Add C++ Trace Event support to PPAPI/NaCl SDK

native_client_sdk/src/examples/trace_events/trace_events.cc

+// Copyright (c) 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+/// @file
+/// This example demonstrates using Trace Events in a simple NaCl module.
+/// See documentation here:
+/// http://www.chromium.org/developers/how-tos/trace-event-profiling-tool/tracing-event-instrumentation
+///
+/// Instead of including <base/debug/trace_event.h>, include
+/// "ppapi/cpp/dev/trace_event_dev.h" for tracing within PPAPI C++.
+
+#include <pthread.h>
+#include <unistd.h>
+
+#include <cstdio>
+#include <sstream>
+#include <string>
+
+#include "ppapi/cpp/dev/trace_event_dev.h"
+#include "ppapi/cpp/instance.h"
+#include "ppapi/cpp/module.h"
+#include "ppapi/cpp/var.h"
+
+namespace trace_event_example {

[binji, 2013/02/14 22:01:28]

we don't usually namespace the examples

[elijahtaylor1, 2013/02/14 23:38:10]

This was cribbed from hello_world_interactive.  Removed

+/// Method name for running a task on a new thread, as seen by JavaScript code.
+const char* const kRunThreadedTask = "runthreadedtask";
+
+/// Method name to send an async begin trace, as seen by Javascript code.
+const char* const kSendAsyncBegin = "sendasyncbegin";
+
+/// Method name to send an async end trace, as seen by Javascript code.
+const char* const kSendAsyncEnd = "sendasyncend";
+
+/// The Instance class for the Trace Events example.
+class TraceEventInstance : public pp::Instance {
+  int thread_num_;

[binji, 2013/02/14 22:01:28]

move to end of class definition

[elijahtaylor1, 2013/02/14 23:38:10]

Done.

+  int async_num_;
+ public:
+  explicit TraceEventInstance(PP_Instance instance) : pp::Instance(instance),

[binji, 2013/02/14 22:01:28]

I usually move the initializer list to the next line w/ 4 spaces, but OK

[elijahtaylor1, 2013/02/14 23:38:10]

Again, cribbed from hello_world_interactive (where admittedly they only have the
base class in the initializer list)

+                                                      thread_num_(0),
+                                                      async_num_(0) {
+    printf("TraceEventInstance.\n");
+  }
+  virtual ~TraceEventInstance() {}
+
+  virtual bool Init(uint32_t argc, const char* argn[], const char* argv[]);
+
+  virtual void HandleMessage(const pp::Var& var_message);
+};
+
+void* RunTaskOnThread(void* arg) {
+  int thread_num = reinterpret_cast<int>(arg);
+  std::ostringstream stream;
+  stream << "Non-main thread #" << thread_num;
+  pp::trace_events::SetThreadName(stream.str().c_str());
+  // TRACE_EVENTx traces scope, so will automatically close on function end.
+  TRACE_EVENT0("ExampleCategory", "traceThisSleep");
+  sleep(2);
+
+  return NULL;
+}
+
+bool TraceEventInstance::Init(uint32_t argc,
+                              const char* argn[],
+                              const char* argv[]) {
+  pp::trace_events::SetThreadName("Main Pepper Thread");

[binji, 2013/02/14 22:01:28]

what is the default name if this is not set?

[elijahtaylor1, 2013/02/14 23:38:10]

Added comment

+}
+
+void TraceEventInstance::HandleMessage(const pp::Var& var_message) {
+  if (!var_message.is_string()) {
+    return;
+  }
+  std::string message = var_message.AsString();
+  pp::Var return_var;
+  if (message == kRunThreadedTask) {
+    pthread_t p;
+    pthread_create(&p, NULL,
+      RunTaskOnThread, reinterpret_cast<void*>(thread_num_));
+    thread_num_++;
+  } else if (message == kSendAsyncBegin) {
+    TRACE_EVENT_ASYNC_BEGIN0("ExampleCategory", "ExampleMessage", async_num_);

[binji, 2013/02/14 22:01:28]

maybe a little more explanation of what this is doing... what is the 0?

[elijahtaylor1, 2013/02/14 23:38:10]

Done.

+  } else if (message == kSendAsyncEnd) {
+    TRACE_EVENT_ASYNC_END0("ExampleCategory", "ExampleMessage", async_num_);
+    async_num_++;
+  }
+}
+
+/// The Module class.
+class TraceEventModule : public pp::Module {
+ public:
+  TraceEventModule() : pp::Module() {
+    printf("TraceEventModule.\n");
+  }
+  virtual ~TraceEventModule() {}
+
+  virtual pp::Instance* CreateInstance(PP_Instance instance) {
+    return new TraceEventInstance(instance);
+  }
+};
+}  // namespace trace_event_example
+
+
+namespace pp {
+Module* CreateModule() {
+  return new trace_event_example::TraceEventModule();
+}
+}  // namespace pp