InMemoryChannelLayer improvements, test fixes (#1976)

channels/layers.py

@@ -198,13 +198,13 @@ def __init__(
         group_expiry=86400,
         capacity=100,
         channel_capacity=None,
-        **kwargs
+        **kwargs,
     ):
         super().__init__(
             expiry=expiry,
             capacity=capacity,
             channel_capacity=channel_capacity,
-            **kwargs
+            **kwargs,
         )
         self.channels = {}
         self.groups = {}
@@ -225,13 +225,14 @@ async def send(self, channel, message):
         # name in message
         assert "__asgi_channel__" not in message
 
-        queue = self.channels.setdefault(channel, asyncio.Queue())
-        # Are we full
-        if queue.qsize() >= self.capacity:
-            raise ChannelFull(channel)
-
+        queue = self.channels.setdefault(
+            channel, asyncio.Queue(maxsize=self.get_capacity(channel))
+        )
         # Add message
-        await queue.put((time.time() + self.expiry, deepcopy(message)))
+        try:
+            queue.put_nowait((time.time() + self.expiry, deepcopy(message)))
+        except asyncio.queues.QueueFull:
+            raise ChannelFull(channel)
 
     async def receive(self, channel):
         """
@@ -242,14 +243,16 @@ async def receive(self, channel):
         assert self.valid_channel_name(channel)
         self._clean_expired()
 
-        queue = self.channels.setdefault(channel, asyncio.Queue())
+        queue = self.channels.setdefault(
+            channel, asyncio.Queue(maxsize=self.get_capacity(channel))
+        )
 
         # Do a plain direct receive
         try:
             _, message = await queue.get()
         finally:
             if queue.empty():
-                del self.channels[channel]
+                self.channels.pop(channel, None)
 
         return message
 
@@ -279,19 +282,17 @@ def _clean_expired(self):
                 self._remove_from_groups(channel)
                 # Is the channel now empty and needs deleting?
                 if queue.empty():
-                    del self.channels[channel]
+                    self.channels.pop(channel, None)
 
         # Group Expiration
         timeout = int(time.time()) - self.group_expiry
-        for group in self.groups:
-            for channel in list(self.groups.get(group, set())):
-                # If join time is older than group_expiry end the group membership
-                if (
-                    self.groups[group][channel]
-                    and int(self.groups[group][channel]) < timeout
-                ):
+        for channels in self.groups.values():
+            for name, timestamp in list(channels.items()):
+                # If join time is older than group_expiry
+                # end the group membership
+                if timestamp and timestamp < timeout:
                     # Delete from group
-                    del self.groups[group][channel]
+                    channels.pop(name, None)
 
     # Flush extension
 
@@ -308,8 +309,7 @@ def _remove_from_groups(self, channel):
         Removes a channel from all groups. Used when a message on it expires.
         """
         for channels in self.groups.values():
-            if channel in channels:
-                del channels[channel]
+            channels.pop(channel, None)
 
     # Groups extension
 
@@ -329,22 +329,29 @@ async def group_discard(self, group, channel):
         assert self.valid_channel_name(channel), "Invalid channel name"
         assert self.valid_group_name(group), "Invalid group name"
         # Remove from group set
-        if group in self.groups:
-            if channel in self.groups[group]:
-                del self.groups[group][channel]
-            if not self.groups[group]:
-                del self.groups[group]
+        group_channels = self.groups.get(group, None)
+        if group_channels:
+            # remove channel if in group
+            group_channels.pop(channel, None)
+            # is group now empty? If yes remove it
+            if not group_channels:
+                self.groups.pop(group, None)
 
     async def group_send(self, group, message):
         # Check types
         assert isinstance(message, dict), "Message is not a dict"
         assert self.valid_group_name(group), "Invalid group name"
         # Run clean
         self._clean_expired()
+
         # Send to each channel
-        for channel in self.groups.get(group, set()):
+        ops = []
+        if group in self.groups:
+            for channel in self.groups[group].keys():
+                ops.append(asyncio.create_task(self.send(channel, message)))
+        for send_result in asyncio.as_completed(ops):
             try:
-                await self.send(channel, message)
+                await send_result
             except ChannelFull:
                 pass
 

tests/test_inmemorychannel.py

@@ -26,9 +26,36 @@ async def test_send_receive(channel_layer):
     await channel_layer.send(
         "test-channel-1", {"type": "test.message", "text": "Ahoy-hoy!"}
     )
+    await channel_layer.send(
+        "test-channel-1", {"type": "test.message", "text": "Ahoy-hoy!"}
+    )
     message = await channel_layer.receive("test-channel-1")
     assert message["type"] == "test.message"
     assert message["text"] == "Ahoy-hoy!"
+    # not removed because not empty
+    assert "test-channel-1" in channel_layer.channels
+    message = await channel_layer.receive("test-channel-1")
+    assert message["type"] == "test.message"
+    assert message["text"] == "Ahoy-hoy!"
+    # removed because empty
+    assert "test-channel-1" not in channel_layer.channels
+
+
+@pytest.mark.asyncio
+async def test_race_empty(channel_layer):
+    """
+    Makes sure the race is handled gracefully.
+    """
+    receive_task = asyncio.create_task(channel_layer.receive("test-channel-1"))
+    await asyncio.sleep(0.1)
+    await channel_layer.send(
+        "test-channel-1", {"type": "test.message", "text": "Ahoy-hoy!"}
+    )
+    del channel_layer.channels["test-channel-1"]
+    await asyncio.sleep(0.1)
+    message = await receive_task
+    assert message["type"] == "test.message"
+    assert message["text"] == "Ahoy-hoy!"
 
 
 @pytest.mark.asyncio
@@ -62,7 +89,6 @@ async def test_multi_send_receive(channel_layer):
     """
     Tests overlapping sends and receives, and ordering.
     """
-    channel_layer = InMemoryChannelLayer()
     await channel_layer.send("test-channel-3", {"type": "message.1"})
     await channel_layer.send("test-channel-3", {"type": "message.2"})
     await channel_layer.send("test-channel-3", {"type": "message.3"})
@@ -76,7 +102,6 @@ async def test_groups_basic(channel_layer):
     """
     Tests basic group operation.
     """
-    channel_layer = InMemoryChannelLayer()
     await channel_layer.group_add("test-group", "test-gr-chan-1")
     await channel_layer.group_add("test-group", "test-gr-chan-2")
     await channel_layer.group_add("test-group", "test-gr-chan-3")
@@ -97,7 +122,6 @@ async def test_groups_channel_full(channel_layer):
     """
     Tests that group_send ignores ChannelFull
     """
-    channel_layer = InMemoryChannelLayer()
     await channel_layer.group_add("test-group", "test-gr-chan-1")
     await channel_layer.group_send("test-group", {"type": "message.1"})
     await channel_layer.group_send("test-group", {"type": "message.1"})