the first __thread/thread_local access calls malloc, which leads
+// to an infinite loop. So we use pthread-based TLS instead, which somehow
+// doesn't have this problem.
+#if !defined(XP_DARWIN)
+# define DMD_THREAD_LOCAL(T) MOZ_THREAD_LOCAL(T)
+#else
+# define DMD_THREAD_LOCAL(T) \
+ detail::ThreadLocal<T, detail::ThreadLocalKeyStorage>
+#endif
+
+class Thread {
+ // Required for allocation via InfallibleAllocPolicy::new_.
+ friend class InfallibleAllocPolicy;
+
+ // When true, this blocks intercepts, which allows malloc interception
+ // functions to themselves call malloc. (Nb: for direct calls to malloc we
+ // can just use InfallibleAllocPolicy::{malloc_,new_}, but we sometimes
+ // indirectly call vanilla malloc via functions like MozStackWalk.)
+ bool mBlockIntercepts;
+
+ Thread() : mBlockIntercepts(false) {}
+
+ Thread(const Thread&) = delete;
+
+ const Thread& operator=(const Thread&) = delete;
+
+ static DMD_THREAD_LOCAL(Thread*) tlsThread;
+
+ public:
+ static void Init() {
+ if (!tlsThread.init()) {
+ MOZ_CRASH();
+ }
+ }
+
+ static Thread* Fetch() {
+ Thread* t = tlsThread.get();
+ if (MOZ_UNLIKELY(!t)) {
+ // This memory is never freed, even if the thread dies. It's a leak, but
+ // only a tiny one.
+ t = InfallibleAllocPolicy::new_<Thread>();
+ tlsThread.set(t);
+ }
+
+ return t;
+ }
+
+ bool BlockIntercepts() {
+ MOZ_ASSERT(!mBlockIntercepts);
+ return mBlockIntercepts = true;
+ }
+
+ bool UnblockIntercepts() {
+ MOZ_ASSERT(mBlockIntercepts);
+ return mBlockIntercepts = false;
+ }
+
+ bool InterceptsAreBlocked() const { return mBlockIntercepts; }
+};
+
+DMD_THREAD_LOCAL(Thread*) Thread::tlsThread;
+
+// An object of this class must be created (on the stack) before running any
+// code that might allocate.
+class AutoBlockIntercepts {
+ Thread* const mT;
+
+ AutoBlockIntercepts(const AutoBlockIntercepts&) = delete;
+
+ const AutoBlockIntercepts& operator=(const AutoBlockIntercepts&) = delete;
+
+ public:
+ explicit AutoBlockIntercepts(Thread* aT) : mT(aT) { mT->BlockIntercepts(); }
+ ~AutoBlockIntercepts() {
+ MOZ_ASSERT(mT->InterceptsAreBlocked());
+ mT->UnblockIntercepts();
+ }
+};
+
+//---------------------------------------------------------------------------
+// Location service
+//---------------------------------------------------------------------------
+
+struct DescribeCodeAddressLock {
+ static void Unlock() { gStateLock->Unlock(); }
+ static void Lock() { gStateLock->Lock(); }
+ static bool IsLocked() { return gStateLock->IsLocked(); }
+};
+
+typedef CodeAddressService<InfallibleAllocPolicy, DescribeCodeAddressLock>
+ CodeAddressService;
+
+//---------------------------------------------------------------------------
+// Stack traces
+//---------------------------------------------------------------------------
+
+class StackTrace {
+ public:
+ static const uint32_t MaxFrames = 24;
+
+ private:
+ uint32_t mLength; // The number of PCs.
+ const void* mPcs[MaxFrames]; // The PCs themselves.
+
+ public:
+ StackTrace() : mLength(0) {}
+ StackTrace(const StackTrace& aOther) : mLength(aOther.mLength) {
+ PodCopy(mPcs, aOther.mPcs, mLength);
+ }
+
+ uint32_t Length() const { return mLength; }
+ const void* Pc(uint32_t i) const {
+ MOZ_ASSERT(i < mLength);
+ return mPcs[i];
+ }
+
+ uint32_t Size() const { return mLength * sizeof(mPcs[0]); }
+
+ // The stack trace returned by this function is interned in gStackTraceTable,
+ // and so is immortal and unmovable.
+ static const StackTrace* Get(Thread* aT);
+
+ // Hash policy.
+
+ typedef StackTrace* Lookup;
+
+ static mozilla::HashNumber hash(const StackTrace* const& aSt) {
+ return mozilla::HashBytes(aSt->mPcs, aSt->Size());
+ }
+
+ static bool match(const StackTrace* const& aA, const StackTrace* const& aB) {
+ return aA->mLength == aB->mLength &&
+ memcmp(aA->mPcs, aB->mPcs, aA->Size()) == 0;
+ }
+
+ private:
+ static void StackWalkCallback(uint32_t aFrameNumber, void* aPc, void* aSp,
+ void* aClosure) {
+ StackTrace* st = (StackTrace*)aClosure;
+ MOZ_ASSERT(st->mLength < MaxFrames);
+ st->mPcs[st->mLength] = aPc;
+ st->mLength++;
+ MOZ_ASSERT(st->mLength == aFrameNumber);
+ }
+};
+
+typedef mozilla::HashSet<StackTrace*, StackTrace, InfallibleAllocPolicy>
+ StackTraceTable;
+static StackTraceTable* gStackTraceTable = nullptr;
+
+typedef mozilla::HashSet<const StackTrace*,
+ mozilla::DefaultHasher<const StackTrace*>,
+ InfallibleAllocPolicy>
+ StackTraceSet;
+
+typedef mozilla::HashSet<const void*, mozilla::DefaultHasher<const void*>,
+ InfallibleAllocPolicy>
+ PointerSet;
+typedef mozilla::HashMap<const void*, uint32_t,
+ mozilla::DefaultHasher<const void*>,
+ InfallibleAllocPolicy>
+ PointerIdMap;
+
+// We won't GC the stack trace table until it this many elements.
+static uint32_t gGCStackTraceTableWhenSizeExceeds = 4 * 1024;
+
+/* static */ const StackTrace* StackTrace::Get(Thread* aT) {
+ MOZ_ASSERT(gStateLock->IsLocked());
+ MOZ_ASSERT(aT->InterceptsAreBlocked());
+
+ // On Windows, MozStackWalk can acquire a lock from the shared library
+ // loader. Another thread might call malloc while holding that lock (when
+ // loading a shared library). So we can't be in gStateLock during the call
+ // to MozStackWalk. For details, see
+ // https://bugzilla.mozilla.org/show_bug.cgi?id=374829#c8
+ // On Linux, something similar can happen; see bug 824340.
+ // So let's just release it on all platforms.
+ StackTrace tmp;
+ {
+ AutoUnlockState unlock;
+ // In each of the following cases, skipFrames is chosen so that the
+ // first frame in each stack trace is a replace_* function (or as close as
+ // possible, given the vagaries of inlining on different platforms).
+#if defined(XP_WIN) && defined(_M_IX86)
+ // This avoids MozStackWalk(), which causes unusably slow startup on Win32
+ // when it is called during static initialization (see bug 1241684).
+ //
+ // This code is cribbed from the Gecko Profiler, which also uses
+ // FramePointerStackWalk() on Win32: Registers::SyncPopulate() for the
+ // frame pointer, and GetStackTop() for the stack end.
+ CONTEXT context;
+ RtlCaptureContext(&context);
+ void** fp = reinterpret_cast<void**>(context.Ebp);
+
+ PNT_TIB pTib = reinterpret_cast<PNT_TIB>(NtCurrentTeb());
+ void* stackEnd = static_cast<void*>(pTib->StackBase);
+ FramePointerStackWalk(StackWalkCallback, MaxFrames, &tmp, fp, stackEnd);
+#elif defined(XP_MACOSX)
+ // This avoids MozStackWalk(), which has become unusably slow on Mac due to
+ // changes in libunwind.
+ //
+ // This code is cribbed from the Gecko Profiler, which also uses
+ // FramePointerStackWalk() on Mac: Registers::SyncPopulate() for the frame
+ // pointer, and GetStackTop() for the stack end.
+# pragma GCC diagnostic push
+# pragma GCC diagnostic ignored "-Wframe-address"
+ void** fp = reinterpret_cast<void**>(__builtin_frame_address(1));
+# pragma GCC diagnostic pop
+ void* stackEnd = pthread_get_stackaddr_np(pthread_self());
+ FramePointerStackWalk(StackWalkCallback, MaxFrames, &tmp, fp, stackEnd);
+#else
+ MozStackWalk(StackWalkCallback, nullptr, MaxFrames, &tmp);
+#endif
+ }
+
+ StackTraceTable::AddPtr p = gStackTraceTable->lookupForAdd(&tmp);
+ if (!p) {
+ StackTrace* stnew = InfallibleAllocPolicy::new_<StackTrace>(tmp);
+ MOZ_ALWAYS_TRUE(gStackTraceTable->add(p, stnew));
+ }
+ return *p;
+}
+
+//---------------------------------------------------------------------------
+// Heap blocks
+//---------------------------------------------------------------------------
+
+// This class combines a 2-byte-aligned pointer (i.e. one whose bottom bit
+// is zero) with a 1-bit tag.
+//
+// |T| is the pointer type, e.g. |int*|, not the pointed-to type. This makes
+// is easier to have const pointers, e.g. |TaggedPtr<const int*>|.
+template <typename T>
+class TaggedPtr {
+ union {
+ T mPtr;
+ uintptr_t mUint;
+ };
+
+ static const uintptr_t kTagMask = uintptr_t(0x1);
+ static const uintptr_t kPtrMask = ~kTagMask;
+
+ static bool IsTwoByteAligned(T aPtr) {
+ return (uintptr_t(aPtr) & kTagMask) == 0;
+ }
+
+ public:
+ TaggedPtr() : mPtr(nullptr) {}
+
+ TaggedPtr(T aPtr, bool aBool) : mPtr(aPtr) {
+ MOZ_ASSERT(IsTwoByteAligned(aPtr));
+ uintptr_t tag = uintptr_t(aBool);
+ MOZ_ASSERT(tag <= kTagMask);
+ mUint |= (tag & kTagMask);
+ }
+
+ void Set(T aPtr, bool aBool) {
+ MOZ_ASSERT(IsTwoByteAligned(aPtr));
+ mPtr = aPtr;
+ uintptr_t tag = uintptr_t(aBool);
+ MOZ_ASSERT(tag <= kTagMask);
+ mUint |= (tag & kTagMask);
+ }
+
+ T Ptr() const { return reinterpret_cast<T>(mUint & kPtrMask); }
+
+ bool Tag() const { return bool(mUint & kTagMask); }
+};
+
+// A live heap block. Stores both basic data and data about reports, if we're
+// in DarkMatter mode.
+class LiveBlock {
+ const void* mPtr;
+ const size_t mReqSize; // size requested
+
+ // The stack trace where this block was allocated, or nullptr if we didn't
+ // record one.
+ const StackTrace* const mAllocStackTrace;
+
+ // This array has two elements because we record at most two reports of a
+ // block.
+ // - Ptr: |mReportStackTrace| - stack trace where this block was reported.
+ // nullptr if not reported.
+ // - Tag bit 0: |mReportedOnAlloc| - was the block reported immediately on
+ // allocation? If so, DMD must not clear the report at the end of
+ // Analyze(). Only relevant if |mReportStackTrace| is non-nullptr.
+ //
+ // |mPtr| is used as the key in LiveBlockTable, so it's ok for this member
+ // to be |mutable|.
+ //
+ // Only used in DarkMatter mode.
+ mutable TaggedPtr<const StackTrace*> mReportStackTrace_mReportedOnAlloc[2];
+
+ public:
+ LiveBlock(const void* aPtr, size_t aReqSize,
+ const StackTrace* aAllocStackTrace)
+ : mPtr(aPtr),
+ mReqSize(aReqSize),
+ mAllocStackTrace(aAllocStackTrace),
+ mReportStackTrace_mReportedOnAlloc() // all fields get zeroed
+ {}
+
+ const void* Address() const { return mPtr; }
+
+ size_t ReqSize() const { return mReqSize; }
+
+ size_t SlopSize() const { return MallocSizeOf(mPtr) - mReqSize; }
+
+ const StackTrace* AllocStackTrace() const { return mAllocStackTrace; }
+
+ const StackTrace* ReportStackTrace1() const {
+ MOZ_ASSERT(gOptions->IsDarkMatterMode());
+ return mReportStackTrace_mReportedOnAlloc[0].Ptr();
+ }
+
+ const StackTrace* ReportStackTrace2() const {
+ MOZ_ASSERT(gOptions->IsDarkMatterMode());
+ return mReportStackTrace_mReportedOnAlloc[1].Ptr();
+ }
+
+ bool ReportedOnAlloc1() const {
+ MOZ_ASSERT(gOptions->IsDarkMatterMode());
+ return mReportStackTrace_mReportedOnAlloc[0].Tag();
+ }
+
+ bool ReportedOnAlloc2() const {
+ MOZ_ASSERT(gOptions->IsDarkMatterMode());
+ return mReportStackTrace_mReportedOnAlloc[1].Tag();
+ }
+
+ void AddStackTracesToTable(StackTraceSet& aStackTraces) const {
+ if (AllocStackTrace()) {
+ MOZ_ALWAYS_TRUE(aStackTraces.put(AllocStackTrace()));
+ }
+ if (gOptions->IsDarkMatterMode()) {
+ if (ReportStackTrace1()) {
+ MOZ_ALWAYS_TRUE(aStackTraces.put(ReportStackTrace1()));
+ }
+ if (ReportStackTrace2()) {
+ MOZ_ALWAYS_TRUE(aStackTraces.put(ReportStackTrace2()));
+ }
+ }
+ }
+
+ uint32_t NumReports() const {
+ MOZ_ASSERT(gOptions->IsDarkMatterMode());
+ if (ReportStackTrace2()) {
+ MOZ_ASSERT(ReportStackTrace1());
+ return 2;
+ }
+ if (ReportStackTrace1()) {
+ return 1;
+ }
+ return 0;
+ }
+
+ // This is |const| thanks to the |mutable| fields above.
+ void Report(Thread* aT, bool aReportedOnAlloc) const {
+ MOZ_ASSERT(gOptions->IsDarkMatterMode());
+ // We don't bother recording reports after the 2nd one.
+ uint32_t numReports = NumReports();
+ if (numReports < 2) {
+ mReportStackTrace_mReportedOnAlloc[numReports].Set(StackTrace::Get(aT),
+ aReportedOnAlloc);
+ }
+ }
+
+ void UnreportIfNotReportedOnAlloc() const {
+ MOZ_ASSERT(gOptions->IsDarkMatterMode());
+ if (!ReportedOnAlloc1() && !ReportedOnAlloc2()) {
+ mReportStackTrace_mReportedOnAlloc[0].Set(nullptr, 0);
+ mReportStackTrace_mReportedOnAlloc[1].Set(nullptr, 0);
+
+ } else if (!ReportedOnAlloc1() && ReportedOnAlloc2()) {
+ // Shift the 2nd report down to the 1st one.
+ mReportStackTrace_mReportedOnAlloc[0] =
+ mReportStackTrace_mReportedOnAlloc[1];
+ mReportStackTrace_mReportedOnAlloc[1].Set(nullptr, 0);
+
+ } else if (ReportedOnAlloc1() && !ReportedOnAlloc2()) {
+ mReportStackTrace_mReportedOnAlloc[1].Set(nullptr, 0);
+ }
+ }
+
+ // Hash policy.
+
+ typedef const void* Lookup;
+
+ static mozilla::HashNumber hash(const void* const& aPtr) {
+ return mozilla::HashGeneric(aPtr);
+ }
+
+ static bool match(const LiveBlock& aB, const void* const& aPtr) {
+ return aB.mPtr == aPtr;
+ }
+};
+
+// A table of live blocks where the lookup key is the block address.
+typedef mozilla::HashSet<LiveBlock, LiveBlock, InfallibleAllocPolicy>
+ LiveBlockTable;
+static LiveBlockTable* gLiveBlockTable = nullptr;
+
+class AggregatedLiveBlockHashPolicy {
+ public:
+ typedef const LiveBlock* const Lookup;
+
+ static mozilla::HashNumber hash(const LiveBlock* const& aB) {
+ return gOptions->IsDarkMatterMode()
+ ? mozilla::HashGeneric(
+ aB->ReqSize(), aB->SlopSize(), aB->AllocStackTrace(),
+ aB->ReportedOnAlloc1(), aB->ReportedOnAlloc2())
+ : mozilla::HashGeneric(aB->ReqSize(), aB->SlopSize(),
+ aB->AllocStackTrace());
+ }
+
+ static bool match(const LiveBlock* const& aA, const LiveBlock* const& aB) {
+ return gOptions->IsDarkMatterMode()
+ ? aA->ReqSize() == aB->ReqSize() &&
+ aA->SlopSize() == aB->SlopSize() &&
+ aA->AllocStackTrace() == aB->AllocStackTrace() &&
+ aA->ReportStackTrace1() == aB->ReportStackTrace1() &&
+ aA->ReportStackTrace2() == aB->ReportStackTrace2()
+ : aA->ReqSize() == aB->ReqSize() &&
+ aA->SlopSize() == aB->SlopSize() &&
+ aA->AllocStackTrace() == aB->AllocStackTrace();
+ }
+};
+
+// A table of live blocks where the lookup key is everything but the block
+// address. For aggregating similar live blocks at output time.
+typedef mozilla::HashMap<const LiveBlock*, size_t,
+ AggregatedLiveBlockHashPolicy, InfallibleAllocPolicy>
+ AggregatedLiveBlockTable;
+
+// A freed heap block.
+class DeadBlock {
+ const size_t mReqSize; // size requested
+ const size_t mSlopSize; // slop above size requested
+
+ // The stack trace where this block was allocated.
+ const StackTrace* const mAllocStackTrace;
+
+ public:
+ DeadBlock() : mReqSize(0), mSlopSize(0), mAllocStackTrace(nullptr) {}
+
+ explicit DeadBlock(const LiveBlock& aLb)
+ : mReqSize(aLb.ReqSize()),
+ mSlopSize(aLb.SlopSize()),
+ mAllocStackTrace(aLb.AllocStackTrace()) {}
+
+ ~DeadBlock() {}
+
+ size_t ReqSize() const { return mReqSize; }
+ size_t SlopSize() const { return mSlopSize; }
+
+ const StackTrace* AllocStackTrace() const { return mAllocStackTrace; }
+
+ void AddStackTracesToTable(StackTraceSet& aStackTraces) const {
+ if (AllocStackTrace()) {
+ MOZ_ALWAYS_TRUE(aStackTraces.put(AllocStackTrace()));
+ }
+ }
+
+ // Hash policy.
+
+ typedef DeadBlock Lookup;
+
+ static mozilla::HashNumber hash(const DeadBlock& aB) {
+ return mozilla::HashGeneric(aB.ReqSize(), aB.SlopSize(),
+ aB.AllocStackTrace());
+ }
+
+ static bool match(const DeadBlock& aA, const DeadBlock& aB) {
+ return aA.ReqSize() == aB.ReqSize() && aA.SlopSize() == aB.SlopSize() &&
+ aA.AllocStackTrace() == aB.AllocStackTrace();
+ }
+};
+
+// For each unique DeadBlock value we store a count of how many actual dead
+// blocks have that value.
+typedef mozilla::HashMap<DeadBlock, size_t, DeadBlock, InfallibleAllocPolicy>
+ DeadBlockTable;
+static DeadBlockTable* gDeadBlockTable = nullptr;
+
+// Add the dead block to the dead block table, if that's appropriate.
+void MaybeAddToDeadBlockTable(const DeadBlock& aDb) {
+ if (gOptions->IsCumulativeMode() && aDb.AllocStackTrace()) {
+ AutoLockState lock;
+ if (DeadBlockTable::AddPtr p = gDeadBlockTable->lookupForAdd(aDb)) {
+ p->value() += 1;
+ } else {
+ MOZ_ALWAYS_TRUE(gDeadBlockTable->add(p, aDb, 1));
+ }
+ }
+}
+
+// Add a pointer to each live stack trace into the given StackTraceSet. (A
+// stack trace is live if it's used by one of the live blocks.)
+static void GatherUsedStackTraces(StackTraceSet& aStackTraces) {
+ MOZ_ASSERT(gStateLock->IsLocked());
+ MOZ_ASSERT(Thread::Fetch()->InterceptsAreBlocked());
+
+ aStackTraces.clear();
+ MOZ_ALWAYS_TRUE(aStackTraces.reserve(512));
+
+ for (auto iter = gLiveBlockTable->iter(); !iter.done(); iter.next()) {
+ iter.get().AddStackTracesToTable(aStackTraces);
+ }
+
+ for (auto iter = gDeadBlockTable->iter(); !iter.done(); iter.next()) {
+ iter.get().key().AddStackTracesToTable(aStackTraces);
+ }
+}
+
+// Delete stack traces that we aren't using, and compact our hashtable.
+static void GCStackTraces() {
+ MOZ_ASSERT(gStateLock->IsLocked());
+ MOZ_ASSERT(Thread::Fetch()->InterceptsAreBlocked());
+
+ StackTraceSet usedStackTraces;
+ GatherUsedStackTraces(usedStackTraces);
+
+ // Delete all unused stack traces from gStackTraceTable. The ModIterator
+ // destructor will automatically rehash and compact the table.
+ for (auto iter = gStackTraceTable->modIter(); !iter.done(); iter.next()) {
+ StackTrace* const& st = iter.get();
+ if (!usedStackTraces.has(st)) {
+ iter.remove();
+ InfallibleAllocPolicy::delete_(st);
+ }
+ }
+
+ // Schedule a GC when we have twice as many stack traces as we had right after
+ // this GC finished.
+ gGCStackTraceTableWhenSizeExceeds = 2 * gStackTraceTable->count();
+}
+
+//---------------------------------------------------------------------------
+// malloc/free callbacks
+//---------------------------------------------------------------------------
+
+static FastBernoulliTrial* gBernoulli;
+
+// In testing, a probability of 0.003 resulted in ~25% of heap blocks getting
+// a stack trace and ~80% of heap bytes getting a stack trace. (This is
+// possible because big heap blocks are more likely to get a stack trace.)
+//
+// We deliberately choose not to give the user control over this probability
+// (other than effectively setting it to 1 via --stacks=full) because it's
+// quite inscrutable and generally the user just wants "faster and imprecise"
+// or "slower and precise".
+//
+// The random number seeds are arbitrary and were obtained from random.org. If
+// you change them you'll need to change the tests as well, because their
+// expected output is based on the particular sequence of trial results that we
+// get with these seeds.
+static void ResetBernoulli() {
+ new (gBernoulli)
+ FastBernoulliTrial(0.003, 0x8e26eeee166bc8ca, 0x56820f304a9c9ae0);
+}
+
+static void AllocCallback(void* aPtr, size_t aReqSize, Thread* aT) {
+ if (!aPtr) {
+ return;
+ }
+
+ AutoLockState lock;
+ AutoBlockIntercepts block(aT);
+
+ size_t actualSize = gMallocTable.malloc_usable_size(aPtr);
+
+ // We may or may not record the allocation stack trace, depending on the
+ // options and the outcome of a Bernoulli trial.
+ bool getTrace = gOptions->DoFullStacks() || gBernoulli->trial(actualSize);
+ LiveBlock b(aPtr, aReqSize, getTrace ? StackTrace::Get(aT) : nullptr);
+ LiveBlockTable::AddPtr p = gLiveBlockTable->lookupForAdd(aPtr);
+ if (!p) {
+ // Most common case: there wasn't a record already.
+ MOZ_ALWAYS_TRUE(gLiveBlockTable->add(p, b));
+ } else {
+ // Edge-case: there was a record for the same address. We'll assume the
+ // allocator is not giving out a pointer to an existing allocation, so
+ // this means the previously recorded allocation was freed while we were
+ // blocking interceptions. This can happen while processing the data in
+ // e.g. AnalyzeImpl.
+ if (gOptions->IsCumulativeMode()) {
+ // Copy it out so it can be added to the dead block list later.
+ DeadBlock db(*p);
+ MaybeAddToDeadBlockTable(db);
+ }
+ gLiveBlockTable->remove(p);
+ MOZ_ALWAYS_TRUE(gLiveBlockTable->putNew(aPtr, b));
+ }
+}
+
+static void FreeCallback(void* aPtr, Thread* aT, DeadBlock* aDeadBlock) {
+ if (!aPtr) {
+ return;
+ }
+
+ AutoLockState lock;
+ AutoBlockIntercepts block(aT);
+
+ if (LiveBlockTable::Ptr lb = gLiveBlockTable->lookup(aPtr)) {
+ if (gOptions->IsCumulativeMode()) {
+ // Copy it out so it can be added to the dead block list later.
+ new (aDeadBlock) DeadBlock(*lb);
+ }
+ gLiveBlockTable->remove(lb);
+ } else {
+ // We have no record of the block. It must be a bogus pointer, or one that
+ // DMD wasn't able to see allocated. This should be extremely rare.
+ }
+
+ if (gStackTraceTable->count() > gGCStackTraceTableWhenSizeExceeds) {
+ GCStackTraces();
+ }
+}
+
+//---------------------------------------------------------------------------
+// malloc/free interception
+//---------------------------------------------------------------------------
+
+static bool Init(malloc_table_t* aMallocTable);
+
+} // namespace dmd
+} // namespace mozilla
+
+static void* replace_malloc(size_t aSize) {
+ using namespace mozilla::dmd;
+
+ Thread* t = Thread::Fetch();
+ if (t->InterceptsAreBlocked()) {
+ // Intercepts are blocked, which means this must be a call to malloc
+ // triggered indirectly by DMD (e.g. via MozStackWalk). Be infallible.
+ return InfallibleAllocPolicy::malloc_(aSize);
+ }
+
+ // This must be a call to malloc from outside DMD. Intercept it.
+ void* ptr = gMallocTable.malloc(aSize);
+ AllocCallback(ptr, aSize, t);
+ return ptr;
+}
+
+static void* replace_calloc(size_t aCount, size_t aSize) {
+ using namespace mozilla::dmd;
+
+ Thread* t = Thread::Fetch();
+ if (t->InterceptsAreBlocked()) {
+ return InfallibleAllocPolicy::calloc_(aCount, aSize);
+ }
+
+ // |aCount * aSize| could overflow, but if that happens then
+ // |gMallocTable.calloc()| will return nullptr and |AllocCallback()| will
+ // return immediately without using the overflowed value.
+ void* ptr = gMallocTable.calloc(aCount, aSize);
+ AllocCallback(ptr, aCount * aSize, t);
+ return ptr;
+}
+
+static void* replace_realloc(void* aOldPtr, size_t aSize) {
+ using namespace mozilla::dmd;
+
+ Thread* t = Thread::Fetch();
+ if (t->InterceptsAreBlocked()) {
+ return InfallibleAllocPolicy::realloc_(aOldPtr, aSize);
+ }
+
+ // If |aOldPtr| is nullptr, the call is equivalent to |malloc(aSize)|.
+ if (!aOldPtr) {
+ return replace_malloc(aSize);
+ }
+
+ // Be very careful here! Must remove the block from the table before doing
+ // the realloc to avoid races, just like in replace_free().
+ // Nb: This does an unnecessary hashtable remove+add if the block doesn't
+ // move, but doing better isn't worth the effort.
+ DeadBlock db;
+ FreeCallback(aOldPtr, t, &db);
+ void* ptr = gMallocTable.realloc(aOldPtr, aSize);
+ if (ptr) {
+ AllocCallback(ptr, aSize, t);
+ MaybeAddToDeadBlockTable(db);
+ } else {
+ // If realloc fails, we undo the prior operations by re-inserting the old
+ // pointer into the live block table. We don't have to do anything with the
+ // dead block list because the dead block hasn't yet been inserted. The
+ // block will end up looking like it was allocated for the first time here,
+ // which is untrue, and the slop bytes will be zero, which may be untrue.
+ // But this case is rare and doing better isn't worth the effort.
+ AllocCallback(aOldPtr, gMallocTable.malloc_usable_size(aOldPtr), t);
+ }
+ return ptr;
+}
+
+static void* replace_memalign(size_t aAlignment, size_t aSize) {
+ using namespace mozilla::dmd;
+
+ Thread* t = Thread::Fetch();
+ if (t->InterceptsAreBlocked()) {
+ return InfallibleAllocPolicy::memalign_(aAlignment, aSize);
+ }
+
+ void* ptr = gMallocTable.memalign(aAlignment, aSize);
+ AllocCallback(ptr, aSize, t);
+ return ptr;
+}
+
+static void replace_free(void* aPtr) {
+ using namespace mozilla::dmd;
+
+ Thread* t = Thread::Fetch();
+ if (t->InterceptsAreBlocked()) {
+ return InfallibleAllocPolicy::free_(aPtr);
+ }
+
+ // Do the actual free after updating the table. Otherwise, another thread
+ // could call malloc and get the freed block and update the table, and then
+ // our update here would remove the newly-malloc'd block.
+ DeadBlock db;
+ FreeCallback(aPtr, t, &db);
+ MaybeAddToDeadBlockTable(db);
+ gMallocTable.free(aPtr);
+}
+
+void replace_init(malloc_table_t* aMallocTable, ReplaceMallocBridge** aBridge) {
+ if (mozilla::dmd::Init(aMallocTable)) {
+#define MALLOC_FUNCS MALLOC_FUNCS_MALLOC_BASE
+#define MALLOC_DECL(name, ...) aMallocTable->name = replace_##name;
+#include "malloc_decls.h"
+ *aBridge = mozilla::dmd::gDMDBridge;
+ }
+}
+
+namespace mozilla {
+namespace dmd {
+
+//---------------------------------------------------------------------------
+// Options (Part 2)
+//---------------------------------------------------------------------------
+
+// Given an |aOptionName| like "foo", succeed if |aArg| has the form "foo=blah"
+// (where "blah" is non-empty) and return the pointer to "blah". |aArg| can
+// have leading space chars (but not other whitespace).
+const char* Options::ValueIfMatch(const char* aArg, const char* aOptionName) {
+ MOZ_ASSERT(!isspace(*aArg)); // any leading whitespace should not remain
+ size_t optionLen = strlen(aOptionName);
+ if (strncmp(aArg, aOptionName, optionLen) == 0 && aArg[optionLen] == '=' &&
+ aArg[optionLen + 1]) {
+ return aArg + optionLen + 1;
+ }
+ return nullptr;
+}
+
+// Extracts a |long| value for an option from an argument. It must be within
+// the range |aMin..aMax| (inclusive).
+bool Options::GetLong(const char* aArg, const char* aOptionName, long aMin,
+ long aMax, long* aValue) {
+ if (const char* optionValue = ValueIfMatch(aArg, aOptionName)) {
+ char* endPtr;
+ *aValue = strtol(optionValue, &endPtr, /* base */ 10);
+ if (!*endPtr && aMin <= *aValue && *aValue <= aMax && *aValue != LONG_MIN &&
+ *aValue != LONG_MAX) {
+ return true;
+ }
+ }
+ return false;
+}
+
+// Extracts a |bool| value for an option -- encoded as "yes" or "no" -- from an
+// argument.
+bool Options::GetBool(const char* aArg, const char* aOptionName, bool* aValue) {
+ if (const char* optionValue = ValueIfMatch(aArg, aOptionName)) {
+ if (strcmp(optionValue, "yes") == 0) {
+ *aValue = true;
+ return true;
+ }
+ if (strcmp(optionValue, "no") == 0) {
+ *aValue = false;
+ return true;
+ }
+ }
+ return false;
+}
+
+Options::Options(const char* aDMDEnvVar)
+ : mDMDEnvVar(aDMDEnvVar ? InfallibleAllocPolicy::strdup_(aDMDEnvVar)
+ : nullptr),
+ mMode(Mode::DarkMatter),
+ mStacks(Stacks::Partial),
+ mShowDumpStats(false) {
+ char* e = mDMDEnvVar;
+ if (e && strcmp(e, "1") != 0) {
+ bool isEnd = false;
+ while (!isEnd) {
+ // Consume leading whitespace.
+ while (isspace(*e)) {
+ e++;
+ }
+
+ // Save the start of the arg.
+ const char* arg = e;
+
+ // Find the first char after the arg, and temporarily change it to '\0'
+ // to isolate the arg.
+ while (!isspace(*e) && *e != '\0') {
+ e++;
+ }
+ char replacedChar = *e;
+ isEnd = replacedChar == '\0';
+ *e = '\0';
+
+ // Handle arg
+ bool myBool;
+ if (strcmp(arg, "--mode=live") == 0) {
+ mMode = Mode::Live;
+ } else if (strcmp(arg, "--mode=dark-matter") == 0) {
+ mMode = Mode::DarkMatter;
+ } else if (strcmp(arg, "--mode=cumulative") == 0) {
+ mMode = Mode::Cumulative;
+ } else if (strcmp(arg, "--mode=scan") == 0) {
+ mMode = Mode::Scan;
+
+ } else if (strcmp(arg, "--stacks=full") == 0) {
+ mStacks = Stacks::Full;
+ } else if (strcmp(arg, "--stacks=partial") == 0) {
+ mStacks = Stacks::Partial;
+
+ } else if (GetBool(arg, "--show-dump-stats", &myBool)) {
+ mShowDumpStats = myBool;
+
+ } else if (strcmp(arg, "") == 0) {
+ // This can only happen if there is trailing whitespace. Ignore.
+ MOZ_ASSERT(isEnd);
+
+ } else {
+ BadArg(arg);
+ }
+
+ // Undo the temporary isolation.
+ *e = replacedChar;
+ }
+ }
+
+ if (mMode == Mode::Scan) {
+ mStacks = Stacks::Full;
+ }
+}
+
+void Options::BadArg(const char* aArg) {
+ StatusMsg("\n");
+ StatusMsg("Bad entry in the $DMD environment variable: '%s'.\n", aArg);
+ StatusMsg("See the output of |mach help run| for the allowed options.\n");
+ exit(1);
+}
+
+const char* Options::ModeString() const {
+ switch (mMode) {
+ case Mode::Live:
+ return "live";
+ case Mode::DarkMatter:
+ return "dark-matter";
+ case Mode::Cumulative:
+ return "cumulative";
+ case Mode::Scan:
+ return "scan";
+ default:
+ MOZ_ASSERT(false);
+ return "(unknown DMD mode)";
+ }
+}
+
+//---------------------------------------------------------------------------
+// DMD start-up
+//---------------------------------------------------------------------------
+
+#ifndef XP_WIN
+static void prefork() {
+ if (gStateLock) {
+ gStateLock->Lock();
+ }
+}
+
+static void postfork() {
+ if (gStateLock) {
+ gStateLock->Unlock();
+ }
+}
+#endif
+
+// WARNING: this function runs *very* early -- before all static initializers
+// have run. For this reason, non-scalar globals such as gStateLock and
+// gStackTraceTable are allocated dynamically (so we can guarantee their
+// construction in this function) rather than statically.
+static bool Init(malloc_table_t* aMallocTable) {
+ // DMD is controlled by the |DMD| environment variable.
+ const char* e = getenv("DMD");
+
+ if (!e) {
+ return false;
+ }
+ // Initialize the function table first, because StatusMsg uses
+ // InfallibleAllocPolicy::malloc_, which uses it.
+ gMallocTable = *aMallocTable;
+
+ StatusMsg("$DMD = '%s'\n", e);
+
+ gDMDBridge = InfallibleAllocPolicy::new_<DMDBridge>();
+
+#ifndef XP_WIN
+ // Avoid deadlocks when forking by acquiring our state lock prior to forking
+ // and releasing it after forking. See |LogAlloc|'s |replace_init| for
+ // in-depth details.
+ //
+ // Note: This must run after attempting an allocation so as to give the
+ // system malloc a chance to insert its own atfork handler.
+ pthread_atfork(prefork, postfork, postfork);
+#endif
+ // Parse $DMD env var.
+ gOptions = InfallibleAllocPolicy::new_<Options>(e);
+
+ gStateLock = InfallibleAllocPolicy::new_<Mutex>();
+
+ gBernoulli = (FastBernoulliTrial*)InfallibleAllocPolicy::malloc_(
+ sizeof(FastBernoulliTrial));
+ ResetBernoulli();
+
+ Thread::Init();
+
+ {
+ AutoLockState lock;
+
+ gStackTraceTable = InfallibleAllocPolicy::new_<StackTraceTable>(8192);
+ gLiveBlockTable = InfallibleAllocPolicy::new_<LiveBlockTable>(8192);
+
+ // Create this even if the mode isn't Cumulative (albeit with a small
+ // size), in case the mode is changed later on (as is done by SmokeDMD.cpp,
+ // for example).
+ size_t tableSize = gOptions->IsCumulativeMode() ? 8192 : 4;
+ gDeadBlockTable = InfallibleAllocPolicy::new_<DeadBlockTable>(tableSize);
+ }
+
+ return true;
+}
+
+//---------------------------------------------------------------------------
+// Block reporting and unreporting
+//---------------------------------------------------------------------------
+
+static void ReportHelper(const void* aPtr, bool aReportedOnAlloc) {
+ if (!gOptions->IsDarkMatterMode() || !aPtr) {
+ return;
+ }
+
+ Thread* t = Thread::Fetch();
+
+ AutoBlockIntercepts block(t);
+ AutoLockState lock;
+
+ if (LiveBlockTable::Ptr p = gLiveBlockTable->lookup(aPtr)) {
+ p->Report(t, aReportedOnAlloc);
+ } else {
+ // We have no record of the block. It must be a bogus pointer. This should
+ // be extremely rare because Report() is almost always called in
+ // conjunction with a malloc_size_of-style function. Print a message so
+ // that we get some feedback.
+ StatusMsg("Unknown pointer %p\n", aPtr);
+ }
+}
+
+void DMDFuncs::Report(const void* aPtr) {
+ ReportHelper(aPtr, /* onAlloc */ false);
+}
+
+void DMDFuncs::ReportOnAlloc(const void* aPtr) {
+ ReportHelper(aPtr, /* onAlloc */ true);
+}
+
+//---------------------------------------------------------------------------
+// DMD output
+//---------------------------------------------------------------------------
+
+// The version number of the output format. Increment this if you make
+// backwards-incompatible changes to the format. See DMD.h for the version
+// history.
+static const int kOutputVersionNumber = 5;
+
+// Note that, unlike most SizeOf* functions, this function does not take a
+// |mozilla::MallocSizeOf| argument. That's because those arguments are
+// primarily to aid DMD track heap blocks... but DMD deliberately doesn't track
+// heap blocks it allocated for itself!
+//
+// SizeOfInternal should be called while you're holding the state lock and
+// while intercepts are blocked; SizeOf acquires the lock and blocks
+// intercepts.
+
+static void SizeOfInternal(Sizes* aSizes) {
+ MOZ_ASSERT(gStateLock->IsLocked());
+ MOZ_ASSERT(Thread::Fetch()->InterceptsAreBlocked());
+
+ aSizes->Clear();
+
+ StackTraceSet usedStackTraces;
+ GatherUsedStackTraces(usedStackTraces);
+
+ for (auto iter = gStackTraceTable->iter(); !iter.done(); iter.next()) {
+ StackTrace* const& st = iter.get();
+
+ if (usedStackTraces.has(st)) {
+ aSizes->mStackTracesUsed += MallocSizeOf(st);
+ } else {
+ aSizes->mStackTracesUnused += MallocSizeOf(st);
+ }
+ }
+
+ aSizes->mStackTraceTable =
+ gStackTraceTable->shallowSizeOfIncludingThis(MallocSizeOf);
+
+ aSizes->mLiveBlockTable =
+ gLiveBlockTable->shallowSizeOfIncludingThis(MallocSizeOf);
+
+ aSizes->mDeadBlockTable =
+ gDeadBlockTable->shallowSizeOfIncludingThis(MallocSizeOf);
+}
+
+void DMDFuncs::SizeOf(Sizes* aSizes) {
+ aSizes->Clear();
+
+ AutoBlockIntercepts block(Thread::Fetch());
+ AutoLockState lock;
+ SizeOfInternal(aSizes);
+}
+
+void DMDFuncs::ClearReports() {
+ if (!gOptions->IsDarkMatterMode()) {
+ return;
+ }
+
+ AutoLockState lock;
+
+ // Unreport all blocks that were marked reported by a memory reporter. This
+ // excludes those that were reported on allocation, because they need to keep
+ // their reported marking.
+ for (auto iter = gLiveBlockTable->iter(); !iter.done(); iter.next()) {
+ iter.get().UnreportIfNotReportedOnAlloc();
+ }
+}
+
+class ToIdStringConverter final {
+ public:
+ ToIdStringConverter() : mIdMap(512), mNextId(0) {}
+
+ // Converts a pointer to a unique ID. Reuses the existing ID for the pointer
+ // if it's been seen before.
+ const char* ToIdString(const void* aPtr) {
+ uint32_t id;
+ PointerIdMap::AddPtr p = mIdMap.lookupForAdd(aPtr);
+ if (!p) {
+ id = mNextId++;
+ MOZ_ALWAYS_TRUE(mIdMap.add(p, aPtr, id));
+ } else {
+ id = p->value();
+ }
+ return Base32(id);
+ }
+
+ size_t sizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const {
+ return mIdMap.shallowSizeOfExcludingThis(aMallocSizeOf);
+ }
+
+ private:
+ // This function converts an integer to base-32. We use base-32 values for
+ // indexing into the traceTable and the frameTable, for the following reasons.
+ //
+ // - Base-32 gives more compact indices than base-16.
+ //
+ // - 32 is a power-of-two, which makes the necessary div/mod calculations
+ // fast.
+ //
+ // - We can (and do) choose non-numeric digits for base-32. When
+ // inspecting/debugging the JSON output, non-numeric indices are easier to
+ // search for than numeric indices.
+ //
+ char* Base32(uint32_t aN) {
+ static const char digits[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdef";
+
+ char* b = mIdBuf + kIdBufLen - 1;
+ *b = '\0';
+ do {
+ b--;
+ if (b == mIdBuf) {
+ MOZ_CRASH("Base32 buffer too small");
+ }
+ *b = digits[aN % 32];
+ aN /= 32;
+ } while (aN);
+
+ return b;
+ }
+
+ PointerIdMap mIdMap;
+ uint32_t mNextId;
+
+ // |mIdBuf| must have space for at least eight chars, which is the space
+ // needed to hold 'Dffffff' (including the terminating null char), which is
+ // the base-32 representation of 0xffffffff.
+ static const size_t kIdBufLen = 16;
+ char mIdBuf[kIdBufLen];
+};
+
+// Helper class for converting a pointer value to a string.
+class ToStringConverter {
+ public:
+ const char* ToPtrString(const void* aPtr) {
+ snprintf(kPtrBuf, sizeof(kPtrBuf) - 1, "%" PRIxPTR, (uintptr_t)aPtr);
+ return kPtrBuf;
+ }
+
+ private:
+ char kPtrBuf[32];
+};
+
+static void WriteBlockContents(JSONWriter& aWriter, const LiveBlock& aBlock) {
+ size_t numWords = aBlock.ReqSize() / sizeof(uintptr_t*);
+ if (numWords == 0) {
+ return;
+ }
+
+ aWriter.StartArrayProperty("contents", aWriter.SingleLineStyle);
+ {
+ const uintptr_t** block = (const uintptr_t**)aBlock.Address();
+ ToStringConverter sc;
+ for (size_t i = 0; i < numWords; ++i) {
+ aWriter.StringElement(MakeStringSpan(sc.ToPtrString(block[i])));
+ }
+ }
+ aWriter.EndArray();
+}
+
+static void AnalyzeImpl(UniquePtr<JSONWriteFunc> aWriter) {
+ // Some blocks may have been allocated while creating |aWriter|. Those blocks
+ // will be freed at the end of this function when |write| is destroyed. The
+ // allocations will have occurred while intercepts were not blocked, so the
+ // frees better be as well, otherwise we'll get assertion failures.
+ // Therefore, this declaration must precede the AutoBlockIntercepts
+ // declaration, to ensure that |write| is destroyed *after* intercepts are
+ // unblocked.
+ JSONWriter writer(std::move(aWriter));
+
+ AutoBlockIntercepts block(Thread::Fetch());
+ AutoLockState lock;
+
+ // Allocate this on the heap instead of the stack because it's fairly large.
+ auto locService = InfallibleAllocPolicy::new_<CodeAddressService>();
+
+ StackTraceSet usedStackTraces(512);
+ PointerSet usedPcs(512);
+
+ size_t iscSize;
+
+ static int analysisCount = 1;
+ StatusMsg("Dump %d {\n", analysisCount++);
+
+ writer.Start();
+ {
+ writer.IntProperty("version", kOutputVersionNumber);
+
+ writer.StartObjectProperty("invocation");
+ {
+ const char* var = gOptions->DMDEnvVar();
+ if (var) {
+ writer.StringProperty("dmdEnvVar", MakeStringSpan(var));
+ } else {
+ writer.NullProperty("dmdEnvVar");
+ }
+
+ writer.StringProperty("mode", MakeStringSpan(gOptions->ModeString()));
+ }
+ writer.EndObject();
+
+ StatusMsg(" Constructing the heap block list...\n");
+
+ ToIdStringConverter isc;
+ ToStringConverter sc;
+
+ writer.StartArrayProperty("blockList");
+ {
+ // Lambda that writes out a live block.
+ auto writeLiveBlock = [&](const LiveBlock& aB, size_t aNum) {
+ aB.AddStackTracesToTable(usedStackTraces);
+
+ MOZ_ASSERT_IF(gOptions->IsScanMode(), aNum == 1);
+
+ writer.StartObjectElement(writer.SingleLineStyle);
+ {
+ if (gOptions->IsScanMode()) {
+ writer.StringProperty("addr",
+ MakeStringSpan(sc.ToPtrString(aB.Address())));
+ WriteBlockContents(writer, aB);
+ }
+ writer.IntProperty("req", aB.ReqSize());
+ if (aB.SlopSize() > 0) {
+ writer.IntProperty("slop", aB.SlopSize());
+ }
+
+ if (aB.AllocStackTrace()) {
+ writer.StringProperty(
+ "alloc", MakeStringSpan(isc.ToIdString(aB.AllocStackTrace())));
+ }
+
+ if (gOptions->IsDarkMatterMode() && aB.NumReports() > 0) {
+ writer.StartArrayProperty("reps");
+ {
+ if (aB.ReportStackTrace1()) {
+ writer.StringElement(
+ MakeStringSpan(isc.ToIdString(aB.ReportStackTrace1())));
+ }
+ if (aB.ReportStackTrace2()) {
+ writer.StringElement(
+ MakeStringSpan(isc.ToIdString(aB.ReportStackTrace2())));
+ }
+ }
+ writer.EndArray();
+ }
+
+ if (aNum > 1) {
+ writer.IntProperty("num", aNum);
+ }
+ }
+ writer.EndObject();
+ };
+
+ // Live blocks.
+ if (!gOptions->IsScanMode()) {
+ // At this point we typically have many LiveBlocks that differ only in
+ // their address. Aggregate them to reduce the size of the output file.
+ AggregatedLiveBlockTable agg(8192);
+ for (auto iter = gLiveBlockTable->iter(); !iter.done(); iter.next()) {
+ const LiveBlock& b = iter.get();
+ b.AddStackTracesToTable(usedStackTraces);
+
+ if (AggregatedLiveBlockTable::AddPtr p = agg.lookupForAdd(&b)) {
+ p->value() += 1;
+ } else {
+ MOZ_ALWAYS_TRUE(agg.add(p, &b, 1));
+ }
+ }
+
+ // Now iterate over the aggregated table.
+ for (auto iter = agg.iter(); !iter.done(); iter.next()) {
+ const LiveBlock& b = *iter.get().key();
+ size_t num = iter.get().value();
+ writeLiveBlock(b, num);
+ }
+
+ } else {
+ // In scan mode we cannot aggregate because we print each live block's
+ // address and contents.
+ for (auto iter = gLiveBlockTable->iter(); !iter.done(); iter.next()) {
+ const LiveBlock& b = iter.get();
+ b.AddStackTracesToTable(usedStackTraces);
+
+ writeLiveBlock(b, 1);
+ }
+ }
+
+ // Dead blocks.
+ for (auto iter = gDeadBlockTable->iter(); !iter.done(); iter.next()) {
+ const DeadBlock& b = iter.get().key();
+ b.AddStackTracesToTable(usedStackTraces);
+
+ size_t num = iter.get().value();
+ MOZ_ASSERT(num > 0);
+
+ writer.StartObjectElement(writer.SingleLineStyle);
+ {
+ writer.IntProperty("req", b.ReqSize());
+ if (b.SlopSize() > 0) {
+ writer.IntProperty("slop", b.SlopSize());
+ }
+ if (b.AllocStackTrace()) {
+ writer.StringProperty(
+ "alloc", MakeStringSpan(isc.ToIdString(b.AllocStackTrace())));
+ }
+
+ if (num > 1) {
+ writer.IntProperty("num", num);
+ }
+ }
+ writer.EndObject();
+ }
+ }
+ writer.EndArray();
+
+ StatusMsg(" Constructing the stack trace table...\n");
+
+ writer.StartObjectProperty("traceTable");
+ {
+ for (auto iter = usedStackTraces.iter(); !iter.done(); iter.next()) {
+ const StackTrace* const st = iter.get();
+ writer.StartArrayProperty(MakeStringSpan(isc.ToIdString(st)),
+ writer.SingleLineStyle);
+ {
+ for (uint32_t i = 0; i < st->Length(); i++) {
+ const void* pc = st->Pc(i);
+ writer.StringElement(MakeStringSpan(isc.ToIdString(pc)));
+ MOZ_ALWAYS_TRUE(usedPcs.put(pc));
+ }
+ }
+ writer.EndArray();
+ }
+ }
+ writer.EndObject();
+
+ StatusMsg(" Constructing the stack frame table...\n");
+
+ writer.StartObjectProperty("frameTable");
+ {
+ static const size_t locBufLen = 1024;
+ char locBuf[locBufLen];
+
+ for (auto iter = usedPcs.iter(); !iter.done(); iter.next()) {
+ const void* const pc = iter.get();
+
+ // Use 0 for the frame number. See the JSON format description comment
+ // in DMD.h to understand why.
+ locService->GetLocation(0, pc, locBuf, locBufLen);
+ writer.StringProperty(MakeStringSpan(isc.ToIdString(pc)),
+ MakeStringSpan(locBuf));
+ }
+ }
+ writer.EndObject();
+
+ iscSize = isc.sizeOfExcludingThis(MallocSizeOf);
+ }
+ writer.End();
+
+ if (gOptions->ShowDumpStats()) {
+ Sizes sizes;
+ SizeOfInternal(&sizes);
+
+ static const size_t kBufLen = 64;
+ char buf1[kBufLen];
+ char buf2[kBufLen];
+ char buf3[kBufLen];
+
+ StatusMsg(" Execution measurements {\n");
+
+ StatusMsg(" Data structures that persist after Dump() ends {\n");
+
+ StatusMsg(" Used stack traces: %10s bytes\n",
+ Show(sizes.mStackTracesUsed, buf1, kBufLen));
+
+ StatusMsg(" Unused stack traces: %10s bytes\n",
+ Show(sizes.mStackTracesUnused, buf1, kBufLen));
+
+ StatusMsg(" Stack trace table: %10s bytes (%s entries, %s used)\n",
+ Show(sizes.mStackTraceTable, buf1, kBufLen),
+ Show(gStackTraceTable->capacity(), buf2, kBufLen),
+ Show(gStackTraceTable->count(), buf3, kBufLen));
+
+ StatusMsg(" Live block table: %10s bytes (%s entries, %s used)\n",
+ Show(sizes.mLiveBlockTable, buf1, kBufLen),
+ Show(gLiveBlockTable->capacity(), buf2, kBufLen),
+ Show(gLiveBlockTable->count(), buf3, kBufLen));
+
+ StatusMsg(" Dead block table: %10s bytes (%s entries, %s used)\n",
+ Show(sizes.mDeadBlockTable, buf1, kBufLen),
+ Show(gDeadBlockTable->capacity(), buf2, kBufLen),
+ Show(gDeadBlockTable->count(), buf3, kBufLen));
+
+ StatusMsg(" }\n");
+ StatusMsg(" Data structures that are destroyed after Dump() ends {\n");
+
+ StatusMsg(
+ " Location service: %10s bytes\n",
+ Show(locService->SizeOfIncludingThis(MallocSizeOf), buf1, kBufLen));
+ StatusMsg(" Used stack traces set: %10s bytes\n",
+ Show(usedStackTraces.shallowSizeOfExcludingThis(MallocSizeOf),
+ buf1, kBufLen));
+ StatusMsg(
+ " Used PCs set: %10s bytes\n",
+ Show(usedPcs.shallowSizeOfExcludingThis(MallocSizeOf), buf1, kBufLen));
+ StatusMsg(" Pointer ID map: %10s bytes\n",
+ Show(iscSize, buf1, kBufLen));
+
+ StatusMsg(" }\n");
+ StatusMsg(" Counts {\n");
+
+ size_t hits = locService->NumCacheHits();
+ size_t misses = locService->NumCacheMisses();
+ size_t requests = hits + misses;
+ StatusMsg(" Location service: %10s requests\n",
+ Show(requests, buf1, kBufLen));
+
+ size_t count = locService->CacheCount();
+ size_t capacity = locService->CacheCapacity();
+ StatusMsg(
+ " Location service cache: "
+ "%4.1f%% hit rate, %.1f%% occupancy at end\n",
+ Percent(hits, requests), Percent(count, capacity));
+
+ StatusMsg(" }\n");
+ StatusMsg(" }\n");
+ }
+
+ InfallibleAllocPolicy::delete_(locService);
+
+ StatusMsg("}\n");
+}
+
+void DMDFuncs::Analyze(UniquePtr<JSONWriteFunc> aWriter) {
+ AnalyzeImpl(std::move(aWriter));
+ ClearReports();
+}
+
+//---------------------------------------------------------------------------
+// Testing
+//---------------------------------------------------------------------------
+
+void DMDFuncs::ResetEverything(const char* aOptions) {
+ AutoLockState lock;
+
+ // Reset options.
+ InfallibleAllocPolicy::delete_(gOptions);
+ gOptions = InfallibleAllocPolicy::new_<Options>(aOptions);
+
+ // Clear all existing blocks.
+ gLiveBlockTable->clear();
+ gDeadBlockTable->clear();
+
+ // Reset gBernoulli to a deterministic state. (Its current state depends on
+ // all previous trials.)
+ ResetBernoulli();
+}
+
+} // namespace dmd
+} // namespace mozilla