Add Platform::Yield

Source/Engine/Platform/Android/AndroidPlatform.cpp

@@ -748,6 +748,11 @@ void AndroidPlatform::Sleep(int32 milliseconds)
     usleep(milliseconds * 1000);
 }
 
+void AndroidPlatform::Yield()
+{
+    pthread_yield();
+}
+
 double AndroidPlatform::GetTimeSeconds()
 {
     struct timespec ts;

Source/Engine/Platform/Android/AndroidPlatform.h

@@ -91,6 +91,7 @@ public:
     static void SetThreadPriority(ThreadPriority priority);
     static void SetThreadAffinityMask(uint64 affinityMask);
     static void Sleep(int32 milliseconds);
+    static void Yield();
     static double GetTimeSeconds();
     static uint64 GetTimeCycles();
     FORCE_INLINE static uint64 GetClockFrequency()

Source/Engine/Platform/Apple/ApplePlatform.cpp

@@ -293,6 +293,11 @@ void ApplePlatform::Sleep(int32 milliseconds)
     usleep(milliseconds * 1000);
 }
 
+void ApplePlatform::Yield()
+{
+    pthread_yield();
+}
+
 double ApplePlatform::GetTimeSeconds()
 {
     return SecondsPerCycle * mach_absolute_time();

Source/Engine/Platform/Apple/ApplePlatform.h

@@ -75,6 +75,7 @@ public:
     static void SetThreadPriority(ThreadPriority priority);
     static void SetThreadAffinityMask(uint64 affinityMask);
     static void Sleep(int32 milliseconds);
+    static void Yield();
     static double GetTimeSeconds();
     static uint64 GetTimeCycles();
     static uint64 GetClockFrequency();

Source/Engine/Platform/Base/PlatformBase.h

@@ -436,11 +436,16 @@ public:
     static void SetThreadAffinityMask(uint64 affinityMask) = delete;
 
     /// <summary>
-    /// Suspends the execution of the current thread until the time-out interval elapses
+    /// Suspends the execution of the current thread until the time-out interval elapses.
     /// </summary>
     /// <param name="milliseconds">The time interval for which execution is to be suspended, in milliseconds.</param>
     static void Sleep(int32 milliseconds) = delete;
 
+    /// <summary>
+    /// Yields the execution of the current thread to another thread that is ready to run on the current processor.
+    /// </summary>
+    static void Yield() = delete;
+
 public:
     /// <summary>
     /// Gets the current time in seconds.

Source/Engine/Platform/Linux/LinuxPlatform.cpp

@@ -1836,6 +1836,11 @@ void LinuxPlatform::Sleep(int32 milliseconds)
     usleep(milliseconds * 1000);
 }
 
+void LinuxPlatform::Yield()
+{
+    pthread_yield();
+}
+
 double LinuxPlatform::GetTimeSeconds()
 {
     struct timespec ts;

Source/Engine/Platform/Linux/LinuxPlatform.h

@@ -106,6 +106,7 @@ public:
     static void SetThreadPriority(ThreadPriority priority);
     static void SetThreadAffinityMask(uint64 affinityMask);
     static void Sleep(int32 milliseconds);
+    static void Yield();
     static double GetTimeSeconds();
     static uint64 GetTimeCycles();
     FORCE_INLINE static uint64 GetClockFrequency()

Source/Engine/Platform/Win32/IncludeWindowsHeaders.h

@@ -68,6 +68,7 @@
 #undef CreateMutex
 #undef DrawState
 #undef LoadLibrary
+#undef Yield
 #undef GetEnvironmentVariable
 #undef SetEnvironmentVariable
 

Source/Engine/Platform/Win32/Win32Platform.cpp

@@ -400,6 +400,11 @@ void Win32Platform::Sleep(int32 milliseconds)
     WaitForSingleObject(timer, INFINITE);
 }
 
+void Win32Platform::Yield()
+{
+    SwitchToThread();
+}
+
 double Win32Platform::GetTimeSeconds()
 {
     LARGE_INTEGER counter;

Source/Engine/Platform/Win32/Win32Platform.h

@@ -100,6 +100,7 @@ public:
     static void SetThreadPriority(ThreadPriority priority);
     static void SetThreadAffinityMask(uint64 affinityMask);
     static void Sleep(int32 milliseconds);
+    static void Yield();
     static double GetTimeSeconds();
     static uint64 GetTimeCycles();
     static uint64 GetClockFrequency();

Source/Engine/Renderer/RenderListBuffer.h

@@ -324,7 +324,7 @@ private:
             // Wait for all threads to stop adding items before resizing can happen
         RETRY:
             while (Platform::AtomicRead(&_threadsAdding))
-                Platform::Sleep(0);
+                Platform::Yield();
 
             // Thread-safe resizing
             _locker.Lock();

Source/Engine/Threading/ConcurrentSystemLocker.cpp

@@ -39,7 +39,7 @@ RETRY:
     {
         // Someone else is doing opposite operation so wait for it's end
         // TODO: use ConditionVariable+CriticalSection to prevent active-waiting
-        Platform::Sleep(0);
+        Platform::Yield();
         goto RETRY;
     }
 
@@ -47,7 +47,7 @@ RETRY:
     if (exclusively && Platform::AtomicRead(thisCounter) != 0)
     {
         // Someone else is doing opposite operation so wait for it's end
-        Platform::Sleep(0);
+        Platform::Yield();
         goto RETRY;
     }