TraceSubscriber implementation that writes to a file.

Review URL: http://codereview.chromium.org/7044010

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@87459 0039d316-1c4b-4281-b951-d872f2087c98

4 files changed, 133 insertions, 0 deletions

diff --git a/content/browser/trace_subscriber_stdio.cc b/content/browser/trace_subscriber_stdio.cc
new file mode 100644
index 0000000..6d4e23b
--- /dev/null
+++ b/content/browser/trace_subscriber_stdio.cc
@@ -0,0 +1,56 @@
+// Copyright (c) 2011 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/trace_subscriber_stdio.h"
+
+#include "base/logging.h"
+
+TraceSubscriberStdio::TraceSubscriberStdio(const FilePath& path) {
+  LOG(INFO) << "Logging performance trace to file: " << path.value();
+  m_file = file_util::OpenFile(path, "w+");
+  if (IsValid()) {
+    // FIXME: the file format expects it to start with "[".
+    fputc('[', m_file);
+  } else {
+    LOG(ERROR) << "Failed to open performance trace file: " << path.value();
+  }
+}
+
+TraceSubscriberStdio::~TraceSubscriberStdio() {
+  OnEndTracingComplete();
+}
+
+bool TraceSubscriberStdio::IsValid() {
+  return m_file && (0 == ferror(m_file));
+}
+
+void TraceSubscriberStdio::OnEndTracingComplete() {
+  if (m_file) {
+    // FIXME: the file format expects it to end with "]".
+    fputc(']', m_file);
+    fclose(m_file);
+    m_file = 0;
+  }
+}
+
+void TraceSubscriberStdio::OnTraceDataCollected(
+    const std::string& json_events) {
+  if (!IsValid()) {
+    return;
+  }
+
+  // FIXME: "json_events" currently comes with "[" and "]". But the file doesn't
+  // expect them. So remove them when writing to the file.
+  CHECK_GE(json_events.size(), 2u);
+  const char* data = json_events.data() + 1;
+  size_t size = json_events.size() - 2;
+
+  size_t written = fwrite(data, 1, size, m_file);
+  if (written != size) {
+    LOG(ERROR) << "Error " << ferror(m_file) << " when writing to trace file";
+    fclose(m_file);
+    m_file = 0;
+  }
+  fputc(',', m_file);
+}
diff --git a/content/browser/trace_subscriber_stdio.h b/content/browser/trace_subscriber_stdio.h
new file mode 100644
index 0000000..6e6fe94
--- /dev/null
+++ b/content/browser/trace_subscriber_stdio.h
@@ -0,0 +1,33 @@
+// Copyright (c) 2011 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_TRACE_SUBSCRIBER_STDIO_H_
+#define CONTENT_BROWSER_TRACE_SUBSCRIBER_STDIO_H_
+#pragma once
+
+#include <string>
+
+#include "base/file_util.h"
+#include "content/browser/trace_controller.h"
+
+// Stdio implementation of TraceSubscriber. Use this to write traces to a file.
+class TraceSubscriberStdio : public TraceSubscriber {
+ public:
+  // Creates or overwrites the specified file. Check IsValid() for success.
+  explicit TraceSubscriberStdio(const FilePath& path);
+
+  // Returns TRUE if we're currently writing data to a file.
+  bool IsValid();
+
+  // Implementation of TraceSubscriber
+  virtual void OnEndTracingComplete();
+  virtual void OnTraceDataCollected(const std::string& json_events);
+
+  virtual ~TraceSubscriberStdio();
+
+ private:
+  FILE* m_file;
+};
+
+#endif  // CONTENT_BROWSER_TRACE_SUBSCRIBER_STDIO_H_
diff --git a/content/browser/trace_subscriber_stdio_unittest.cc b/content/browser/trace_subscriber_stdio_unittest.cc
new file mode 100644
index 0000000..afced0d
--- /dev/null
+++ b/content/browser/trace_subscriber_stdio_unittest.cc
@@ -0,0 +1,42 @@
+// Copyright (c) 2011 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/trace_subscriber_stdio.h"
+
+#include "base/scoped_temp_dir.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace {
+
+class TraceSubscriberStdioTest : public testing::Test {
+ public:
+  virtual void SetUp() {
+    ASSERT_TRUE(trace_dir_.CreateUniqueTempDir());
+    trace_file_ = trace_dir_.path().AppendASCII("trace.txt");
+  }
+
+  std::string ReadTraceFile() {
+    std::string result;
+    EXPECT_TRUE(file_util::ReadFileToString(trace_file_, &result));
+    return result;
+  }
+
+  ScopedTempDir trace_dir_;
+  FilePath trace_file_;
+};
+
+}  // namespace
+
+TEST_F(TraceSubscriberStdioTest, CanWriteBracketedDataToFile) {
+  TraceSubscriberStdio subscriber(trace_file_);
+  subscriber.OnTraceDataCollected("[foo]");
+  subscriber.OnTraceDataCollected("[bar]");
+  EXPECT_TRUE(subscriber.IsValid());
+
+  subscriber.OnEndTracingComplete();
+  EXPECT_FALSE(subscriber.IsValid());
+
+  EXPECT_EQ("[foo,bar,]", ReadTraceFile());
+}
+
diff --git a/content/content_browser.gypi b/content/content_browser.gypi
index 9793f01..6ec29f3 100644
--- a/content/content_browser.gypi
+++ b/content/content_browser.gypi
@@ -335,6 +335,8 @@
         'browser/trace_controller.h',
         'browser/trace_message_filter.cc',
         'browser/trace_message_filter.h',
+        'browser/trace_subscriber_stdio.cc',
+        'browser/trace_subscriber_stdio.h',
         'browser/user_metrics.cc',
         'browser/user_metrics.h',
         'browser/webui/empty_web_ui_factory.cc',