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 <vector>
+
 #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 "content/common/content_export.h"
 
 namespace base {
 class DiscardableSharedMemory;
 }
@@ skipping 19 matching lines @@
          size_t start,
          size_t length);
 
     base::DiscardableSharedMemory* shared_memory_;
     size_t start_;
     size_t length_;
 
     DISALLOW_COPY_AND_ASSIGN(Span);
   };
 
+  class CONTENT_EXPORT MemoryStatistics {

[Primiano Tucci (use gerrit), 2015/04/23 16:11:55]

do you really need CONTENT_EXPORT here?

[ssid, 2015/04/24 11:23:04]

No, removed.

+   public:
+    class SegmentStatistics {

[Primiano Tucci (use gerrit), 2015/04/23 16:11:55]

make this a struct and remove public:

[ssid, 2015/04/24 11:23:04]

Changed.

+     public:
+      size_t size;
+      size_t num_of_objects;
+      size_t used_size;
+    };
+
+    MemoryStatistics();
+    ~MemoryStatistics();
+
+    size_t block_size;
+    size_t total_size;
+    size_t total_objects;
+    size_t total_used_size;
+    std::vector<SegmentStatistics> segments_stats;
+  };
+
   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,
                         const base::Closure& deleted_callback);
@@ skipping 19 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;
 
+  // Fills statistics about memory used.
+  void GetMemoryStatistics(MemoryStatistics* statistics);

[reveman, 2015/04/23 17:32:30]

Why don't we just add "void DumpInto(base::trace_event::ProcessMemoryDump* pmd)"
instead of having to define and build a temporary struct+vector for this?
ChildDMM can just ask the heap instance to dump its stats...

[ssid, 2015/04/23 18:03:07]

This sounds like a good idea, since later we would have to get details about
spans, and then the api will have to change again. primiano@ WDYT?

+
  private:
   class ScopedMemorySegment {
    public:
     ScopedMemorySegment(DiscardableSharedMemoryHeap* heap,
                         scoped_ptr<base::DiscardableSharedMemory> shared_memory,
                         size_t size,
                         const base::Closure& deleted_callback);
     ~ScopedMemorySegment();
 
     bool IsUsed() const;
     bool IsResident() const;
 
+    void GetStatistics(MemoryStatistics::SegmentStatistics* segment_stats);
+
    private:
     DiscardableSharedMemoryHeap* const heap_;
     scoped_ptr<base::DiscardableSharedMemory> shared_memory_;
     const size_t size_;
     const base::Closure deleted_callback_;
 
     DISALLOW_COPY_AND_ASSIGN(ScopedMemorySegment);
   };
 
   void InsertIntoFreeList(scoped_ptr<Span> span);
@@ skipping 23 matching lines @@
   // 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_