Update set_timer patch

Author: e-dong

platform_wasm/pygame/timer.py

@@ -1,4 +1,6 @@
 import asyncio
+from typing import Union
+import uuid
 
 # =================================================
 # do no change import order for *thread*
@@ -27,20 +29,75 @@
 #   - could be possibly very late
 #   - delay cannot be less than frametime at device refresh rate.
 
+# Local testing wrap patch_set_timer in a function and
+# only apply on emscripten platform, so running pygame vanilla doesn't break
+#
+# import platform
+#
+# def patch_timer():
+#     THREADS = {}
+#
+#     def patch_set_timer(
+#         event: Union[int, pygame.event.Event], millis: int, loops: int = 0):
+#         ...
+
+#         async def fire_event(thread_uuid):
+#             ...
+#
+#     pygame.time.set_timer = patch_set_timer
+#
+# if platform.system().lower() == "emscripten":
+#     patch_timer()
+
+
+# Global var to keep track of timer threads
+#   - key: event type
+#   - value: thread uuid
+THREADS = {}
+
+
+def patch_set_timer(
+        event: Union[int, pygame.event.Event], millis: int, loops: int = 0):
+    """Patches the pygame.time.set_timer function to use gthreads"""
 
-def patch_set_timer(cust_event_no, millis, loops=0):
     dlay = float(millis) / 1000
-    cevent = pygame.event.Event(cust_event_no)
-    loop = asyncio.get_event_loop()
+    cevent = pygame.event.Event(event)
+    event_loop = asyncio.get_event_loop()
+
+    async def fire_event(thread_uuid):
+        """The thread's target function to handle the timer
 
-    async def fire_event():
+        Early exit conditions:
+          - event loop is closed
+          - event type is no longer in THREADS dictionary
+          - the thread's uuid is not the latest one
+          - Max loop iterations if loops param is not zero
+        """
+        loop_counter = 0
         while True:
             await asyncio.sleep(dlay)
-            if loop.is_closed():
+            if (
+                event_loop.is_closed()
+                or event not in THREADS
+                or THREADS[event] != thread_uuid
+                or (loops and loop_counter >= loops)
+            ):
                 break
+
             pygame.event.post(cevent)
+            loop_counter += 1 if loops else 0
+
+    if dlay > 0:
+        # uuid is used to track the latest thread,
+        # stale threads will be terminated
+        thread_uuid = uuid.uuid4()
+        Thread(target=fire_event, args=[thread_uuid]).start()
+        THREADS[event] = thread_uuid
 
-    Thread(target=fire_event).start()
+    else:
+        # This cancels the timer for the event
+        if event in THREADS:
+            del THREADS[event]
 
 
 pygame.time.set_timer = patch_set_timer