Heap profiler: implement diffing of snapshots.

include/v8-profiler.h

 // Copyright 2010 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 240 matching lines @@
   /** Returns node type (see HeapGraphNode::Type). */
   Type GetType() const;
 
   /**
    * Returns node name. Depending on node's type this can be the name
    * of the constructor (for objects), the name of the function (for
    * closures), string value, or an empty string (for compiled code).
    */
   Handle<String> GetName() const;
 
+  /**
+   * Returns node id. For the same heap object, the id remains the same
+   * across all snapshots.
+   */
+  uint64_t GetId() const;
+
   /** Returns node's own size, in bytes. */
   int GetSelfSize() const;
 
   /** Returns node's network (self + reachable nodes) size, in bytes. */
   int GetTotalSize() const;
 
   /**
    * Returns node's private size, in bytes. That is, the size of memory
    * that will be reclaimed having this node collected.
    */
@@ skipping 12 matching lines @@
   const HeapGraphEdge* GetRetainer(int index) const;
 
   /** Returns the number of simple retaining paths from the root to the node. */
   int GetRetainingPathsCount() const;
 
   /** Returns a retaining path by index. */
   const HeapGraphPath* GetRetainingPath(int index) const;
 };
 
 
+class V8EXPORT HeapSnapshotsDiff {
+ public:
+  /** Returns the root node for added nodes. */
+  const HeapGraphNode* GetAdditionsRoot() const;
+
+  /** Returns the root node for deleted nodes. */
+  const HeapGraphNode* GetDeletionsRoot() const;
+};
+
+
 /**
  * HeapSnapshots record the state of the JS heap at some moment.
  */
 class V8EXPORT HeapSnapshot {
  public:
   /** Returns heap snapshot UID (assigned by the profiler.) */
   unsigned GetUid() const;
 
   /** Returns heap snapshot title. */
   Handle<String> GetTitle() const;
 
   /** Returns the root node of the heap graph. */
-  const HeapGraphNode* GetHead() const;
+  const HeapGraphNode* GetRoot() const;
+
+  /** Returns a diff between this snapshot and another one. */
+  const HeapSnapshotsDiff* CompareWith(const HeapSnapshot* snapshot) const;
 };
 
 
 /**
  * Interface for controlling heap profiling.
  */
 class V8EXPORT HeapProfiler {
  public:
   /** Returns the number of snapshots taken. */
   static int GetSnapshotsCount();
 
   /** Returns a snapshot by index. */
   static const HeapSnapshot* GetSnapshot(int index);
 
   /** Returns a profile by uid. */
   static const HeapSnapshot* FindSnapshot(unsigned uid);
 
   /** Takes a heap snapshot and returns it. Title may be an empty string. */
   static const HeapSnapshot* TakeSnapshot(Handle<String> title);
 };
 
 
 }  // namespace v8
 
 
 #undef V8EXPORT
 
 
 #endif  // V8_V8_PROFILER_H_