Implements Windows system tracing.

content/browser/tracing/etw_system_event_consumer_win.cc

+// Copyright 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.
+
+#include "content/browser/tracing/etw_system_event_consumer_win.h"
+
+#include "base/base64.h"
+#include "base/json/json_string_value_serializer.h"
+#include "base/lazy_instance.h"
+#include "base/memory/singleton.h"
+#include "base/strings/stringprintf.h"
+#include "content/public/browser/browser_thread.h"
+
+namespace content {
+
+namespace {
+
+const int kEtwBufferSizeInKBytes = 16;
+const int kEtwBufferFlushTimeoutInSeconds = 1;
+
+std::string GuidToString(const GUID& guid) {
+  return base::StringPrintf("%08X-%04X-%04X-%02X%02X-%02X%02X%02X%02X%02X%02X",
+      guid.Data1, guid.Data2, guid.Data3,
+      guid.Data4[0], guid.Data4[1], guid.Data4[2], guid.Data4[3],
+      guid.Data4[4], guid.Data4[5], guid.Data4[6], guid.Data4[7]);
+}
+
+}  // namespace
+
+EtwSystemEventConsumer::EtwSystemEventConsumer()
+    : thread_("EtwConsumerThread") {
+}
+
+EtwSystemEventConsumer::~EtwSystemEventConsumer() {
+}
+
+bool EtwSystemEventConsumer::StartSystemTracing() {
+  // Activate kernel tracing.
+  if (!StartKernelSessionTracing())
+    return false;
+
+  // Create the events buffer.
+  events_.reset(new base::ListValue());
+
+  // Start the consumer thread and start consuming events.
+  thread_.Start();
+  thread_.message_loop()->PostTask(
+      FROM_HERE,
+      base::Bind(&EtwSystemEventConsumer::TraceAndConsumeOnThread,
+                 base::Unretained(this)));
+
+  return true;
+}
+
+bool EtwSystemEventConsumer::StopSystemTracing(const OutputCallback& callback) {
+  // Deactivate kernel tracing.
+  if (!StopKernelSessionTracing())

[nduca, 2014/02/21 05:23:43]

little worried about this... if the kernel session tracing couldn't be stopped,
should this be a critical error? The thread is now left running.... i think
there's a way to do a criticail error that just takes down the browser process
in this case?

[etienneb, 2014/02/24 14:59:33]

I agree.
It can only happen if someone is playing with the controller outside of our
scope.

On 2014/02/21 05:23:43, nduca wrote:

+    return false;
+
+  // Stop consuming and flush events.
+  OutputCallback on_stop_system_tracing_done_callback =
+      base::Bind(&EtwSystemEventConsumer::OnStopSystemTracingDone,
+                 base::Unretained(this),
+                 callback);
+  thread_.message_loop()->PostTask(FROM_HERE,
+      base::Bind(&EtwSystemEventConsumer::FlushOnThread,
+                 base::Unretained(this), on_stop_system_tracing_done_callback));
+
+  return true;
+}
+
+void EtwSystemEventConsumer::OnStopSystemTracingDone(
+    const OutputCallback& callback,
+    const scoped_refptr<base::RefCountedString>& result) {
+
+  // Stop the consumer thread.
+  thread_.Stop();
+
+  // Pass the serialized events.
+  callback.Run(result);
+}
+
+bool EtwSystemEventConsumer::StartKernelSessionTracing() {
+  // Enabled flags (tracing facilities).
+  uint32 enabled_flags = EVENT_TRACE_FLAG_IMAGE_LOAD |
+                         EVENT_TRACE_FLAG_PROCESS |
+                         EVENT_TRACE_FLAG_THREAD |
+                         EVENT_TRACE_FLAG_CSWITCH;
+
+  EVENT_TRACE_PROPERTIES& p = *properties_.get();
+  p.LogFileMode = EVENT_TRACE_REAL_TIME_MODE;
+  p.FlushTimer = kEtwBufferFlushTimeoutInSeconds;
+  p.BufferSize = kEtwBufferSizeInKBytes;
+  p.LogFileNameOffset = 0;
+  p.EnableFlags = enabled_flags;
+
+  HRESULT hr = base::win::EtwTraceController::Start(
+      KERNEL_LOGGER_NAME, &properties_, &session_handle_);
+  if (FAILED(hr)) {
+    VLOG(1) << "StartRealtimeSession() failed with " << hr << ".";
+    return false;
+  }
+
+  return true;
+}
+
+bool EtwSystemEventConsumer::StopKernelSessionTracing() {
+  HRESULT hr = base::win::EtwTraceController::Stop(
+      KERNEL_LOGGER_NAME, &properties_);
+  return SUCCEEDED(hr);
+}
+
+// static
+EtwSystemEventConsumer* EtwSystemEventConsumer::GetInstance() {
+  return Singleton<EtwSystemEventConsumer>::get();
+}
+
+// static
+void EtwSystemEventConsumer::ProcessEvent(EVENT_TRACE* event) {
+  EtwSystemEventConsumer::GetInstance()->AppendEventToBuffer(event);
+}
+
+void EtwSystemEventConsumer::AppendEventToBuffer(EVENT_TRACE* event) {
+  using base::FundamentalValue;
+  using base::StringPrintf;
+
+  scoped_ptr<base::DictionaryValue> value(new base::DictionaryValue());
+
+  // Add header fields to the event.
+  value->Set("ts", new base::StringValue(
+      StringPrintf("%08X%08X",
+                   event->Header.TimeStamp.HighPart,
+                   event->Header.TimeStamp.LowPart)));
+
+  value->Set("guid", new base::StringValue(GuidToString(event->Header.Guid)));
+
+  value->Set("op", new FundamentalValue(event->Header.Class.Type));
+  value->Set("ver", new FundamentalValue(event->Header.Class.Version));
+  value->Set("pid",
+             new FundamentalValue(static_cast<int>(event->Header.ProcessId)));
+  value->Set("tid",
+             new FundamentalValue(static_cast<int>(event->Header.ThreadId)));
+  value->Set("cpu", new FundamentalValue(event->BufferContext.ProcessorNumber));
+
+  // Base64 encode the payload bytes.
+  base::StringPiece buffer(static_cast<const char*>(event->MofData),
+                           event->MofLength);
+  std::string payload;
+  base::Base64Encode(buffer, &payload);
+  value->Set("payload", new base::StringValue(payload));
+
+  // Append it to the events buffer.
+  events_->Append(value.release());
+}
+
+void EtwSystemEventConsumer::TraceAndConsumeOnThread() {
+  HRESULT hr = OpenRealtimeSession(KERNEL_LOGGER_NAME);
+  if (FAILED(hr))
+    return;
+  Consume();
+  Close();
+}
+
+void EtwSystemEventConsumer::FlushOnThread(const OutputCallback& callback) {
+  // Add the header information to the stream.
+  scoped_ptr<base::DictionaryValue> header(new base::DictionaryValue());
+  header->Set("name", base::Value::CreateStringValue("ETW"));
+  header->Set("content", events_.release());
+
+  // Serialize the results as a JSon string.
+  std::string output;
+  JSONStringValueSerializer serializer(&output);
+  serializer.set_pretty_print(true);
+  serializer.Serialize(*header.get());
+
+  // Pass the result to the UI Thread.
+  scoped_refptr<base::RefCountedString> result =
+      base::RefCountedString::TakeString(&output);
+  BrowserThread::PostTask(BrowserThread::UI, FROM_HERE,
+                          base::Bind(callback, result));
+}
+
+}  // namespace content