1 files changed, 163 insertions, 0 deletions
diff --git a/layout/base/nsPresArena.h b/layout/base/nsPresArena.h
new file mode 100644
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--- /dev/null
+++ b/layout/base/nsPresArena.h
@@ -0,0 +1,163 @@
+/* -*- 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