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diff --git a/layout/base/nsPresArena.h b/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/ArenaObjectID.h"
+#include "mozilla/ArenaRefPtr.h"
+#include "mozilla/MemoryChecking.h" // Note: Do not remove this, needed for MOZ_HAVE_MEM_CHECKS below
+#include "mozilla/MemoryReporting.h"
+#include <stdint.h>
+#include "nscore.h"
+#include "nsDataHashtable.h"
+#include "nsHashKeys.h"
+#include "nsTArray.h"
+#include "nsTHashtable.h"
+#include "plarena.h"
+
+struct nsArenaMemoryStats;
+
+class nsPresArena {
+public:
+ nsPresArena();
+ ~nsPresArena();
+
+ /**
+ * Pool allocation with recycler lists indexed by object size, aSize.
+ */
+ void* AllocateBySize(size_t aSize)
+ {
+ return Allocate(uint32_t(aSize) |
+ uint32_t(mozilla::eArenaObjectID_NON_OBJECT_MARKER), aSize);
+ }
+ void FreeBySize(size_t aSize, void* aPtr)
+ {
+ Free(uint32_t(aSize) |
+ uint32_t(mozilla::eArenaObjectID_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.
+ */
+ void* AllocateByFrameID(nsQueryFrame::FrameIID aID, size_t aSize)
+ {
+ return Allocate(aID, aSize);
+ }
+ 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.
+ */
+ void* AllocateByObjectID(mozilla::ArenaObjectID aID, size_t aSize)
+ {
+ return Allocate(aID, aSize);
+ }
+ void FreeByObjectID(mozilla::ArenaObjectID aID, void* aPtr)
+ {
+ Free(aID, aPtr);
+ }
+
+ /**
+ * Register an ArenaRefPtr to be cleared when this arena is about to
+ * be destroyed.
+ *
+ * (Defined in ArenaRefPtrInlines.h.)
+ *
+ * @param aPtr The ArenaRefPtr to clear.
+ * @param aObjectID The ArenaObjectID value that uniquely identifies
+ * the type of object the ArenaRefPtr holds.
+ */
+ template<typename T>
+ void RegisterArenaRefPtr(mozilla::ArenaRefPtr<T>* aPtr);
+
+ /**
+ * Deregister an ArenaRefPtr that was previously registered with
+ * RegisterArenaRefPtr.
+ */
+ template<typename T>
+ void DeregisterArenaRefPtr(mozilla::ArenaRefPtr<T>* aPtr)
+ {
+ MOZ_ASSERT(mArenaRefPtrs.Contains(aPtr));
+ mArenaRefPtrs.Remove(aPtr);
+ }
+
+ /**
+ * Clears all currently registered ArenaRefPtrs. This will be called during
+ * the destructor, but can be called by users of nsPresArena who want to
+ * ensure arena-allocated objects are released earlier.
+ */
+ void ClearArenaRefPtrs();
+
+ /**
+ * Clears all currently registered ArenaRefPtrs for the given ArenaObjectID.
+ * This is called when we reconstruct the rule tree so that style contexts
+ * pointing into the old rule tree aren't released afterwards, triggering an
+ * assertion in ~nsStyleContext.
+ */
+ void ClearArenaRefPtrs(mozilla::ArenaObjectID aObjectID);
+
+ /**
+ * Increment aArenaStats with sizes of interesting objects allocated in this
+ * arena and its mOther field with the size of everything else.
+ */
+ void AddSizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf,
+ nsArenaMemoryStats* aArenaStats);
+
+private:
+ void* Allocate(uint32_t aCode, size_t aSize);
+ void Free(uint32_t aCode, void* aPtr);
+
+ inline void ClearArenaRefPtrWithoutDeregistering(
+ void* aPtr,
+ mozilla::ArenaObjectID aObjectID);
+
+ // 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;
+
+ explicit 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); }
+
+ size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const
+ { return mEntries.ShallowSizeOfExcludingThis(aMallocSizeOf); }
+
+ enum { ALLOW_MEMMOVE = false };
+ };
+
+ nsTHashtable<FreeList> mFreeLists;
+ PLArenaPool mPool;
+ nsDataHashtable<nsPtrHashKey<void>, mozilla::ArenaObjectID> mArenaRefPtrs;
+};
+
+#endif