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gecko/memory/replace/dmd/DMD.cpp
Catalin Iacob 4f03e5bb1a Bug 798914 (part 5) - Use newly introduced mozilla::MallocSizeOf instead of nsMallocSizeOfFun. r=njn. 
--HG--
extra : rebase_source : fc472490dd978d165f02f77ed37f07aed6e5bb61
2013-06-23 14:03:39 +02:00

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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 "DMD.h"
#include <ctype.h>
#include <errno.h>
#include <limits.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#ifdef XP_WIN
#include <windows.h>
#include <process.h>
#else
#include <unistd.h>
#endif
#ifdef ANDROID
#include <android/log.h>
#endif
#include "nscore.h"
#include "nsStackWalk.h"
#include "js/HashTable.h"
#include "js/Vector.h"
#include "mozilla/Assertions.h"
#include "mozilla/HashFunctions.h"
#include "mozilla/Likely.h"
#include "mozilla/MemoryReporting.h"
// MOZ_REPLACE_ONLY_MEMALIGN saves us from having to define
// replace_{posix_memalign,aligned_alloc,valloc}. It requires defining
// PAGE_SIZE. Nb: sysconf() is expensive, but it's only used for (the obsolete
// and rarely used) valloc.
#define MOZ_REPLACE_ONLY_MEMALIGN 1
#ifdef XP_WIN
#define PAGE_SIZE GetPageSize()
static long GetPageSize()
{
SYSTEM_INFO si;
GetSystemInfo(&si);
return si.dwPageSize;
}
#else
#define PAGE_SIZE sysconf(_SC_PAGESIZE)
#endif
#include "replace_malloc.h"
#undef MOZ_REPLACE_ONLY_MEMALIGN
#undef PAGE_SIZE
namespace mozilla {
namespace dmd {
//---------------------------------------------------------------------------
// Utilities
//---------------------------------------------------------------------------
#ifndef DISALLOW_COPY_AND_ASSIGN
#define DISALLOW_COPY_AND_ASSIGN(T) \
T(const T&); \
void operator=(const T&)
#endif
static const malloc_table_t* gMallocTable = nullptr;
// This enables/disables DMD.
static bool gIsDMDRunning = false;
// 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 js::{Vector,HashSet,HashMap} -- this class serves
// as their AllocPolicy.
// - Other indirect allocations (e.g. NS_StackWalk) -- see the comments on
// Thread::mBlockIntercepts and in replace_malloc for how these work.
//
class InfallibleAllocPolicy
{
static void ExitOnFailure(const void* aP);
public:
static void* malloc_(size_t aSize)
{
void* p = gMallocTable->malloc(aSize);
ExitOnFailure(p);
return p;
}
static void* calloc_(size_t aSize)
{
void* p = gMallocTable->calloc(1, aSize);
ExitOnFailure(p);
return p;
}
// This realloc_ is the one we use for direct reallocs within DMD.
static void* realloc_(void* aPtr, size_t aNewSize)
{
void* p = gMallocTable->realloc(aPtr, aNewSize);
ExitOnFailure(p);
return p;
}
// This realloc_ is required for this to be a JS container AllocPolicy.
static void* realloc_(void* aPtr, size_t aOldSize, size_t aNewSize)
{
return InfallibleAllocPolicy::realloc_(aPtr, aNewSize);
}
static void* memalign_(size_t aAlignment, size_t aSize)
{
void* p = gMallocTable->memalign(aAlignment, aSize);
ExitOnFailure(p);
return p;
}
static void free_(void* aPtr) { 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));
ExitOnFailure(mem);
return new (mem) T;
}
template <class T, typename P1>
static T* new_(P1 p1)
{
void* mem = malloc_(sizeof(T));
ExitOnFailure(mem);
return new (mem) T(p1);
}
template <class T>
static void delete_(T *p)
{
if (p) {
p->~T();
InfallibleAllocPolicy::free_(p);
}
}
static void reportAllocOverflow() { ExitOnFailure(nullptr); }
};
// 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));
}
static void
StatusMsg(const char* aFmt, ...)
{
va_list ap;
va_start(ap, aFmt);
#ifdef ANDROID
__android_log_vprint(ANDROID_LOG_INFO, "DMD", aFmt, ap);
#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, ap);
InfallibleAllocPolicy::free_(fmt);
#endif
va_end(ap);
}
/* static */ void
InfallibleAllocPolicy::ExitOnFailure(const void* aP)
{
if (!aP) {
StatusMsg("out of memory; aborting\n");
MOZ_CRASH();
}
}
void
Writer::Write(const char* aFmt, ...) const
{
va_list ap;
va_start(ap, aFmt);
mWriterFun(mWriteState, aFmt, ap);
va_end(ap);
}
#define W(...) aWriter.Write(__VA_ARGS__);
#define WriteTitle(...) \
W("------------------------------------------------------------------\n"); \
W(__VA_ARGS__); \
W("------------------------------------------------------------------\n\n");
MOZ_EXPORT void
FpWrite(void* aWriteState, const char* aFmt, va_list aAp)
{
FILE* fp = static_cast<FILE*>(aWriteState);
vfprintf(fp, aFmt, aAp);
}
static double
Percent(size_t part, size_t whole)
{
return (whole == 0) ? 0 : 100 * (double)part / whole;
}
// Commifies the number and prepends a '~' if requested. Best used with
// |kBufLen| and |gBuf[1234]|, because they should be big enough for any number
// we'll see.
static char*
Show(size_t n, char* buf, size_t buflen, bool addTilde = false)
{
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;
if (addTilde) {
firstCharIndex--;
buf[firstCharIndex] = '~';
}
MOZ_ASSERT(firstCharIndex >= 0);
return &buf[firstCharIndex];
}
static const char*
Plural(size_t aN)
{
return aN == 1 ? "" : "s";
}
// Used by calls to Show().
static const size_t kBufLen = 64;
static char gBuf1[kBufLen];
static char gBuf2[kBufLen];
static char gBuf3[kBufLen];
static char gBuf4[kBufLen];
//---------------------------------------------------------------------------
// 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)
{}
};
enum Mode {
Normal, // run normally
Test, // do some basic correctness tests
Stress // do some performance stress tests
};
char* mDMDEnvVar; // a saved copy, for printing during Dump()
NumOption<size_t> mSampleBelowSize;
NumOption<uint32_t> mMaxFrames;
NumOption<uint32_t> mMaxRecords;
Mode mMode;
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* aN);
public:
Options(const char* aDMDEnvVar);
const char* DMDEnvVar() const { return mDMDEnvVar; }
size_t SampleBelowSize() const { return mSampleBelowSize.mActual; }
size_t MaxFrames() const { return mMaxFrames.mActual; }
size_t MaxRecords() const { return mMaxRecords.mActual; }
void SetSampleBelowSize(size_t aN) { mSampleBelowSize.mActual = aN; }
bool IsTestMode() const { return mMode == Test; }
bool IsStressMode() const { return mMode == Stress; }
};
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
#include <pthread.h>
#include <sys/types.h>
class MutexBase
{
pthread_mutex_t mMutex;
DISALLOW_COPY_AND_ASSIGN(MutexBase);
public:
MutexBase()
{
pthread_mutex_init(&mMutex, NULL);
}
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, gBlockTable, etc.
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();
}
};
//---------------------------------------------------------------------------
// Thread-local storage and blocking of intercepts
//---------------------------------------------------------------------------
#ifdef XP_WIN
#define DMD_TLS_INDEX_TYPE DWORD
#define DMD_CREATE_TLS_INDEX(i_) do { \
(i_) = TlsAlloc(); \
} while (0)
#define DMD_DESTROY_TLS_INDEX(i_) TlsFree((i_))
#define DMD_GET_TLS_DATA(i_) TlsGetValue((i_))
#define DMD_SET_TLS_DATA(i_, v_) TlsSetValue((i_), (v_))
#else
#include <pthread.h>
#define DMD_TLS_INDEX_TYPE pthread_key_t
#define DMD_CREATE_TLS_INDEX(i_) pthread_key_create(&(i_), nullptr)
#define DMD_DESTROY_TLS_INDEX(i_) pthread_key_delete((i_))
#define DMD_GET_TLS_DATA(i_) pthread_getspecific((i_))
#define DMD_SET_TLS_DATA(i_, v_) pthread_setspecific((i_), (v_))
#endif
static DMD_TLS_INDEX_TYPE gTlsIndex;
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 NS_StackWalk.)
bool mBlockIntercepts;
Thread()
: mBlockIntercepts(false)
{}
DISALLOW_COPY_AND_ASSIGN(Thread);
public:
static Thread* Fetch();
bool BlockIntercepts()
{
MOZ_ASSERT(!mBlockIntercepts);
return mBlockIntercepts = true;
}
bool UnblockIntercepts()
{
MOZ_ASSERT(mBlockIntercepts);
return mBlockIntercepts = false;
}
bool InterceptsAreBlocked() const
{
return mBlockIntercepts;
}
};
/* static */ Thread*
Thread::Fetch()
{
Thread* t = static_cast<Thread*>(DMD_GET_TLS_DATA(gTlsIndex));
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>();
DMD_SET_TLS_DATA(gTlsIndex, t);
}
return t;
}
// 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:
AutoBlockIntercepts(Thread* aT)
: mT(aT)
{
mT->BlockIntercepts();
}
~AutoBlockIntercepts()
{
MOZ_ASSERT(mT->InterceptsAreBlocked());
mT->UnblockIntercepts();
}
};
//---------------------------------------------------------------------------
// Location service
//---------------------------------------------------------------------------
// This class is used to print details about code locations.
class LocationService
{
// WriteLocation() is the key function in this class. It's basically a
// wrapper around NS_DescribeCodeAddress.
//
// However, NS_DescribeCodeAddress is very slow on some platforms, and we
// have lots of repeated (i.e. same PC) calls to it. So we do some caching
// of results. Each cached result includes two strings (|mFunction| and
// |mLibrary|), so we also optimize them for space in the following ways.
//
// - The number of distinct library names is small, e.g. a few dozen. There
// is lots of repetition, especially of libxul. So we intern them in their
// own table, which saves space over duplicating them for each cache entry.
//
// - The number of distinct function names is much higher, so we duplicate
// them in each cache entry. That's more space-efficient than interning
// because entries containing single-occurrence function names are quickly
// overwritten, and their copies released. In addition, empty function
// names are common, so we use nullptr to represent them compactly.
struct StringHasher
{
typedef const char* Lookup;
static uint32_t hash(const char* const& aS)
{
return HashString(aS);
}
static bool match(const char* const& aA, const char* const& aB)
{
return strcmp(aA, aB) == 0;
}
};
typedef js::HashSet<const char*, StringHasher, InfallibleAllocPolicy>
StringTable;
StringTable mLibraryStrings;
struct Entry
{
static const void* const kUnused;
const void* mPc; // if mPc==kUnused, the entry is unused
char* mFunction; // owned by the Entry; may be null
const char* mLibrary; // owned by mLibraryStrings; never null
// in a non-empty entry is in use
ptrdiff_t mLOffset;
Entry()
: mPc(kUnused), mFunction(nullptr), mLibrary(nullptr), mLOffset(0)
{}
~Entry()
{
// We don't free mLibrary because it's externally owned.
InfallibleAllocPolicy::free_(mFunction);
}
void Replace(const void* aPc, const char* aFunction, const char* aLibrary,
ptrdiff_t aLOffset)
{
mPc = aPc;
// Convert "" to nullptr. Otherwise, make a copy of the name.
InfallibleAllocPolicy::free_(mFunction);
mFunction =
!aFunction[0] ? nullptr : InfallibleAllocPolicy::strdup_(aFunction);
mLibrary = aLibrary;
mLOffset = aLOffset;
}
size_t SizeOfExcludingThis() {
// Don't measure mLibrary because it's externally owned.
return MallocSizeOf(mFunction);
}
};
// A direct-mapped cache. When doing a dump just after starting desktop
// Firefox (which is similar to dumping after a longer-running session,
// thanks to the limit on how many records we dump), a cache with 2^24
// entries (which approximates an infinite-entry cache) has a ~91% hit rate.
// A cache with 2^12 entries has a ~83% hit rate, and takes up ~85 KiB (on
// 32-bit platforms) or ~150 KiB (on 64-bit platforms).
static const size_t kNumEntries = 1 << 12;
static const size_t kMask = kNumEntries - 1;
Entry mEntries[kNumEntries];
size_t mNumCacheHits;
size_t mNumCacheMisses;
public:
LocationService()
: mEntries(), mNumCacheHits(0), mNumCacheMisses(0)
{
(void)mLibraryStrings.init(64);
}
void WriteLocation(const Writer& aWriter, const void* aPc)
{
MOZ_ASSERT(gStateLock->IsLocked());
uint32_t index = HashGeneric(aPc) & kMask;
MOZ_ASSERT(index < kNumEntries);
Entry& entry = mEntries[index];
MOZ_ASSERT(aPc != Entry::kUnused);
if (entry.mPc != aPc) {
mNumCacheMisses++;
// NS_DescribeCodeAddress can (on Linux) acquire a lock inside
// the shared library loader. Another thread might call malloc
// while holding that lock (when loading a shared library). So
// we have to exit gStateLock around this call. For details, see
// https://bugzilla.mozilla.org/show_bug.cgi?id=363334#c3
nsCodeAddressDetails details;
{
AutoUnlockState unlock;
(void)NS_DescribeCodeAddress(const_cast<void*>(aPc), &details);
}
// Intern the library name.
const char* library = nullptr;
StringTable::AddPtr p = mLibraryStrings.lookupForAdd(details.library);
if (!p) {
library = InfallibleAllocPolicy::strdup_(details.library);
(void)mLibraryStrings.add(p, library);
} else {
library = *p;
}
entry.Replace(aPc, details.function, library, details.loffset);
} else {
mNumCacheHits++;
}
MOZ_ASSERT(entry.mPc == aPc);
// Sometimes we get nothing useful. Just print "???" for the entire entry
// so that fix-linux-stack.pl doesn't complain about an empty filename.
if (!entry.mFunction && !entry.mLibrary[0] && entry.mLOffset == 0) {
W(" ??? %p\n", entry.mPc);
} else {
// Use "???" for unknown functions.
W(" %s[%s +0x%X] %p\n", entry.mFunction ? entry.mFunction : "???",
entry.mLibrary, entry.mLOffset, entry.mPc);
}
}
size_t SizeOfIncludingThis()
{
size_t n = MallocSizeOf(this);
for (uint32_t i = 0; i < kNumEntries; i++) {
n += mEntries[i].SizeOfExcludingThis();
}
n += mLibraryStrings.sizeOfExcludingThis(MallocSizeOf);
for (StringTable::Range r = mLibraryStrings.all();
!r.empty();
r.popFront()) {
n += MallocSizeOf(r.front());
}
return n;
}
size_t CacheCapacity() const { return kNumEntries; }
size_t CacheCount() const
{
size_t n = 0;
for (size_t i = 0; i < kNumEntries; i++) {
if (mEntries[i].mPc != Entry::kUnused) {
n++;
}
}
return n;
}
size_t NumCacheHits() const { return mNumCacheHits; }
size_t NumCacheMisses() const { return mNumCacheMisses; }
};
// We can't use 0 because that sometimes shows up as a PC in stack traces.
const void* const LocationService::Entry::kUnused =
reinterpret_cast<const void* const>(intptr_t(-1));
//---------------------------------------------------------------------------
// Stack traces
//---------------------------------------------------------------------------
class StackTrace
{
public:
static const uint32_t MaxFrames = 24;
private:
uint32_t mLength; // The number of PCs.
void* mPcs[MaxFrames]; // The PCs themselves. If --max-frames is less
// than 24, this array is bigger than necessary,
// but that case is unusual.
public:
StackTrace() : mLength(0) {}
uint32_t Length() const { return mLength; }
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);
void Sort()
{
qsort(mPcs, mLength, sizeof(mPcs[0]), StackTrace::QsortCmp);
}
void Print(const Writer& aWriter, LocationService* aLocService) const;
// Hash policy.
typedef StackTrace* Lookup;
static uint32_t 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(void* aPc, void* aSp, void* aClosure)
{
StackTrace* st = (StackTrace*) aClosure;
MOZ_ASSERT(st->mLength < MaxFrames);
st->mPcs[st->mLength] = aPc;
st->mLength++;
}
static int QsortCmp(const void* aA, const void* aB)
{
const void* const a = *static_cast<const void* const*>(aA);
const void* const b = *static_cast<const void* const*>(aB);
if (a < b) return -1;
if (a > b) return 1;
return 0;
}
};
typedef js::HashSet<StackTrace*, StackTrace, InfallibleAllocPolicy>
StackTraceTable;
static StackTraceTable* gStackTraceTable = nullptr;
// We won't GC the stack trace table until it this many elements.
static uint32_t gGCStackTraceTableWhenSizeExceeds = 4 * 1024;
void
StackTrace::Print(const Writer& aWriter, LocationService* aLocService) const
{
if (mLength == 0) {
W(" (empty)\n"); // StackTrace::Get() must have failed
return;
}
for (uint32_t i = 0; i < mLength; i++) {
aLocService->WriteLocation(aWriter, Pc(i));
}
}
/* static */ const StackTrace*
StackTrace::Get(Thread* aT)
{
MOZ_ASSERT(gStateLock->IsLocked());
MOZ_ASSERT(aT->InterceptsAreBlocked());
// On Windows, NS_StackWalk 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 NS_StackWalk. 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.
nsresult rv;
StackTrace tmp;
{
AutoUnlockState unlock;
uint32_t skipFrames = 2;
rv = NS_StackWalk(StackWalkCallback, skipFrames,
gOptions->MaxFrames(), &tmp, 0, nullptr);
}
if (rv == NS_OK) {
// Handle the common case first. All is ok. Nothing to do.
} else if (rv == NS_ERROR_NOT_IMPLEMENTED || rv == NS_ERROR_FAILURE) {
tmp.mLength = 0;
} else if (rv == NS_ERROR_UNEXPECTED) {
// XXX: This |rv| only happens on Mac, and it indicates that we're handling
// a call to malloc that happened inside a mutex-handling function. Any
// attempt to create a semaphore (which can happen in printf) could
// deadlock.
//
// However, the most complex thing DMD does after Get() returns is to put
// something in a hash table, which might call
// InfallibleAllocPolicy::malloc_. I'm not yet sure if this needs special
// handling, hence the forced abort. Sorry. If you hit this, please file
// a bug and CC nnethercote.
MOZ_CRASH();
} else {
MOZ_CRASH(); // should be impossible
}
StackTraceTable::AddPtr p = gStackTraceTable->lookupForAdd(&tmp);
if (!p) {
StackTrace* stnew = InfallibleAllocPolicy::new_<StackTrace>(tmp);
(void)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.
class Block
{
const void* mPtr;
const size_t mReqSize; // size requested
// Ptr: |mAllocStackTrace| - stack trace where this block was allocated.
// Tag bit 0: |mSampled| - was this block sampled? (if so, slop == 0).
TaggedPtr<const StackTrace* const>
mAllocStackTrace_mSampled;
// 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 Dump().
// Only relevant if |mReportStackTrace| is non-nullptr.
//
// |mPtr| is used as the key in BlockTable, so it's ok for this member
// to be |mutable|.
mutable TaggedPtr<const StackTrace*> mReportStackTrace_mReportedOnAlloc[2];
public:
Block(const void* aPtr, size_t aReqSize, const StackTrace* aAllocStackTrace,
bool aSampled)
: mPtr(aPtr),
mReqSize(aReqSize),
mAllocStackTrace_mSampled(aAllocStackTrace, aSampled),
mReportStackTrace_mReportedOnAlloc() // all fields get zeroed
{
MOZ_ASSERT(aAllocStackTrace);
}
size_t ReqSize() const { return mReqSize; }
// Sampled blocks always have zero slop.
size_t SlopSize() const
{
return IsSampled() ? 0 : MallocSizeOf(mPtr) - mReqSize;
}
size_t UsableSize() const
{
return IsSampled() ? mReqSize : MallocSizeOf(mPtr);
}
bool IsSampled() const
{
return mAllocStackTrace_mSampled.Tag();
}
const StackTrace* AllocStackTrace() const
{
return mAllocStackTrace_mSampled.Ptr();
}
const StackTrace* ReportStackTrace1() const {
return mReportStackTrace_mReportedOnAlloc[0].Ptr();
}
const StackTrace* ReportStackTrace2() const {
return mReportStackTrace_mReportedOnAlloc[1].Ptr();
}
bool ReportedOnAlloc1() const {
return mReportStackTrace_mReportedOnAlloc[0].Tag();
}
bool ReportedOnAlloc2() const {
return mReportStackTrace_mReportedOnAlloc[1].Tag();
}
uint32_t NumReports() const {
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
{
// 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
{
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 uint32_t hash(const void* const& aPtr)
{
return mozilla::HashGeneric(aPtr);
}
static bool match(const Block& aB, const void* const& aPtr)
{
return aB.mPtr == aPtr;
}
};
typedef js::HashSet<Block, Block, InfallibleAllocPolicy> BlockTable;
static BlockTable* gBlockTable = nullptr;
typedef js::HashSet<const StackTrace*, js::DefaultHasher<const StackTrace*>,
InfallibleAllocPolicy>
StackTraceSet;
// 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.finish();
aStackTraces.init(1024);
for (BlockTable::Range r = gBlockTable->all(); !r.empty(); r.popFront()) {
const Block& b = r.front();
aStackTraces.put(b.AllocStackTrace());
aStackTraces.put(b.ReportStackTrace1());
aStackTraces.put(b.ReportStackTrace2());
}
// Any of the stack traces added above may have been null. For the sake of
// cleanliness, don't leave the null pointer in the set.
aStackTraces.remove(nullptr);
}
// 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 Enum destructor
// will automatically rehash and compact the table.
for (StackTraceTable::Enum e(*gStackTraceTable);
!e.empty();
e.popFront()) {
StackTrace* const& st = e.front();
if (!usedStackTraces.has(st)) {
e.removeFront();
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 size_t gSmallBlockActualSizeCounter = 0;
static void
AllocCallback(void* aPtr, size_t aReqSize, Thread* aT)
{
MOZ_ASSERT(gIsDMDRunning);
if (!aPtr) {
return;
}
AutoLockState lock;
AutoBlockIntercepts block(aT);
size_t actualSize = gMallocTable->malloc_usable_size(aPtr);
size_t sampleBelowSize = gOptions->SampleBelowSize();
if (actualSize < sampleBelowSize) {
// If this allocation is smaller than the sample-below size, increment the
// cumulative counter. Then, if that counter now exceeds the sample size,
// blame this allocation for |sampleBelowSize| bytes. This precludes the
// measurement of slop.
gSmallBlockActualSizeCounter += actualSize;
if (gSmallBlockActualSizeCounter >= sampleBelowSize) {
gSmallBlockActualSizeCounter -= sampleBelowSize;
Block b(aPtr, sampleBelowSize, StackTrace::Get(aT), /* sampled */ true);
(void)gBlockTable->putNew(aPtr, b);
}
} else {
// If this block size is larger than the sample size, record it exactly.
Block b(aPtr, aReqSize, StackTrace::Get(aT), /* sampled */ false);
(void)gBlockTable->putNew(aPtr, b);
}
}
static void
FreeCallback(void* aPtr, Thread* aT)
{
MOZ_ASSERT(gIsDMDRunning);
if (!aPtr) {
return;
}
AutoLockState lock;
AutoBlockIntercepts block(aT);
gBlockTable->remove(aPtr);
if (gStackTraceTable->count() > gGCStackTraceTableWhenSizeExceeds) {
GCStackTraces();
}
}
//---------------------------------------------------------------------------
// malloc/free interception
//---------------------------------------------------------------------------
static void Init(const malloc_table_t* aMallocTable);
} // namespace dmd
} // namespace mozilla
void
replace_init(const malloc_table_t* aMallocTable)
{
mozilla::dmd::Init(aMallocTable);
}
void*
replace_malloc(size_t aSize)
{
using namespace mozilla::dmd;
if (!gIsDMDRunning) {
// DMD hasn't started up, either because it wasn't enabled by the user, or
// we're still in Init() and something has indirectly called malloc. Do a
// vanilla malloc. (In the latter case, if it fails we'll crash. But
// OOM is highly unlikely so early on.)
return gMallocTable->malloc(aSize);
}
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 NS_StackWalk). 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;
}
void*
replace_calloc(size_t aCount, size_t aSize)
{
using namespace mozilla::dmd;
if (!gIsDMDRunning) {
return gMallocTable->calloc(aCount, aSize);
}
Thread* t = Thread::Fetch();
if (t->InterceptsAreBlocked()) {
return InfallibleAllocPolicy::calloc_(aCount * aSize);
}
void* ptr = gMallocTable->calloc(aCount, aSize);
AllocCallback(ptr, aCount * aSize, t);
return ptr;
}
void*
replace_realloc(void* aOldPtr, size_t aSize)
{
using namespace mozilla::dmd;
if (!gIsDMDRunning) {
return gMallocTable->realloc(aOldPtr, aSize);
}
Thread* t = Thread::Fetch();
if (t->InterceptsAreBlocked()) {
return InfallibleAllocPolicy::realloc_(aOldPtr, aSize);
}
// If |aOldPtr| is NULL, 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.
FreeCallback(aOldPtr, t);
void* ptr = gMallocTable->realloc(aOldPtr, aSize);
if (ptr) {
AllocCallback(ptr, aSize, t);
} else {
// If realloc fails, we re-insert the old pointer. It will look 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;
}
void*
replace_memalign(size_t aAlignment, size_t aSize)
{
using namespace mozilla::dmd;
if (!gIsDMDRunning) {
return gMallocTable->memalign(aAlignment, aSize);
}
Thread* t = Thread::Fetch();
if (t->InterceptsAreBlocked()) {
return InfallibleAllocPolicy::memalign_(aAlignment, aSize);
}
void* ptr = gMallocTable->memalign(aAlignment, aSize);
AllocCallback(ptr, aSize, t);
return ptr;
}
void
replace_free(void* aPtr)
{
using namespace mozilla::dmd;
if (!gIsDMDRunning) {
gMallocTable->free(aPtr);
return;
}
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.
FreeCallback(aPtr, t);
gMallocTable->free(aPtr);
}
namespace mozilla {
namespace dmd {
//---------------------------------------------------------------------------
// Stack trace records
//---------------------------------------------------------------------------
class TraceRecordKey
{
public:
const StackTrace* const mAllocStackTrace; // never null
protected:
const StackTrace* const mReportStackTrace1; // nullptr if unreported
const StackTrace* const mReportStackTrace2; // nullptr if not 2x-reported
public:
TraceRecordKey(const Block& aB)
: mAllocStackTrace(aB.AllocStackTrace()),
mReportStackTrace1(aB.ReportStackTrace1()),
mReportStackTrace2(aB.ReportStackTrace2())
{
MOZ_ASSERT(mAllocStackTrace);
}
// Hash policy.
typedef TraceRecordKey Lookup;
static uint32_t hash(const TraceRecordKey& aKey)
{
return mozilla::HashGeneric(aKey.mAllocStackTrace,
aKey.mReportStackTrace1,
aKey.mReportStackTrace2);
}
static bool match(const TraceRecordKey& aA, const TraceRecordKey& aB)
{
return aA.mAllocStackTrace == aB.mAllocStackTrace &&
aA.mReportStackTrace1 == aB.mReportStackTrace1 &&
aA.mReportStackTrace2 == aB.mReportStackTrace2;
}
};
class RecordSize
{
static const size_t kReqBits = sizeof(size_t) * 8 - 1; // 31 or 63
size_t mReq; // size requested
size_t mSlop:kReqBits; // slop bytes
size_t mSampled:1; // were one or more blocks contributing to this
// RecordSize sampled?
public:
RecordSize()
: mReq(0),
mSlop(0),
mSampled(false)
{}
size_t Req() const { return mReq; }
size_t Slop() const { return mSlop; }
size_t Usable() const { return mReq + mSlop; }
bool IsSampled() const { return mSampled; }
void Add(const Block& aB)
{
mReq += aB.ReqSize();
mSlop += aB.SlopSize();
mSampled = mSampled || aB.IsSampled();
}
void Add(const RecordSize& aRecordSize)
{
mReq += aRecordSize.Req();
mSlop += aRecordSize.Slop();
mSampled = mSampled || aRecordSize.IsSampled();
}
static int Cmp(const RecordSize& aA, const RecordSize& aB)
{
// Primary sort: put bigger usable sizes first.
if (aA.Usable() > aB.Usable()) return -1;
if (aA.Usable() < aB.Usable()) return 1;
// Secondary sort: put bigger requested sizes first.
if (aA.Req() > aB.Req()) return -1;
if (aA.Req() < aB.Req()) return 1;
// Tertiary sort: put non-sampled records before sampled records.
if (!aA.mSampled && aB.mSampled) return -1;
if ( aA.mSampled && !aB.mSampled) return 1;
return 0;
}
};
// A collection of one or more heap blocks with a common TraceRecordKey.
class TraceRecord : public TraceRecordKey
{
// The TraceRecordKey base class serves as the key in TraceRecordTables.
// These two fields constitute the value, so it's ok for them to be
// |mutable|.
mutable uint32_t mNumBlocks; // number of blocks with this TraceRecordKey
mutable RecordSize mRecordSize; // combined size of those blocks
public:
explicit TraceRecord(const TraceRecordKey& aKey)
: TraceRecordKey(aKey),
mNumBlocks(0),
mRecordSize()
{}
uint32_t NumBlocks() const { return mNumBlocks; }
const RecordSize& GetRecordSize() const { return mRecordSize; }
// This is |const| thanks to the |mutable| fields above.
void Add(const Block& aB) const
{
mNumBlocks++;
mRecordSize.Add(aB);
}
// For PrintSortedRecords.
static const char* const kRecordKind;
static bool recordsOverlap() { return false; }
void Print(const Writer& aWriter, LocationService* aLocService,
uint32_t aM, uint32_t aN, const char* aStr, const char* astr,
size_t aCategoryUsableSize, size_t aCumulativeUsableSize,
size_t aTotalUsableSize) const;
static int QsortCmp(const void* aA, const void* aB)
{
const TraceRecord* const a = *static_cast<const TraceRecord* const*>(aA);
const TraceRecord* const b = *static_cast<const TraceRecord* const*>(aB);
return RecordSize::Cmp(a->mRecordSize, b->mRecordSize);
}
};
const char* const TraceRecord::kRecordKind = "trace";
typedef js::HashSet<TraceRecord, TraceRecord, InfallibleAllocPolicy>
TraceRecordTable;
void
TraceRecord::Print(const Writer& aWriter, LocationService* aLocService,
uint32_t aM, uint32_t aN, const char* aStr, const char* astr,
size_t aCategoryUsableSize, size_t aCumulativeUsableSize,
size_t aTotalUsableSize) const
{
bool showTilde = mRecordSize.IsSampled();
W("%s: %s block%s in stack trace record %s of %s\n",
aStr,
Show(mNumBlocks, gBuf1, kBufLen, showTilde), Plural(mNumBlocks),
Show(aM, gBuf2, kBufLen),
Show(aN, gBuf3, kBufLen));
W(" %s bytes (%s requested / %s slop)\n",
Show(mRecordSize.Usable(), gBuf1, kBufLen, showTilde),
Show(mRecordSize.Req(), gBuf2, kBufLen, showTilde),
Show(mRecordSize.Slop(), gBuf3, kBufLen, showTilde));
W(" %4.2f%% of the heap (%4.2f%% cumulative); "
" %4.2f%% of %s (%4.2f%% cumulative)\n",
Percent(mRecordSize.Usable(), aTotalUsableSize),
Percent(aCumulativeUsableSize, aTotalUsableSize),
Percent(mRecordSize.Usable(), aCategoryUsableSize),
astr,
Percent(aCumulativeUsableSize, aCategoryUsableSize));
W(" Allocated at\n");
mAllocStackTrace->Print(aWriter, aLocService);
if (mReportStackTrace1) {
W("\n Reported at\n");
mReportStackTrace1->Print(aWriter, aLocService);
}
if (mReportStackTrace2) {
W("\n Reported again at\n");
mReportStackTrace2->Print(aWriter, aLocService);
}
W("\n");
}
//---------------------------------------------------------------------------
// Stack frame records
//---------------------------------------------------------------------------
// A collection of one or more stack frames (from heap block allocation stack
// traces) with a common PC.
class FrameRecord
{
// mPc is used as the key in FrameRecordTable, and the other members
// constitute the value, so it's ok for them to be |mutable|.
const void* const mPc;
mutable size_t mNumBlocks;
mutable size_t mNumTraceRecords;
mutable RecordSize mRecordSize;
public:
explicit FrameRecord(const void* aPc)
: mPc(aPc),
mNumBlocks(0),
mNumTraceRecords(0),
mRecordSize()
{}
const RecordSize& GetRecordSize() const { return mRecordSize; }
// This is |const| thanks to the |mutable| fields above.
void Add(const TraceRecord& aTr) const
{
mNumBlocks += aTr.NumBlocks();
mNumTraceRecords++;
mRecordSize.Add(aTr.GetRecordSize());
}
void Print(const Writer& aWriter, LocationService* aLocService,
uint32_t aM, uint32_t aN, const char* aStr, const char* astr,
size_t aCategoryUsableSize, size_t aCumulativeUsableSize,
size_t aTotalUsableSize) const;
static int QsortCmp(const void* aA, const void* aB)
{
const FrameRecord* const a = *static_cast<const FrameRecord* const*>(aA);
const FrameRecord* const b = *static_cast<const FrameRecord* const*>(aB);
return RecordSize::Cmp(a->mRecordSize, b->mRecordSize);
}
// For PrintSortedRecords.
static const char* const kRecordKind;
static bool recordsOverlap() { return true; }
// Hash policy.
typedef const void* Lookup;
static uint32_t hash(const void* const& aPc)
{
return mozilla::HashGeneric(aPc);
}
static bool match(const FrameRecord& aFr, const void* const& aPc)
{
return aFr.mPc == aPc;
}
};
const char* const FrameRecord::kRecordKind = "frame";
typedef js::HashSet<FrameRecord, FrameRecord, InfallibleAllocPolicy>
FrameRecordTable;
void
FrameRecord::Print(const Writer& aWriter, LocationService* aLocService,
uint32_t aM, uint32_t aN, const char* aStr, const char* astr,
size_t aCategoryUsableSize, size_t aCumulativeUsableSize,
size_t aTotalUsableSize) const
{
(void)aCumulativeUsableSize;
bool showTilde = mRecordSize.IsSampled();
W("%s: %s block%s from %s stack trace record%s in stack frame record %s of %s\n",
aStr,
Show(mNumBlocks, gBuf1, kBufLen, showTilde), Plural(mNumBlocks),
Show(mNumTraceRecords, gBuf2, kBufLen, showTilde), Plural(mNumTraceRecords),
Show(aM, gBuf3, kBufLen),
Show(aN, gBuf4, kBufLen));
W(" %s bytes (%s requested / %s slop)\n",
Show(mRecordSize.Usable(), gBuf1, kBufLen, showTilde),
Show(mRecordSize.Req(), gBuf2, kBufLen, showTilde),
Show(mRecordSize.Slop(), gBuf3, kBufLen, showTilde));
W(" %4.2f%% of the heap; %4.2f%% of %s\n",
Percent(mRecordSize.Usable(), aTotalUsableSize),
Percent(mRecordSize.Usable(), aCategoryUsableSize),
astr);
W(" PC is\n");
aLocService->WriteLocation(aWriter, mPc);
W("\n");
}
//---------------------------------------------------------------------------
// 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* aN)
{
if (const char* optionValue = ValueIfMatch(aArg, aOptionName)) {
char* endPtr;
*aN = strtol(optionValue, &endPtr, /* base */ 10);
if (!*endPtr && aMin <= *aN && *aN <= aMax &&
*aN != LONG_MIN && *aN != LONG_MAX) {
return true;
}
}
return false;
}
// The sample-below default is a prime number close to 4096.
// - Why that size? Because it's *much* faster but only moderately less precise
// than a size of 1.
// - Why prime? Because it makes our sampling more random. If we used a size
// of 4096, for example, then our alloc counter would only take on even
// values, because jemalloc always rounds up requests sizes. In contrast, a
// prime size will explore all possible values of the alloc counter.
//
Options::Options(const char* aDMDEnvVar)
: mDMDEnvVar(InfallibleAllocPolicy::strdup_(aDMDEnvVar)),
mSampleBelowSize(4093, 100 * 100 * 1000),
mMaxFrames(StackTrace::MaxFrames, StackTrace::MaxFrames),
mMaxRecords(1000, 1000000),
mMode(Normal)
{
char* e = mDMDEnvVar;
if (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
long myLong;
if (GetLong(arg, "--sample-below", 1, mSampleBelowSize.mMax, &myLong)) {
mSampleBelowSize.mActual = myLong;
} else if (GetLong(arg, "--max-frames", 1, mMaxFrames.mMax, &myLong)) {
mMaxFrames.mActual = myLong;
} else if (GetLong(arg, "--max-records", 1, mMaxRecords.mMax, &myLong)) {
mMaxRecords.mActual = myLong;
} else if (strcmp(arg, "--mode=normal") == 0) {
mMode = Options::Normal;
} else if (strcmp(arg, "--mode=test") == 0) {
mMode = Options::Test;
} else if (strcmp(arg, "--mode=stress") == 0) {
mMode = Options::Stress;
} 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;
}
}
}
void
Options::BadArg(const char* aArg)
{
StatusMsg("\n");
StatusMsg("Bad entry in the $DMD environment variable: '%s'.\n", aArg);
StatusMsg("\n");
StatusMsg("Valid values of $DMD are:\n");
StatusMsg("- undefined or \"\" or \"0\", which disables DMD, or\n");
StatusMsg("- \"1\", which enables it with the default options, or\n");
StatusMsg("- a whitespace-separated list of |--option=val| entries, which\n");
StatusMsg(" enables it with non-default options.\n");
StatusMsg("\n");
StatusMsg("The following options are allowed; defaults are shown in [].\n");
StatusMsg(" --sample-below=<1..%d> Sample blocks smaller than this [%d]\n",
int(mSampleBelowSize.mMax),
int(mSampleBelowSize.mDefault));
StatusMsg(" (prime numbers are recommended)\n");
StatusMsg(" --max-frames=<1..%d> Max. depth of stack traces [%d]\n",
int(mMaxFrames.mMax),
int(mMaxFrames.mDefault));
StatusMsg(" --max-records=<1..%u> Max. number of records printed [%u]\n",
mMaxRecords.mMax,
mMaxRecords.mDefault);
StatusMsg(" --mode=<normal|test|stress> Mode of operation [normal]\n");
StatusMsg("\n");
exit(1);
}
//---------------------------------------------------------------------------
// DMD start-up
//---------------------------------------------------------------------------
#ifdef XP_MACOSX
static void
NopStackWalkCallback(void* aPc, void* aSp, void* aClosure)
{
}
#endif
// Note that fopen() can allocate.
static FILE*
OpenOutputFile(const char* aFilename)
{
FILE* fp = fopen(aFilename, "w");
if (!fp) {
StatusMsg("can't create %s file: %s\n", aFilename, strerror(errno));
exit(1);
}
return fp;
}
static void RunTestMode(FILE* fp);
static void RunStressMode(FILE* fp);
// 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 void
Init(const malloc_table_t* aMallocTable)
{
MOZ_ASSERT(!gIsDMDRunning);
gMallocTable = aMallocTable;
// DMD is controlled by the |DMD| environment variable.
// - If it's unset or empty or "0", DMD doesn't run.
// - Otherwise, the contents dictate DMD's behaviour.
char* e = getenv("DMD");
StatusMsg("$DMD = '%s'\n", e);
if (!e || strcmp(e, "") == 0 || strcmp(e, "0") == 0) {
StatusMsg("DMD is not enabled\n");
return;
}
// Parse $DMD env var.
gOptions = InfallibleAllocPolicy::new_<Options>(e);
StatusMsg("DMD is enabled\n");
#ifdef XP_MACOSX
// On Mac OS X we need to call StackWalkInitCriticalAddress() very early
// (prior to the creation of any mutexes, apparently) otherwise we can get
// hangs when getting stack traces (bug 821577). But
// StackWalkInitCriticalAddress() isn't exported from xpcom/, so instead we
// just call NS_StackWalk, because that calls StackWalkInitCriticalAddress().
// See the comment above StackWalkInitCriticalAddress() for more details.
(void)NS_StackWalk(NopStackWalkCallback, /* skipFrames */ 0,
/* maxFrames */ 1, nullptr, 0, nullptr);
#endif
gStateLock = InfallibleAllocPolicy::new_<Mutex>();
gSmallBlockActualSizeCounter = 0;
DMD_CREATE_TLS_INDEX(gTlsIndex);
gStackTraceTable = InfallibleAllocPolicy::new_<StackTraceTable>();
gStackTraceTable->init(8192);
gBlockTable = InfallibleAllocPolicy::new_<BlockTable>();
gBlockTable->init(8192);
if (gOptions->IsTestMode()) {
// OpenOutputFile() can allocate. So do this before setting
// gIsDMDRunning so those allocations don't show up in our results. Once
// gIsDMDRunning is set we are intercepting malloc et al. in earnest.
FILE* fp = OpenOutputFile("test.dmd");
gIsDMDRunning = true;
StatusMsg("running test mode...\n");
RunTestMode(fp);
StatusMsg("finished test mode\n");
fclose(fp);
exit(0);
}
if (gOptions->IsStressMode()) {
FILE* fp = OpenOutputFile("stress.dmd");
gIsDMDRunning = true;
StatusMsg("running stress mode...\n");
RunStressMode(fp);
StatusMsg("finished stress mode\n");
fclose(fp);
exit(0);
}
gIsDMDRunning = true;
}
//---------------------------------------------------------------------------
// DMD reporting and unreporting
//---------------------------------------------------------------------------
static void
ReportHelper(const void* aPtr, bool aReportedOnAlloc)
{
if (!gIsDMDRunning || !aPtr) {
return;
}
Thread* t = Thread::Fetch();
AutoBlockIntercepts block(t);
AutoLockState lock;
if (BlockTable::Ptr p = gBlockTable->lookup(aPtr)) {
p->Report(t, aReportedOnAlloc);
} else {
// We have no record of the block. Do nothing. Either:
// - We're sampling and we skipped this block. This is likely.
// - It's a bogus pointer. This is unlikely because Report() is almost
// always called in conjunction with a malloc_size_of-style function.
}
}
MOZ_EXPORT void
Report(const void* aPtr)
{
ReportHelper(aPtr, /* onAlloc */ false);
}
MOZ_EXPORT void
ReportOnAlloc(const void* aPtr)
{
ReportHelper(aPtr, /* onAlloc */ true);
}
//---------------------------------------------------------------------------
// DMD output
//---------------------------------------------------------------------------
// This works for both TraceRecords and StackFrameRecords.
template <class Record>
static void
PrintSortedRecords(const Writer& aWriter, LocationService* aLocService,
const char* aStr, const char* astr,
const js::HashSet<Record, Record, InfallibleAllocPolicy>&
aRecordTable,
size_t aCategoryUsableSize, size_t aTotalUsableSize)
{
const char* kind = Record::kRecordKind;
StatusMsg(" creating and sorting %s stack %s record array...\n", astr, kind);
// Convert the table into a sorted array.
js::Vector<const Record*, 0, InfallibleAllocPolicy> recordArray;
recordArray.reserve(aRecordTable.count());
typedef js::HashSet<Record, Record, InfallibleAllocPolicy> RecordTable;
for (typename RecordTable::Range r = aRecordTable.all();
!r.empty();
r.popFront()) {
recordArray.infallibleAppend(&r.front());
}
qsort(recordArray.begin(), recordArray.length(), sizeof(recordArray[0]),
Record::QsortCmp);
WriteTitle("%s stack %s records\n", aStr, kind);
if (recordArray.length() == 0) {
W("(none)\n\n");
return;
}
StatusMsg(" printing %s stack %s record array...\n", astr, kind);
size_t cumulativeUsableSize = 0;
// Limit the number of records printed, because fix-linux-stack.pl is too
// damn slow. Note that we don't break out of this loop because we need to
// keep adding to |cumulativeUsableSize|.
uint32_t numRecords = recordArray.length();
uint32_t maxRecords = gOptions->MaxRecords();
for (uint32_t i = 0; i < numRecords; i++) {
const Record* r = recordArray[i];
cumulativeUsableSize += r->GetRecordSize().Usable();
if (i < maxRecords) {
r->Print(aWriter, aLocService, i+1, numRecords, aStr, astr,
aCategoryUsableSize, cumulativeUsableSize, aTotalUsableSize);
} else if (i == maxRecords) {
W("%s: stopping after %s stack %s records\n\n", aStr,
Show(maxRecords, gBuf1, kBufLen), kind);
}
}
// This holds for TraceRecords, but not for FrameRecords.
MOZ_ASSERT_IF(!Record::recordsOverlap(),
aCategoryUsableSize == cumulativeUsableSize);
}
static void
PrintSortedTraceAndFrameRecords(const Writer& aWriter,
LocationService* aLocService,
const char* aStr, const char* astr,
const TraceRecordTable& aTraceRecordTable,
size_t aCategoryUsableSize,
size_t aTotalUsableSize)
{
PrintSortedRecords(aWriter, aLocService, aStr, astr, aTraceRecordTable,
aCategoryUsableSize, aTotalUsableSize);
FrameRecordTable frameRecordTable;
(void)frameRecordTable.init(2048);
for (TraceRecordTable::Range r = aTraceRecordTable.all();
!r.empty();
r.popFront()) {
const TraceRecord& tr = r.front();
const StackTrace* st = tr.mAllocStackTrace;
// A single PC can appear multiple times in a stack trace. We ignore
// duplicates by first sorting and then ignoring adjacent duplicates.
StackTrace sorted(*st);
sorted.Sort(); // sorts the copy, not the original
void* prevPc = (void*)intptr_t(-1);
for (uint32_t i = 0; i < sorted.Length(); i++) {
void* pc = sorted.Pc(i);
if (pc == prevPc) {
continue; // ignore duplicate
}
prevPc = pc;
FrameRecordTable::AddPtr p = frameRecordTable.lookupForAdd(pc);
if (!p) {
FrameRecord fr(pc);
(void)frameRecordTable.add(p, fr);
}
p->Add(tr);
}
}
PrintSortedRecords(aWriter, aLocService, aStr, astr, frameRecordTable,
aCategoryUsableSize, aTotalUsableSize);
}
// 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();
if (!gIsDMDRunning) {
return;
}
StackTraceSet usedStackTraces;
GatherUsedStackTraces(usedStackTraces);
for (StackTraceTable::Range r = gStackTraceTable->all();
!r.empty();
r.popFront()) {
StackTrace* const& st = r.front();
if (usedStackTraces.has(st)) {
aSizes->mStackTracesUsed += MallocSizeOf(st);
} else {
aSizes->mStackTracesUnused += MallocSizeOf(st);
}
}
aSizes->mStackTraceTable =
gStackTraceTable->sizeOfIncludingThis(MallocSizeOf);
aSizes->mBlockTable = gBlockTable->sizeOfIncludingThis(MallocSizeOf);
}
MOZ_EXPORT void
SizeOf(Sizes* aSizes)
{
aSizes->Clear();
if (!gIsDMDRunning) {
return;
}
AutoBlockIntercepts block(Thread::Fetch());
AutoLockState lock;
SizeOfInternal(aSizes);
}
MOZ_EXPORT void
ClearReports()
{
if (!gIsDMDRunning) {
return;
}
// 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 (BlockTable::Range r = gBlockTable->all(); !r.empty(); r.popFront()) {
r.front().UnreportIfNotReportedOnAlloc();
}
}
MOZ_EXPORT void
Dump(Writer aWriter)
{
if (!gIsDMDRunning) {
const char* msg = "cannot Dump(); DMD was not enabled at startup\n";
StatusMsg("%s", msg);
W("%s", msg);
return;
}
AutoBlockIntercepts block(Thread::Fetch());
AutoLockState lock;
static int dumpCount = 1;
StatusMsg("Dump %d {\n", dumpCount++);
StatusMsg(" gathering stack trace records...\n");
TraceRecordTable unreportedTraceRecordTable;
(void)unreportedTraceRecordTable.init(1024);
size_t unreportedUsableSize = 0;
size_t unreportedNumBlocks = 0;
TraceRecordTable onceReportedTraceRecordTable;
(void)onceReportedTraceRecordTable.init(1024);
size_t onceReportedUsableSize = 0;
size_t onceReportedNumBlocks = 0;
TraceRecordTable twiceReportedTraceRecordTable;
(void)twiceReportedTraceRecordTable.init(0);
size_t twiceReportedUsableSize = 0;
size_t twiceReportedNumBlocks = 0;
bool anyBlocksSampled = false;
for (BlockTable::Range r = gBlockTable->all(); !r.empty(); r.popFront()) {
const Block& b = r.front();
TraceRecordTable* table;
uint32_t numReports = b.NumReports();
if (numReports == 0) {
unreportedUsableSize += b.UsableSize();
unreportedNumBlocks++;
table = &unreportedTraceRecordTable;
} else if (numReports == 1) {
onceReportedUsableSize += b.UsableSize();
onceReportedNumBlocks++;
table = &onceReportedTraceRecordTable;
} else {
MOZ_ASSERT(numReports == 2);
twiceReportedUsableSize += b.UsableSize();
twiceReportedNumBlocks++;
table = &twiceReportedTraceRecordTable;
}
TraceRecordKey key(b);
TraceRecordTable::AddPtr p = table->lookupForAdd(key);
if (!p) {
TraceRecord tr(b);
(void)table->add(p, tr);
}
p->Add(b);
anyBlocksSampled = anyBlocksSampled || b.IsSampled();
}
size_t totalUsableSize =
unreportedUsableSize + onceReportedUsableSize + twiceReportedUsableSize;
size_t totalNumBlocks =
unreportedNumBlocks + onceReportedNumBlocks + twiceReportedNumBlocks;
WriteTitle("Invocation\n");
W("$DMD = '%s'\n", gOptions->DMDEnvVar());
W("Sample-below size = %lld\n\n",
(long long)(gOptions->SampleBelowSize()));
// Allocate this on the heap instead of the stack because it's fairly large.
LocationService* locService = InfallibleAllocPolicy::new_<LocationService>();
PrintSortedRecords(aWriter, locService, "Twice-reported", "twice-reported",
twiceReportedTraceRecordTable, twiceReportedUsableSize,
totalUsableSize);
PrintSortedTraceAndFrameRecords(aWriter, locService,
"Unreported", "unreported",
unreportedTraceRecordTable,
unreportedUsableSize, totalUsableSize);
PrintSortedTraceAndFrameRecords(aWriter, locService,
"Once-reported", "once-reported",
onceReportedTraceRecordTable,
onceReportedUsableSize, totalUsableSize);
bool showTilde = anyBlocksSampled;
WriteTitle("Summary\n");
W("Total: %12s bytes (%6.2f%%) in %7s blocks (%6.2f%%)\n",
Show(totalUsableSize, gBuf1, kBufLen, showTilde),
100.0,
Show(totalNumBlocks, gBuf2, kBufLen, showTilde),
100.0);
W("Unreported: %12s bytes (%6.2f%%) in %7s blocks (%6.2f%%)\n",
Show(unreportedUsableSize, gBuf1, kBufLen, showTilde),
Percent(unreportedUsableSize, totalUsableSize),
Show(unreportedNumBlocks, gBuf2, kBufLen, showTilde),
Percent(unreportedNumBlocks, totalNumBlocks));
W("Once-reported: %12s bytes (%6.2f%%) in %7s blocks (%6.2f%%)\n",
Show(onceReportedUsableSize, gBuf1, kBufLen, showTilde),
Percent(onceReportedUsableSize, totalUsableSize),
Show(onceReportedNumBlocks, gBuf2, kBufLen, showTilde),
Percent(onceReportedNumBlocks, totalNumBlocks));
W("Twice-reported: %12s bytes (%6.2f%%) in %7s blocks (%6.2f%%)\n",
Show(twiceReportedUsableSize, gBuf1, kBufLen, showTilde),
Percent(twiceReportedUsableSize, totalUsableSize),
Show(twiceReportedNumBlocks, gBuf2, kBufLen, showTilde),
Percent(twiceReportedNumBlocks, totalNumBlocks));
W("\n");
// Stats are non-deterministic, so don't show them in test mode.
if (!gOptions->IsTestMode()) {
Sizes sizes;
SizeOfInternal(&sizes);
WriteTitle("Execution measurements\n");
W("Data structures that persist after Dump() ends:\n");
W(" Used stack traces: %10s bytes\n",
Show(sizes.mStackTracesUsed, gBuf1, kBufLen));
W(" Unused stack traces: %10s bytes\n",
Show(sizes.mStackTracesUnused, gBuf1, kBufLen));
W(" Stack trace table: %10s bytes (%s entries, %s used)\n",
Show(sizes.mStackTraceTable, gBuf1, kBufLen),
Show(gStackTraceTable->capacity(), gBuf2, kBufLen),
Show(gStackTraceTable->count(), gBuf3, kBufLen));
W(" Block table: %10s bytes (%s entries, %s used)\n",
Show(sizes.mBlockTable, gBuf1, kBufLen),
Show(gBlockTable->capacity(), gBuf2, kBufLen),
Show(gBlockTable->count(), gBuf3, kBufLen));
W("\nData structures that are destroyed after Dump() ends:\n");
size_t unreportedSize =
unreportedTraceRecordTable.sizeOfIncludingThis(MallocSizeOf);
W(" Unreported table: %10s bytes (%s entries, %s used)\n",
Show(unreportedSize, gBuf1, kBufLen),
Show(unreportedTraceRecordTable.capacity(), gBuf2, kBufLen),
Show(unreportedTraceRecordTable.count(), gBuf3, kBufLen));
size_t onceReportedSize =
onceReportedTraceRecordTable.sizeOfIncludingThis(MallocSizeOf);
W(" Once-reported table: %10s bytes (%s entries, %s used)\n",
Show(onceReportedSize, gBuf1, kBufLen),
Show(onceReportedTraceRecordTable.capacity(), gBuf2, kBufLen),
Show(onceReportedTraceRecordTable.count(), gBuf3, kBufLen));
size_t twiceReportedSize =
twiceReportedTraceRecordTable.sizeOfIncludingThis(MallocSizeOf);
W(" Twice-reported table: %10s bytes (%s entries, %s used)\n",
Show(twiceReportedSize, gBuf1, kBufLen),
Show(twiceReportedTraceRecordTable.capacity(), gBuf2, kBufLen),
Show(twiceReportedTraceRecordTable.count(), gBuf3, kBufLen));
W(" Location service: %10s bytes\n",
Show(locService->SizeOfIncludingThis(), gBuf1, kBufLen));
W("\nCounts:\n");
size_t hits = locService->NumCacheHits();
size_t misses = locService->NumCacheMisses();
size_t requests = hits + misses;
W(" Location service: %10s requests\n",
Show(requests, gBuf1, kBufLen));
size_t count = locService->CacheCount();
size_t capacity = locService->CacheCapacity();
W(" Location service cache: %4.1f%% hit rate, %.1f%% occupancy at end\n",
Percent(hits, requests), Percent(count, capacity));
W("\n");
}
InfallibleAllocPolicy::delete_(locService);
ClearReports();
StatusMsg("}\n");
}
//---------------------------------------------------------------------------
// Testing
//---------------------------------------------------------------------------
// This function checks that heap blocks that have the same stack trace but
// different (or no) reporters get aggregated separately.
void foo()
{
char* a[6];
for (int i = 0; i < 6; i++) {
a[i] = (char*) malloc(128 - 16*i);
}
for (int i = 0; i <= 1; i++)
Report(a[i]); // reported
Report(a[2]); // reported
Report(a[3]); // reported
// a[4], a[5] unreported
}
// This stops otherwise-unused variables from being optimized away.
static void
UseItOrLoseIt(void* a)
{
if (a == 0) {
fprintf(stderr, "UseItOrLoseIt: %p\n", a);
}
}
// The output from this should be compared against test-expected.dmd. It's
// been tested on Linux64, and probably will give different results on other
// platforms.
static void
RunTestMode(FILE* fp)
{
Writer writer(FpWrite, fp);
// The first part of this test requires sampling to be disabled.
gOptions->SetSampleBelowSize(1);
// 0th Dump. Zero for everything.
Dump(writer);
// 1st Dump: 1 freed, 9 out of 10 unreported.
// 2nd Dump: still present and unreported.
int i;
char* a;
for (i = 0; i < 10; i++) {
a = (char*) malloc(100);
UseItOrLoseIt(a);
}
free(a);
// Min-sized block.
// 1st Dump: reported.
// 2nd Dump: thrice-reported.
char* a2 = (char*) malloc(0);
Report(a2);
// Operator new[].
// 1st Dump: reported.
// 2nd Dump: reportedness carries over, due to ReportOnAlloc.
char* b = new char[10];
ReportOnAlloc(b);
// ReportOnAlloc, then freed.
// 1st Dump: freed, irrelevant.
// 2nd Dump: freed, irrelevant.
char* b2 = new char;
ReportOnAlloc(b2);
free(b2);
// 1st Dump: reported 4 times.
// 2nd Dump: freed, irrelevant.
char* c = (char*) calloc(10, 3);
Report(c);
for (int i = 0; i < 3; i++) {
Report(c);
}
// 1st Dump: ignored.
// 2nd Dump: irrelevant.
Report((void*)(intptr_t)i);
// jemalloc rounds this up to 8192.
// 1st Dump: reported.
// 2nd Dump: freed.
char* e = (char*) malloc(4096);
e = (char*) realloc(e, 4097);
Report(e);
// First realloc is like malloc; second realloc is shrinking.
// 1st Dump: reported.
// 2nd Dump: re-reported.
char* e2 = (char*) realloc(nullptr, 1024);
e2 = (char*) realloc(e2, 512);
Report(e2);
// First realloc is like malloc; second realloc creates a min-sized block.
// XXX: on Windows, second realloc frees the block.
// 1st Dump: reported.
// 2nd Dump: freed, irrelevant.
char* e3 = (char*) realloc(nullptr, 1023);
//e3 = (char*) realloc(e3, 0);
MOZ_ASSERT(e3);
Report(e3);
// 1st Dump: freed, irrelevant.
// 2nd Dump: freed, irrelevant.
char* f = (char*) malloc(64);
free(f);
// 1st Dump: ignored.
// 2nd Dump: irrelevant.
Report((void*)(intptr_t)0x0);
// 1st Dump: mixture of reported and unreported.
// 2nd Dump: all unreported.
foo();
foo();
// 1st Dump: twice-reported.
// 2nd Dump: twice-reported.
char* g1 = (char*) malloc(77);
ReportOnAlloc(g1);
ReportOnAlloc(g1);
// 1st Dump: twice-reported.
// 2nd Dump: once-reported.
char* g2 = (char*) malloc(78);
Report(g2);
ReportOnAlloc(g2);
// 1st Dump: twice-reported.
// 2nd Dump: once-reported.
char* g3 = (char*) malloc(79);
ReportOnAlloc(g3);
Report(g3);
// All the odd-ball ones.
// 1st Dump: all unreported.
// 2nd Dump: all freed, irrelevant.
// XXX: no memalign on Mac
//void* x = memalign(64, 65); // rounds up to 128
//UseItOrLoseIt(x);
// XXX: posix_memalign doesn't work on B2G
//void* y;
//posix_memalign(&y, 128, 129); // rounds up to 256
//UseItOrLoseIt(y);
// XXX: valloc doesn't work on Windows.
//void* z = valloc(1); // rounds up to 4096
//UseItOrLoseIt(z);
//aligned_alloc(64, 256); // XXX: C11 only
// 1st Dump.
Dump(writer);
//---------
Report(a2);
Report(a2);
free(c);
free(e);
Report(e2);
free(e3);
//free(x);
//free(y);
//free(z);
// 2nd Dump.
Dump(writer);
//---------
// Clear all knowledge of existing blocks to give us a clean slate.
gBlockTable->clear();
gOptions->SetSampleBelowSize(128);
char* s;
// This equals the sample size, and so is reported exactly. It should be
// listed before records of the same size that are sampled.
s = (char*) malloc(128);
UseItOrLoseIt(s);
// This exceeds the sample size, and so is reported exactly.
s = (char*) malloc(144);
UseItOrLoseIt(s);
// These together constitute exactly one sample.
for (int i = 0; i < 16; i++) {
s = (char*) malloc(8);
UseItOrLoseIt(s);
}
MOZ_ASSERT(gSmallBlockActualSizeCounter == 0);
// These fall 8 bytes short of a full sample.
for (int i = 0; i < 15; i++) {
s = (char*) malloc(8);
UseItOrLoseIt(s);
}
MOZ_ASSERT(gSmallBlockActualSizeCounter == 120);
// This exceeds the sample size, and so is recorded exactly.
s = (char*) malloc(256);
UseItOrLoseIt(s);
MOZ_ASSERT(gSmallBlockActualSizeCounter == 120);
// This gets more than to a full sample from the |i < 15| loop above.
s = (char*) malloc(96);
UseItOrLoseIt(s);
MOZ_ASSERT(gSmallBlockActualSizeCounter == 88);
// This gets to another full sample.
for (int i = 0; i < 5; i++) {
s = (char*) malloc(8);
UseItOrLoseIt(s);
}
MOZ_ASSERT(gSmallBlockActualSizeCounter == 0);
// This allocates 16, 32, ..., 128 bytes, which results in a stack trace
// record that contains a mix of sample and non-sampled blocks, and so should
// be printed with '~' signs.
for (int i = 1; i <= 8; i++) {
s = (char*) malloc(i * 16);
UseItOrLoseIt(s);
}
MOZ_ASSERT(gSmallBlockActualSizeCounter == 64);
// At the end we're 64 bytes into the current sample so we report ~1,424
// bytes of allocation overall, which is 64 less than the real value 1,488.
Dump(writer);
}
//---------------------------------------------------------------------------
// Stress testing microbenchmark
//---------------------------------------------------------------------------
MOZ_NEVER_INLINE static void
stress5()
{
for (int i = 0; i < 10; i++) {
void* x = malloc(64);
UseItOrLoseIt(x);
if (i & 1) {
free(x);
}
}
}
MOZ_NEVER_INLINE static void
stress4()
{
stress5(); stress5(); stress5(); stress5(); stress5();
stress5(); stress5(); stress5(); stress5(); stress5();
}
MOZ_NEVER_INLINE static void
stress3()
{
for (int i = 0; i < 10; i++) {
stress4();
}
}
MOZ_NEVER_INLINE static void
stress2()
{
stress3(); stress3(); stress3(); stress3(); stress3();
stress3(); stress3(); stress3(); stress3(); stress3();
}
MOZ_NEVER_INLINE static void
stress1()
{
for (int i = 0; i < 10; i++) {
stress2();
}
}
// This stress test does lots of allocations and frees, which is where most of
// DMD's overhead occurs. It allocates 1,000,000 64-byte blocks, spread evenly
// across 1,000 distinct stack traces. It frees every second one immediately
// after allocating it.
//
// It's highly artificial, but it's deterministic and easy to run. It can be
// timed under different conditions to glean performance data.
static void
RunStressMode(FILE* fp)
{
Writer writer(FpWrite, fp);
// Disable sampling for maximum stress.
gOptions->SetSampleBelowSize(1);
stress1(); stress1(); stress1(); stress1(); stress1();
stress1(); stress1(); stress1(); stress1(); stress1();
Dump(writer);
}
} // namespace dmd
} // namespace mozilla
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