Allow TracingController to output trace data to specified file

content/browser/tracing/tracing_controller_impl.cc

 // Copyright 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.
 
 #include "content/browser/tracing/tracing_controller_impl.h"
 
 #include "base/bind.h"
 #include "base/file_util.h"
 #include "base/json/string_escape.h"
 #include "base/strings/string_number_conversions.h"
+#include "base/threading/thread_restrictions.h"
 #include "content/browser/tracing/trace_message_filter.h"
 #include "content/common/child_process_messages.h"
 #include "content/public/browser/browser_message_filter.h"
 #include "content/public/common/content_switches.h"
 
 using base::debug::TraceLog;
 
 namespace content {
 
 namespace {
 
 base::LazyInstance<TracingControllerImpl>::Leaky g_controller =
     LAZY_INSTANCE_INITIALIZER;
 
 }  // namespace
 
 TracingController* TracingController::GetInstance() {
   return TracingControllerImpl::GetInstance();
 }
 
+class TracingControllerImpl::ResultFile {
+ public:
+  ResultFile(const base::FilePath& path);
+  void Write(const scoped_refptr<base::RefCountedString>& events_str_ptr) {
+    BrowserThread::PostBlockingPoolSequencedTask(sequence_token_, FROM_HERE,
+        base::Bind(&TracingControllerImpl::ResultFile::WriteTask,
+                   base::Unretained(this), events_str_ptr));
+  }
+  void Close(const base::Closure& callback) {
+    BrowserThread::PostBlockingPoolSequencedTask(sequence_token_, FROM_HERE,
+        base::Bind(&TracingControllerImpl::ResultFile::CloseTask,
+                   base::Unretained(this), callback));
+  }
+  const base::FilePath& path() const { return path_; }
+
+ private:
+  void OpenTask();
+  void WriteTask(const scoped_refptr<base::RefCountedString>& events_str_ptr);
+  void CloseTask(const base::Closure& callback);
+
+  FILE* file_;
+  std::string sequence_token_;
+  base::FilePath path_;
+  bool has_at_least_one_result_;

[dsinclair, 2013/11/18 16:32:18]

Should this be DISALLOW_COPY_AND_ASSIGN?

[Xianzhu, 2013/11/18 21:50:39]

Done.

+};
+
+TracingControllerImpl::ResultFile::ResultFile(const base::FilePath& path)
+    : file_(NULL),
+      sequence_token_("trace_result_file"),
+      path_(path),
+      has_at_least_one_result_(false) {
+  BrowserThread::PostBlockingPoolSequencedTask(sequence_token_, FROM_HERE,
+      base::Bind(&TracingControllerImpl::ResultFile::OpenTask,
+                 base::Unretained(this)));
+}
+
+void TracingControllerImpl::ResultFile::OpenTask() {
+  if (path_.empty())
+    file_util::CreateTemporaryFile(&path_);
+  file_ = file_util::OpenFile(path_, "w");
+  if (!file_) {
+    LOG(ERROR) << "Failed to open " << path_.value();
+    return;
+  }
+  const char* preamble = "{\"traceEvents\": [";
+  size_t written = fwrite(preamble, strlen(preamble), 1, file_);

[dsinclair, 2013/11/18 16:32:18]

This (and the DCHECK) are a little weird, we aren't writing 1 element of length
strlen(preamble) we're writing strlen(preamble) items of length 1.

[Xianzhu, 2013/11/18 21:50:39]

This is original code moved here. According to the sequence of parameters, it
does write 1 element of length strlen(preable). Compared to write
strlen(preable) items of length 1, the current code is simpler in the checking
(otherwise we'd need to save strlen(preable) or repeat it).

+  DCHECK(written == 1);
+}
+
+void TracingControllerImpl::ResultFile::WriteTask(
+    const scoped_refptr<base::RefCountedString>& events_str_ptr) {
+  if (!file_)
+    return;
+
+  // If there is already a result in the file, then put a commma
+  // before the next batch of results.
+  if (has_at_least_one_result_)
+    fwrite(",", 1, 1, file_);
+  else
+    has_at_least_one_result_ = true;

[dsinclair, 2013/11/18 16:32:18]

Don't really need the else as we can always just set has_at_least_one_result to
true.

[Xianzhu, 2013/11/18 21:50:39]

Done.

+  size_t written = fwrite(events_str_ptr->data().c_str(),
+                          events_str_ptr->data().size(), 1,

[dsinclair, 2013/11/18 16:32:18]

As above, params seem backwards.

+                          file_);
+  DCHECK(written == 1);
+}
+
+void TracingControllerImpl::ResultFile::CloseTask(
+    const base::Closure& callback) {
+  if (!file_)
+    return;
+
+  const char* trailout = "]}";
+  size_t written = fwrite(trailout, strlen(trailout), 1, file_);
+  DCHECK(written == 1);
+  file_util::CloseFile(file_);
+  file_ = NULL;
+
+  BrowserThread::PostTask(BrowserThread::UI, FROM_HERE, callback);
+}
+
+
 TracingControllerImpl::TracingControllerImpl() :
     pending_disable_recording_ack_count_(0),
     pending_capture_monitoring_snapshot_ack_count_(0),
     is_recording_(false),
     is_monitoring_(false),
+    trace_options_(TraceLog::RECORD_UNTIL_FULL),
     category_filter_(
-        base::debug::CategoryFilter::kDefaultCategoryFilterString),
-    result_file_(0),
-    result_file_has_at_least_one_result_(false) {
+        base::debug::CategoryFilter::kDefaultCategoryFilterString) {
 }
 
 TracingControllerImpl::~TracingControllerImpl() {
   // This is a Leaky instance.
   NOTREACHED();
 }
 
 TracingControllerImpl* TracingControllerImpl::GetInstance() {
   return g_controller.Pointer();
 }
 
 void TracingControllerImpl::GetCategories(
     const GetCategoriesDoneCallback& callback) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
   // Known categories come back from child processes with the EndTracingAck
   // message. So to get known categories, just begin and end tracing immediately
   // afterwards. This will ping all the child processes for categories.
   pending_get_categories_done_callback_ = callback;
   EnableRecording(base::debug::CategoryFilter("*"),
                   TracingController::Options(),
                   EnableRecordingDoneCallback());
-  DisableRecording(TracingFileResultCallback());
+  DisableRecording(base::FilePath(), TracingFileResultCallback());
 }
 
 bool TracingControllerImpl::EnableRecording(
     const base::debug::CategoryFilter& filter,
     TracingController::Options options,
     const EnableRecordingDoneCallback& callback) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
   if (!can_enable_recording())
     return false;
@@ skipping 14 matching lines @@
     it->get()->SendBeginTracing(
         category_filter_.ToString(), trace_options_, false);
   }
 
   if (!callback.is_null())
     callback.Run();
   return true;
 }
 
 bool TracingControllerImpl::DisableRecording(
+    const base::FilePath& result_file_path,
     const TracingFileResultCallback& callback) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
   if (!can_disable_recording())
     return false;
 
   pending_disable_recording_done_callback_ = callback;
 
   // Disable local trace early to avoid traces during end-tracing process from
   // interfering with the process.
   TraceLog::GetInstance()->SetDisabled();
 
 #if defined(OS_ANDROID)
   if (pending_get_categories_done_callback_.is_null())
     TraceLog::GetInstance()->AddClockSyncMetadataEvent();
 #endif
 
-  // We don't need to create a temporary file when getting categories.
-  if (pending_get_categories_done_callback_.is_null()) {
-    base::FilePath temporary_file;
-    file_util::CreateTemporaryFile(&temporary_file);
-    result_file_path_.reset(new base::FilePath(temporary_file));
-    result_file_ = file_util::OpenFile(*result_file_path_, "w");
-    result_file_has_at_least_one_result_ = false;
-    const char* preamble = "{\"traceEvents\": [";
-    size_t written = fwrite(preamble, strlen(preamble), 1, result_file_);
-    DCHECK(written == 1);
-  }
+  if (!callback.is_null() || !result_file_path.empty())
+    result_file_.reset(new ResultFile(result_file_path));
 
   // There could be a case where there are no child processes and filters_
   // is empty. In that case we can immediately tell the subscriber that tracing
   // has ended. To avoid recursive calls back to the subscriber, we will just
   // use the existing asynchronous OnDisableRecordingAcked code.
   // Count myself (local trace) in pending_disable_recording_ack_count_,
   // acked below.
   pending_disable_recording_ack_count_ = filters_.size() + 1;
 
   // Handle special case of zero child processes.
@@ skipping 61 matching lines @@
 }
 
 void TracingControllerImpl::GetMonitoringStatus(
     bool* out_enabled,
     base::debug::CategoryFilter* out_filter,
     TracingController::Options* out_options) {
   NOTIMPLEMENTED();
 }
 
 void TracingControllerImpl::CaptureMonitoringSnapshot(
+    const base::FilePath& result_file_path,
     const TracingFileResultCallback& callback) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
   if (!can_disable_monitoring())
     return;
 
   pending_capture_monitoring_snapshot_done_callback_ = callback;
 
-  base::FilePath temporary_file;
-  file_util::CreateTemporaryFile(&temporary_file);
-  result_file_path_.reset(new base::FilePath(temporary_file));
-  result_file_ = file_util::OpenFile(*result_file_path_, "w");
-  result_file_has_at_least_one_result_ = false;
-  const char* preamble = "{\"traceEvents\": [";
-  size_t written = fwrite(preamble, strlen(preamble), 1, result_file_);
-  DCHECK(written == 1);
+  if (!callback.is_null() || !result_file_path.empty())
+    monitoring_snapshot_file_.reset(new ResultFile(result_file_path));
 
   // There could be a case where there are no child processes and filters_
   // is empty. In that case we can immediately tell the subscriber that tracing
   // has ended. To avoid recursive calls back to the subscriber, we will just
   // use the existing asynchronous OnCaptureMonitoringSnapshotAcked code.
   // Count myself in pending_capture_monitoring_snapshot_ack_count_,
   // acked below.
   pending_capture_monitoring_snapshot_ack_count_ = filters_.size() + 1;
 
   // Handle special case of zero child processes.
@@ skipping 69 matching lines @@
     return;
 
   // All acks (including from the subprocesses and the local trace) have been
   // received.
   is_recording_ = false;
 
   // Trigger callback if one is set.
   if (!pending_get_categories_done_callback_.is_null()) {
     pending_get_categories_done_callback_.Run(known_category_groups_);
     pending_get_categories_done_callback_.Reset();
-  } else if (!pending_disable_recording_done_callback_.is_null()) {
-    const char* trailout = "]}";
-    size_t written = fwrite(trailout, strlen(trailout), 1, result_file_);
-    DCHECK(written == 1);
-    file_util::CloseFile(result_file_);
-    result_file_ = 0;
-    pending_disable_recording_done_callback_.Run(result_file_path_.Pass());
-    pending_disable_recording_done_callback_.Reset();
+  } else if (result_file_) {
+    result_file_->Close(
+        base::Bind(&TracingControllerImpl::OnResultFileClosed,
+                   base::Unretained(this)));
   }
 }
 
+void TracingControllerImpl::OnResultFileClosed() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+
+  if (!result_file_)
+    return;
+
+  if (!pending_disable_recording_done_callback_.is_null()) {
+    pending_disable_recording_done_callback_.Run(result_file_->path());
+    pending_disable_recording_done_callback_.Reset();
+  }
+  result_file_.reset();
+}
+
 void TracingControllerImpl::OnCaptureMonitoringSnapshotAcked() {
   if (!BrowserThread::CurrentlyOn(BrowserThread::UI)) {
     BrowserThread::PostTask(BrowserThread::UI, FROM_HERE,
         base::Bind(&TracingControllerImpl::OnCaptureMonitoringSnapshotAcked,
                    base::Unretained(this)));
     return;
   }
 
   if (pending_capture_monitoring_snapshot_ack_count_ == 0)
     return;
 
   if (--pending_capture_monitoring_snapshot_ack_count_ == 1) {
     // All acks from subprocesses have been received. Now flush the local trace.
     // During or after this call, our OnLocalMonitoringTraceDataCollected
     // will be called with the last of the local trace data.
     TraceLog::GetInstance()->FlushButLeaveBufferIntact(
         base::Bind(&TracingControllerImpl::OnLocalMonitoringTraceDataCollected,
                    base::Unretained(this)));
   }
 
   if (pending_capture_monitoring_snapshot_ack_count_ != 0)
     return;
 
-  if (!pending_capture_monitoring_snapshot_done_callback_.is_null()) {
-    const char* trailout = "]}";
-    size_t written = fwrite(trailout, strlen(trailout), 1, result_file_);
-    DCHECK(written == 1);
-    file_util::CloseFile(result_file_);
-    result_file_ = 0;
-    pending_capture_monitoring_snapshot_done_callback_.Run(
-        result_file_path_.Pass());
-    pending_capture_monitoring_snapshot_done_callback_.Reset();
+  if (monitoring_snapshot_file_) {
+    monitoring_snapshot_file_->Close(
+        base::Bind(&TracingControllerImpl::OnMonitoringSnapshotFileClosed,
+                   base::Unretained(this)));
   }
 }
 
+void TracingControllerImpl::OnMonitoringSnapshotFileClosed() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+
+  if (!monitoring_snapshot_file_)
+    return;
+
+  if (!pending_capture_monitoring_snapshot_done_callback_.is_null()) {
+    pending_capture_monitoring_snapshot_done_callback_.Run(
+        monitoring_snapshot_file_->path());
+    pending_capture_monitoring_snapshot_done_callback_.Reset();
+  }
+  monitoring_snapshot_file_.reset();
+}
+
 void TracingControllerImpl::OnTraceDataCollected(
     const scoped_refptr<base::RefCountedString>& events_str_ptr) {
   // OnTraceDataCollected may be called from any browser thread, either by the
   // local event trace system or from child processes via TraceMessageFilter.
   if (!BrowserThread::CurrentlyOn(BrowserThread::UI)) {
     BrowserThread::PostTask(BrowserThread::UI, FROM_HERE,
         base::Bind(&TracingControllerImpl::OnTraceDataCollected,
                    base::Unretained(this), events_str_ptr));
     return;
   }
 
-  // Drop trace events if we are just getting categories.
-  if (!pending_get_categories_done_callback_.is_null())
+  if (result_file_)
+    result_file_->Write(events_str_ptr);
+}
+
+void TracingControllerImpl::OnMonitoringTraceDataCollected(
+    const scoped_refptr<base::RefCountedString>& events_str_ptr) {
+  if (!BrowserThread::CurrentlyOn(BrowserThread::UI)) {
+    BrowserThread::PostTask(BrowserThread::UI, FROM_HERE,
+        base::Bind(&TracingControllerImpl::OnMonitoringTraceDataCollected,
+                   base::Unretained(this), events_str_ptr));
     return;
+  }
 
-  // If there is already a result in the file, then put a commma
-  // before the next batch of results.
-  if (result_file_has_at_least_one_result_) {
-    size_t written = fwrite(",", 1, 1, result_file_);
-    DCHECK(written == 1);
-  } else {
-    result_file_has_at_least_one_result_ = true;
-  }
-  size_t written = fwrite(events_str_ptr->data().c_str(),
-                          events_str_ptr->data().size(), 1,
-                          result_file_);
-  DCHECK(written == 1);
+  if (!monitoring_snapshot_file_)
+    monitoring_snapshot_file_->Write(events_str_ptr);
 }
 
 void TracingControllerImpl::OnLocalTraceDataCollected(
     const scoped_refptr<base::RefCountedString>& events_str_ptr,
     bool has_more_events) {
   if (events_str_ptr->data().size())
     OnTraceDataCollected(events_str_ptr);
 
   if (has_more_events)
     return;
 
   // Simulate an DisableRecordingAcked for the local trace.
   std::vector<std::string> category_groups;
   TraceLog::GetInstance()->GetKnownCategoryGroups(&category_groups);
   OnDisableRecordingAcked(category_groups);
 }
 
 void TracingControllerImpl::OnLocalMonitoringTraceDataCollected(
     const scoped_refptr<base::RefCountedString>& events_str_ptr,
     bool has_more_events) {
   if (events_str_ptr->data().size())
-    OnTraceDataCollected(events_str_ptr);
+    OnMonitoringTraceDataCollected(events_str_ptr);
 
   if (has_more_events)
     return;
 
   // Simulate an CaptureMonitoringSnapshotAcked for the local trace.
   OnCaptureMonitoringSnapshotAcked();
 }
 
 }  // namespace content