tenfourfox/layout/base/nsPresArena.cpp

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2017-04-19 07:56:45 +00:00
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* vim: set ts=2 sw=2 et tw=78:
* 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/.
*/
/* arena allocation for the frame tree and closely-related objects */
// Even on 32-bit systems, we allocate objects from the frame arena
// that require 8-byte alignment. The cast to uintptr_t is needed
// because plarena isn't as careful about mask construction as it
// ought to be.
#define ALIGN_SHIFT 3
#define PL_ARENA_CONST_ALIGN_MASK ((uintptr_t(1) << ALIGN_SHIFT) - 1)
#include "plarena.h"
// plarena.h needs to be included first to make it use the above
// PL_ARENA_CONST_ALIGN_MASK in this file.
#include "nsPresArena.h"
#include "mozilla/Poison.h"
#include "nsDebug.h"
#include "nsArenaMemoryStats.h"
#include "nsPrintfCString.h"
#include "nsStyleContext.h"
#include <inttypes.h>
using namespace mozilla;
// Size to use for PLArena block allocations.
static const size_t ARENA_PAGE_SIZE = 8192;
nsPresArena::nsPresArena()
{
PL_INIT_ARENA_POOL(&mPool, "PresArena", ARENA_PAGE_SIZE);
}
nsPresArena::~nsPresArena()
{
ClearArenaRefPtrs();
#if defined(MOZ_HAVE_MEM_CHECKS)
for (auto iter = mFreeLists.Iter(); !iter.Done(); iter.Next()) {
FreeList* entry = iter.Get();
nsTArray<void*>::index_type len;
while ((len = entry->mEntries.Length())) {
void* result = entry->mEntries.ElementAt(len - 1);
entry->mEntries.RemoveElementAt(len - 1);
MOZ_MAKE_MEM_UNDEFINED(result, entry->mEntrySize);
}
}
#endif
PL_FinishArenaPool(&mPool);
}
/* inline */ void
nsPresArena::ClearArenaRefPtrWithoutDeregistering(void* aPtr,
ArenaObjectID aObjectID)
{
switch (aObjectID) {
#define PRES_ARENA_OBJECT_WITH_ARENAREFPTR_SUPPORT(name_) \
case eArenaObjectID_##name_: \
static_cast<ArenaRefPtr<name_>*>(aPtr)->ClearWithoutDeregistering(); \
return;
#include "nsPresArenaObjectList.h"
#undef PRES_ARENA_OBJECT_WITH_ARENAREFPTR_SUPPORT
default:
break;
}
switch (aObjectID) {
#define PRES_ARENA_OBJECT_WITHOUT_ARENAREFPTR_SUPPORT(name_) \
case eArenaObjectID_##name_: \
MOZ_ASSERT(false, #name_ " must be declared in nsPresArenaObjectList.h "\
"with PRES_ARENA_OBJECT_SUPPORTS_ARENAREFPTR"); \
break;
#include "nsPresArenaObjectList.h"
#undef PRES_ARENA_OBJECT_WITHOUT_ARENAREFPTR_SUPPORT
default:
MOZ_ASSERT(false, "unexpected ArenaObjectID value");
break;
}
}
void
nsPresArena::ClearArenaRefPtrs()
{
for (auto iter = mArenaRefPtrs.Iter(); !iter.Done(); iter.Next()) {
void* ptr = iter.Key();
ArenaObjectID id = iter.UserData();
ClearArenaRefPtrWithoutDeregistering(ptr, id);
}
mArenaRefPtrs.Clear();
}
void
nsPresArena::ClearArenaRefPtrs(ArenaObjectID aObjectID)
{
for (auto iter = mArenaRefPtrs.Iter(); !iter.Done(); iter.Next()) {
void* ptr = iter.Key();
ArenaObjectID id = iter.UserData();
if (id == aObjectID) {
ClearArenaRefPtrWithoutDeregistering(ptr, id);
iter.Remove();
}
}
}
void*
nsPresArena::Allocate(uint32_t aCode, size_t aSize)
{
MOZ_ASSERT(aSize > 0, "PresArena cannot allocate zero bytes");
// We only hand out aligned sizes
aSize = PL_ARENA_ALIGN(&mPool, aSize);
// If there is no free-list entry for this type already, we have
// to create one now, to record its size.
FreeList* list = mFreeLists.PutEntry(aCode);
nsTArray<void*>::index_type len = list->mEntries.Length();
if (list->mEntrySize == 0) {
MOZ_ASSERT(len == 0, "list with entries but no recorded size");
list->mEntrySize = aSize;
} else {
MOZ_ASSERT(list->mEntrySize == aSize,
"different sizes for same object type code");
}
void* result;
if (len > 0) {
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// Remove from the end of the mEntries array to avoid memmoving entries,
// and use SetLengthAndRetainStorage to avoid a lot of malloc/free
// from ShrinkCapacity on smaller sizes. 500 pointers means the malloc size
// for the array is 4096 bytes or more on a 64-bit system. The next smaller
// size is 2048 (with jemalloc), which we consider not worth compacting.
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result = list->mEntries.ElementAt(len - 1);
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if (list->mEntries.Capacity() > 500) {
list->mEntries.RemoveElementAt(len - 1);
} else {
list->mEntries.SetLengthAndRetainStorage(len - 1);
}
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#if defined(DEBUG)
{
MOZ_MAKE_MEM_DEFINED(result, list->mEntrySize);
char* p = reinterpret_cast<char*>(result);
char* limit = p + list->mEntrySize;
for (; p < limit; p += sizeof(uintptr_t)) {
uintptr_t val = *reinterpret_cast<uintptr_t*>(p);
if (val != mozPoisonValue()) {
MOZ_ReportAssertionFailure(
nsPrintfCString("PresArena: poison overwritten; "
"wanted %.16" PRIx64 " "
"found %.16" PRIx64 " "
"errors in bits %.16" PRIx64 " ",
uint64_t(mozPoisonValue()),
uint64_t(val),
uint64_t(mozPoisonValue() ^ val)).get(),
__FILE__, __LINE__);
MOZ_CRASH();
}
}
}
#endif
MOZ_MAKE_MEM_UNDEFINED(result, list->mEntrySize);
return result;
}
// Allocate a new chunk from the arena
list->mEntriesEverAllocated++;
PL_ARENA_ALLOCATE(result, &mPool, aSize);
if (!result) {
NS_ABORT_OOM(aSize);
}
return result;
}
void
nsPresArena::Free(uint32_t aCode, void* aPtr)
{
// Try to recycle this entry.
FreeList* list = mFreeLists.GetEntry(aCode);
MOZ_ASSERT(list, "no free list for pres arena object");
MOZ_ASSERT(list->mEntrySize > 0, "PresArena cannot free zero bytes");
mozWritePoison(aPtr, list->mEntrySize);
MOZ_MAKE_MEM_NOACCESS(aPtr, list->mEntrySize);
list->mEntries.AppendElement(aPtr);
}
void
nsPresArena::AddSizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf,
nsArenaMemoryStats* aArenaStats)
{
// We do a complicated dance here because we want to measure the
// space taken up by the different kinds of objects in the arena,
// but we don't have pointers to those objects. And even if we did,
// we wouldn't be able to use aMallocSizeOf on them, since they were
// allocated out of malloc'd chunks of memory. So we compute the
// size of the arena as known by malloc and we add up the sizes of
// all the objects that we care about. Subtracting these two
// quantities gives us a catch-all "other" number, which includes
// slop in the arena itself as well as the size of objects that
// we've not measured explicitly.
size_t mallocSize = PL_SizeOfArenaPoolExcludingPool(&mPool, aMallocSizeOf);
mallocSize += mFreeLists.SizeOfExcludingThis(aMallocSizeOf);
size_t totalSizeInFreeLists = 0;
for (auto iter = mFreeLists.Iter(); !iter.Done(); iter.Next()) {
FreeList* entry = iter.Get();
// Note that we're not measuring the size of the entries on the free
// list here. The free list knows how many objects we've allocated
// ever (which includes any objects that may be on the FreeList's
// |mEntries| at this point) and we're using that to determine the
// total size of objects allocated with a given ID.
size_t totalSize = entry->mEntrySize * entry->mEntriesEverAllocated;
size_t* p;
switch (NS_PTR_TO_INT32(entry->mKey)) {
#define FRAME_ID(classname) \
case nsQueryFrame::classname##_id: \
p = &aArenaStats->FRAME_ID_STAT_FIELD(classname); \
break;
#include "nsFrameIdList.h"
#undef FRAME_ID
case eArenaObjectID_nsLineBox:
p = &aArenaStats->mLineBoxes;
break;
case eArenaObjectID_nsRuleNode:
p = &aArenaStats->mRuleNodes;
break;
case eArenaObjectID_nsStyleContext:
p = &aArenaStats->mStyleContexts;
break;
#define STYLE_STRUCT(name_, checkdata_cb_) \
case eArenaObjectID_nsStyle##name_:
#include "nsStyleStructList.h"
#undef STYLE_STRUCT
p = &aArenaStats->mStyleStructs;
break;
default:
continue;
}
*p += totalSize;
totalSizeInFreeLists += totalSize;
}
aArenaStats->mOther += mallocSize - totalSizeInFreeLists;
}