Implements Windows system tracing.

content/browser/tracing/etw_system_event_consumer_win.h

+// Copyright (c) 2014 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.
+
+#ifndef CONTENT_BROWSER_TRACING_TRACING_CONSUMER_WIN_H_
+#define CONTENT_BROWSER_TRACING_TRACING_CONSUMER_WIN_H_
+
+#include "base/bind.h"
+#include "base/memory/ref_counted_memory.h"
+#include "base/threading/thread.h"
+#include "base/values.h"
+#include "base/win/event_trace_consumer.h"
+#include "base/win/event_trace_controller.h"
+
+template <typename Type>
+struct DefaultSingletonTraits;
+
+namespace content {
+
+class EtwSystemEventConsumer :
+    public base::win::EtwTraceConsumerBase<EtwSystemEventConsumer> {
+ public:
+  typedef base::Callback<void(const scoped_refptr<base::RefCountedString>&)>
+      OutputCallback;
+
+  bool StartSystemTracing();
+  void StopSystemTracing(const OutputCallback& callback);
+
+  // Retrieve the ETW consumer instance.
+  static EtwSystemEventConsumer* GetInstance();
+
+ private:
+  // This allows constructor and destructor to be private and usable only
+  // by the Singleton class.
+  friend struct DefaultSingletonTraits<EtwSystemEventConsumer>;
+
+  // Constructor.
+  EtwSystemEventConsumer();
+  virtual ~EtwSystemEventConsumer();
+
+  void AddSyncEventToBuffer();
+  void AppendEventToBuffer(EVENT_TRACE* event);
+
+  // Static override of EtwTraceConsumerBase::ProcessEvent.
+  // @param event the raw ETW event to process.
+  friend class base::win::EtwTraceConsumerBase<EtwSystemEventConsumer>;
+  static void ProcessEvent(EVENT_TRACE* event);
+
+  // Request the ETW trace controller to activate the kernel tracing.
+  // returns true on success, false if the kernel tracing isn't activated.
+  bool StartKernelSessionTracing();
+
+  // Request the ETW trace controller to deactivate the kernel tracing.
+  // @param callback the callback to call with the consumed events.
+  // @returns true on success, false if an error occurred.
+  bool StopKernelSessionTracing();
+
+  void OnStopSystemTracingDone(
+    const OutputCallback& callback,
+    const scoped_refptr<base::RefCountedString>& result);
+
+  void TraceAndConsumeOnThread();
+  void FlushOnThread(const OutputCallback& callback);
+
+  scoped_ptr<base::ListValue> events_;
+  base::Thread thread_;
+  TRACEHANDLE session_handle_;
+  base::win::EtwTraceProperties properties_;
+
+  DISALLOW_COPY_AND_ASSIGN(EtwSystemEventConsumer);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_TRACING_TRACING_CONSUMER_WIN_H_