[AUDIO_WORKLET] Enable AW spinlocks, verify them in the browser tests

system/lib/pthread/emscripten_thread_state.S

@@ -53,7 +53,7 @@ emscripten_is_main_browser_thread:
   global.get is_main_thread
   end_function
 
-# Semantically the same as testing "!ENVIRONMENT_IS_WEB" in JS
+# Semantically the same as testing "!ENVIRONMENT_IS_WEB && !ENVIRONMENT_IS_AUDIO_WORKLET" in JS
 .globl _emscripten_thread_supports_atomics_wait
 _emscripten_thread_supports_atomics_wait:
   .functype _emscripten_thread_supports_atomics_wait () -> (i32)

system/lib/wasm_worker/library_wasm_worker.c

@@ -105,15 +105,17 @@ void emscripten_lock_waitinf_acquire(emscripten_lock_t *lock) {
 }
 
 bool emscripten_lock_busyspin_wait_acquire(emscripten_lock_t *lock, double maxWaitMilliseconds) {
+  // TODO: we changed the performance_now calls to get_now, which can be applied
+  // to the remaining code (since all calls defer to the best internal option).
   emscripten_lock_t val = emscripten_atomic_cas_u32((void*)lock, 0, 1);
   if (!val) return true;
 
-  double t = emscripten_performance_now();
+  double t = emscripten_get_now();
   double waitEnd = t + maxWaitMilliseconds;
   while (t < waitEnd) {
     val = emscripten_atomic_cas_u32((void*)lock, 0, 1);
     if (!val) return true;
-    t = emscripten_performance_now();
+    t = emscripten_get_now();
   }
   return false;
 }

test/test_browser.py

@@ -5516,12 +5516,13 @@ def test_audio_worklet_params_mixing(self, args):
     shutil.copy(test_file('webaudio/audio_files/emscripten-bass.mp3'), 'audio_files/')
     self.btest_exit('webaudio/audioworklet_params_mixing.c', args=['-sAUDIO_WORKLET', '-sWASM_WORKERS', '-DTEST_AND_EXIT'] + args)
 
-  # Tests AudioWorklet with emscripten_futex_wake().
+  # Tests AudioWorklet with emscripten_lock_busyspin_wait_acquire() and friends
+  @no_wasm64('https://github.com/emscripten-core/emscripten/pull/23508')
+  @no_2gb('https://github.com/emscripten-core/emscripten/pull/23508')
   @requires_sound_hardware
   @also_with_minimal_runtime
-  @disabled('https://github.com/emscripten-core/emscripten/issues/22962')
-  def test_audio_worklet_emscripten_futex_wake(self):
-    self.btest('webaudio/audioworklet_emscripten_futex_wake.cpp', expected='0', args=['-sAUDIO_WORKLET', '-sWASM_WORKERS', '-pthread', '-sPTHREAD_POOL_SIZE=2'])
+  def test_audio_worklet_emscripten_locks(self):
+    self.btest_exit('webaudio/audioworklet_emscripten_futex_wake.cpp', args=['-sAUDIO_WORKLET', '-sWASM_WORKERS', '-pthread'])
 
   def test_error_reporting(self):
     # Test catching/reporting Error objects

test/webaudio/audioworklet_emscripten_futex_wake.cpp

@@ -1,32 +1,105 @@
-#include <emscripten/webaudio.h>
 #include <emscripten/threading.h>
-#include <stdio.h>
-#include <stdlib.h>
+#include <emscripten/wasm_worker.h>
+#include <emscripten/webaudio.h>
 #include <assert.h>
 
-// Tests that
-// - _emscripten_thread_supports_atomics_wait() returns true in a Wasm Audio Worklet.
-// - emscripten_futex_wake() does not crash in a Wasm Audio Worklet.
-// - emscripten_futex_wait() does not crash in a Wasm Audio Worklet.
-// - emscripten_get_now() does not crash in a Wasm Audio Worklet.
-
-int futexLocation = 0;
-int testSuccess = 0;
+// Tests that these audio worklet compatible functions work, details in comments below:
+//
+// - _emscripten_thread_supports_atomics_wait()
+// - emscripten_lock_init()
+// - emscripten_lock_try_acquire()
+// - emscripten_lock_busyspin_wait_acquire()
+// - emscripten_lock_busyspin_waitinf_acquire()
+// - emscripten_lock_release()
+// - emscripten_get_now()
 
-// Internal, found in 'system/lib/pthread/threading_internal.h'
-extern "C" int _emscripten_thread_supports_atomics_wait();
+// Internal, found in 'system/lib/pthread/threading_internal.h' (and requires building with -pthread)
+extern "C" int _emscripten_thread_supports_atomics_wait(void);
 
-bool ProcessAudio(int numInputs, const AudioSampleFrame *inputs, int numOutputs, AudioSampleFrame *outputs, int numParams, const AudioParamFrame *params, void *userData) {
-  int supportsAtomicWait = _emscripten_thread_supports_atomics_wait();
-  printf("supportsAtomicWait: %d\n", supportsAtomicWait);
-  assert(!supportsAtomicWait);
-  emscripten_futex_wake(&futexLocation, 1);
-  printf("%f\n", emscripten_get_now());
+typedef enum {
+  // No wait support in audio worklets
+  TEST_HAS_WAIT,
+  // Acquired in main, fail in process
+  TEST_TRY_ACQUIRE,
+  // Keep acquired so time-out
+  TEST_WAIT_ACQUIRE_FAIL,
+  // Release in main, succeed in process
+  TEST_WAIT_ACQUIRE,
+  // Release in process after above
+  TEST_RELEASE,
+  // Released in process above, spin in main
+  TEST_WAIT_INFINTE_1,
+  // Release in process to stop spinning in main
+  TEST_WAIT_INFINTE_2,
+  // Call emscripten_get_now() in process
+  TEST_GET_NOW,
+  // Test finished
+  TEST_DONE
+} Test;
 
-  emscripten_futex_wait(&futexLocation, 1, /*maxWaitMs=*/2);
-  testSuccess = 1;
+// Lock used in all the tests
+emscripten_lock_t testLock = EMSCRIPTEN_LOCK_T_STATIC_INITIALIZER;
+// Which test is running (sometimes in the worklet, sometimes in the main thread)
+_Atomic Test whichTest = TEST_HAS_WAIT;
+// Time at which the test starts taken in main()
+double startTime = 0;
 
-  return false;
+bool ProcessAudio(int numInputs, const AudioSampleFrame *inputs, int numOutputs, AudioSampleFrame *outputs, int numParams, const AudioParamFrame *params, void *userData) {
+  int result = 0;
+  switch (whichTest) {
+  case TEST_HAS_WAIT:
+    // Should not have wait support here
+    result = _emscripten_thread_supports_atomics_wait();
+    emscripten_outf("TEST_HAS_WAIT: %d (expect: 0)", result);
+    assert(!result);
+    whichTest = TEST_TRY_ACQUIRE;
+    break;
+  case TEST_TRY_ACQUIRE:
+    // Was locked after init, should fail to acquire
+    result = emscripten_lock_try_acquire(&testLock);
+    emscripten_outf("TEST_TRY_ACQUIRE: %d (expect: 0)", result);
+    assert(!result);
+    whichTest = TEST_WAIT_ACQUIRE_FAIL;
+    break;
+  case TEST_WAIT_ACQUIRE_FAIL:
+    // Still locked so we fail to acquire
+    result = emscripten_lock_busyspin_wait_acquire(&testLock, 100);
+    emscripten_outf("TEST_WAIT_ACQUIRE_FAIL: %d (expect: 0)", result);
+    assert(!result);
+    whichTest = TEST_WAIT_ACQUIRE;
+  case TEST_WAIT_ACQUIRE:
+    // Will get unlocked in main thread, so should quickly acquire
+    result = emscripten_lock_busyspin_wait_acquire(&testLock, 100);
+    emscripten_outf("TEST_WAIT_ACQUIRE: %d  (expect: 1)", result);
+    assert(result);
+    whichTest = TEST_RELEASE;
+    break;
+  case TEST_RELEASE:
+    // Unlock, check the result
+    emscripten_lock_release(&testLock);
+    result = emscripten_lock_try_acquire(&testLock);
+    emscripten_outf("TEST_RELEASE: %d (expect: 1)", result);
+    assert(result);
+    whichTest = TEST_WAIT_INFINTE_1;
+    break;
+  case TEST_WAIT_INFINTE_1:
+    // Still locked when we enter here but move on in the main thread
+    break;
+  case TEST_WAIT_INFINTE_2:
+    emscripten_lock_release(&testLock);
+    whichTest = TEST_GET_NOW;
+    break;
+  case TEST_GET_NOW:
+    result = (int) (emscripten_get_now() - startTime);
+    emscripten_outf("TEST_GET_NOW: %d  (expect: > 0)", result);
+    assert(result > 0);
+    whichTest = TEST_DONE;
+  case TEST_DONE:
+    return false;
+  default:
+    break;
+  }
+  return true;
 }
 
 EM_JS(void, InitHtmlUi, (EMSCRIPTEN_WEBAUDIO_T audioContext), {
@@ -40,34 +113,55 @@ EM_JS(void, InitHtmlUi, (EMSCRIPTEN_WEBAUDIO_T audioContext), {
   };
 });
 
-bool PollTestSuccess(double, void *) {
-  if (testSuccess) {
-    printf("Test success!\n");
-#ifdef REPORT_RESULT
-    REPORT_RESULT(0);
-#endif
+bool MainLoop(double time, void* data) {
+  switch (whichTest) {
+  case TEST_WAIT_ACQUIRE:
+    // Release here to acquire in process
+    emscripten_lock_release(&testLock);
+    break;
+  case TEST_WAIT_INFINTE_1:
+    // Spin here until released in process (but don't change test until we know this case ran)
+    whichTest = TEST_WAIT_INFINTE_2;
+    emscripten_lock_busyspin_waitinf_acquire(&testLock);
+    emscripten_out("TEST_WAIT_INFINTE (from main)");
+    break;
+  case TEST_DONE:
+    // Finished, exit from the main thread
+    emscripten_out("Test success");
+    emscripten_force_exit(0);
     return false;
+  default:
+    break;
   }
   return true;
 }
 
 void AudioWorkletProcessorCreated(EMSCRIPTEN_WEBAUDIO_T audioContext, bool success, void *userData) {
   int outputChannelCounts[1] = { 1 };
   EmscriptenAudioWorkletNodeCreateOptions options = { .numberOfInputs = 0, .numberOfOutputs = 1, .outputChannelCounts = outputChannelCounts };
-  EMSCRIPTEN_AUDIO_WORKLET_NODE_T wasmAudioWorklet = emscripten_create_wasm_audio_worklet_node(audioContext, "noise-generator", &options, &ProcessAudio, 0);
+  EMSCRIPTEN_AUDIO_WORKLET_NODE_T wasmAudioWorklet = emscripten_create_wasm_audio_worklet_node(audioContext, "noise-generator", &options, &ProcessAudio, NULL);
   emscripten_audio_node_connect(wasmAudioWorklet, audioContext, 0, 0);
   InitHtmlUi(audioContext);
 }
 
 void WebAudioWorkletThreadInitialized(EMSCRIPTEN_WEBAUDIO_T audioContext, bool success, void *userData) {
   WebAudioWorkletProcessorCreateOptions opts = { .name = "noise-generator" };
-  emscripten_create_wasm_audio_worklet_processor_async(audioContext, &opts, AudioWorkletProcessorCreated, 0);
+  emscripten_create_wasm_audio_worklet_processor_async(audioContext, &opts, AudioWorkletProcessorCreated, NULL);
 }
 
-uint8_t wasmAudioWorkletStack[4096];
+uint8_t wasmAudioWorkletStack[2048];
 
 int main() {
-  emscripten_set_timeout_loop(PollTestSuccess, 10, 0);
-  EMSCRIPTEN_WEBAUDIO_T context = emscripten_create_audio_context(0);
-  emscripten_start_wasm_audio_worklet_thread_async(context, wasmAudioWorkletStack, sizeof(wasmAudioWorkletStack), WebAudioWorkletThreadInitialized, 0);
+  // Main thread init and acquire (work passes to the processor)
+  emscripten_lock_init(&testLock);
+  int hasLock = emscripten_lock_busyspin_wait_acquire(&testLock, 0);
+  assert(hasLock);
+
+  startTime = emscripten_get_now();
+
+  emscripten_set_timeout_loop(MainLoop, 10, NULL);
+  EMSCRIPTEN_WEBAUDIO_T context = emscripten_create_audio_context(NULL);
+  emscripten_start_wasm_audio_worklet_thread_async(context, wasmAudioWorkletStack, sizeof(wasmAudioWorkletStack), WebAudioWorkletThreadInitialized, NULL);
+
+  emscripten_exit_with_live_runtime();
 }