[WIP] Added CodeEventListener to the sampler API.

include/v8.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 /** \mainpage V8 API Reference Guide
  *
  * V8 is Google's open source JavaScript engine.
  *
  * This set of documents provides reference material generated from the
  * V8 header file, include/v8.h.
  *
  * For other documentation see http://code.google.com/apis/v8/
  */
 
 #ifndef V8_H_
 #define V8_H_
 
+#include <string>
+
 #include "v8stdint.h"
 
 // We reserve the V8_* prefix for macros defined in V8 public API and
 // assume there are no name conflicts with the embedder's code.
 
 #ifdef V8_OS_WIN
 
 // Setup for Windows DLL export/import. When building the V8 DLL the
 // BUILDING_V8_SHARED needs to be defined. When building a program which uses
 // the V8 DLL USING_V8_SHARED needs to be defined. When either building the V8
@@ skipping 1262 matching lines @@
   bool IsEval() const;
 
   /**
    * Returns whether or not the associated function is called as a
    * constructor via "new".
    */
   bool IsConstructor() const;
 };
 
 
+// --- Sampler API ---
+
+
+/* TODO(gholap): This should go away and struct Sample should
+                 just use const void* instead of Address.
+                 Currently we need it because of implementation details. */
+typedef unsigned char* Address;
+
+
+/**
+ * Isolate::Getsample collects the current JS execution state as a sample.
+ * A collected sample contains,
+ * - stack       : An array of addresses.
+ *                 One address per stack frame.
+ *                 The address is the instruction pointer,
+ *                 pointing to the instruction which led to the
+ *                 creation of the stack frame.
+ *                 (for example, a function call)
+ * - frames_count: Number of stack frames that were captured.
+ *                 That is, stack[frames_count+i] might contain meaningless
+ *                 addresses for any i >= 0.
+ */
+struct V8_EXPORT Sample {
+  Sample()
+      : frames_count(0) {}
+  static const unsigned kMaxFramesCount = 255;
+
+  Address stack[kMaxFramesCount];  // Call stack.
+  unsigned frames_count;           // Number of captured frames.
+};
+
+
+/**
+ * To make sense of the PC values gotten from each sample,
+ * information like the location of compiled code for functions,
+ * whether the code ever moved from that address etc is required.
+ *
+ * Whenever v8 creates/moves/deletes code, or links a shared library,
+ * this handler will be called to notify of the code event.
+ */
+class V8_EXPORT CodeEventHandler {
+ public:
+  virtual ~CodeEventHandler() {}
+
+  /**
+   * Called when code is created.
+   * @from: The address where this newly created code begins.
+   * @size: Size of the code.
+   * @name: String representing the name of the code.
+   */
+  virtual void Create(const void* from,
+                      const int size,
+                      const std::string& name) = 0;
+
+  /**
+   * Called when code is deleted.
+   * @from: The address from where the code was deleted.
+   */
+  virtual void Delete(const void* from) = 0;
+
+  /**
+   * Called when code is moved.
+   * @from: The initial address where code was.
+   * @to: New address where the code currently resides.
+   */
+  virtual void Move(const void* from, const void* to) = 0;
+
+  /**
+   * Called when v8 loads a shared library.
+   * @library_path: Path to the shared library as a string.
+   * @start: The shared library is loaded into memory starting at this address.
+   * @end: Code beyond this address doesn't belong to the shared library.
+   */
+  virtual void SharedLibrary(const std::string& library_path,
+                             const void* start,
+                             const void* end) = 0;
+};
+
+
 /**
  * A JSON Parser.
  */
 class V8_EXPORT JSON {
  public:
   /**
    * Tries to parse the string |json_string| and returns it as value if
    * successful.
    *
    * \param json_string The string to parse.
@@ skipping 2900 matching lines @@
    * are in the range of 0 - GetNumberOfDataSlots() - 1.
    */
   V8_INLINE static uint32_t GetNumberOfDataSlots();
 
   /**
    * Get statistics about the heap memory usage.
    */
   void GetHeapStatistics(HeapStatistics* heap_statistics);
 
   /**
+   * Get a sample from the isolate.
+   */
+  void GetSample(Sample* sample);
+
+  /**
+   * Install the handler which listens to code creation/move/delete events
+   * which are needed to eventually make sense of PC values inside a sample.
+   */
+  void InstallCodeEventHandler(CodeEventHandler* handler);
+
+  /**
    * Adjusts the amount of registered external memory. Used to give V8 an
    * indication of the amount of externally allocated memory that is kept alive
    * by JavaScript objects. V8 uses this to decide when to perform global
    * garbage collections. Registering externally allocated memory will trigger
    * global garbage collections more often than it would otherwise in an attempt
    * to garbage collect the JavaScript objects that keep the externally
    * allocated memory alive.
    *
    * \param change_in_bytes the change in externally allocated memory that is
    *   kept alive by JavaScript objects.
@@ skipping 2473 matching lines @@
  */
 
 
 }  // namespace v8
 
 
 #undef TYPE_CHECK
 
 
 #endif  // V8_H_