Modernize Thread

- Based on C++11's `thread` and `thread_local`
- No more need to allocate-deallocate or check for null
- No pointer anymore, just a member variable
- Platform-specific implementations no longer needed (except for the few cases of non-portable functions)
- Simpler for `NO_THREADS`
- Thread ids are now the same across platforms (main is 1; others follow)

2 files changed, 3 insertions, 13 deletions

diff --git a/drivers/xaudio2/audio_driver_xaudio2.cpp b/drivers/xaudio2/audio_driver_xaudio2.cpp
index 3b3c3481b6..1bb8da769b 100644
--- a/drivers/xaudio2/audio_driver_xaudio2.cpp
+++ b/drivers/xaudio2/audio_driver_xaudio2.cpp
@@ -78,7 +78,7 @@ Error AudioDriverXAudio2::init() {
 	hr = xaudio->CreateSourceVoice(&source_voice, &wave_format, 0, XAUDIO2_MAX_FREQ_RATIO, &voice_callback);
 	ERR_FAIL_COND_V_MSG(hr != S_OK, ERR_UNAVAILABLE, "Error creating XAudio2 source voice. Error code: " + itos(hr) + ".");
 
-	thread = Thread::create(AudioDriverXAudio2::thread_func, this);
+	thread.start(AudioDriverXAudio2::thread_func, this);
 
 	return OK;
 }
@@ -146,23 +146,16 @@ float AudioDriverXAudio2::get_latency() {
 }
 
 void AudioDriverXAudio2::lock() {
-	if (!thread)
-		return;
 	mutex.lock();
 }
 
 void AudioDriverXAudio2::unlock() {
-	if (!thread)
-		return;
 	mutex.unlock();
 }
 
 void AudioDriverXAudio2::finish() {
-	if (!thread)
-		return;
-
 	exit_thread = true;
-	Thread::wait_to_finish(thread);
+	thread.wait_to_finish();
 
 	if (source_voice) {
 		source_voice->Stop(0);
@@ -179,9 +172,6 @@ void AudioDriverXAudio2::finish() {
 	}
 
 	mastering_voice->DestroyVoice();
-
-	memdelete(thread);
-	thread = nullptr;
 }
 
 AudioDriverXAudio2::AudioDriverXAudio2() {
diff --git a/drivers/xaudio2/audio_driver_xaudio2.h b/drivers/xaudio2/audio_driver_xaudio2.h
index e3c2d3a326..d3938a19d0 100644
--- a/drivers/xaudio2/audio_driver_xaudio2.h
+++ b/drivers/xaudio2/audio_driver_xaudio2.h
@@ -62,7 +62,7 @@ class AudioDriverXAudio2 : public AudioDriver {
 		void STDMETHODCALLTYPE OnVoiceError(void *pBufferContext, HRESULT Error) {}
 	};
 
-	Thread *thread = nullptr;
+	Thread thread;
 	Mutex mutex;
 
 	int32_t *samples_in = nullptr;