gecko-dev/layout/base/nsPresArena.h

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/* -*- 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 */
#ifndef nsPresArena_h___
#define nsPresArena_h___
#include "mozilla/MemoryChecking.h"
#include "mozilla/StandardInteger.h"
#include "nscore.h"
#include "nsQueryFrame.h"
#include "nsTArray.h"
#include "nsTHashtable.h"
#include "plarena.h"
struct nsArenaMemoryStats;
class nsPresArena {
public:
nsPresArena();
~nsPresArena();
enum ObjectID {
nsLineBox_id = nsQueryFrame::NON_FRAME_MARKER,
nsRuleNode_id,
nsStyleContext_id,
nsFrameList_id,
/**
* The PresArena implementation uses this bit to distinguish objects
* allocated by size from objects allocated by type ID (that is, frames
* using AllocateByFrameID and other objects using AllocateByObjectID).
* It should not collide with any Object ID (above) or frame ID (in
* nsQueryFrame.h). It is not 0x80000000 to avoid the question of
* whether enumeration constants are signed.
*/
NON_OBJECT_MARKER = 0x40000000
};
/**
* Pool allocation with recycler lists indexed by object size, aSize.
*/
NS_HIDDEN_(void*) AllocateBySize(size_t aSize)
{
return Allocate(uint32_t(aSize) | uint32_t(NON_OBJECT_MARKER), aSize);
}
NS_HIDDEN_(void) FreeBySize(size_t aSize, void* aPtr)
{
Free(uint32_t(aSize) | uint32_t(NON_OBJECT_MARKER), aPtr);
}
/**
* Pool allocation with recycler lists indexed by frame-type ID.
* Every aID must always be used with the same object size, aSize.
*/
NS_HIDDEN_(void*) AllocateByFrameID(nsQueryFrame::FrameIID aID, size_t aSize)
{
return Allocate(aID, aSize);
}
NS_HIDDEN_(void) FreeByFrameID(nsQueryFrame::FrameIID aID, void* aPtr)
{
Free(aID, aPtr);
}
/**
* Pool allocation with recycler lists indexed by object-type ID (see above).
* Every aID must always be used with the same object size, aSize.
*/
NS_HIDDEN_(void*) AllocateByObjectID(ObjectID aID, size_t aSize)
{
return Allocate(aID, aSize);
}
NS_HIDDEN_(void) FreeByObjectID(ObjectID aID, void* aPtr)
{
Free(aID, aPtr);
}
/**
* Fill aArenaStats with sizes of interesting objects allocated in
* this arena and its mOther field with the size of everything else.
*/
void SizeOfExcludingThis(nsMallocSizeOfFun aMallocSizeOf,
nsArenaMemoryStats* aArenaStats);
private:
NS_HIDDEN_(void*) Allocate(uint32_t aCode, size_t aSize);
NS_HIDDEN_(void) Free(uint32_t aCode, void* aPtr);
// All keys to this hash table fit in 32 bits (see below) so we do not
// bother actually hashing them.
class FreeList : public PLDHashEntryHdr
{
public:
typedef uint32_t KeyType;
nsTArray<void *> mEntries;
size_t mEntrySize;
size_t mEntriesEverAllocated;
typedef const void* KeyTypePointer;
KeyTypePointer mKey;
FreeList(KeyTypePointer aKey)
: mEntrySize(0), mEntriesEverAllocated(0), mKey(aKey) {}
// Default copy constructor and destructor are ok.
bool KeyEquals(KeyTypePointer const aKey) const
{ return mKey == aKey; }
static KeyTypePointer KeyToPointer(KeyType aKey)
{ return NS_INT32_TO_PTR(aKey); }
static PLDHashNumber HashKey(KeyTypePointer aKey)
{ return NS_PTR_TO_INT32(aKey); }
enum { ALLOW_MEMMOVE = false };
};
#if defined(MOZ_HAVE_MEM_CHECKS)
static PLDHashOperator UnpoisonFreeList(FreeList* aEntry, void*);
#endif
static PLDHashOperator FreeListEnumerator(FreeList* aEntry, void* aData);
static size_t SizeOfFreeListEntryExcludingThis(FreeList* aEntry,
nsMallocSizeOfFun aMallocSizeOf,
void*);
nsTHashtable<FreeList> mFreeLists;
PLArenaPool mPool;
};
#endif