Adding discardable memory dump provider.

content/common/discardable_shared_memory_heap.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CONTENT_COMMON_DISCARDABLE_SHARED_MEMORY_HEAP_H_
 #define CONTENT_COMMON_DISCARDABLE_SHARED_MEMORY_HEAP_H_
 
 #include "base/callback.h"
 #include "base/containers/hash_tables.h"
 #include "base/containers/linked_list.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/scoped_vector.h"
+#include "base/trace_event/process_memory_dump.h"
 #include "content/common/content_export.h"
+#include "content/common/host_discardable_shared_memory_manager.h"

[reveman, 2015/04/27 15:08:58]

nit: this might be a circular dependency in the future as the host might want to
use this class. Let's avoid it be just using int32_t below instead for now.
Ideally we'd define this somewhere else but I don't think we have to worry about
that for now.

[ssid, 2015/04/27 15:21:56]

Done.

 
 namespace base {
 class DiscardableSharedMemory;
 }
 
 namespace content {
 
 // Implements a heap of discardable shared memory. An array of free lists
 // is used to keep track of free blocks.
 class CONTENT_EXPORT DiscardableSharedMemoryHeap {
@@ skipping 22 matching lines @@
 
   explicit DiscardableSharedMemoryHeap(size_t block_size);
   ~DiscardableSharedMemoryHeap();
 
   // Grow heap using |shared_memory| and return a span for this new memory.
   // |shared_memory| must be aligned to the block size and |size| must be a
   // multiple of the block size. |deleted_callback| is called when
   // |shared_memory| has been deleted.
   scoped_ptr<Span> Grow(scoped_ptr<base::DiscardableSharedMemory> shared_memory,
                         size_t size,
+                        DiscardableSharedMemoryId id,

[reveman, 2015/04/27 15:08:58]

int32_t to avoid circular dep

[ssid, 2015/04/27 15:21:56]

Done.

                         const base::Closure& deleted_callback);
 
   // Merge |span| into the free lists. This will coalesce |span| with
   // neighboring free spans when possible.
   void MergeIntoFreeLists(scoped_ptr<Span> span);
 
   // Split an allocated span into two spans, one of length |blocks| followed
   // by another span of length "span->length - blocks" blocks. Modifies |span|
   // to point to the first span of length |blocks|. Return second span.
   scoped_ptr<Span> Split(Span* span, size_t blocks);
@@ skipping 10 matching lines @@
 
   // Release shared memory segments that have been purged.
   void ReleasePurgedMemory();
 
   // Returns total bytes of memory in heap.
   size_t GetSize() const;
 
   // Returns bytes of memory currently in the free lists.
   size_t GetSizeOfFreeLists() const;
 
+  // Dumps memory statistics for chrome://tracing.
+  bool DumpInto(base::trace_event::ProcessMemoryDump* pmd);
+
  private:
   class ScopedMemorySegment {
    public:
     ScopedMemorySegment(DiscardableSharedMemoryHeap* heap,
                         scoped_ptr<base::DiscardableSharedMemory> shared_memory,
                         size_t size,
+                        DiscardableSharedMemoryId id,

[reveman, 2015/04/27 15:08:58]

int32_t to avoid circular dep

[ssid, 2015/04/27 15:21:56]

Done.

                         const base::Closure& deleted_callback);
     ~ScopedMemorySegment();
 
     bool IsUsed() const;
     bool IsResident() const;
 
+    // Used for dumping memory statistics from the segment to chrome://tracing.
+    void DumpInto(base::trace_event::ProcessMemoryDump* pmd) const;
+
    private:
     DiscardableSharedMemoryHeap* const heap_;
     scoped_ptr<base::DiscardableSharedMemory> shared_memory_;
     const size_t size_;
+    const DiscardableSharedMemoryId id_;
     const base::Closure deleted_callback_;
 
     DISALLOW_COPY_AND_ASSIGN(ScopedMemorySegment);
   };
 
   void InsertIntoFreeList(scoped_ptr<Span> span);
   scoped_ptr<Span> RemoveFromFreeList(Span* span);
   scoped_ptr<Span> Carve(Span* span, size_t blocks);
   void RegisterSpan(Span* span);
   void UnregisterSpan(Span* span);
   bool IsMemoryUsed(const base::DiscardableSharedMemory* shared_memory,
                     size_t size);
   bool IsMemoryResident(const base::DiscardableSharedMemory* shared_memory);
   void ReleaseMemory(const base::DiscardableSharedMemory* shared_memory,
                      size_t size);
 
+  // Dumps memory statistics about a memory segment for chrome://tracing.
+  void DumpInto(const base::DiscardableSharedMemory* shared_memory,
+                size_t segment_size,

[reveman, 2015/04/27 15:08:58]

nit: s/segment_size/size/

[ssid, 2015/04/27 15:21:56]

Done.

+                DiscardableSharedMemoryId id,

[reveman, 2015/04/27 15:08:58]

int32_t to avoid circular dep

[ssid, 2015/04/27 15:21:56]

Done.

+                base::trace_event::ProcessMemoryDump* pmd);
+
   size_t block_size_;
   size_t num_blocks_;
   size_t num_free_blocks_;
 
   // Vector of memory segments.
   ScopedVector<ScopedMemorySegment> memory_segments_;
 
   // Mapping from first/last block of span to Span instance.
   typedef base::hash_map<size_t, Span*> SpanMap;
   SpanMap spans_;
 
   // Array of linked-lists with free discardable memory regions. For i < 256,
   // where the 1st entry is located at index 0 of the array, the kth entry
   // is a free list of runs that consist of k blocks. The 256th entry is a
   // free list of runs that have length >= 256 blocks.
   base::LinkedList<Span> free_spans_[256];
 
   DISALLOW_COPY_AND_ASSIGN(DiscardableSharedMemoryHeap);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_COMMON_DISCARDABLE_SHARED_MEMORY_HEAP_H_