Hibernate the thread if there are no events in the queue. Wake it up when an event is added to the …

webrtc/call/rtc_event_log_helper_thread.cc

 /*
  *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 17 matching lines @@
          event_type == rtclog::Event::VIDEO_SENDER_CONFIG_EVENT ||
          event_type == rtclog::Event::AUDIO_RECEIVER_CONFIG_EVENT ||
          event_type == rtclog::Event::AUDIO_SENDER_CONFIG_EVENT;
 }
 }  // namespace
 
 // RtcEventLogImpl member functions.
 RtcEventLogHelperThread::RtcEventLogHelperThread(
     SwapQueue<ControlMessage>* message_queue,
     SwapQueue<std::unique_ptr<rtclog::Event>>* event_queue,
-    rtc::Event* wake_up,
-    rtc::Event* stopped,
     const Clock* const clock)
     : message_queue_(message_queue),
       event_queue_(event_queue),
       history_(kEventsInHistory),
       config_history_(),
       file_(FileWrapper::Create()),
       thread_(&ThreadOutputFunction, this, "RtcEventLog thread"),
       max_size_bytes_(std::numeric_limits<int64_t>::max()),
       written_bytes_(0),
       start_time_(0),
       stop_time_(std::numeric_limits<int64_t>::max()),
       has_recent_event_(false),
       most_recent_event_(),
       output_string_(),
-      wake_up_(wake_up),
-      stopped_(stopped),
+      wake_periodically_(false, false),
+      wake_from_hibernation_(false, false),
+      file_finished_(false, false),
       clock_(clock) {
   RTC_DCHECK(message_queue_);
   RTC_DCHECK(event_queue_);
-  RTC_DCHECK(wake_up_);
-  RTC_DCHECK(stopped_);
   RTC_DCHECK(clock_);
   thread_.Start();
 }
 
 RtcEventLogHelperThread::~RtcEventLogHelperThread() {
   ControlMessage message;
   message.message_type = ControlMessage::TERMINATE_THREAD;
   message.stop_time = clock_->TimeInMicroseconds();
   while (!message_queue_->Insert(&message)) {
     // We can't destroy the event log until we have stopped the thread,
     // so clear the message queue and try again. Note that if we clear
     // any STOP_FILE events, then the threads calling StopLogging would likely
     // wait indefinitely. However, there should not be any such calls as we
     // are executing the destructor.
     LOG(LS_WARNING) << "Clearing message queue to terminate thread.";
     message_queue_->Clear();
   }
-  wake_up_->Set();  // Wake up the output thread.
+  wake_from_hibernation_.Set();
+  wake_periodically_.Set();  // Wake up the output thread.
   thread_.Stop();   // Wait for the thread to terminate.
 }
 
+void RtcEventLogHelperThread::WaitForFileFinished() {
+  wake_from_hibernation_.Set();
+  wake_periodically_.Set();
+  file_finished_.Wait(rtc::Event::kForever);
+}
+
+void RtcEventLogHelperThread::SignalNewEvent() {
+  wake_from_hibernation_.Set();
+}
+
 bool RtcEventLogHelperThread::AppendEventToString(rtclog::Event* event) {
   rtclog::EventStream event_stream;
   event_stream.add_stream();
   event_stream.mutable_stream(0)->Swap(event);
   // We create a new event stream per event but because of the way protobufs
   // are encoded, events can be merged by concatenating them. Therefore,
   // it will look like a single stream when we read it back from file.
   bool stop = true;
   if (written_bytes_ + static_cast<int64_t>(output_string_.size()) +
           event_stream.ByteSize() <=
       max_size_bytes_) {
     event_stream.AppendToString(&output_string_);
     stop = false;
   }
   // Swap the event back so that we don't mix event types in the queues.
   event_stream.mutable_stream(0)->Swap(event);
   return stop;
 }
 
-void RtcEventLogHelperThread::LogToMemory() {
+bool RtcEventLogHelperThread::LogToMemory() {
   RTC_DCHECK(!file_->Open());
+  bool message_received = false;
 
   // Process each event earlier than the current time and append it to the
   // appropriate history_.
   int64_t current_time = clock_->TimeInMicroseconds();
   if (!has_recent_event_) {
     has_recent_event_ = event_queue_->Remove(&most_recent_event_);
   }
   while (has_recent_event_ &&
          most_recent_event_->timestamp_us() <= current_time) {
     if (IsConfigEvent(*most_recent_event_)) {
       config_history_.push_back(std::move(most_recent_event_));
     } else {
       history_.push_back(std::move(most_recent_event_));
     }
     has_recent_event_ = event_queue_->Remove(&most_recent_event_);
+    message_received = true;
   }
+  return message_received;
 }
 
 void RtcEventLogHelperThread::StartLogFile() {
   RTC_DCHECK(file_->Open());
   bool stop = false;
   output_string_.clear();
 
   // Create and serialize the LOG_START event.
   rtclog::Event start_event;
   start_event.set_timestamp_us(start_time_);
@@ skipping 26 matching lines @@
   // space again.
   output_string_.clear();
   output_string_.shrink_to_fit();
 
   if (stop) {
     RTC_DCHECK(file_->Open());
     StopLogFile();
   }
 }
 
-void RtcEventLogHelperThread::LogToFile() {
+bool RtcEventLogHelperThread::LogToFile() {
   RTC_DCHECK(file_->Open());
   output_string_.clear();
+  bool message_received = false;
 
   // Append each event older than both the current time and the stop time
   // to the output_string_.
   int64_t current_time = clock_->TimeInMicroseconds();
   int64_t time_limit = std::min(current_time, stop_time_);
   if (!has_recent_event_) {
     has_recent_event_ = event_queue_->Remove(&most_recent_event_);
   }
   bool stop = false;
   while (!stop && has_recent_event_ &&
          most_recent_event_->timestamp_us() <= time_limit) {
     stop = AppendEventToString(most_recent_event_.get());
     if (!stop) {
       if (IsConfigEvent(*most_recent_event_)) {
         config_history_.push_back(std::move(most_recent_event_));
       }
       has_recent_event_ = event_queue_->Remove(&most_recent_event_);
     }
+    message_received = true;
   }
 
   // Write string to file.
   if (!file_->Write(output_string_.data(), output_string_.size())) {
     LOG(LS_ERROR) << "FileWrapper failed to write WebRtcEventLog file.";
     // The current FileWrapper implementation closes the file on error.
     RTC_DCHECK(!file_->Open());
-    return;
+    return message_received;
   }
   written_bytes_ += output_string_.size();
 
   // We want to stop logging if we have reached the file size limit. We also
   // want to stop logging if the remaining events are more recent than the
   // time limit, or in other words if we have terminated the loop despite
   // having more events in the queue.
   if ((has_recent_event_ && most_recent_event_->timestamp_us() > stop_time_) ||
       stop) {
     RTC_DCHECK(file_->Open());
     StopLogFile();
   }
+  return message_received;
 }
 
 void RtcEventLogHelperThread::StopLogFile() {
   RTC_DCHECK(file_->Open());
   output_string_.clear();
 
   rtclog::Event end_event;
   end_event.set_timestamp_us(stop_time_);
   end_event.set_type(rtclog::Event::LOG_END);
   AppendEventToString(&end_event);
@@ skipping 10 matching lines @@
 
   max_size_bytes_ = std::numeric_limits<int64_t>::max();
   written_bytes_ = 0;
   start_time_ = 0;
   stop_time_ = std::numeric_limits<int64_t>::max();
   output_string_.clear();
   file_->CloseFile();
   RTC_DCHECK(!file_->Open());
 }
 
-void RtcEventLogHelperThread::WriteLog() {
+void RtcEventLogHelperThread::ProcessEvents() {
   ControlMessage message;
 
   while (true) {
+    bool message_received = false;
     // Process control messages.
     while (message_queue_->Remove(&message)) {
       switch (message.message_type) {
         case ControlMessage::START_FILE:
           if (!file_->Open()) {
             max_size_bytes_ = message.max_size_bytes;
             start_time_ = message.start_time;
             stop_time_ = message.stop_time;
             file_.swap(message.file);
             StartLogFile();
           } else {
             // Already started. Ignore message and close file handle.
             message.file->CloseFile();
           }
+          message_received = true;
           break;
         case ControlMessage::STOP_FILE:
           if (file_->Open()) {
             stop_time_ = message.stop_time;
             LogToFile();  // Log remaining events from message queues.
           }
           // LogToFile might stop on it's own so we need to recheck the state.
           if (file_->Open()) {
             StopLogFile();
           }
-          stopped_->Set();
+          file_finished_.Set();
+          message_received = true;
           break;
         case ControlMessage::TERMINATE_THREAD:
           if (file_->Open()) {
             StopLogFile();
           }
           return;
       }
     }
 
-    // Write events to file or memory
+    // Write events to file or memory.
     if (file_->Open()) {
-      LogToFile();
+      message_received |= LogToFile();
     } else {
-      LogToMemory();
+      message_received |= LogToMemory();
     }
 
     // Accumulate a new batch of events instead of processing them one at a
     // time.
-    wake_up_->Wait(50);
+    if (message_received) {
+      wake_periodically_.Wait(100);
+    } else {
+      wake_from_hibernation_.Wait(rtc::Event::kForever);
+    }
   }
 }
 
 bool RtcEventLogHelperThread::ThreadOutputFunction(void* obj) {
   RtcEventLogHelperThread* helper = static_cast<RtcEventLogHelperThread*>(obj);
-  helper->WriteLog();
+  helper->ProcessEvents();
   return false;
 }
 
 }  // namespace webrtc
 
 #endif  // ENABLE_RTC_EVENT_LOG