wip replace deque with asyncio.Semaphore

Lib/asyncio/queues.py

@@ -38,7 +38,8 @@ class Queue(mixins._LoopBoundMixin):
     def __init__(self, maxsize=0):
         self._maxsize = maxsize
 
-        self._sem_putters = locks.Semaphore(maxsize)
+        if maxsize > 0:
+            self._sem_putters = locks.Semaphore(maxsize)
         self._sem_getters = locks.Semaphore(0)
         self._unfinished_tasks = 0
         self._finished = locks.Event()
@@ -47,11 +48,13 @@ def __init__(self, maxsize=0):
 
     @property
     def _putters(self):
-        return self._sem_putters._waiters or []
+        if self.maxsize > 0:
+            return self._sem_putters._waiters if self._sem_putters._waiters is not None else []
+        return []
 
     @property
     def _getters(self):
-        return self._sem_getters._waiters or []
+        return self._sem_getters._waiters if self._sem_getters._waiters is not None else []
 
     # These three are overridable in subclasses.
     def _init(self, maxsize):
@@ -67,11 +70,12 @@ def _put(self, item):
 
     def _wakeup_next(self, waiters):
         # Wake up the next waiter (if any) that isn't cancelled.
-        if waiters is self._sem_putters:
-            if self._maxsize > 0:
-                self._sem_putters.release()
-        else:
+        if waiters is self._sem_getters:
             self._sem_getters.release()
+            return
+
+        if self._maxsize > 0:
+            self._sem_putters.release()
 
     def __repr__(self):
         return f'<{type(self).__name__} at {id(self):#x} {self._format()}>'
@@ -137,7 +141,7 @@ def put_nowait(self, item):
         """
         if self.full():
             raise QueueFull
-        if self._sem_putters._waiters:
+        if self._maxsize > 0 and self._sem_putters.locked():
             raise QueueFull # PendingPutTasks
         self._put_and_wakeup_next(item)
 
@@ -166,15 +170,16 @@ def get_nowait(self):
         """
         if self.empty():
             raise QueueEmpty
-        if self._sem_getters._waiters:
+        if self._sem_getters.locked():
             raise QueueEmpty # PendingGetTasks
         return self._get_and_wakeup_next()
 
     def _get_and_wakeup_next(self):
         """Remove and return an item from the queue.
         """
         item = self._get()
-        self._wakeup_next(self._sem_putters)
+        if self.maxsize > 0:
+            self._wakeup_next(self._sem_putters)
         return item
 
     def task_done(self):