Replace the stop_event_ in PlatformThread with an atomic flag

webrtc/base/platform_thread.cc

Index: webrtc/base/platform_thread.cc
diff --git a/webrtc/base/platform_thread.cc b/webrtc/base/platform_thread.cc
index 0b025f2af048f94d9e776f171276850f54ef952e..12420f17b983600520b6ab6fa91c8466ed4c1b46 100644
--- a/webrtc/base/platform_thread.cc
+++ b/webrtc/base/platform_thread.cc
@@ -10,6 +10,7 @@
 
 #include "webrtc/base/platform_thread.h"
 
+#include "webrtc/base/atomicops.h"
 #include "webrtc/base/checks.h"
 
 #if defined(WEBRTC_LINUX)
@@ -96,15 +97,7 @@ PlatformThread::PlatformThread(ThreadRunFunction func,
                                const char* thread_name)
     : run_function_(func),
       obj_(obj),
-      name_(thread_name ? thread_name : "webrtc"),
-#if defined(WEBRTC_WIN)
-      stop_(false),
-      thread_(NULL),
-      thread_id_(0) {
-#else
-      stop_event_(false, false),
-      thread_(0) {
-#endif  // defined(WEBRTC_WIN)
+      name_(thread_name ? thread_name : "webrtc") {
   RTC_DCHECK(func);
   RTC_DCHECK(name_.length() < 64);
 }
@@ -187,8 +180,9 @@ void PlatformThread::Stop() {
   thread_ = nullptr;
   thread_id_ = 0;
 #else
-  stop_event_.Set();
+  RTC_CHECK_EQ(1, AtomicOps::Increment(&stop_flag_));
   RTC_CHECK_EQ(0, pthread_join(thread_, nullptr));
+  AtomicOps::ReleaseStore(&stop_flag_, 0);
   thread_ = 0;
 #endif  // defined(WEBRTC_WIN)
 }
@@ -207,7 +201,7 @@ void PlatformThread::Run() {
     SleepEx(0, true);
   } while (!stop_);
 #else

[the sun, 2017/02/18 23:18:25]

Do we want to give up the reminder of our time slice with e.g. sleep(0),
pthread_yield_np() or sched_yield()? 

Unfortunately I don't know Linux/Posix well enough to make a proper
recommendation in favor of one of the above...

-  } while (!stop_event_.Wait(0));
+  } while (!AtomicOps::AcquireLoad(&stop_flag_));
 #endif  // defined(WEBRTC_WIN)
 }