Implement tracing interface for v8

include/v8-platform.h

 // Copyright 2013 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.
 
 #ifndef V8_V8_PLATFORM_H_
 #define V8_V8_PLATFORM_H_
 
+#include <stdint.h>
+
 namespace v8 {
 
 class Isolate;
 
 /**
  * A Task represents a unit of work.
  */
 class Task {
  public:
   virtual ~Task() {}
@@ skipping 82 matching lines @@
   }
 
   /**
    * Monotonically increasing time in seconds from an arbitrary fixed point in
    * the past. This function is expected to return at least
    * millisecond-precision values. For this reason,
    * it is recommended that the fixed point be no further in the past than
    * the epoch.
    **/
   virtual double MonotonicallyIncreasingTime() = 0;
+
+  /**
+   * Called by TRACE_EVENT* macros, don't call this directly.
+   * The name parameter is a category group for example:
+   * TRACE_EVENT0("v8,parse", "V8.Parse")
+   * The pointer returned points to a value with zero or more of the bits
+   * defined in CategoryGroupEnabledFlags.
+   **/
+  virtual const uint8_t* GetCategoryGroupEnabled(const char* name) = 0;

[jochen (gone - plz use gerrit), 2015/12/16 15:41:21]

we might also want to provide default implementations here to make it easier for
embedders to roll forward

+
+  /**
+   * Gets the category group name of the given category_enabled_flag pointer.
+   * Usually used while serliazing TRACE_EVENTs.
+   **/
+  virtual const char* GetCategoryGroupName(
+      const uint8_t* category_enabled_flag) = 0;
+
+  /**
+   * Adds a trace event to the platform tracing system. This function call is
+   * usually the result of a TRACE_* macro from trace_event_common.h when
+   * tracing and the category of the particular trace are enabled. It is not
+   * advisable to call this function on its own; it is really only meant to be
+   * used by the trace macros. The returned handle can be used by
+   * UpdateTraceEventDuration to update the duration of COMPLETE events.
+   */
+  virtual uint64_t AddTraceEvent(
+      char phase, const uint8_t* category_enabled_flag, const char* name,
+      uint64_t id, uint64_t bind_id, int32_t num_args, const char** arg_names,
+      const uint8_t* arg_types, const uint64_t* arg_values,
+      unsigned int flags) = 0;
+
+  /**
+   * Sets the duration field of a COMPLETE trace event. It must be called with
+   * the handle returned from AddTraceEvent().
+   **/
+  virtual void UpdateTraceEventDuration(const uint8_t* category_enabled_flag,
+                                        const char* name, uint64_t handle) = 0;
 };
 
 }  // namespace v8
 
 #endif  // V8_V8_PLATFORM_H_