Implement tracing interface for v8

include/v8-tracing.h

+// Copyright 2015 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 INCLUDE_V8_TRACING_H_
+#define INCLUDE_V8_TRACING_H_
+
+#include <stdint.h>
+
+namespace v8 {
+
+// This will mark the trace event as disabled by default. The user will need
+// to explicitly enable the event.
+#define TRACE_DISABLED_BY_DEFAULT(name) "disabled-by-default-" name
+
+class EventTracer {
+ public:
+  typedef uint64_t Handle;
+
+  static EventTracer* GetInstance();
+
+  static void SetInstance(EventTracer* tracer) {
+    delete (EventTracer::instance);
+    EventTracer::instance = tracer;
+  }
+
+  virtual ~EventTracer() {}
+
+  // The pointer returned from GetCategoryGroupEnabled() points to a
+  // value with zero or more of the following bits. Used in this class only.
+  // The TRACE_EVENT macros should only use the value as a bool.
+  // These values must be in sync with macro values in trace_event.h in
+  // chromium.
+  enum CategoryGroupEnabledFlags {
+    // Category group enabled for the recording mode.
+    kEnabledForRecording_CategoryGroupEnabledFlags = 1 << 0,
+    // Category group enabled for the monitoring mode.
+    kEnabledForMonitoring_CategoryGroupEnabledFlags = 1 << 1,
+    // Category group enabled by SetEventCallbackEnabled().
+    kEnabledForEventCallback_CategoryGroupEnabledFlags = 1 << 2,
+  };

[dsinclair, 2015/06/24 19:05:09]

There is also a ENABLED_FOR_ETW_EXPORT = 1 << 3 should that be here for
completeness, or a note that it's skipped on purpose?

+
+  virtual const uint8_t* GetCategoryGroupEnabled(const char* name) = 0;
+  virtual const char* GetCategoryGroupName(
+      const uint8_t* categoryEnabledFlag) = 0;
+
+  virtual EventTracer::Handle AddTraceEvent(
+      char phase, const uint8_t* categoryEnabledFlag, const char* name,
+      uint64_t id, int32_t numArgs, const char** argNames,
+      const uint8_t* argTypes, const uint64_t* argValues, uint8_t flags) = 0;
+
+  virtual void UpdateTraceEventDuration(const uint8_t* categoryEnabledFlag,
+                                        const char* name,
+                                        EventTracer::Handle handle) = 0;
+
+ private:
+  static EventTracer* instance;
+};
+}  // namespace v8
+
+#endif  // INCLUDE_V8_TRACING_H_