Revert "Refactor the PlatformThread API."

This reverts commit c89fdd716c.

Reason for revert: Causes rare compilation error on win-libfuzzer-asan trybot.
See https://ci.chromium.org/p/chromium/builders/try/win-libfuzzer-asan-rel/713745?

Original change's description:
> Refactor the PlatformThread API.
>
> PlatformThread's API is using old style function pointers, causes
> casting, is unintuitive and forces artificial call sequences, and
> is additionally possible to misuse in release mode.
>
> Fix this by an API face lift:
> 1. The class is turned into a handle, which can be empty.
> 2. The only way of getting a non-empty PlatformThread is by calling
> SpawnJoinable or SpawnDetached, clearly conveying the semantics to the
> code reader.
> 3. Handles can be Finalized, which works differently for joinable and
> detached threads:
>   a) Handles for detached threads are simply closed where applicable.
>   b) Joinable threads are joined before handles are closed.
> 4. The destructor finalizes handles. No explicit call is needed.
>
> Fixed: webrtc:12727
> Change-Id: Id00a0464edf4fc9e552b6a1fbb5d2e1280e88811
> Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/215075
> Commit-Queue: Markus Handell <handellm@webrtc.org>
> Reviewed-by: Harald Alvestrand <hta@webrtc.org>
> Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
> Reviewed-by: Tommi <tommi@webrtc.org>
> Cr-Commit-Position: refs/heads/master@{#33923}

# Not skipping CQ checks because original CL landed > 1 day ago.

TBR=handellm@webrtc.org

Bug: webrtc:12727
Change-Id: Ic0146be8866f6dd3ad9c364fb8646650b8e07419
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/217583
Reviewed-by: Guido Urdaneta <guidou@webrtc.org>
Reviewed-by: Markus Handell <handellm@webrtc.org>
Commit-Queue: Guido Urdaneta <guidou@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#33936}

api/sequence_checker_unittest.cc

@@ -40,14 +40,21 @@ class CompileTimeTestForGuardedBy {
 };
 
 void RunOnDifferentThread(rtc::FunctionView<void()> run) {
-  rtc::Event thread_has_run_event;
+  struct Object {
-  rtc::PlatformThread::SpawnJoinable(
+    static void Run(void* obj) {
-      [&] {
+      auto* me = static_cast<Object*>(obj);
-        run();
+      me->run();
-        thread_has_run_event.Set();
+      me->thread_has_run_event.Set();
-      },
+    }
-      "thread");
+
-  EXPECT_TRUE(thread_has_run_event.Wait(1000));
+    rtc::FunctionView<void()> run;
+    rtc::Event thread_has_run_event;
+  } object{run};
+
+  rtc::PlatformThread thread(&Object::Run, &object, "thread");
+  thread.Start();
+  EXPECT_TRUE(object.thread_has_run_event.Wait(1000));
+  thread.Stop();
 }
 
 }  // namespace

modules/audio_coding/acm2/audio_coding_module_unittest.cc

@@ -429,6 +429,21 @@ class AudioCodingModuleMtTestOldApi : public AudioCodingModuleTestOldApi {
 
   AudioCodingModuleMtTestOldApi()
       : AudioCodingModuleTestOldApi(),
+        send_thread_(
+            CbSendThread,
+            this,
+            "send",
+            rtc::ThreadAttributes().SetPriority(rtc::kRealtimePriority)),
+        insert_packet_thread_(
+            CbInsertPacketThread,
+            this,
+            "insert_packet",
+            rtc::ThreadAttributes().SetPriority(rtc::kRealtimePriority)),
+        pull_audio_thread_(
+            CbPullAudioThread,
+            this,
+            "pull_audio",
+            rtc::ThreadAttributes().SetPriority(rtc::kRealtimePriority)),
         send_count_(0),
         insert_packet_count_(0),
         pull_audio_count_(0),
@@ -445,38 +460,17 @@ class AudioCodingModuleMtTestOldApi : public AudioCodingModuleTestOldApi {
 
   void StartThreads() {
     quit_.store(false);
-
+    send_thread_.Start();
-    const auto attributes =
+    insert_packet_thread_.Start();
-        rtc::ThreadAttributes().SetPriority(rtc::ThreadPriority::kRealtime);
+    pull_audio_thread_.Start();
-    send_thread_ = rtc::PlatformThread::SpawnJoinable(
-        [this] {
-          while (!quit_.load()) {
-            CbSendImpl();
-          }
-        },
-        "send", attributes);
-    insert_packet_thread_ = rtc::PlatformThread::SpawnJoinable(
-        [this] {
-          while (!quit_.load()) {
-            CbInsertPacketImpl();
-          }
-        },
-        "insert_packet", attributes);
-    pull_audio_thread_ = rtc::PlatformThread::SpawnJoinable(
-        [this] {
-          while (!quit_.load()) {
-            CbPullAudioImpl();
-          }
-        },
-        "pull_audio", attributes);
   }
 
   void TearDown() {
     AudioCodingModuleTestOldApi::TearDown();
     quit_.store(true);
-    pull_audio_thread_.Finalize();
+    pull_audio_thread_.Stop();
-    send_thread_.Finalize();
+    send_thread_.Stop();
-    insert_packet_thread_.Finalize();
+    insert_packet_thread_.Stop();
   }
 
   bool RunTest() {
@@ -494,6 +488,14 @@ class AudioCodingModuleMtTestOldApi : public AudioCodingModuleTestOldApi {
     return false;
   }
 
+  static void CbSendThread(void* context) {
+    AudioCodingModuleMtTestOldApi* fixture =
+        reinterpret_cast<AudioCodingModuleMtTestOldApi*>(context);
+    while (!fixture->quit_.load()) {
+      fixture->CbSendImpl();
+    }
+  }
+
   // The send thread doesn't have to care about the current simulated time,
   // since only the AcmReceiver is using the clock.
   void CbSendImpl() {
@@ -509,6 +511,14 @@ class AudioCodingModuleMtTestOldApi : public AudioCodingModuleTestOldApi {
     }
   }
 
+  static void CbInsertPacketThread(void* context) {
+    AudioCodingModuleMtTestOldApi* fixture =
+        reinterpret_cast<AudioCodingModuleMtTestOldApi*>(context);
+    while (!fixture->quit_.load()) {
+      fixture->CbInsertPacketImpl();
+    }
+  }
+
   void CbInsertPacketImpl() {
     SleepMs(1);
     {
@@ -523,6 +533,14 @@ class AudioCodingModuleMtTestOldApi : public AudioCodingModuleTestOldApi {
     InsertPacket();
   }
 
+  static void CbPullAudioThread(void* context) {
+    AudioCodingModuleMtTestOldApi* fixture =
+        reinterpret_cast<AudioCodingModuleMtTestOldApi*>(context);
+    while (!fixture->quit_.load()) {
+      fixture->CbPullAudioImpl();
+    }
+  }
+
   void CbPullAudioImpl() {
     SleepMs(1);
     {
@@ -681,6 +699,16 @@ class AcmReRegisterIsacMtTestOldApi : public AudioCodingModuleTestOldApi {
 
   AcmReRegisterIsacMtTestOldApi()
       : AudioCodingModuleTestOldApi(),
+        receive_thread_(
+            CbReceiveThread,
+            this,
+            "receive",
+            rtc::ThreadAttributes().SetPriority(rtc::kRealtimePriority)),
+        codec_registration_thread_(
+            CbCodecRegistrationThread,
+            this,
+            "codec_registration",
+            rtc::ThreadAttributes().SetPriority(rtc::kRealtimePriority)),
         codec_registered_(false),
         receive_packet_count_(0),
         next_insert_packet_time_ms_(0),
@@ -712,34 +740,28 @@ class AcmReRegisterIsacMtTestOldApi : public AudioCodingModuleTestOldApi {
 
   void StartThreads() {
     quit_.store(false);
-    const auto attributes =
+    receive_thread_.Start();
-        rtc::ThreadAttributes().SetPriority(rtc::ThreadPriority::kRealtime);
+    codec_registration_thread_.Start();
-    receive_thread_ = rtc::PlatformThread::SpawnJoinable(
-        [this] {
-          while (!quit_.load() && CbReceiveImpl()) {
-          }
-        },
-        "receive", attributes);
-    codec_registration_thread_ = rtc::PlatformThread::SpawnJoinable(
-        [this] {
-          while (!quit_.load()) {
-            CbCodecRegistrationImpl();
-          }
-        },
-        "codec_registration", attributes);
   }
 
   void TearDown() override {
     AudioCodingModuleTestOldApi::TearDown();
     quit_.store(true);
-    receive_thread_.Finalize();
+    receive_thread_.Stop();
-    codec_registration_thread_.Finalize();
+    codec_registration_thread_.Stop();
   }
 
   bool RunTest() {
     return test_complete_.Wait(10 * 60 * 1000);  // 10 minutes' timeout.
   }
 
+  static void CbReceiveThread(void* context) {
+    AcmReRegisterIsacMtTestOldApi* fixture =
+        reinterpret_cast<AcmReRegisterIsacMtTestOldApi*>(context);
+    while (!fixture->quit_.load() && fixture->CbReceiveImpl()) {
+    }
+  }
+
   bool CbReceiveImpl() {
     SleepMs(1);
     rtc::Buffer encoded;
@@ -785,6 +807,14 @@ class AcmReRegisterIsacMtTestOldApi : public AudioCodingModuleTestOldApi {
     return true;
   }
 
+  static void CbCodecRegistrationThread(void* context) {
+    AcmReRegisterIsacMtTestOldApi* fixture =
+        reinterpret_cast<AcmReRegisterIsacMtTestOldApi*>(context);
+    while (!fixture->quit_.load()) {
+      fixture->CbCodecRegistrationImpl();
+    }
+  }
+
   void CbCodecRegistrationImpl() {
     SleepMs(1);
     if (HasFatalFailure()) {

modules/audio_device/dummy/file_audio_device.cc

@@ -216,13 +216,10 @@ int32_t FileAudioDevice::StartPlayout() {
     }
   }
 
-  _ptrThreadPlay = rtc::PlatformThread::SpawnJoinable(
+  _ptrThreadPlay.reset(new rtc::PlatformThread(
-      [this] {
+      PlayThreadFunc, this, "webrtc_audio_module_play_thread",
-        while (PlayThreadProcess()) {
+      rtc::ThreadAttributes().SetPriority(rtc::kRealtimePriority)));
-        }
+  _ptrThreadPlay->Start();
-      },
-      "webrtc_audio_module_play_thread",
-      rtc::ThreadAttributes().SetPriority(rtc::ThreadPriority::kRealtime));
 
   RTC_LOG(LS_INFO) << "Started playout capture to output file: "
                    << _outputFilename;
@@ -236,8 +233,10 @@ int32_t FileAudioDevice::StopPlayout() {
   }
 
   // stop playout thread first
-  if (!_ptrThreadPlay.empty())
+  if (_ptrThreadPlay) {
-    _ptrThreadPlay.Finalize();
+    _ptrThreadPlay->Stop();
+    _ptrThreadPlay.reset();
+  }
 
   MutexLock lock(&mutex_);
 
@@ -277,13 +276,11 @@ int32_t FileAudioDevice::StartRecording() {
     }
   }
 
-  _ptrThreadRec = rtc::PlatformThread::SpawnJoinable(
+  _ptrThreadRec.reset(new rtc::PlatformThread(
-      [this] {
+      RecThreadFunc, this, "webrtc_audio_module_capture_thread",
-        while (RecThreadProcess()) {
+      rtc::ThreadAttributes().SetPriority(rtc::kRealtimePriority)));
-        }
+
-      },
+  _ptrThreadRec->Start();
-      "webrtc_audio_module_capture_thread",
-      rtc::ThreadAttributes().SetPriority(rtc::ThreadPriority::kRealtime));
 
   RTC_LOG(LS_INFO) << "Started recording from input file: " << _inputFilename;
 
@@ -296,8 +293,10 @@ int32_t FileAudioDevice::StopRecording() {
     _recording = false;
   }
 
-  if (!_ptrThreadRec.empty())
+  if (_ptrThreadRec) {
-    _ptrThreadRec.Finalize();
+    _ptrThreadRec->Stop();
+    _ptrThreadRec.reset();
+  }
 
   MutexLock lock(&mutex_);
   _recordingFramesLeft = 0;
@@ -440,6 +439,18 @@ void FileAudioDevice::AttachAudioBuffer(AudioDeviceBuffer* audioBuffer) {
   _ptrAudioBuffer->SetPlayoutChannels(0);
 }
 
+void FileAudioDevice::PlayThreadFunc(void* pThis) {
+  FileAudioDevice* device = static_cast<FileAudioDevice*>(pThis);
+  while (device->PlayThreadProcess()) {
+  }
+}
+
+void FileAudioDevice::RecThreadFunc(void* pThis) {
+  FileAudioDevice* device = static_cast<FileAudioDevice*>(pThis);
+  while (device->RecThreadProcess()) {
+  }
+}
+
 bool FileAudioDevice::PlayThreadProcess() {
   if (!_playing) {
     return false;

modules/audio_device/dummy/file_audio_device.h

@@ -17,11 +17,14 @@
 #include <string>
 
 #include "modules/audio_device/audio_device_generic.h"
-#include "rtc_base/platform_thread.h"
 #include "rtc_base/synchronization/mutex.h"
 #include "rtc_base/system/file_wrapper.h"
 #include "rtc_base/time_utils.h"
 
+namespace rtc {
+class PlatformThread;
+}  // namespace rtc
+
 namespace webrtc {
 
 // This is a fake audio device which plays audio from a file as its microphone
@@ -142,8 +145,9 @@ class FileAudioDevice : public AudioDeviceGeneric {
   size_t _recordingFramesIn10MS;
   size_t _playoutFramesIn10MS;
 
-  rtc::PlatformThread _ptrThreadRec;
+  // TODO(pbos): Make plain members instead of pointers and stop resetting them.
-  rtc::PlatformThread _ptrThreadPlay;
+  std::unique_ptr<rtc::PlatformThread> _ptrThreadRec;
+  std::unique_ptr<rtc::PlatformThread> _ptrThreadPlay;
 
   bool _playing;
   bool _recording;

modules/audio_device/linux/audio_device_alsa_linux.cc

@@ -178,13 +178,26 @@ int32_t AudioDeviceLinuxALSA::Terminate() {
   _mixerManager.Close();
 
   // RECORDING
-  mutex_.Unlock();
+  if (_ptrThreadRec) {
-  _ptrThreadRec.Finalize();
+    rtc::PlatformThread* tmpThread = _ptrThreadRec.release();
+    mutex_.Unlock();
+
+    tmpThread->Stop();
+    delete tmpThread;
+
+    mutex_.Lock();
+  }
 
   // PLAYOUT
-  _ptrThreadPlay.Finalize();
+  if (_ptrThreadPlay) {
-  mutex_.Lock();
+    rtc::PlatformThread* tmpThread = _ptrThreadPlay.release();
+    mutex_.Unlock();
 
+    tmpThread->Stop();
+    delete tmpThread;
+
+    mutex_.Lock();
+  }
 #if defined(WEBRTC_USE_X11)
   if (_XDisplay) {
     XCloseDisplay(_XDisplay);
@@ -1027,13 +1040,11 @@ int32_t AudioDeviceLinuxALSA::StartRecording() {
     return -1;
   }
   // RECORDING
-  _ptrThreadRec = rtc::PlatformThread::SpawnJoinable(
+  _ptrThreadRec.reset(new rtc::PlatformThread(
-      [this] {
+      RecThreadFunc, this, "webrtc_audio_module_capture_thread",
-        while (RecThreadProcess()) {
+      rtc::ThreadAttributes().SetPriority(rtc::kRealtimePriority)));
-        }
+
-      },
+  _ptrThreadRec->Start();
-      "webrtc_audio_module_capture_thread",
-      rtc::ThreadAttributes().SetPriority(rtc::ThreadPriority::kRealtime));
 
   errVal = LATE(snd_pcm_prepare)(_handleRecord);
   if (errVal < 0) {
@@ -1077,7 +1088,10 @@ int32_t AudioDeviceLinuxALSA::StopRecordingLocked() {
   _recIsInitialized = false;
   _recording = false;
 
-  _ptrThreadRec.Finalize();
+  if (_ptrThreadRec) {
+    _ptrThreadRec->Stop();
+    _ptrThreadRec.reset();
+  }
 
   _recordingFramesLeft = 0;
   if (_recordingBuffer) {
@@ -1144,13 +1158,10 @@ int32_t AudioDeviceLinuxALSA::StartPlayout() {
   }
 
   // PLAYOUT
-  _ptrThreadPlay = rtc::PlatformThread::SpawnJoinable(
+  _ptrThreadPlay.reset(new rtc::PlatformThread(
-      [this] {
+      PlayThreadFunc, this, "webrtc_audio_module_play_thread",
-        while (PlayThreadProcess()) {
+      rtc::ThreadAttributes().SetPriority(rtc::kRealtimePriority)));
-        }
+  _ptrThreadPlay->Start();
-      },
-      "webrtc_audio_module_play_thread",
-      rtc::ThreadAttributes().SetPriority(rtc::ThreadPriority::kRealtime));
 
   int errVal = LATE(snd_pcm_prepare)(_handlePlayout);
   if (errVal < 0) {
@@ -1180,7 +1191,10 @@ int32_t AudioDeviceLinuxALSA::StopPlayoutLocked() {
   _playing = false;
 
   // stop playout thread first
-  _ptrThreadPlay.Finalize();
+  if (_ptrThreadPlay) {
+    _ptrThreadPlay->Stop();
+    _ptrThreadPlay.reset();
+  }
 
   _playoutFramesLeft = 0;
   delete[] _playoutBuffer;
@@ -1455,6 +1469,18 @@ int32_t AudioDeviceLinuxALSA::ErrorRecovery(int32_t error,
 //                                  Thread Methods
 // ============================================================================
 
+void AudioDeviceLinuxALSA::PlayThreadFunc(void* pThis) {
+  AudioDeviceLinuxALSA* device = static_cast<AudioDeviceLinuxALSA*>(pThis);
+  while (device->PlayThreadProcess()) {
+  }
+}
+
+void AudioDeviceLinuxALSA::RecThreadFunc(void* pThis) {
+  AudioDeviceLinuxALSA* device = static_cast<AudioDeviceLinuxALSA*>(pThis);
+  while (device->RecThreadProcess()) {
+  }
+}
+
 bool AudioDeviceLinuxALSA::PlayThreadProcess() {
   if (!_playing)
     return false;

modules/audio_device/linux/audio_device_alsa_linux.h

@@ -155,8 +155,10 @@ class AudioDeviceLinuxALSA : public AudioDeviceGeneric {
 
   Mutex mutex_;
 
-  rtc::PlatformThread _ptrThreadRec;
+  // TODO(pbos): Make plain members and start/stop instead of resetting these
-  rtc::PlatformThread _ptrThreadPlay;
+  // pointers. A thread can be reused.
+  std::unique_ptr<rtc::PlatformThread> _ptrThreadRec;
+  std::unique_ptr<rtc::PlatformThread> _ptrThreadPlay;
 
   AudioMixerManagerLinuxALSA _mixerManager;
 

modules/audio_device/linux/audio_device_pulse_linux.cc

@@ -15,7 +15,6 @@
 #include "modules/audio_device/linux/latebindingsymboltable_linux.h"
 #include "rtc_base/checks.h"
 #include "rtc_base/logging.h"
-#include "rtc_base/platform_thread.h"
 
 WebRTCPulseSymbolTable* GetPulseSymbolTable() {
   static WebRTCPulseSymbolTable* pulse_symbol_table =
@@ -159,22 +158,18 @@ AudioDeviceGeneric::InitStatus AudioDeviceLinuxPulse::Init() {
 #endif
 
   // RECORDING
-  const auto attributes =
+  _ptrThreadRec.reset(new rtc::PlatformThread(
-      rtc::ThreadAttributes().SetPriority(rtc::ThreadPriority::kRealtime);
+      RecThreadFunc, this, "webrtc_audio_module_rec_thread",
-  _ptrThreadRec = rtc::PlatformThread::SpawnJoinable(
+      rtc::ThreadAttributes().SetPriority(rtc::kRealtimePriority)));
-      [this] {
+
-        while (RecThreadProcess()) {
+  _ptrThreadRec->Start();
-        }
-      },
-      "webrtc_audio_module_rec_thread", attributes);
 
   // PLAYOUT
-  _ptrThreadPlay = rtc::PlatformThread::SpawnJoinable(
+  _ptrThreadPlay.reset(new rtc::PlatformThread(
-      [this] {
+      PlayThreadFunc, this, "webrtc_audio_module_play_thread",
-        while (PlayThreadProcess()) {
+      rtc::ThreadAttributes().SetPriority(rtc::kRealtimePriority)));
-        }
+  _ptrThreadPlay->Start();
-      },
+
-      "webrtc_audio_module_play_thread", attributes);
   _initialized = true;
 
   return InitStatus::OK;
@@ -192,12 +187,22 @@ int32_t AudioDeviceLinuxPulse::Terminate() {
   _mixerManager.Close();
 
   // RECORDING
-  _timeEventRec.Set();
+  if (_ptrThreadRec) {
-  _ptrThreadRec.Finalize();
+    rtc::PlatformThread* tmpThread = _ptrThreadRec.release();
+
+    _timeEventRec.Set();
+    tmpThread->Stop();
+    delete tmpThread;
+  }
 
   // PLAYOUT
-  _timeEventPlay.Set();
+  if (_ptrThreadPlay) {
-  _ptrThreadPlay.Finalize();
+    rtc::PlatformThread* tmpThread = _ptrThreadPlay.release();
+
+    _timeEventPlay.Set();
+    tmpThread->Stop();
+    delete tmpThread;
+  }
 
   // Terminate PulseAudio
   if (TerminatePulseAudio() < 0) {
@@ -1976,6 +1981,18 @@ int32_t AudioDeviceLinuxPulse::ProcessRecordedData(int8_t* bufferData,
   return 0;
 }
 
+void AudioDeviceLinuxPulse::PlayThreadFunc(void* pThis) {
+  AudioDeviceLinuxPulse* device = static_cast<AudioDeviceLinuxPulse*>(pThis);
+  while (device->PlayThreadProcess()) {
+  }
+}
+
+void AudioDeviceLinuxPulse::RecThreadFunc(void* pThis) {
+  AudioDeviceLinuxPulse* device = static_cast<AudioDeviceLinuxPulse*>(pThis);
+  while (device->RecThreadProcess()) {
+  }
+}
+
 bool AudioDeviceLinuxPulse::PlayThreadProcess() {
   if (!_timeEventPlay.Wait(1000)) {
     return true;

modules/audio_device/linux/audio_device_pulse_linux.h

@@ -268,8 +268,9 @@ class AudioDeviceLinuxPulse : public AudioDeviceGeneric {
   rtc::Event _recStartEvent;
   rtc::Event _playStartEvent;
 
-  rtc::PlatformThread _ptrThreadPlay;
+  // TODO(pbos): Remove unique_ptr and use directly without resetting.
-  rtc::PlatformThread _ptrThreadRec;
+  std::unique_ptr<rtc::PlatformThread> _ptrThreadPlay;
+  std::unique_ptr<rtc::PlatformThread> _ptrThreadRec;
 
   AudioMixerManagerLinuxPulse _mixerManager;
 

modules/audio_device/mac/audio_device_mac.cc

@@ -166,8 +166,8 @@ AudioDeviceMac::~AudioDeviceMac() {
     Terminate();
   }
 
-  RTC_DCHECK(capture_worker_thread_.empty());
+  RTC_DCHECK(!capture_worker_thread_.get());
-  RTC_DCHECK(render_worker_thread_.empty());
+  RTC_DCHECK(!render_worker_thread_.get());
 
   if (_paRenderBuffer) {
     delete _paRenderBuffer;
@@ -1308,14 +1308,12 @@ int32_t AudioDeviceMac::StartRecording() {
     return -1;
   }
 
-  RTC_DCHECK(capture_worker_thread_.empty());
+  RTC_DCHECK(!capture_worker_thread_.get());
-  capture_worker_thread_ = rtc::PlatformThread::SpawnJoinable(
+  capture_worker_thread_.reset(new rtc::PlatformThread(
-      [this] {
+      RunCapture, this, "CaptureWorkerThread",
-        while (CaptureWorkerThread()) {
+      rtc::ThreadAttributes().SetPriority(rtc::kRealtimePriority)));
-        }
+  RTC_DCHECK(capture_worker_thread_.get());
-      },
+  capture_worker_thread_->Start();
-      "CaptureWorkerThread",
-      rtc::ThreadAttributes().SetPriority(rtc::ThreadPriority::kRealtime));
 
   OSStatus err = noErr;
   if (_twoDevices) {
@@ -1397,9 +1395,10 @@ int32_t AudioDeviceMac::StopRecording() {
   // Setting this signal will allow the worker thread to be stopped.
   AtomicSet32(&_captureDeviceIsAlive, 0);
 
-  if (!capture_worker_thread_.empty()) {
+  if (capture_worker_thread_.get()) {
     mutex_.Unlock();
-    capture_worker_thread_.Finalize();
+    capture_worker_thread_->Stop();
+    capture_worker_thread_.reset();
     mutex_.Lock();
   }
 
@@ -1445,14 +1444,11 @@ int32_t AudioDeviceMac::StartPlayout() {
     return 0;
   }
 
-  RTC_DCHECK(render_worker_thread_.empty());
+  RTC_DCHECK(!render_worker_thread_.get());
-  render_worker_thread_ = rtc::PlatformThread::SpawnJoinable(
+  render_worker_thread_.reset(new rtc::PlatformThread(
-      [this] {
+      RunRender, this, "RenderWorkerThread",
-        while (RenderWorkerThread()) {
+      rtc::ThreadAttributes().SetPriority(rtc::kRealtimePriority)));
-        }
+  render_worker_thread_->Start();
-      },
-      "RenderWorkerThread",
-      rtc::ThreadAttributes().SetPriority(rtc::ThreadPriority::kRealtime));
 
   if (_twoDevices || !_recording) {
     OSStatus err = noErr;
@@ -1510,9 +1506,10 @@ int32_t AudioDeviceMac::StopPlayout() {
 
   // Setting this signal will allow the worker thread to be stopped.
   AtomicSet32(&_renderDeviceIsAlive, 0);
-  if (!render_worker_thread_.empty()) {
+  if (render_worker_thread_.get()) {
     mutex_.Unlock();
-    render_worker_thread_.Finalize();
+    render_worker_thread_->Stop();
+    render_worker_thread_.reset();
     mutex_.Lock();
   }
 
@@ -2374,6 +2371,12 @@ OSStatus AudioDeviceMac::implInConverterProc(UInt32* numberDataPackets,
   return 0;
 }
 
+void AudioDeviceMac::RunRender(void* ptrThis) {
+  AudioDeviceMac* device = static_cast<AudioDeviceMac*>(ptrThis);
+  while (device->RenderWorkerThread()) {
+  }
+}
+
 bool AudioDeviceMac::RenderWorkerThread() {
   PaRingBufferSize numSamples =
       ENGINE_PLAY_BUF_SIZE_IN_SAMPLES * _outDesiredFormat.mChannelsPerFrame;
@@ -2439,6 +2442,12 @@ bool AudioDeviceMac::RenderWorkerThread() {
   return true;
 }
 
+void AudioDeviceMac::RunCapture(void* ptrThis) {
+  AudioDeviceMac* device = static_cast<AudioDeviceMac*>(ptrThis);
+  while (device->CaptureWorkerThread()) {
+  }
+}
+
 bool AudioDeviceMac::CaptureWorkerThread() {
   OSStatus err = noErr;
   UInt32 noRecSamples =

modules/audio_device/mac/audio_device_mac.h

@@ -21,12 +21,15 @@
 #include "modules/audio_device/mac/audio_mixer_manager_mac.h"
 #include "rtc_base/event.h"
 #include "rtc_base/logging.h"
-#include "rtc_base/platform_thread.h"
 #include "rtc_base/synchronization/mutex.h"
 #include "rtc_base/thread_annotations.h"
 
 struct PaUtilRingBuffer;
 
+namespace rtc {
+class PlatformThread;
+}  // namespace rtc
+
 namespace webrtc {
 
 const uint32_t N_REC_SAMPLES_PER_SEC = 48000;
@@ -268,11 +271,13 @@ class AudioDeviceMac : public AudioDeviceGeneric {
   rtc::Event _stopEventRec;
   rtc::Event _stopEvent;
 
+  // TODO(pbos): Replace with direct members, just start/stop, no need to
+  // recreate the thread.
   // Only valid/running between calls to StartRecording and StopRecording.
-  rtc::PlatformThread capture_worker_thread_;
+  std::unique_ptr<rtc::PlatformThread> capture_worker_thread_;
 
   // Only valid/running between calls to StartPlayout and StopPlayout.
-  rtc::PlatformThread render_worker_thread_;
+  std::unique_ptr<rtc::PlatformThread> render_worker_thread_;
 
   AudioMixerManagerMac _mixerManager;
 

modules/audio_device/win/core_audio_base_win.cc

@@ -119,6 +119,11 @@ const char* SessionDisconnectReasonToString(
   }
 }
 
+void Run(void* obj) {
+  RTC_DCHECK(obj);
+  reinterpret_cast<CoreAudioBase*>(obj)->ThreadRun();
+}
+
 // Returns true if the selected audio device supports low latency, i.e, if it
 // is possible to initialize the engine using periods less than the default
 // period (10ms).
@@ -548,19 +553,24 @@ bool CoreAudioBase::Start() {
     // Audio thread should be alive during internal restart since the restart
     // callback is triggered on that thread and it also makes the restart
     // sequence less complex.
-    RTC_DCHECK(!audio_thread_.empty());
+    RTC_DCHECK(audio_thread_);
   }
 
   // Start an audio thread but only if one does not already exist (which is the
   // case during restart).
-  if (audio_thread_.empty()) {
+  if (!audio_thread_) {
-    const absl::string_view name =
+    audio_thread_ = std::make_unique<rtc::PlatformThread>(
-        IsInput() ? "wasapi_capture_thread" : "wasapi_render_thread";
+        Run, this, IsInput() ? "wasapi_capture_thread" : "wasapi_render_thread",
-    audio_thread_ = rtc::PlatformThread::SpawnJoinable(
+        rtc::ThreadAttributes().SetPriority(rtc::kRealtimePriority));
-        [this] { ThreadRun(); }, name,
+    RTC_DCHECK(audio_thread_);
-        rtc::ThreadAttributes().SetPriority(rtc::ThreadPriority::kRealtime));
+    audio_thread_->Start();
-    RTC_DLOG(INFO) << "Started thread with name: " << name
+    if (!audio_thread_->IsRunning()) {
-                   << " and handle: " << *audio_thread_.GetHandle();
+      StopThread();
+      RTC_LOG(LS_ERROR) << "Failed to start audio thread";
+      return false;
+    }
+    RTC_DLOG(INFO) << "Started thread with name: " << audio_thread_->name()
+                   << " and id: " << audio_thread_->GetThreadRef();
   }
 
   // Start streaming data between the endpoint buffer and the audio engine.
@@ -687,11 +697,14 @@ bool CoreAudioBase::Restart() {
 void CoreAudioBase::StopThread() {
   RTC_DLOG(INFO) << __FUNCTION__;
   RTC_DCHECK(!IsRestarting());
-  if (!audio_thread_.empty()) {
+  if (audio_thread_) {
-    RTC_DLOG(INFO) << "Sets stop_event...";
+    if (audio_thread_->IsRunning()) {
-    SetEvent(stop_event_.Get());
+      RTC_DLOG(INFO) << "Sets stop_event...";
-    RTC_DLOG(INFO) << "PlatformThread::Finalize...";
+      SetEvent(stop_event_.Get());
-    audio_thread_.Finalize();
+      RTC_DLOG(INFO) << "PlatformThread::Stop...";
+      audio_thread_->Stop();
+    }
+    audio_thread_.reset();
 
     // Ensure that we don't quit the main thread loop immediately next
     // time Start() is called.
@@ -704,7 +717,7 @@ bool CoreAudioBase::HandleRestartEvent() {
   RTC_DLOG(INFO) << __FUNCTION__ << "[" << DirectionToString(direction())
                  << "]";
   RTC_DCHECK_RUN_ON(&thread_checker_audio_);
-  RTC_DCHECK(!audio_thread_.empty());
+  RTC_DCHECK(audio_thread_);
   RTC_DCHECK(IsRestarting());
   // Let each client (input and/or output) take care of its own restart
   // sequence since each side might need unique actions.

modules/audio_device/win/core_audio_base_win.h

@@ -158,7 +158,7 @@ class CoreAudioBase : public IAudioSessionEvents {
   // Set when restart process starts and cleared when restart stops
   // successfully. Accessed atomically.
   std::atomic<bool> is_restarting_;
-  rtc::PlatformThread audio_thread_;
+  std::unique_ptr<rtc::PlatformThread> audio_thread_;
   Microsoft::WRL::ComPtr<IAudioSessionControl> audio_session_control_;
 
   void StopThread();

modules/audio_processing/audio_processing_impl_locking_unittest.cc

@@ -387,6 +387,33 @@ class AudioProcessingImplLockTest
   void SetUp() override;
   void TearDown() override;
 
+  // Thread callback for the render thread
+  static void RenderProcessorThreadFunc(void* context) {
+    AudioProcessingImplLockTest* impl =
+        reinterpret_cast<AudioProcessingImplLockTest*>(context);
+    while (!impl->MaybeEndTest()) {
+      impl->render_thread_state_.Process();
+    }
+  }
+
+  // Thread callback for the capture thread
+  static void CaptureProcessorThreadFunc(void* context) {
+    AudioProcessingImplLockTest* impl =
+        reinterpret_cast<AudioProcessingImplLockTest*>(context);
+    while (!impl->MaybeEndTest()) {
+      impl->capture_thread_state_.Process();
+    }
+  }
+
+  // Thread callback for the stats thread
+  static void StatsProcessorThreadFunc(void* context) {
+    AudioProcessingImplLockTest* impl =
+        reinterpret_cast<AudioProcessingImplLockTest*>(context);
+    while (!impl->MaybeEndTest()) {
+      impl->stats_thread_state_.Process();
+    }
+  }
+
   // Tests whether all the required render and capture side calls have been
   // done.
   bool TestDone() {
@@ -396,28 +423,9 @@ class AudioProcessingImplLockTest
 
   // Start the threads used in the test.
   void StartThreads() {
-    const auto attributes =
+    render_thread_.Start();
-        rtc::ThreadAttributes().SetPriority(rtc::ThreadPriority::kRealtime);
+    capture_thread_.Start();
-    render_thread_ = rtc::PlatformThread::SpawnJoinable(
+    stats_thread_.Start();
-        [this] {
-          while (!MaybeEndTest())
-            render_thread_state_.Process();
-        },
-        "render", attributes);
-    capture_thread_ = rtc::PlatformThread::SpawnJoinable(
-        [this] {
-          while (!MaybeEndTest()) {
-            capture_thread_state_.Process();
-          }
-        },
-        "capture", attributes);
-
-    stats_thread_ = rtc::PlatformThread::SpawnJoinable(
-        [this] {
-          while (!MaybeEndTest())
-            stats_thread_state_.Process();
-        },
-        "stats", attributes);
   }
 
   // Event handlers for the test.
@@ -426,6 +434,9 @@ class AudioProcessingImplLockTest
   rtc::Event capture_call_event_;
 
   // Thread related variables.
+  rtc::PlatformThread render_thread_;
+  rtc::PlatformThread capture_thread_;
+  rtc::PlatformThread stats_thread_;
   mutable RandomGenerator rand_gen_;
 
   std::unique_ptr<AudioProcessing> apm_;
@@ -434,9 +445,6 @@ class AudioProcessingImplLockTest
   RenderProcessor render_thread_state_;
   CaptureProcessor capture_thread_state_;
   StatsProcessor stats_thread_state_;
-  rtc::PlatformThread render_thread_;
-  rtc::PlatformThread capture_thread_;
-  rtc::PlatformThread stats_thread_;
 };
 
 // Sleeps a random time between 0 and max_sleep milliseconds.
@@ -477,7 +485,22 @@ void PopulateAudioFrame(float amplitude,
 }
 
 AudioProcessingImplLockTest::AudioProcessingImplLockTest()
-    : apm_(AudioProcessingBuilderForTesting().Create()),
+    : render_thread_(
+          RenderProcessorThreadFunc,
+          this,
+          "render",
+          rtc::ThreadAttributes().SetPriority(rtc::kRealtimePriority)),
+      capture_thread_(
+          CaptureProcessorThreadFunc,
+          this,
+          "capture",
+          rtc::ThreadAttributes().SetPriority(rtc::kRealtimePriority)),
+      stats_thread_(
+          StatsProcessorThreadFunc,
+          this,
+          "stats",
+          rtc::ThreadAttributes().SetPriority(rtc::kRealtimePriority)),
+      apm_(AudioProcessingBuilderForTesting().Create()),
       render_thread_state_(kMaxFrameSize,
                            &rand_gen_,
                            &render_call_event_,
@@ -529,6 +552,9 @@ void AudioProcessingImplLockTest::SetUp() {
 void AudioProcessingImplLockTest::TearDown() {
   render_call_event_.Set();
   capture_call_event_.Set();
+  render_thread_.Stop();
+  capture_thread_.Stop();
+  stats_thread_.Stop();
 }
 
 StatsProcessor::StatsProcessor(RandomGenerator* rand_gen,

modules/audio_processing/audio_processing_performance_unittest.cc

@@ -391,7 +391,17 @@ class TimedThreadApiProcessor {
 class CallSimulator : public ::testing::TestWithParam<SimulationConfig> {
  public:
   CallSimulator()
-      : rand_gen_(42U),
+      : render_thread_(new rtc::PlatformThread(
+            RenderProcessorThreadFunc,
+            this,
+            "render",
+            rtc::ThreadAttributes().SetPriority(rtc::kRealtimePriority))),
+        capture_thread_(new rtc::PlatformThread(
+            CaptureProcessorThreadFunc,
+            this,
+            "capture",
+            rtc::ThreadAttributes().SetPriority(rtc::kRealtimePriority))),
+        rand_gen_(42U),
         simulation_config_(static_cast<SimulationConfig>(GetParam())) {}
 
   // Run the call simulation with a timeout.
@@ -426,10 +436,13 @@ class CallSimulator : public ::testing::TestWithParam<SimulationConfig> {
   static const int kMinNumFramesToProcess = 150;
   static const int32_t kTestTimeout = 3 * 10 * kMinNumFramesToProcess;
 
+  // ::testing::TestWithParam<> implementation.
+  void TearDown() override { StopThreads(); }
+
   // Stop all running threads.
   void StopThreads() {
-    render_thread_.Finalize();
+    render_thread_->Stop();
-    capture_thread_.Finalize();
+    capture_thread_->Stop();
   }
 
   // Simulator and APM setup.
@@ -520,28 +533,32 @@ class CallSimulator : public ::testing::TestWithParam<SimulationConfig> {
         kMinNumFramesToProcess, kCaptureInputFloatLevel, num_capture_channels));
   }
 
+  // Thread callback for the render thread.
+  static void RenderProcessorThreadFunc(void* context) {
+    CallSimulator* call_simulator = reinterpret_cast<CallSimulator*>(context);
+    while (call_simulator->render_thread_state_->Process()) {
+    }
+  }
+
+  // Thread callback for the capture thread.
+  static void CaptureProcessorThreadFunc(void* context) {
+    CallSimulator* call_simulator = reinterpret_cast<CallSimulator*>(context);
+    while (call_simulator->capture_thread_state_->Process()) {
+    }
+  }
+
   // Start the threads used in the test.
   void StartThreads() {
-    const auto attributes =
+    ASSERT_NO_FATAL_FAILURE(render_thread_->Start());
-        rtc::ThreadAttributes().SetPriority(rtc::ThreadPriority::kRealtime);
+    ASSERT_NO_FATAL_FAILURE(capture_thread_->Start());
-    render_thread_ = rtc::PlatformThread::SpawnJoinable(
-        [this] {
-          while (render_thread_state_->Process()) {
-          }
-        },
-        "render", attributes);
-    capture_thread_ = rtc::PlatformThread::SpawnJoinable(
-        [this] {
-          while (capture_thread_state_->Process()) {
-          }
-        },
-        "capture", attributes);
   }
 
   // Event handler for the test.
   rtc::Event test_complete_;
 
   // Thread related variables.
+  std::unique_ptr<rtc::PlatformThread> render_thread_;
+  std::unique_ptr<rtc::PlatformThread> capture_thread_;
   Random rand_gen_;
 
   std::unique_ptr<AudioProcessing> apm_;
@@ -550,8 +567,6 @@ class CallSimulator : public ::testing::TestWithParam<SimulationConfig> {
   LockedFlag capture_call_checker_;
   std::unique_ptr<TimedThreadApiProcessor> render_thread_state_;
   std::unique_ptr<TimedThreadApiProcessor> capture_thread_state_;
-  rtc::PlatformThread render_thread_;
-  rtc::PlatformThread capture_thread_;
 };
 
 // Implements the callback functionality for the threads.

modules/desktop_capture/screen_drawer_unittest.cc

@@ -48,12 +48,13 @@ void TestScreenDrawerLock(
 
     ~Task() = default;
 
-    void RunTask() {
+    static void RunTask(void* me) {
-      std::unique_ptr<ScreenDrawerLock> lock = ctor_();
+      Task* task = static_cast<Task*>(me);
+      std::unique_ptr<ScreenDrawerLock> lock = task->ctor_();
       ASSERT_TRUE(!!lock);
-      created_->store(true);
+      task->created_->store(true);
       // Wait for the main thread to get the signal of created_.
-      while (!ready_.load()) {
+      while (!task->ready_.load()) {
         SleepMs(1);
       }
       // At this point, main thread should begin to create a second lock. Though
@@ -76,8 +77,8 @@ void TestScreenDrawerLock(
     const rtc::FunctionView<std::unique_ptr<ScreenDrawerLock>()> ctor_;
   } task(&created, ready, ctor);
 
-  auto lock_thread = rtc::PlatformThread::SpawnJoinable(
+  rtc::PlatformThread lock_thread(&Task::RunTask, &task, "lock_thread");
-      [&task] { task.RunTask(); }, "lock_thread");
+  lock_thread.Start();
 
   // Wait for the first lock in Task::RunTask() to be created.
   // TODO(zijiehe): Find a better solution to wait for the creation of the first
@@ -94,6 +95,7 @@ void TestScreenDrawerLock(
   ASSERT_GT(kLockDurationMs, rtc::TimeMillis() - start_ms);
   ctor();
   ASSERT_LE(kLockDurationMs, rtc::TimeMillis() - start_ms);
+  lock_thread.Stop();
 }
 
 }  // namespace

modules/utility/source/process_thread_impl.cc

@@ -48,6 +48,7 @@ ProcessThreadImpl::ProcessThreadImpl(const char* thread_name)
 
 ProcessThreadImpl::~ProcessThreadImpl() {
   RTC_DCHECK(thread_checker_.IsCurrent());
+  RTC_DCHECK(!thread_.get());
   RTC_DCHECK(!stop_);
 
   while (!delayed_tasks_.empty()) {
@@ -71,8 +72,8 @@ void ProcessThreadImpl::Delete() {
 // Doesn't need locking, because the contending thread isn't running.
 void ProcessThreadImpl::Start() RTC_NO_THREAD_SAFETY_ANALYSIS {
   RTC_DCHECK(thread_checker_.IsCurrent());
-  RTC_DCHECK(thread_.empty());
+  RTC_DCHECK(!thread_.get());
-  if (!thread_.empty())
+  if (thread_.get())
     return;
 
   RTC_DCHECK(!stop_);
@@ -80,18 +81,14 @@ void ProcessThreadImpl::Start() RTC_NO_THREAD_SAFETY_ANALYSIS {
   for (ModuleCallback& m : modules_)
     m.module->ProcessThreadAttached(this);
 
-  thread_ = rtc::PlatformThread::SpawnJoinable(
+  thread_.reset(
-      [this] {
+      new rtc::PlatformThread(&ProcessThreadImpl::Run, this, thread_name_));
-        CurrentTaskQueueSetter set_current(this);
+  thread_->Start();
-        while (Process()) {
-        }
-      },
-      thread_name_);
 }
 
 void ProcessThreadImpl::Stop() {
   RTC_DCHECK(thread_checker_.IsCurrent());
-  if (thread_.empty())
+  if (!thread_.get())
     return;
 
   {
@@ -101,7 +98,9 @@ void ProcessThreadImpl::Stop() {
   }
 
   wake_up_.Set();
-  thread_.Finalize();
+
+  thread_->Stop();
+  thread_.reset();
 
   StopNoLocks();
 }
@@ -109,7 +108,7 @@ void ProcessThreadImpl::Stop() {
 // No locking needed, since this is called after the contending thread is
 // stopped.
 void ProcessThreadImpl::StopNoLocks() RTC_NO_THREAD_SAFETY_ANALYSIS {
-  RTC_DCHECK(thread_.empty());
+  RTC_DCHECK(!thread_);
   stop_ = false;
 
   for (ModuleCallback& m : modules_)
@@ -200,7 +199,7 @@ void ProcessThreadImpl::RegisterModule(Module* module,
   // Now that we know the module isn't in the list, we'll call out to notify
   // the module that it's attached to the worker thread.  We don't hold
   // the lock while we make this call.
-  if (!thread_.empty())
+  if (thread_.get())
     module->ProcessThreadAttached(this);
 
   {
@@ -228,6 +227,14 @@ void ProcessThreadImpl::DeRegisterModule(Module* module) {
   module->ProcessThreadAttached(nullptr);
 }
 
+// static
+void ProcessThreadImpl::Run(void* obj) {
+  ProcessThreadImpl* impl = static_cast<ProcessThreadImpl*>(obj);
+  CurrentTaskQueueSetter set_current(impl);
+  while (impl->Process()) {
+  }
+}
+
 bool ProcessThreadImpl::Process() {
   TRACE_EVENT1("webrtc", "ProcessThreadImpl", "name", thread_name_);
   int64_t now = rtc::TimeMillis();

modules/utility/source/process_thread_impl.h

@@ -45,6 +45,7 @@ class ProcessThreadImpl : public ProcessThread {
   void DeRegisterModule(Module* module) override;
 
  protected:
+  static void Run(void* obj);
   bool Process();
 
  private:
@@ -96,7 +97,8 @@ class ProcessThreadImpl : public ProcessThread {
 
   SequenceChecker thread_checker_;
   rtc::Event wake_up_;
-  rtc::PlatformThread thread_;
+  // TODO(pbos): Remove unique_ptr and stop recreating the thread.
+  std::unique_ptr<rtc::PlatformThread> thread_;
 
   ModuleList modules_ RTC_GUARDED_BY(mutex_);
   // Set to true when calling Process, to allow reentrant calls to WakeUp.

modules/video_capture/linux/video_capture_linux.cc

@@ -240,15 +240,12 @@ int32_t VideoCaptureModuleV4L2::StartCapture(
   }
 
   // start capture thread;
-  if (_captureThread.empty()) {
+  if (!_captureThread) {
     quit_ = false;
-    _captureThread = rtc::PlatformThread::SpawnJoinable(
+    _captureThread.reset(new rtc::PlatformThread(
-        [this] {
+        VideoCaptureModuleV4L2::CaptureThread, this, "CaptureThread",
-          while (CaptureProcess()) {
+        rtc::ThreadAttributes().SetPriority(rtc::kHighPriority)));
-          }
+    _captureThread->Start();
-        },
-        "CaptureThread",
-        rtc::ThreadAttributes().SetPriority(rtc::ThreadPriority::kHigh));
   }
 
   // Needed to start UVC camera - from the uvcview application
@@ -264,13 +261,14 @@ int32_t VideoCaptureModuleV4L2::StartCapture(
 }
 
 int32_t VideoCaptureModuleV4L2::StopCapture() {
-  if (!_captureThread.empty()) {
+  if (_captureThread) {
     {
       MutexLock lock(&capture_lock_);
       quit_ = true;
     }
-    // Make sure the capture thread stops using the mutex.
+    // Make sure the capture thread stop stop using the critsect.
-    _captureThread.Finalize();
+    _captureThread->Stop();
+    _captureThread.reset();
   }
 
   MutexLock lock(&capture_lock_);
@@ -358,6 +356,11 @@ bool VideoCaptureModuleV4L2::CaptureStarted() {
   return _captureStarted;
 }
 
+void VideoCaptureModuleV4L2::CaptureThread(void* obj) {
+  VideoCaptureModuleV4L2* capture = static_cast<VideoCaptureModuleV4L2*>(obj);
+  while (capture->CaptureProcess()) {
+  }
+}
 bool VideoCaptureModuleV4L2::CaptureProcess() {
   int retVal = 0;
   fd_set rSet;

modules/video_capture/linux/video_capture_linux.h

@@ -41,7 +41,8 @@ class VideoCaptureModuleV4L2 : public VideoCaptureImpl {
   bool AllocateVideoBuffers();
   bool DeAllocateVideoBuffers();
 
-  rtc::PlatformThread _captureThread;
+  // TODO(pbos): Stop using unique_ptr and resetting the thread.
+  std::unique_ptr<rtc::PlatformThread> _captureThread;
   Mutex capture_lock_;
   bool quit_ RTC_GUARDED_BY(capture_lock_);
   int32_t _deviceId;

rtc_base/BUILD.gn

@@ -245,7 +245,6 @@ rtc_library("platform_thread") {
   absl_deps = [
     "//third_party/abseil-cpp/absl/memory",
     "//third_party/abseil-cpp/absl/strings",
-    "//third_party/abseil-cpp/absl/types:optional",
   ]
 }
 
@@ -562,10 +561,7 @@ if (is_win) {
       "../api/task_queue",
       "synchronization:mutex",
     ]
-    absl_deps = [
+    absl_deps = [ "//third_party/abseil-cpp/absl/strings" ]
-      "//third_party/abseil-cpp/absl/strings",
-      "//third_party/abseil-cpp/absl/types:optional",
-    ]
   }
 }
 
@@ -1417,7 +1413,6 @@ if (rtc_include_tests) {
       absl_deps = [
         "//third_party/abseil-cpp/absl/base:core_headers",
         "//third_party/abseil-cpp/absl/memory",
-        "//third_party/abseil-cpp/absl/types:optional",
       ]
     }
 

rtc_base/async_resolver.cc

@@ -123,7 +123,7 @@ void AsyncResolver::Start(const SocketAddress& addr) {
   RTC_DCHECK_RUN_ON(&sequence_checker_);
   RTC_DCHECK(!destroy_called_);
   addr_ = addr;
-  PlatformThread::SpawnDetached(
+  auto thread_function =
       [this, addr, caller_task_queue = webrtc::TaskQueueBase::Current(),
        state = state_] {
         std::vector<IPAddress> addresses;
@@ -146,8 +146,14 @@ void AsyncResolver::Start(const SocketAddress& addr) {
                 }
               }));
         }
-      },
+      };
-      "AsyncResolver");
+  PlatformThread thread(RunResolution,
+                        new std::function<void()>(std::move(thread_function)),
+                        "NameResolution", ThreadAttributes().SetDetached());
+  thread.Start();
+  // Although |thread| is detached, the PlatformThread contract mandates to call
+  // Stop() before destruction. The call doesn't actually stop anything.
+  thread.Stop();
 }
 
 bool AsyncResolver::GetResolvedAddress(int family, SocketAddress* addr) const {

rtc_base/cpu_time_unittest.cc

@@ -30,7 +30,8 @@ const int kProcessingTimeMillisecs = 500;
 const int kWorkingThreads = 2;
 
 // Consumes approximately kProcessingTimeMillisecs of CPU time in single thread.
-void WorkingFunction(int64_t* counter) {
+void WorkingFunction(void* counter_pointer) {
+  int64_t* counter = reinterpret_cast<int64_t*>(counter_pointer);
   *counter = 0;
   int64_t stop_cpu_time =
       rtc::GetThreadCpuTimeNanos() +
@@ -61,12 +62,14 @@ TEST(CpuTimeTest, MAYBE_TEST(TwoThreads)) {
   int64_t thread_start_time_nanos = GetThreadCpuTimeNanos();
   int64_t counter1;
   int64_t counter2;
-  auto thread1 = PlatformThread::SpawnJoinable(
+  PlatformThread thread1(WorkingFunction, reinterpret_cast<void*>(&counter1),
-      [&counter1] { WorkingFunction(&counter1); }, "Thread1");
+                         "Thread1");
-  auto thread2 = PlatformThread::SpawnJoinable(
+  PlatformThread thread2(WorkingFunction, reinterpret_cast<void*>(&counter2),
-      [&counter2] { WorkingFunction(&counter2); }, "Thread2");
+                         "Thread2");
-  thread1.Finalize();
+  thread1.Start();
-  thread2.Finalize();
+  thread2.Start();
+  thread1.Stop();
+  thread2.Stop();
 
   EXPECT_GE(counter1, 0);
   EXPECT_GE(counter2, 0);

rtc_base/deprecated/recursive_critical_section_unittest.cc

@@ -329,28 +329,33 @@ class PerfTestData {
 
 class PerfTestThread {
  public:
+  PerfTestThread() : thread_(&ThreadFunc, this, "CsPerf") {}
+
   void Start(PerfTestData* data, int repeats, int id) {
+    RTC_DCHECK(!thread_.IsRunning());
     RTC_DCHECK(!data_);
     data_ = data;
     repeats_ = repeats;
     my_id_ = id;
-    thread_ = PlatformThread::SpawnJoinable(
+    thread_.Start();
-        [this] {
-          for (int i = 0; i < repeats_; ++i)
-            data_->AddToCounter(my_id_);
-        },
-        "CsPerf");
   }
 
   void Stop() {
+    RTC_DCHECK(thread_.IsRunning());
     RTC_DCHECK(data_);
-    thread_.Finalize();
+    thread_.Stop();
     repeats_ = 0;
     data_ = nullptr;
     my_id_ = 0;
   }
 
  private:
+  static void ThreadFunc(void* param) {
+    PerfTestThread* me = static_cast<PerfTestThread*>(param);
+    for (int i = 0; i < me->repeats_; ++i)
+      me->data_->AddToCounter(me->my_id_);
+  }
+
   PlatformThread thread_;
   PerfTestData* data_ = nullptr;
   int repeats_ = 0;

rtc_base/event_tracer.cc

@@ -79,12 +79,19 @@ namespace rtc {
 namespace tracing {
 namespace {
 
+static void EventTracingThreadFunc(void* params);
+
 // Atomic-int fast path for avoiding logging when disabled.
 static volatile int g_event_logging_active = 0;
 
 // TODO(pbos): Log metadata for all threads, etc.
 class EventLogger final {
  public:
+  EventLogger()
+      : logging_thread_(EventTracingThreadFunc,
+                        this,
+                        "EventTracingThread",
+                        ThreadAttributes().SetPriority(kLowPriority)) {}
   ~EventLogger() { RTC_DCHECK(thread_checker_.IsCurrent()); }
 
   void AddTraceEvent(const char* name,
@@ -202,8 +209,7 @@ class EventLogger final {
                  rtc::AtomicOps::CompareAndSwap(&g_event_logging_active, 0, 1));
 
     // Finally start, everything should be set up now.
-    logging_thread_ =
+    logging_thread_.Start();
-        PlatformThread::SpawnJoinable([this] { Log(); }, "EventTracingThread");
     TRACE_EVENT_INSTANT0("webrtc", "EventLogger::Start");
   }
 
@@ -217,7 +223,7 @@ class EventLogger final {
     // Wake up logging thread to finish writing.
     shutdown_event_.Set();
     // Join the logging thread.
-    logging_thread_.Finalize();
+    logging_thread_.Stop();
   }
 
  private:
@@ -320,6 +326,10 @@ class EventLogger final {
   bool output_file_owned_ = false;
 };
 
+static void EventTracingThreadFunc(void* params) {
+  static_cast<EventLogger*>(params)->Log();
+}
+
 static EventLogger* volatile g_event_logger = nullptr;
 static const char* const kDisabledTracePrefix = TRACE_DISABLED_BY_DEFAULT("");
 const unsigned char* InternalGetCategoryEnabled(const char* name) {

rtc_base/event_unittest.cc

@@ -43,21 +43,22 @@ TEST(EventTest, AutoReset) {
 
 class SignalerThread {
  public:
+  SignalerThread() : thread_(&ThreadFn, this, "EventPerf") {}
   void Start(Event* writer, Event* reader) {
     writer_ = writer;
     reader_ = reader;
-    thread_ = PlatformThread::SpawnJoinable(
+    thread_.Start();
-        [this] {
-          while (!stop_event_.Wait(0)) {
-            writer_->Set();
-            reader_->Wait(Event::kForever);
-          }
-        },
-        "EventPerf");
   }
   void Stop() {
     stop_event_.Set();
-    thread_.Finalize();
+    thread_.Stop();
+  }
+  static void ThreadFn(void* param) {
+    auto* me = static_cast<SignalerThread*>(param);
+    while (!me->stop_event_.Wait(0)) {
+      me->writer_->Set();
+      me->reader_->Wait(Event::kForever);
+    }
   }
   Event stop_event_;
   Event* writer_;

rtc_base/logging_unittest.cc

@@ -160,13 +160,18 @@ TEST(LogTest, MultipleStreams) {
 
 class LogThread {
  public:
-  void Start() {
+  LogThread() : thread_(&ThreadEntry, this, "LogThread") {}
-    thread_ = PlatformThread::SpawnJoinable(
+  ~LogThread() { thread_.Stop(); }
-        [] { RTC_LOG(LS_VERBOSE) << "RTC_LOG"; }, "LogThread");
+
-  }
+  void Start() { thread_.Start(); }
 
  private:
+  void Run() { RTC_LOG(LS_VERBOSE) << "RTC_LOG"; }
+
+  static void ThreadEntry(void* p) { static_cast<LogThread*>(p)->Run(); }
+
   PlatformThread thread_;
+  Event event_;
 };
 
 // Ensure we don't crash when adding/removing streams while threads are going.

rtc_base/platform_thread.cc

@@ -10,37 +10,32 @@
 
 #include "rtc_base/platform_thread.h"
 
-#include <algorithm>
 #include <memory>
 
 #if !defined(WEBRTC_WIN)
 #include <sched.h>
 #endif
+#include <stdint.h>
+#include <time.h>
 
+#include <algorithm>
+
+#include "absl/memory/memory.h"
 #include "rtc_base/checks.h"
 
 namespace rtc {
-namespace {
 
-#if defined(WEBRTC_WIN)
+namespace {
-int Win32PriorityFromThreadPriority(ThreadPriority priority) {
+struct ThreadStartData {
-  switch (priority) {
+  ThreadRunFunction run_function;
-    case ThreadPriority::kLow:
+  void* obj;
-      return THREAD_PRIORITY_BELOW_NORMAL;
+  std::string thread_name;
-    case ThreadPriority::kNormal:
+  ThreadPriority priority;
-      return THREAD_PRIORITY_NORMAL;
+};
-    case ThreadPriority::kHigh:
-      return THREAD_PRIORITY_ABOVE_NORMAL;
-    case ThreadPriority::kRealtime:
-      return THREAD_PRIORITY_TIME_CRITICAL;
-  }
-}
-#endif
 
 bool SetPriority(ThreadPriority priority) {
 #if defined(WEBRTC_WIN)
-  return SetThreadPriority(GetCurrentThread(),
+  return SetThreadPriority(GetCurrentThread(), priority) != FALSE;
-                           Win32PriorityFromThreadPriority(priority)) != FALSE;
 #elif defined(__native_client__) || defined(WEBRTC_FUCHSIA)
   // Setting thread priorities is not supported in NaCl or Fuchsia.
   return true;
@@ -64,18 +59,21 @@ bool SetPriority(ThreadPriority priority) {
   const int top_prio = max_prio - 1;
   const int low_prio = min_prio + 1;
   switch (priority) {
-    case ThreadPriority::kLow:
+    case kLowPriority:
       param.sched_priority = low_prio;
       break;
-    case ThreadPriority::kNormal:
+    case kNormalPriority:
       // The -1 ensures that the kHighPriority is always greater or equal to
       // kNormalPriority.
       param.sched_priority = (low_prio + top_prio - 1) / 2;
       break;
-    case ThreadPriority::kHigh:
+    case kHighPriority:
       param.sched_priority = std::max(top_prio - 2, low_prio);
       break;
-    case ThreadPriority::kRealtime:
+    case kHighestPriority:
+      param.sched_priority = std::max(top_prio - 1, low_prio);
+      break;
+    case kRealtimePriority:
       param.sched_priority = top_prio;
       break;
   }
@@ -83,129 +81,124 @@ bool SetPriority(ThreadPriority priority) {
 #endif  // defined(WEBRTC_WIN)
 }
 
+void RunPlatformThread(std::unique_ptr<ThreadStartData> data) {
+  rtc::SetCurrentThreadName(data->thread_name.c_str());
+  data->thread_name.clear();
+  SetPriority(data->priority);
+  data->run_function(data->obj);
+}
+
 #if defined(WEBRTC_WIN)
-DWORD WINAPI RunPlatformThread(void* param) {
+DWORD WINAPI StartThread(void* param) {
   // The GetLastError() function only returns valid results when it is called
   // after a Win32 API function that returns a "failed" result. A crash dump
   // contains the result from GetLastError() and to make sure it does not
   // falsely report a Windows error we call SetLastError here.
   ::SetLastError(ERROR_SUCCESS);
-  auto function = static_cast<std::function<void()>*>(param);
+  RunPlatformThread(absl::WrapUnique(static_cast<ThreadStartData*>(param)));
-  (*function)();
-  delete function;
   return 0;
 }
 #else
-void* RunPlatformThread(void* param) {
+void* StartThread(void* param) {
-  auto function = static_cast<std::function<void()>*>(param);
+  RunPlatformThread(absl::WrapUnique(static_cast<ThreadStartData*>(param)));
-  (*function)();
-  delete function;
   return 0;
 }
 #endif  // defined(WEBRTC_WIN)
 
 }  // namespace
 
-PlatformThread::PlatformThread(Handle handle, bool joinable)
+PlatformThread::PlatformThread(ThreadRunFunction func,
-    : handle_(handle), joinable_(joinable) {}
+                               void* obj,
-
+                               absl::string_view thread_name,
-PlatformThread::PlatformThread(PlatformThread&& rhs)
+                               ThreadAttributes attributes)
-    : handle_(rhs.handle_), joinable_(rhs.joinable_) {
+    : run_function_(func),
-  rhs.handle_ = absl::nullopt;
+      attributes_(attributes),
-}
+      obj_(obj),
-
+      name_(thread_name) {
-PlatformThread& PlatformThread::operator=(PlatformThread&& rhs) {
+  RTC_DCHECK(func);
-  Finalize();
+  RTC_DCHECK(!name_.empty());
-  handle_ = rhs.handle_;
+  // TODO(tommi): Consider lowering the limit to 15 (limit on Linux).
-  joinable_ = rhs.joinable_;
+  RTC_DCHECK(name_.length() < 64);
-  rhs.handle_ = absl::nullopt;
-  return *this;
 }
 
 PlatformThread::~PlatformThread() {
-  Finalize();
+  RTC_DCHECK_RUN_ON(&thread_checker_);
-}
+  RTC_DCHECK(!thread_);
-
-PlatformThread PlatformThread::SpawnJoinable(
-    std::function<void()> thread_function,
-    absl::string_view name,
-    ThreadAttributes attributes) {
-  return SpawnThread(std::move(thread_function), name, attributes,
-                     /*joinable=*/true);
-}
-
-PlatformThread PlatformThread::SpawnDetached(
-    std::function<void()> thread_function,
-    absl::string_view name,
-    ThreadAttributes attributes) {
-  return SpawnThread(std::move(thread_function), name, attributes,
-                     /*joinable=*/false);
-}
-
-absl::optional<PlatformThread::Handle> PlatformThread::GetHandle() const {
-  return handle_;
-}
-
 #if defined(WEBRTC_WIN)
-bool PlatformThread::QueueAPC(PAPCFUNC function, ULONG_PTR data) {
+  RTC_DCHECK(!thread_id_);
-  RTC_DCHECK(handle_.has_value());
+#endif  // defined(WEBRTC_WIN)
-  return handle_.has_value() ? QueueUserAPC(function, *handle_, data) != FALSE
-                             : false;
-}
-#endif
-
-void PlatformThread::Finalize() {
-  if (!handle_.has_value())
-    return;
-#if defined(WEBRTC_WIN)
-  if (joinable_)
-    WaitForSingleObject(*handle_, INFINITE);
-  CloseHandle(*handle_);
-#else
-  if (joinable_)
-    RTC_CHECK_EQ(0, pthread_join(*handle_, nullptr));
-#endif
-  handle_ = absl::nullopt;
 }
 
-PlatformThread PlatformThread::SpawnThread(
+void PlatformThread::Start() {
-    std::function<void()> thread_function,
+  RTC_DCHECK_RUN_ON(&thread_checker_);
-    absl::string_view name,
+  RTC_DCHECK(!thread_) << "Thread already started?";
-    ThreadAttributes attributes,
+  ThreadStartData* data =
-    bool joinable) {
+      new ThreadStartData{run_function_, obj_, name_, attributes_.priority};
-  RTC_DCHECK(thread_function);
-  RTC_DCHECK(!name.empty());
-  // TODO(tommi): Consider lowering the limit to 15 (limit on Linux).
-  RTC_DCHECK(name.length() < 64);
-  auto start_thread_function_ptr =
-      new std::function<void()>([thread_function = std::move(thread_function),
-                                 name = std::string(name), attributes] {
-        rtc::SetCurrentThreadName(name.c_str());
-        SetPriority(attributes.priority);
-        thread_function();
-      });
 #if defined(WEBRTC_WIN)
   // See bug 2902 for background on STACK_SIZE_PARAM_IS_A_RESERVATION.
   // Set the reserved stack stack size to 1M, which is the default on Windows
   // and Linux.
-  DWORD thread_id = 0;
+  thread_ = ::CreateThread(nullptr, 1024 * 1024, &StartThread, data,
-  PlatformThread::Handle handle = ::CreateThread(
+                           STACK_SIZE_PARAM_IS_A_RESERVATION, &thread_id_);
-      nullptr, 1024 * 1024, &RunPlatformThread, start_thread_function_ptr,
+  RTC_CHECK(thread_) << "CreateThread failed";
-      STACK_SIZE_PARAM_IS_A_RESERVATION, &thread_id);
+  RTC_DCHECK(thread_id_);
-  RTC_CHECK(handle) << "CreateThread failed";
 #else
   pthread_attr_t attr;
   pthread_attr_init(&attr);
   // Set the stack stack size to 1M.
   pthread_attr_setstacksize(&attr, 1024 * 1024);
-  pthread_attr_setdetachstate(
+  pthread_attr_setdetachstate(&attr, attributes_.joinable
-      &attr, joinable ? PTHREAD_CREATE_JOINABLE : PTHREAD_CREATE_DETACHED);
+                                         ? PTHREAD_CREATE_JOINABLE
-  PlatformThread::Handle handle;
+                                         : PTHREAD_CREATE_DETACHED);
-  RTC_CHECK_EQ(0, pthread_create(&handle, &attr, &RunPlatformThread,
+  RTC_CHECK_EQ(0, pthread_create(&thread_, &attr, &StartThread, data));
-                                 start_thread_function_ptr));
   pthread_attr_destroy(&attr);
 #endif  // defined(WEBRTC_WIN)
-  return PlatformThread(handle, joinable);
 }
 
+bool PlatformThread::IsRunning() const {
+  RTC_DCHECK_RUN_ON(&thread_checker_);
+#if defined(WEBRTC_WIN)
+  return thread_ != nullptr;
+#else
+  return thread_ != 0;
+#endif  // defined(WEBRTC_WIN)
+}
+
+PlatformThreadRef PlatformThread::GetThreadRef() const {
+#if defined(WEBRTC_WIN)
+  return thread_id_;
+#else
+  return thread_;
+#endif  // defined(WEBRTC_WIN)
+}
+
+void PlatformThread::Stop() {
+  RTC_DCHECK_RUN_ON(&thread_checker_);
+  if (!IsRunning())
+    return;
+
+#if defined(WEBRTC_WIN)
+  if (attributes_.joinable) {
+    WaitForSingleObject(thread_, INFINITE);
+  }
+  CloseHandle(thread_);
+  thread_ = nullptr;
+  thread_id_ = 0;
+#else
+  if (attributes_.joinable) {
+    RTC_CHECK_EQ(0, pthread_join(thread_, nullptr));
+  }
+  thread_ = 0;
+#endif  // defined(WEBRTC_WIN)
+}
+
+#if defined(WEBRTC_WIN)
+bool PlatformThread::QueueAPC(PAPCFUNC function, ULONG_PTR data) {
+  RTC_DCHECK_RUN_ON(&thread_checker_);
+  RTC_DCHECK(IsRunning());
+
+  return QueueUserAPC(function, thread_, data) != FALSE;
+}
+#endif
+
 }  // namespace rtc

rtc_base/platform_thread.h

@@ -11,101 +11,103 @@
 #ifndef RTC_BASE_PLATFORM_THREAD_H_
 #define RTC_BASE_PLATFORM_THREAD_H_
 
-#include <functional>
+#ifndef WEBRTC_WIN
+#include <pthread.h>
+#endif
 #include <string>
 
 #include "absl/strings/string_view.h"
-#include "absl/types/optional.h"
+#include "api/sequence_checker.h"
+#include "rtc_base/constructor_magic.h"
 #include "rtc_base/platform_thread_types.h"
 
 namespace rtc {
 
-enum class ThreadPriority {
+// Callback function that the spawned thread will enter once spawned.
-  kLow = 1,
+typedef void (*ThreadRunFunction)(void*);
-  kNormal,
+
-  kHigh,
+enum ThreadPriority {
-  kRealtime,
+#ifdef WEBRTC_WIN
+  kLowPriority = THREAD_PRIORITY_BELOW_NORMAL,
+  kNormalPriority = THREAD_PRIORITY_NORMAL,
+  kHighPriority = THREAD_PRIORITY_ABOVE_NORMAL,
+  kHighestPriority = THREAD_PRIORITY_HIGHEST,
+  kRealtimePriority = THREAD_PRIORITY_TIME_CRITICAL
+#else
+  kLowPriority = 1,
+  kNormalPriority = 2,
+  kHighPriority = 3,
+  kHighestPriority = 4,
+  kRealtimePriority = 5
+#endif
 };
 
 struct ThreadAttributes {
-  ThreadPriority priority = ThreadPriority::kNormal;
+  ThreadPriority priority = kNormalPriority;
+  bool joinable = true;
+
   ThreadAttributes& SetPriority(ThreadPriority priority_param) {
     priority = priority_param;
     return *this;
   }
+  ThreadAttributes& SetDetached() {
+    joinable = false;
+    return *this;
+  }
 };
 
-// Represents a simple worker thread.
+// Represents a simple worker thread.  The implementation must be assumed
-class PlatformThread final {
+// to be single threaded, meaning that all methods of the class, must be
+// called from the same thread, including instantiation.
+class PlatformThread {
  public:
-  // Handle is the base platform thread handle.
+  PlatformThread(ThreadRunFunction func,
-#if defined(WEBRTC_WIN)
+                 void* obj,
-  using Handle = HANDLE;
+                 absl::string_view thread_name,
-#else
+                 ThreadAttributes attributes = ThreadAttributes());
-  using Handle = pthread_t;
-#endif  // defined(WEBRTC_WIN)
-  // This ctor creates the PlatformThread with an unset handle (returning true
-  // in empty()) and is provided for convenience.
-  // TODO(bugs.webrtc.org/12727) Look into if default and move support can be
-  // removed.
-  PlatformThread() = default;
-
-  // Moves |rhs| into this, storing an empty state in |rhs|.
-  // TODO(bugs.webrtc.org/12727) Look into if default and move support can be
-  // removed.
-  PlatformThread(PlatformThread&& rhs);
-
-  // Moves |rhs| into this, storing an empty state in |rhs|.
-  // TODO(bugs.webrtc.org/12727) Look into if default and move support can be
-  // removed.
-  PlatformThread& operator=(PlatformThread&& rhs);
-
-  // For a PlatformThread that's been spawned joinable, the destructor suspends
-  // the calling thread until the created thread exits unless the thread has
-  // already exited.
   virtual ~PlatformThread();
 
-  // Finalizes any allocated resources.
+  const std::string& name() const { return name_; }
-  // For a PlatformThread that's been spawned joinable, Finalize() suspends
-  // the calling thread until the created thread exits unless the thread has
-  // already exited.
-  // empty() returns true after completion.
-  void Finalize();
 
-  // Returns true if default constructed, moved from, or Finalize()ed.
+  // Spawns a thread and tries to set thread priority according to the priority
-  bool empty() const { return !handle_.has_value(); }
+  // from when CreateThread was called.
+  // Start can only be called after the constructor or after a call to Stop().
+  void Start();
 
-  // Creates a started joinable thread which will be joined when the returned
+  bool IsRunning() const;
-  // PlatformThread destructs or Finalize() is called.
-  static PlatformThread SpawnJoinable(
-      std::function<void()> thread_function,
-      absl::string_view name,
-      ThreadAttributes attributes = ThreadAttributes());
 
-  // Creates a started detached thread. The caller has to use external
+  // Returns an identifier for the worker thread that can be used to do
-  // synchronization as nothing is provided by the PlatformThread construct.
+  // thread checks.
-  static PlatformThread SpawnDetached(
+  PlatformThreadRef GetThreadRef() const;
-      std::function<void()> thread_function,
-      absl::string_view name,
-      ThreadAttributes attributes = ThreadAttributes());
 
-  // Returns the base platform thread handle of this thread.
+  // Stop() prepares the PlatformThread for destruction or another call to
-  absl::optional<Handle> GetHandle() const;
+  // Start(). For a PlatformThread that's been created with
+  // ThreadAttributes::joinable true (the default), Stop() suspends the calling
+  // thread until the created thread exits unless the thread has already exited.
+  // Stop() can only be called after calling Start().
+  void Stop();
 
+ protected:
 #if defined(WEBRTC_WIN)
-  // Queue a Windows APC function that runs when the thread is alertable.
+  // Exposed to derived classes to allow for special cases specific to Windows.
   bool QueueAPC(PAPCFUNC apc_function, ULONG_PTR data);
 #endif
 
  private:
-  PlatformThread(Handle handle, bool joinable);
+  ThreadRunFunction const run_function_ = nullptr;
-  static PlatformThread SpawnThread(std::function<void()> thread_function,
+  const ThreadAttributes attributes_;
-                                    absl::string_view name,
+  void* const obj_;
-                                    ThreadAttributes attributes,
+  // TODO(pbos): Make sure call sites use string literals and update to a const
-                                    bool joinable);
+  // char* instead of a std::string.
-
+  const std::string name_;
-  absl::optional<Handle> handle_;
+  webrtc::SequenceChecker thread_checker_;
-  bool joinable_ = false;
+#if defined(WEBRTC_WIN)
+  HANDLE thread_ = nullptr;
+  DWORD thread_id_ = 0;
+#else
+  pthread_t thread_ = 0;
+#endif  // defined(WEBRTC_WIN)
+  RTC_DISALLOW_COPY_AND_ASSIGN(PlatformThread);
 };
 
 }  // namespace rtc

rtc_base/platform_thread_unittest.cc

@@ -10,73 +10,69 @@
 
 #include "rtc_base/platform_thread.h"
 
-#include "absl/types/optional.h"
 #include "rtc_base/event.h"
 #include "system_wrappers/include/sleep.h"
 #include "test/gmock.h"
 
 namespace rtc {
+namespace {
 
-TEST(PlatformThreadTest, DefaultConstructedIsEmpty) {
+void NullRunFunction(void* obj) {}
-  PlatformThread thread;
+
-  EXPECT_EQ(thread.GetHandle(), absl::nullopt);
+// Function that sets a boolean.
-  EXPECT_TRUE(thread.empty());
+void SetFlagRunFunction(void* obj) {
+  bool* obj_as_bool = static_cast<bool*>(obj);
+  *obj_as_bool = true;
 }
 
-TEST(PlatformThreadTest, StartFinalize) {
+void StdFunctionRunFunction(void* obj) {
-  PlatformThread thread = PlatformThread::SpawnJoinable([] {}, "1");
+  std::function<void()>* fun = static_cast<std::function<void()>*>(obj);
-  EXPECT_NE(thread.GetHandle(), absl::nullopt);
+  (*fun)();
-  EXPECT_FALSE(thread.empty());
-  thread.Finalize();
-  EXPECT_TRUE(thread.empty());
-  thread = PlatformThread::SpawnDetached([] {}, "2");
-  EXPECT_FALSE(thread.empty());
-  thread.Finalize();
-  EXPECT_TRUE(thread.empty());
 }
 
-TEST(PlatformThreadTest, MovesEmpty) {
+}  // namespace
-  PlatformThread thread1;
+
-  PlatformThread thread2 = std::move(thread1);
+TEST(PlatformThreadTest, StartStop) {
-  EXPECT_TRUE(thread1.empty());
+  PlatformThread thread(&NullRunFunction, nullptr, "PlatformThreadTest");
-  EXPECT_TRUE(thread2.empty());
+  EXPECT_TRUE(thread.name() == "PlatformThreadTest");
+  EXPECT_TRUE(thread.GetThreadRef() == 0);
+  thread.Start();
+  EXPECT_TRUE(thread.GetThreadRef() != 0);
+  thread.Stop();
+  EXPECT_TRUE(thread.GetThreadRef() == 0);
 }
 
-TEST(PlatformThreadTest, MovesHandles) {
+TEST(PlatformThreadTest, StartStop2) {
-  PlatformThread thread1 = PlatformThread::SpawnJoinable([] {}, "1");
+  PlatformThread thread1(&NullRunFunction, nullptr, "PlatformThreadTest1");
-  PlatformThread thread2 = std::move(thread1);
+  PlatformThread thread2(&NullRunFunction, nullptr, "PlatformThreadTest2");
-  EXPECT_TRUE(thread1.empty());
+  EXPECT_TRUE(thread1.GetThreadRef() == thread2.GetThreadRef());
-  EXPECT_FALSE(thread2.empty());
+  thread1.Start();
-  thread1 = PlatformThread::SpawnDetached([] {}, "2");
+  thread2.Start();
-  thread2 = std::move(thread1);
+  EXPECT_TRUE(thread1.GetThreadRef() != thread2.GetThreadRef());
-  EXPECT_TRUE(thread1.empty());
+  thread2.Stop();
-  EXPECT_FALSE(thread2.empty());
+  thread1.Stop();
-}
-
-TEST(PlatformThreadTest,
-     TwoThreadHandlesAreDifferentWhenStartedAndEqualWhenJoined) {
-  PlatformThread thread1 = PlatformThread();
-  PlatformThread thread2 = PlatformThread();
-  EXPECT_EQ(thread1.GetHandle(), thread2.GetHandle());
-  thread1 = PlatformThread::SpawnJoinable([] {}, "1");
-  thread2 = PlatformThread::SpawnJoinable([] {}, "2");
-  EXPECT_NE(thread1.GetHandle(), thread2.GetHandle());
-  thread1.Finalize();
-  EXPECT_NE(thread1.GetHandle(), thread2.GetHandle());
-  thread2.Finalize();
-  EXPECT_EQ(thread1.GetHandle(), thread2.GetHandle());
 }
 
 TEST(PlatformThreadTest, RunFunctionIsCalled) {
   bool flag = false;
-  PlatformThread::SpawnJoinable([&] { flag = true; }, "T");
+  PlatformThread thread(&SetFlagRunFunction, &flag, "RunFunctionIsCalled");
+  thread.Start();
+
+  // At this point, the flag may be either true or false.
+  thread.Stop();
+
+  // We expect the thread to have run at least once.
   EXPECT_TRUE(flag);
 }
 
 TEST(PlatformThreadTest, JoinsThread) {
   // This test flakes if there are problems with the join implementation.
+  EXPECT_TRUE(ThreadAttributes().joinable);
   rtc::Event event;
-  PlatformThread::SpawnJoinable([&] { event.Set(); }, "T");
+  std::function<void()> thread_function = [&] { event.Set(); };
+  PlatformThread thread(&StdFunctionRunFunction, &thread_function, "T");
+  thread.Start();
+  thread.Stop();
   EXPECT_TRUE(event.Wait(/*give_up_after_ms=*/0));
 }
 
@@ -87,14 +83,18 @@ TEST(PlatformThreadTest, StopsBeforeDetachedThreadExits) {
   rtc::Event thread_started;
   rtc::Event thread_continue;
   rtc::Event thread_exiting;
-  PlatformThread::SpawnDetached(
+  std::function<void()> thread_function = [&] {
-      [&] {
+    thread_started.Set();
-        thread_started.Set();
+    thread_continue.Wait(Event::kForever);
-        thread_continue.Wait(Event::kForever);
+    flag = true;
-        flag = true;
+    thread_exiting.Set();
-        thread_exiting.Set();
+  };
-      },
+  {
-      "T");
+    PlatformThread thread(&StdFunctionRunFunction, &thread_function, "T",
+                          ThreadAttributes().SetDetached());
+    thread.Start();
+    thread.Stop();
+  }
   thread_started.Wait(Event::kForever);
   EXPECT_FALSE(flag);
   thread_continue.Set();

rtc_base/rate_limiter_unittest.cc

@@ -127,6 +127,10 @@ class ThreadTask {
   rtc::Event end_signal_;
 };
 
+void RunTask(void* thread_task) {
+  reinterpret_cast<ThreadTask*>(thread_task)->Run();
+}
+
 TEST_F(RateLimitTest, MultiThreadedUsage) {
   // Simple sanity test, with different threads calling the various methods.
   // Runs a few simple tasks, each on its own thread, but coordinated with
@@ -145,8 +149,8 @@ TEST_F(RateLimitTest, MultiThreadedUsage) {
       EXPECT_TRUE(rate_limiter_->SetWindowSize(kWindowSizeMs / 2));
     }
   } set_window_size_task(rate_limiter.get());
-  auto thread1 = rtc::PlatformThread::SpawnJoinable(
+  rtc::PlatformThread thread1(RunTask, &set_window_size_task, "Thread1");
-      [&set_window_size_task] { set_window_size_task.Run(); }, "Thread1");
+  thread1.Start();
 
   class SetMaxRateTask : public ThreadTask {
    public:
@@ -156,8 +160,8 @@ TEST_F(RateLimitTest, MultiThreadedUsage) {
 
     void DoRun() override { rate_limiter_->SetMaxRate(kMaxRateBps * 2); }
   } set_max_rate_task(rate_limiter.get());
-  auto thread2 = rtc::PlatformThread::SpawnJoinable(
+  rtc::PlatformThread thread2(RunTask, &set_max_rate_task, "Thread2");
-      [&set_max_rate_task] { set_max_rate_task.Run(); }, "Thread2");
+  thread2.Start();
 
   class UseRateTask : public ThreadTask {
    public:
@@ -173,8 +177,8 @@ TEST_F(RateLimitTest, MultiThreadedUsage) {
 
     SimulatedClock* const clock_;
   } use_rate_task(rate_limiter.get(), &clock_);
-  auto thread3 = rtc::PlatformThread::SpawnJoinable(
+  rtc::PlatformThread thread3(RunTask, &use_rate_task, "Thread3");
-      [&use_rate_task] { use_rate_task.Run(); }, "Thread3");
+  thread3.Start();
 
   set_window_size_task.start_signal_.Set();
   EXPECT_TRUE(set_window_size_task.end_signal_.Wait(kMaxTimeoutMs));
@@ -187,6 +191,10 @@ TEST_F(RateLimitTest, MultiThreadedUsage) {
 
   // All rate consumed.
   EXPECT_FALSE(rate_limiter->TryUseRate(1));
+
+  thread1.Stop();
+  thread2.Stop();
+  thread3.Stop();
 }
 
 }  // namespace webrtc

rtc_base/task_queue_libevent.cc

@@ -93,12 +93,16 @@ void EventAssign(struct event* ev,
 rtc::ThreadPriority TaskQueuePriorityToThreadPriority(Priority priority) {
   switch (priority) {
     case Priority::HIGH:
-      return rtc::ThreadPriority::kRealtime;
+      return rtc::kRealtimePriority;
     case Priority::LOW:
-      return rtc::ThreadPriority::kLow;
+      return rtc::kLowPriority;
     case Priority::NORMAL:
-      return rtc::ThreadPriority::kNormal;
+      return rtc::kNormalPriority;
+    default:
+      RTC_NOTREACHED();
+      break;
   }
+  return rtc::kNormalPriority;
 }
 
 class TaskQueueLibevent final : public TaskQueueBase {
@@ -116,6 +120,7 @@ class TaskQueueLibevent final : public TaskQueueBase {
 
   ~TaskQueueLibevent() override = default;
 
+  static void ThreadMain(void* context);
   static void OnWakeup(int socket, short flags, void* context);  // NOLINT
   static void RunTimer(int fd, short flags, void* context);      // NOLINT
 
@@ -167,7 +172,11 @@ class TaskQueueLibevent::SetTimerTask : public QueuedTask {
 
 TaskQueueLibevent::TaskQueueLibevent(absl::string_view queue_name,
                                      rtc::ThreadPriority priority)
-    : event_base_(event_base_new()) {
+    : event_base_(event_base_new()),
+      thread_(&TaskQueueLibevent::ThreadMain,
+              this,
+              queue_name,
+              rtc::ThreadAttributes().SetPriority(priority)) {
   int fds[2];
   RTC_CHECK(pipe(fds) == 0);
   SetNonBlocking(fds[0]);
@@ -178,18 +187,7 @@ TaskQueueLibevent::TaskQueueLibevent(absl::string_view queue_name,
   EventAssign(&wakeup_event_, event_base_, wakeup_pipe_out_,
               EV_READ | EV_PERSIST, OnWakeup, this);
   event_add(&wakeup_event_, 0);
-  thread_ = rtc::PlatformThread::SpawnJoinable(
+  thread_.Start();
-      [this] {
-        {
-          CurrentTaskQueueSetter set_current(this);
-          while (is_active_)
-            event_base_loop(event_base_, 0);
-        }
-
-        for (TimerEvent* timer : pending_timers_)
-          delete timer;
-      },
-      queue_name, rtc::ThreadAttributes().SetPriority(priority));
 }
 
 void TaskQueueLibevent::Delete() {
@@ -204,7 +202,7 @@ void TaskQueueLibevent::Delete() {
     nanosleep(&ts, nullptr);
   }
 
-  thread_.Finalize();
+  thread_.Stop();
 
   event_del(&wakeup_event_);
 
@@ -257,6 +255,20 @@ void TaskQueueLibevent::PostDelayedTask(std::unique_ptr<QueuedTask> task,
   }
 }
 
+// static
+void TaskQueueLibevent::ThreadMain(void* context) {
+  TaskQueueLibevent* me = static_cast<TaskQueueLibevent*>(context);
+
+  {
+    CurrentTaskQueueSetter set_current(me);
+    while (me->is_active_)
+      event_base_loop(me->event_base_, 0);
+  }
+
+  for (TimerEvent* timer : me->pending_timers_)
+    delete timer;
+}
+
 // static
 void TaskQueueLibevent::OnWakeup(int socket,
                                  short flags,  // NOLINT

rtc_base/task_queue_stdlib.cc

@@ -36,11 +36,14 @@ rtc::ThreadPriority TaskQueuePriorityToThreadPriority(
     TaskQueueFactory::Priority priority) {
   switch (priority) {
     case TaskQueueFactory::Priority::HIGH:
-      return rtc::ThreadPriority::kRealtime;
+      return rtc::kRealtimePriority;
     case TaskQueueFactory::Priority::LOW:
-      return rtc::ThreadPriority::kLow;
+      return rtc::kLowPriority;
     case TaskQueueFactory::Priority::NORMAL:
-      return rtc::ThreadPriority::kNormal;
+      return rtc::kNormalPriority;
+    default:
+      RTC_NOTREACHED();
+      return rtc::kNormalPriority;
   }
 }
 
@@ -75,6 +78,8 @@ class TaskQueueStdlib final : public TaskQueueBase {
 
   NextTask GetNextTask();
 
+  static void ThreadMain(void* context);
+
   void ProcessTasks();
 
   void NotifyWake();
@@ -121,13 +126,11 @@ TaskQueueStdlib::TaskQueueStdlib(absl::string_view queue_name,
     : started_(/*manual_reset=*/false, /*initially_signaled=*/false),
       stopped_(/*manual_reset=*/false, /*initially_signaled=*/false),
       flag_notify_(/*manual_reset=*/false, /*initially_signaled=*/false),
-      thread_(rtc::PlatformThread::SpawnJoinable(
+      thread_(&TaskQueueStdlib::ThreadMain,
-          [this] {
+              this,
-            CurrentTaskQueueSetter set_current(this);
+              queue_name,
-            ProcessTasks();
+              rtc::ThreadAttributes().SetPriority(priority)) {
-          },
+  thread_.Start();
-          queue_name,
-          rtc::ThreadAttributes().SetPriority(priority))) {
   started_.Wait(rtc::Event::kForever);
 }
 
@@ -142,7 +145,7 @@ void TaskQueueStdlib::Delete() {
   NotifyWake();
 
   stopped_.Wait(rtc::Event::kForever);
-  thread_.Finalize();
+  thread_.Stop();
   delete this;
 }
 
@@ -219,6 +222,13 @@ TaskQueueStdlib::NextTask TaskQueueStdlib::GetNextTask() {
   return result;
 }
 
+// static
+void TaskQueueStdlib::ThreadMain(void* context) {
+  TaskQueueStdlib* me = static_cast<TaskQueueStdlib*>(context);
+  CurrentTaskQueueSetter set_current(me);
+  me->ProcessTasks();
+}
+
 void TaskQueueStdlib::ProcessTasks() {
   started_.Set();
 

rtc_base/task_queue_win.cc

@@ -29,7 +29,6 @@
 #include <utility>
 
 #include "absl/strings/string_view.h"
-#include "absl/types/optional.h"
 #include "api/task_queue/queued_task.h"
 #include "api/task_queue/task_queue_base.h"
 #include "rtc_base/arraysize.h"
@@ -57,12 +56,16 @@ rtc::ThreadPriority TaskQueuePriorityToThreadPriority(
     TaskQueueFactory::Priority priority) {
   switch (priority) {
     case TaskQueueFactory::Priority::HIGH:
-      return rtc::ThreadPriority::kRealtime;
+      return rtc::kRealtimePriority;
     case TaskQueueFactory::Priority::LOW:
-      return rtc::ThreadPriority::kLow;
+      return rtc::kLowPriority;
     case TaskQueueFactory::Priority::NORMAL:
-      return rtc::ThreadPriority::kNormal;
+      return rtc::kNormalPriority;
+    default:
+      RTC_NOTREACHED();
+      break;
   }
+  return rtc::kNormalPriority;
 }
 
 int64_t GetTick() {
@@ -164,6 +167,24 @@ class TaskQueueWin : public TaskQueueBase {
   void RunPendingTasks();
 
  private:
+  static void ThreadMain(void* context);
+
+  class WorkerThread : public rtc::PlatformThread {
+   public:
+    WorkerThread(rtc::ThreadRunFunction func,
+                 void* obj,
+                 absl::string_view thread_name,
+                 rtc::ThreadPriority priority)
+        : PlatformThread(func,
+                         obj,
+                         thread_name,
+                         rtc::ThreadAttributes().SetPriority(priority)) {}
+
+    bool QueueAPC(PAPCFUNC apc_function, ULONG_PTR data) {
+      return rtc::PlatformThread::QueueAPC(apc_function, data);
+    }
+  };
+
   void RunThreadMain();
   bool ProcessQueuedMessages();
   void RunDueTasks();
@@ -186,7 +207,7 @@ class TaskQueueWin : public TaskQueueBase {
                       greater<DelayedTaskInfo>>
       timer_tasks_;
   UINT_PTR timer_id_ = 0;
-  rtc::PlatformThread thread_;
+  WorkerThread thread_;
   Mutex pending_lock_;
   std::queue<std::unique_ptr<QueuedTask>> pending_
       RTC_GUARDED_BY(pending_lock_);
@@ -195,12 +216,10 @@ class TaskQueueWin : public TaskQueueBase {
 
 TaskQueueWin::TaskQueueWin(absl::string_view queue_name,
                            rtc::ThreadPriority priority)
-    : in_queue_(::CreateEvent(nullptr, true, false, nullptr)) {
+    : thread_(&TaskQueueWin::ThreadMain, this, queue_name, priority),
+      in_queue_(::CreateEvent(nullptr, true, false, nullptr)) {
   RTC_DCHECK(in_queue_);
-  thread_ = rtc::PlatformThread::SpawnJoinable(
+  thread_.Start();
-      [this] { RunThreadMain(); }, queue_name,
-      rtc::ThreadAttributes().SetPriority(priority));
-
   rtc::Event event(false, false);
   RTC_CHECK(thread_.QueueAPC(&InitializeQueueThread,
                              reinterpret_cast<ULONG_PTR>(&event)));
@@ -209,13 +228,11 @@ TaskQueueWin::TaskQueueWin(absl::string_view queue_name,
 
 void TaskQueueWin::Delete() {
   RTC_DCHECK(!IsCurrent());
-  RTC_CHECK(thread_.GetHandle() != absl::nullopt);
+  while (!::PostThreadMessage(thread_.GetThreadRef(), WM_QUIT, 0, 0)) {
-  while (
-      !::PostThreadMessage(GetThreadId(*thread_.GetHandle()), WM_QUIT, 0, 0)) {
     RTC_CHECK_EQ(ERROR_NOT_ENOUGH_QUOTA, ::GetLastError());
     Sleep(1);
   }
-  thread_.Finalize();
+  thread_.Stop();
   ::CloseHandle(in_queue_);
   delete this;
 }
@@ -238,9 +255,7 @@ void TaskQueueWin::PostDelayedTask(std::unique_ptr<QueuedTask> task,
   // and WPARAM is 32bits in 32bit builds.  Otherwise, we could pass the
   // task pointer and timestamp as LPARAM and WPARAM.
   auto* task_info = new DelayedTaskInfo(milliseconds, std::move(task));
-  RTC_CHECK(thread_.GetHandle() != absl::nullopt);
+  if (!::PostThreadMessage(thread_.GetThreadRef(), WM_QUEUE_DELAYED_TASK, 0,
-  if (!::PostThreadMessage(GetThreadId(*thread_.GetHandle()),
-                           WM_QUEUE_DELAYED_TASK, 0,
                            reinterpret_cast<LPARAM>(task_info))) {
     delete task_info;
   }
@@ -262,6 +277,11 @@ void TaskQueueWin::RunPendingTasks() {
   }
 }
 
+// static
+void TaskQueueWin::ThreadMain(void* context) {
+  static_cast<TaskQueueWin*>(context)->RunThreadMain();
+}
+
 void TaskQueueWin::RunThreadMain() {
   CurrentTaskQueueSetter set_current(this);
   HANDLE handles[2] = {*timer_.event_for_wait(), in_queue_};

sdk/android/native_unittests/stacktrace/stacktrace_unittest.cc

@@ -153,24 +153,28 @@ class SleepDeadlock : public DeadlockInterface {
   }
 };
 
+// This is the function that is exectued by the thread that will deadlock and
+// have its stacktrace captured.
+void ThreadFunction(void* void_params) {
+  ThreadParams* params = static_cast<ThreadParams*>(void_params);
+  params->tid = gettid();
+
+  params->deadlock_region_start_address = GetCurrentRelativeExecutionAddress();
+  params->deadlock_start_event.Set();
+  params->deadlock_impl->Deadlock();
+  params->deadlock_region_end_address = GetCurrentRelativeExecutionAddress();
+
+  params->deadlock_done_event.Set();
+}
+
 void TestStacktrace(std::unique_ptr<DeadlockInterface> deadlock_impl) {
   // Set params that will be sent to other thread.
   ThreadParams params;
   params.deadlock_impl = deadlock_impl.get();
 
   // Spawn thread.
-  auto thread = rtc::PlatformThread::SpawnJoinable(
+  rtc::PlatformThread thread(&ThreadFunction, &params, "StacktraceTest");
-      [&params] {
+  thread.Start();
-        params.tid = gettid();
-        params.deadlock_region_start_address =
-            GetCurrentRelativeExecutionAddress();
-        params.deadlock_start_event.Set();
-        params.deadlock_impl->Deadlock();
-        params.deadlock_region_end_address =
-            GetCurrentRelativeExecutionAddress();
-        params.deadlock_done_event.Set();
-      },
-      "StacktraceTest");
 
   // Wait until the thread has entered the deadlock region, and take a very
   // brief nap to give it time to reach the actual deadlock.
@@ -194,6 +198,8 @@ void TestStacktrace(std::unique_ptr<DeadlockInterface> deadlock_impl) {
       << rtc::ToHex(params.deadlock_region_start_address) << ", "
       << rtc::ToHex(params.deadlock_region_end_address)
       << "] not contained in: " << StackTraceToString(stack_trace);
+
+  thread.Stop();
 }
 
 class LookoutLogSink final : public rtc::LogSink {
@@ -253,9 +259,13 @@ TEST(Stacktrace, TestRtcEventDeadlockDetection) {
 
   // Start a thread that waits for an event.
   rtc::Event ev;
-  auto thread = rtc::PlatformThread::SpawnJoinable(
+  rtc::PlatformThread thread(
-      [&ev] { ev.Wait(rtc::Event::kForever); },
+      [](void* arg) {
-      "TestRtcEventDeadlockDetection");
+        auto* ev = static_cast<rtc::Event*>(arg);
+        ev->Wait(rtc::Event::kForever);
+      },
+      &ev, "TestRtcEventDeadlockDetection");
+  thread.Start();
 
   // The message should appear after 3 sec. We'll wait up to 10 sec in an
   // attempt to not be flaky.
@@ -263,7 +273,7 @@ TEST(Stacktrace, TestRtcEventDeadlockDetection) {
 
   // Unblock the thread and shut it down.
   ev.Set();
-  thread.Finalize();
+  thread.Stop();
   rtc::LogMessage::RemoveLogToStream(&sink);
 }
 

test/pc/e2e/analyzer/video/default_video_quality_analyzer.cc

@@ -142,9 +142,12 @@ void DefaultVideoQualityAnalyzer::Start(
     int max_threads_count) {
   test_label_ = std::move(test_case_name);
   for (int i = 0; i < max_threads_count; i++) {
-    thread_pool_.push_back(rtc::PlatformThread::SpawnJoinable(
+    auto thread = std::make_unique<rtc::PlatformThread>(
-        [this] { ProcessComparisons(); },
+        &DefaultVideoQualityAnalyzer::ProcessComparisonsThread, this,
-        "DefaultVideoQualityAnalyzerWorker-" + std::to_string(i)));
+        ("DefaultVideoQualityAnalyzerWorker-" + std::to_string(i)).data(),
+        rtc::ThreadAttributes().SetPriority(rtc::kNormalPriority));
+    thread->Start();
+    thread_pool_.push_back(std::move(thread));
   }
   {
     MutexLock lock(&lock_);
@@ -544,6 +547,10 @@ void DefaultVideoQualityAnalyzer::Stop() {
   }
   StopMeasuringCpuProcessTime();
   comparison_available_event_.Set();
+  for (auto& thread : thread_pool_) {
+    thread->Stop();
+  }
+  // PlatformThread have to be deleted on the same thread, where it was created
   thread_pool_.clear();
 
   // Perform final Metrics update. On this place analyzer is stopped and no one
@@ -670,6 +677,10 @@ void DefaultVideoQualityAnalyzer::AddComparison(
   StopExcludingCpuThreadTime();
 }
 
+void DefaultVideoQualityAnalyzer::ProcessComparisonsThread(void* obj) {
+  static_cast<DefaultVideoQualityAnalyzer*>(obj)->ProcessComparisons();
+}
+
 void DefaultVideoQualityAnalyzer::ProcessComparisons() {
   while (true) {
     // Try to pick next comparison to perform from the queue.

test/pc/e2e/analyzer/video/default_video_quality_analyzer.h

@@ -560,7 +560,7 @@ class DefaultVideoQualityAnalyzer : public VideoQualityAnalyzerInterface {
   std::deque<FrameComparison> comparisons_ RTC_GUARDED_BY(comparison_lock_);
   AnalyzerStats analyzer_stats_ RTC_GUARDED_BY(comparison_lock_);
 
-  std::vector<rtc::PlatformThread> thread_pool_;
+  std::vector<std::unique_ptr<rtc::PlatformThread>> thread_pool_;
   rtc::Event comparison_available_event_;
 
   Mutex cpu_measurement_lock_;

video/video_analyzer.cc

@@ -137,12 +137,10 @@ VideoAnalyzer::VideoAnalyzer(test::LayerFilteringTransport* transport,
   }
 
   for (uint32_t i = 0; i < num_cores; ++i) {
-    comparison_thread_pool_.push_back(rtc::PlatformThread::SpawnJoinable(
+    rtc::PlatformThread* thread =
-        [this] {
+        new rtc::PlatformThread(&FrameComparisonThread, this, "Analyzer");
-          while (CompareFrames()) {
+    thread->Start();
-          }
+    comparison_thread_pool_.push_back(thread);
-        },
-        "Analyzer"));
   }
 
   if (!rtp_dump_name.empty()) {
@@ -157,8 +155,10 @@ VideoAnalyzer::~VideoAnalyzer() {
     MutexLock lock(&comparison_lock_);
     quit_ = true;
   }
-  // Joins all threads.
+  for (rtc::PlatformThread* thread : comparison_thread_pool_) {
-  comparison_thread_pool_.clear();
+    thread->Stop();
+    delete thread;
+  }
 }
 
 void VideoAnalyzer::SetReceiver(PacketReceiver* receiver) {
@@ -533,6 +533,12 @@ void VideoAnalyzer::PollStats() {
   memory_usage_.AddSample(rtc::GetProcessResidentSizeBytes());
 }
 
+void VideoAnalyzer::FrameComparisonThread(void* obj) {
+  VideoAnalyzer* analyzer = static_cast<VideoAnalyzer*>(obj);
+  while (analyzer->CompareFrames()) {
+  }
+}
+
 bool VideoAnalyzer::CompareFrames() {
   if (AllFramesRecorded())
     return false;

video/video_analyzer.h

@@ -302,7 +302,7 @@ class VideoAnalyzer : public PacketReceiver,
   const double avg_ssim_threshold_;
   bool is_quick_test_enabled_;
 
-  std::vector<rtc::PlatformThread> comparison_thread_pool_;
+  std::vector<rtc::PlatformThread*> comparison_thread_pool_;
   rtc::Event comparison_available_event_;
   std::deque<FrameComparison> comparisons_ RTC_GUARDED_BY(comparison_lock_);
   bool quit_ RTC_GUARDED_BY(comparison_lock_);