1 files changed, 143 insertions, 0 deletions
diff --git a/base/event_trace_consumer_win.h b/base/event_trace_consumer_win.h
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+++ b/base/event_trace_consumer_win.h
@@ -0,0 +1,143 @@
+// Copyright (c) 2009 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.
+//
+// Declaration of a Windows event trace consumer base class.
+#ifndef BASE_EVENT_TRACE_CONSUMER_WIN_H_
+#define BASE_EVENT_TRACE_CONSUMER_WIN_H_
+
+#include <windows.h>
+#include <wmistr.h>
+#include <evntrace.h>
+#include <vector>
+#include "base/basictypes.h"
+
+// This class is a base class that makes it easier to consume events
+// from realtime or file sessions. Concrete consumers need to sublass
+// a specialization of this class and override the ProcessEvent and/or
+// the ProcessBuffer methods to implement the event consumption logic.
+// Usage might look like:
+// class MyConsumer: public EtwTraceConsumerBase<MyConsumer, 1> {
+//  protected:
+//    static VOID WINAPI ProcessEvent(PEVENT_TRACE event);
+// };
+//
+// MyConsumer consumer;
+// consumer.OpenFileSession(file_path);
+// consumer.Consume();
+template <class ImplClass>
+class EtwTraceConsumerBase {
+ public:
+  // Constructs a closed consumer.
+  EtwTraceConsumerBase() {
+  }
+
+  ~EtwTraceConsumerBase() {
+    Close();
+  }
+
+  // Opens the named realtime session, which must be existent.
+  // Note: You can use OpenRealtimeSession or OpenFileSession
+  //    to open as many as MAXIMUM_WAIT_OBJECTS (63) sessions at
+  //    any one time, though only one of them may be a realtime
+  //    session.
+  HRESULT OpenRealtimeSession(const wchar_t* session_name);
+
+  // Opens the event trace log in "file_name", which must be a full or
+  // relative path to an existing event trace log file.
+  // Note: You can use OpenRealtimeSession or OpenFileSession
+  //    to open as many as kNumSessions at any one time.
+  HRESULT OpenFileSession(const wchar_t* file_name);
+
+  // Consume all open sessions from beginning to end.
+  HRESULT Consume();
+
+  // Close all open sessions.
+  HRESULT Close();
+
+ protected:
+  // Override in subclasses to handle events.
+  static void ProcessEvent(EVENT_TRACE* event) {
+  }
+  // Override in subclasses to handle buffers.
+  static bool ProcessBuffer(EVENT_TRACE_LOGFILE* buffer) {
+    return true;  // keep going
+  }
+
+ protected:
+  // Currently open sessions.
+  std::vector<TRACEHANDLE> trace_handles_;
+
+ private:
+  // These delegate to ImplClass callbacks with saner signatures.
+  static void WINAPI ProcessEventCallback(EVENT_TRACE* event) {
+    ImplClass::ProcessEvent(event);
+  }
+  static ULONG WINAPI ProcessBufferCallback(PEVENT_TRACE_LOGFILE buffer) {
+    return ImplClass::ProcessBuffer(buffer);
+  }
+
+  DISALLOW_COPY_AND_ASSIGN(EtwTraceConsumerBase);
+};
+
+template <class ImplClass> inline
+HRESULT EtwTraceConsumerBase<ImplClass>::OpenRealtimeSession(
+    const wchar_t* session_name) {
+  EVENT_TRACE_LOGFILE logfile = {};
+  logfile.LoggerName = const_cast<wchar_t*>(session_name);
+  logfile.LogFileMode = EVENT_TRACE_REAL_TIME_MODE;
+  logfile.BufferCallback = &ProcessBufferCallback;
+  logfile.EventCallback = &ProcessEventCallback;
+  logfile.Context = this;
+  TRACEHANDLE trace_handle = ::OpenTrace(&logfile);
+  if (reinterpret_cast<TRACEHANDLE>(INVALID_HANDLE_VALUE) == trace_handle)
+    return HRESULT_FROM_WIN32(::GetLastError());
+
+  trace_handles_.push_back(trace_handle);
+  return S_OK;
+}
+
+template <class ImplClass> inline
+HRESULT EtwTraceConsumerBase<ImplClass>::OpenFileSession(
+    const wchar_t* file_name) {
+  EVENT_TRACE_LOGFILE logfile = {};
+  logfile.LogFileName = const_cast<wchar_t*>(file_name);
+  logfile.BufferCallback = &ProcessBufferCallback;
+  logfile.EventCallback = &ProcessEventCallback;
+  logfile.Context = this;
+  TRACEHANDLE trace_handle = ::OpenTrace(&logfile);
+  if (reinterpret_cast<TRACEHANDLE>(INVALID_HANDLE_VALUE) == trace_handle)
+    return HRESULT_FROM_WIN32(::GetLastError());
+
+  trace_handles_.push_back(trace_handle);
+  return S_OK;
+}
+
+template <class ImplClass> inline
+HRESULT EtwTraceConsumerBase<ImplClass>::Consume() {
+  ULONG err = ::ProcessTrace(&trace_handles_[0],
+                             trace_handles_.size(),
+                             NULL,
+                             NULL);
+  return HRESULT_FROM_WIN32(err);
+}
+
+template <class ImplClass> inline
+HRESULT EtwTraceConsumerBase<ImplClass>::Close() {
+  HRESULT hr = S_OK;
+  for (size_t i = 0; i < trace_handles_.size(); ++i) {
+    if (NULL != trace_handles_[i]) {
+      ULONG ret = ::CloseTrace(trace_handles_[i]);
+      trace_handles_[i] = NULL;
+
+      if (FAILED(HRESULT_FROM_WIN32(ret)))
+        hr = HRESULT_FROM_WIN32(ret);
+    }
+
+    trace_handles_.clear();
+  }
+
+  return hr;
+}
+
+#endif  // BASE_EVENT_TRACE_CONSUMER_WIN_H_