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gecko-dev/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.
char* fmt = (char*)InfallibleAllocPolicy::malloc_(strlen(aFmt) + 64);
sprintf(fmt, "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;
DISALLOW_COPY_AND_ASSIGN(MutexBase);
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;
DISALLOW_COPY_AND_ASSIGN(Mutex);
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 {
DISALLOW_COPY_AND_ASSIGN(AutoLockState);
public:
AutoLockState() { gStateLock->Lock(); }
~AutoLockState() { gStateLock->Unlock(); }
};
class AutoUnlockState {
DISALLOW_COPY_AND_ASSIGN(AutoUnlockState);
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) {}
DISALLOW_COPY_AND_ASSIGN(Thread);
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;
DISALLOW_COPY_AND_ASSIGN(AutoBlockIntercepts);
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, /* skipFrames = */ 0, 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.
void** fp;
asm(
// Dereference %rbp to get previous %rbp
"movq (%%rbp), %0\n\t"
: "=r"(fp));
void* stackEnd = pthread_get_stackaddr_np(pthread_self());
FramePointerStackWalk(StackWalkCallback, /* skipFrames = */ 0, MaxFrames,
&tmp, fp, stackEnd);
#else
# if defined(XP_WIN) && defined(_M_X64)
int skipFrames = 1;
# else
int skipFrames = 2;
# endif
MozStackWalk(StackWalkCallback, skipFrames, 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);
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(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", var);
} else {
writer.NullProperty("dmdEnvVar");
}
writer.StringProperty("mode", 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", 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",
isc.ToIdString(aB.AllocStackTrace()));
}
if (gOptions->IsDarkMatterMode() && aB.NumReports() > 0) {
writer.StartArrayProperty("reps");
{
if (aB.ReportStackTrace1()) {
writer.StringElement(isc.ToIdString(aB.ReportStackTrace1()));
}
if (aB.ReportStackTrace2()) {
writer.StringElement(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", 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(isc.ToIdString(st), writer.SingleLineStyle);
{
for (uint32_t i = 0; i < st->Length(); i++) {
const void* pc = st->Pc(i);
writer.StringElement(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(isc.ToIdString(pc), 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
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