Clean up PlatformThread.

webrtc/base/platform_thread.cc

 /*
  *  Copyright (c) 2015 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 58 matching lines @@
                      reinterpret_cast<ULONG_PTR*>(&threadname_info));
   } __except (EXCEPTION_EXECUTE_HANDLER) {
   }
 #elif defined(WEBRTC_LINUX) || defined(WEBRTC_ANDROID)
   prctl(PR_SET_NAME, reinterpret_cast<unsigned long>(name));
 #elif defined(WEBRTC_MAC) || defined(WEBRTC_IOS)
   pthread_setname_np(name);
 #endif
 }
 
-}  // namespace rtc
-
-namespace webrtc {
-
-rtc::scoped_ptr<PlatformThread> PlatformThread::CreateThread(
-    ThreadRunFunction func,
-    void* obj,
-    const char* thread_name) {
-  return rtc::scoped_ptr<PlatformThread>(
-      new PlatformThread(func, obj, thread_name));
-}
-
 namespace {
 #if defined(WEBRTC_WIN)
 void CALLBACK RaiseFlag(ULONG_PTR param) {
   *reinterpret_cast<bool*>(param) = true;
 }
 #else
 struct ThreadAttributes {
   ThreadAttributes() { pthread_attr_init(&attr); }
   ~ThreadAttributes() { pthread_attr_destroy(&attr); }
   pthread_attr_t* operator&() { return &attr; }
@@ skipping 31 matching lines @@
   static_cast<PlatformThread*>(param)->Run();
   return 0;
 }
 #else
 void* PlatformThread::StartThread(void* param) {
   static_cast<PlatformThread*>(param)->Run();
   return 0;
 }
 #endif  // defined(WEBRTC_WIN)
 
-bool PlatformThread::Start() {
+void PlatformThread::Start() {
   RTC_DCHECK(thread_checker_.CalledOnValidThread());
   RTC_DCHECK(!thread_) << "Thread already started?";
 #if defined(WEBRTC_WIN)
   stop_ = false;
 
   // 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;
   thread_ = ::CreateThread(NULL, 1024 * 1024, &StartThread, this,
                            STACK_SIZE_PARAM_IS_A_RESERVATION, &thread_id);
   RTC_CHECK(thread_) << "CreateThread failed";
 #else
   ThreadAttributes attr;
   // Set the stack stack size to 1M.
   pthread_attr_setstacksize(&attr, 1024 * 1024);
   RTC_CHECK_EQ(0, pthread_create(&thread_, &attr, &StartThread, this));
 #endif  // defined(WEBRTC_WIN)
-  return true;
 }
 
-bool PlatformThread::Stop() {
+bool PlatformThread::IsRunning() const {
   RTC_DCHECK(thread_checker_.CalledOnValidThread());
 #if defined(WEBRTC_WIN)
-  if (thread_) {
-    // Set stop_ to |true| on the worker thread.
-    QueueUserAPC(&RaiseFlag, thread_, reinterpret_cast<ULONG_PTR>(&stop_));
-    WaitForSingleObject(thread_, INFINITE);
-    CloseHandle(thread_);
-    thread_ = nullptr;
-  }
+  return thread_ != nullptr;
 #else
-  if (!thread_)
-    return true;
+  return thread_ != 0;
+#endif  // defined(WEBRTC_WIN)
+}
 
+void PlatformThread::Stop() {
+  RTC_DCHECK(thread_checker_.CalledOnValidThread());
+  if (!IsRunning())
+    return;
+
+#if defined(WEBRTC_WIN)
+  // Set stop_ to |true| on the worker thread.
+  QueueUserAPC(&RaiseFlag, thread_, reinterpret_cast<ULONG_PTR>(&stop_));
+  WaitForSingleObject(thread_, INFINITE);
+  CloseHandle(thread_);
+  thread_ = nullptr;
+#else
   stop_event_.Set();
   RTC_CHECK_EQ(0, pthread_join(thread_, nullptr));
   thread_ = 0;
 #endif  // defined(WEBRTC_WIN)
-  return true;
 }
 
 void PlatformThread::Run() {
   if (!name_.empty())
     rtc::SetCurrentThreadName(name_.c_str());
   do {
     // The interface contract of Start/Stop is that for a successfull call to
     // Start, there should be at least one call to the run function.  So we
     // call the function before checking |stop_|.
     if (!run_function_(obj_))
       break;
 #if defined(WEBRTC_WIN)
     // Alertable sleep to permit RaiseFlag to run and update |stop_|.
     SleepEx(0, true);
   } while (!stop_);
 #else
   } while (!stop_event_.Wait(0));
 #endif  // defined(WEBRTC_WIN)
 }
 
 bool PlatformThread::SetPriority(ThreadPriority priority) {
   RTC_DCHECK(thread_checker_.CalledOnValidThread());
+  if (!IsRunning())

[tommi, 2015/11/26 16:26:45]

nit: this isn't needed.  E.g. SetThreadPriority handles it and sets the
appropriate 'last error' value, which is better than this handling. 
pthread_setschedparam must do something similar.  For cases where we don't have
an implementation and just return true, we can return IsRunning() instead.

[pbos-webrtc, 2015/11/26 16:43:03]

Turned into a DCHECK. All compiling code uses Start() just before which cannot
fail.

+    return false;
 #if defined(WEBRTC_WIN)
-  return thread_ && SetThreadPriority(thread_, priority);
+  return SetThreadPriority(thread_, priority) != FALSE;
 #elif defined(__native_client__)
   // Setting thread priorities is not supported in NaCl.
   return true;
 #elif defined(WEBRTC_CHROMIUM_BUILD) && defined(WEBRTC_LINUX)
   // TODO(tommi): Switch to the same mechanism as Chromium uses for changing
   // thread priorities.
   return true;
 #else
-  if (!thread_)
-    return false;
 #ifdef WEBRTC_THREAD_RR
   const int policy = SCHED_RR;
 #else
   const int policy = SCHED_FIFO;
 #endif
   const int min_prio = sched_get_priority_min(policy);
   const int max_prio = sched_get_priority_max(policy);
   if (min_prio == -1 || max_prio == -1) {
     return false;
   }
@@ skipping 21 matching lines @@
       param.sched_priority = std::max(top_prio - 1, low_prio);
       break;
     case kRealtimePriority:
       param.sched_priority = top_prio;
       break;
   }
   return pthread_setschedparam(thread_, policy, &param) == 0;
 #endif  // defined(WEBRTC_WIN)
 }
 
-}  // namespace webrtc
+}  // namespace rtc