Implement tracing interface for v8

src/tracing/event-tracer.cc

+// Copyright 2015 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
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include <include/v8-tracing.h>
+
+#include "src/log.h"
+#include "src/v8.h"
+
+class DefaultEventTracer : public v8::EventTracer {
+  // TODO(fmeawad): remove once embedders support tracing.
+  i::Isolate* isolate_ = i::Isolate::Current();

[Yang, 2015/03/13 08:07:48]

- Do not use Isolate::Current anymore. We are trying to get rid of it.
- This use of default init value seems wrong. We would use the same Isolate
returned Isolate::Current() at the point of the first call to GetInstance. It's
not guaranteed that the isolate is even alive when we run addTraceEvent.

[fmeawad, 2015/03/17 01:18:04]

Done.

+  virtual v8::EventTracer::Handle addTraceEvent(
+      char phase, const uint8_t* categoryEnabledFlag, const char* name,
+      uint64_t id, int numArgs, const char** argNames, const uint8_t* argTypes,
+      const uint64_t* argValues, uint8_t flags) {
+    // TODO(fmeawad): remove the event_logger once embedders support tracing.
+    if (isolate_ && isolate_->event_logger()) {
+      isolate_->event_logger()(name, phase == 'B' ? 0 : 1);
+    }
+    return 0;
+  }
+
+  virtual void updateTraceEventDuration(const uint8_t* categoryEnabledFlag,
+                                        const char* name,
+                                        EventTracer::Handle handle) {}
+
+  virtual const uint8_t* getCategoryGroupEnabled(const char* name) {
+  // TODO(fmeawad): remove the event_logger once embedders support tracing.
+  if (isolate_ && isolate_->event_logger()) {
+      static uint8_t yes = 0x7;
+      return &yes;
+    }
+    static uint8_t no = 0;
+    return &no;
+  }
+
+  virtual const char* getCategoryGroupName(const uint8_t* categoryEnabledFlag) {
+    static const char* dummy = "dummy";
+    return dummy;
+  }
+};
+
+
+static void cleanup_tracer() {

[Yang, 2015/03/13 07:52:10]

I'd use CamelCase for those function names.

[fmeawad, 2015/03/17 01:18:04]

Done.

+  // calling SetInstance will delete the existing instance.
+  v8::EventTracer::SetInstance(NULL);
+}
+
+
+static void intialize_default_tracer(v8::EventTracer* current_instance) {
+  if (current_instance == NULL) {
+    v8::EventTracer::SetInstance(new (DefaultEventTracer));
+  }
+  atexit(cleanup_tracer);
+}
+
+
+V8_DECLARE_ONCE(init_once);
+v8::EventTracer* v8::EventTracer::gInstance;
+v8::EventTracer* v8::EventTracer::GetInstance() {
+  base::CallOnce(&init_once, intialize_default_tracer,
+                 v8::EventTracer::gInstance);
+  DCHECK(v8::EventTracer::gInstance);
+  return v8::EventTracer::gInstance;
+}