channel.py: fix to use coros.Channel

eventlet/channel.py

@@ -1,16 +1,23 @@
 from eventlet import coros
 
-class channel(coros.queue):
-
-    def __init__(self):
-        coros.queue.__init__(self, 0)
+class channel(coros.Channel):
 
     def receive(self):
         return self.wait()
 
     @property
     def balance(self):
-        return self.sem.balance
+        return len(self.items) - len(self._waiters)
 
 import warnings
-warnings.warn("channel is deprecated; use coros.queue(0) which behaves the same", DeprecationWarning, stacklevel=2)
+warnings.warn("channel.py is deprecated by coros.Channel", DeprecationWarning, stacklevel=2)
+
+if __name__ == '__main__':
+    from eventlet import proc, api
+    c = channel()
+    proc.spawn(c.send, 'X')
+    proc.spawn(c.send, 'Y')
+    assert c.wait() == 'X', c
+    assert c.wait() == 'Y', c
+    assert api.with_timeout(1, c.wait, timeout_value='hello') == 'hello', c
+