Fixing cancelled async futures (#2666)

Co-authored-by: James R T <[email protected]>
Co-authored-by: dvora-h <[email protected]>

Author: 3 people

.github/workflows/integration.yaml

@@ -51,6 +51,7 @@ jobs:
      timeout-minutes: 30
      strategy:
        max-parallel: 15
+       fail-fast: false
        matrix:
          python-version: ['3.7', '3.8', '3.9', '3.10', '3.11', 'pypy-3.7', 'pypy-3.8']
          test-type: ['standalone', 'cluster']
@@ -108,6 +109,7 @@ jobs:
     name: Install package from commit hash
     runs-on: ubuntu-latest
     strategy:
+      fail-fast: false
       matrix:
         python-version: ['3.7', '3.8', '3.9', '3.10', '3.11', 'pypy-3.7']
     steps:

redis/asyncio/client.py

@@ -493,24 +493,34 @@ async def _disconnect_raise(self, conn: Connection, error: Exception):
         ):
             raise error
 
-    # COMMAND EXECUTION AND PROTOCOL PARSING
-    async def execute_command(self, *args, **options):
-        """Execute a command and return a parsed response"""
-        await self.initialize()
-        pool = self.connection_pool
-        command_name = args[0]
-        conn = self.connection or await pool.get_connection(command_name, **options)
-
+    async def _try_send_command_parse_response(self, conn, *args, **options):
         try:
             return await conn.retry.call_with_retry(
                 lambda: self._send_command_parse_response(
-                    conn, command_name, *args, **options
+                    conn, args[0], *args, **options
                 ),
                 lambda error: self._disconnect_raise(conn, error),
             )
+        except asyncio.CancelledError:
+            await conn.disconnect(nowait=True)
+            raise
         finally:
+            if self.single_connection_client:
+                self._single_conn_lock.release()
             if not self.connection:
-                await pool.release(conn)
+                await self.connection_pool.release(conn)
+
+    # COMMAND EXECUTION AND PROTOCOL PARSING
+    async def execute_command(self, *args, **options):
+        """Execute a command and return a parsed response"""
+        await self.initialize()
+        pool = self.connection_pool
+        command_name = args[0]
+        conn = self.connection or await pool.get_connection(command_name, **options)
+
+        return await asyncio.shield(
+            self._try_send_command_parse_response(conn, *args, **options)
+        )
 
     async def parse_response(
         self, connection: Connection, command_name: Union[str, bytes], **options
@@ -749,10 +759,18 @@ async def _disconnect_raise_connect(self, conn, error):
         is not a TimeoutError. Otherwise, try to reconnect
         """
         await conn.disconnect()
+
         if not (conn.retry_on_timeout and isinstance(error, TimeoutError)):
             raise error
         await conn.connect()
 
+    async def _try_execute(self, conn, command, *arg, **kwargs):
+        try:
+            return await command(*arg, **kwargs)
+        except asyncio.CancelledError:
+            await conn.disconnect()
+            raise
+
     async def _execute(self, conn, command, *args, **kwargs):
         """
         Connect manually upon disconnection. If the Redis server is down,
@@ -761,9 +779,11 @@ async def _execute(self, conn, command, *args, **kwargs):
         called by the # connection to resubscribe us to any channels and
         patterns we were previously listening to
         """
-        return await conn.retry.call_with_retry(
-            lambda: command(*args, **kwargs),
-            lambda error: self._disconnect_raise_connect(conn, error),
+        return await asyncio.shield(
+            conn.retry.call_with_retry(
+                lambda: self._try_execute(conn, command, *args, **kwargs),
+                lambda error: self._disconnect_raise_connect(conn, error),
+            )
         )
 
     async def parse_response(self, block: bool = True, timeout: float = 0):
@@ -1165,6 +1185,18 @@ async def _disconnect_reset_raise(self, conn, error):
             await self.reset()
             raise
 
+    async def _try_send_command_parse_response(self, conn, *args, **options):
+        try:
+            return await conn.retry.call_with_retry(
+                lambda: self._send_command_parse_response(
+                    conn, args[0], *args, **options
+                ),
+                lambda error: self._disconnect_reset_raise(conn, error),
+            )
+        except asyncio.CancelledError:
+            await conn.disconnect()
+            raise
+
     async def immediate_execute_command(self, *args, **options):
         """
         Execute a command immediately, but don't auto-retry on a
@@ -1180,13 +1212,13 @@ async def immediate_execute_command(self, *args, **options):
                 command_name, self.shard_hint
             )
             self.connection = conn
-
-        return await conn.retry.call_with_retry(
-            lambda: self._send_command_parse_response(
-                conn, command_name, *args, **options
-            ),
-            lambda error: self._disconnect_reset_raise(conn, error),
-        )
+        try:
+            return await asyncio.shield(
+                self._try_send_command_parse_response(conn, *args, **options)
+            )
+        except asyncio.CancelledError:
+            await conn.disconnect()
+            raise
 
     def pipeline_execute_command(self, *args, **options):
         """
@@ -1353,6 +1385,19 @@ async def _disconnect_raise_reset(self, conn: Connection, error: Exception):
             await self.reset()
             raise
 
+    async def _try_execute(self, conn, execute, stack, raise_on_error):
+        try:
+            return await conn.retry.call_with_retry(
+                lambda: execute(conn, stack, raise_on_error),
+                lambda error: self._disconnect_raise_reset(conn, error),
+            )
+        except asyncio.CancelledError:
+            # not supposed to be possible, yet here we are
+            await conn.disconnect(nowait=True)
+            raise
+        finally:
+            await self.reset()
+
     async def execute(self, raise_on_error: bool = True):
         """Execute all the commands in the current pipeline"""
         stack = self.command_stack
@@ -1375,15 +1420,10 @@ async def execute(self, raise_on_error: bool = True):
 
         try:
             return await asyncio.shield(
-                conn.retry.call_with_retry(
-                    lambda: execute(conn, stack, raise_on_error),
-                    lambda error: self._disconnect_raise_reset(conn, error),
-                )
+                self._try_execute(conn, execute, stack, raise_on_error)
             )
-        except asyncio.CancelledError:
-            # not supposed to be possible, yet here we are
-            await conn.disconnect(nowait=True)
-            raise
+        except RuntimeError:
+            await self.reset()
         finally:
             await self.reset()
 

redis/asyncio/cluster.py

@@ -1016,6 +1016,19 @@ async def _parse_and_release(self, connection, *args, **kwargs):
         finally:
             self._free.append(connection)
 
+    async def _try_parse_response(self, cmd, connection, ret):
+        try:
+            cmd.result = await asyncio.shield(
+                self.parse_response(connection, cmd.args[0], **cmd.kwargs)
+            )
+        except asyncio.CancelledError:
+            await connection.disconnect(nowait=True)
+            raise
+        except Exception as e:
+            cmd.result = e
+            ret = True
+        return ret
+
     async def execute_pipeline(self, commands: List["PipelineCommand"]) -> bool:
         # Acquire connection
         connection = self.acquire_connection()
@@ -1028,13 +1041,7 @@ async def execute_pipeline(self, commands: List["PipelineCommand"]) -> bool:
         # Read responses
         ret = False
         for cmd in commands:
-            try:
-                cmd.result = await self.parse_response(
-                    connection, cmd.args[0], **cmd.kwargs
-                )
-            except Exception as e:
-                cmd.result = e
-                ret = True
+            ret = await asyncio.shield(self._try_parse_response(cmd, connection, ret))
 
         # Release connection
         self._free.append(connection)

tests/test_asyncio/test_cluster.py

@@ -340,23 +340,6 @@ async def test_from_url(self, request: FixtureRequest) -> None:
         rc = RedisCluster.from_url("rediss://localhost:16379")
         assert rc.connection_kwargs["connection_class"] is SSLConnection
 
-    async def test_asynckills(self, r) -> None:
-
-        await r.set("foo", "foo")
-        await r.set("bar", "bar")
-
-        t = asyncio.create_task(r.get("foo"))
-        await asyncio.sleep(1)
-        t.cancel()
-        try:
-            await t
-        except asyncio.CancelledError:
-            pytest.fail("connection is left open with unread response")
-
-        assert await r.get("bar") == b"bar"
-        assert await r.ping()
-        assert await r.get("foo") == b"foo"
-
     async def test_max_connections(
         self, create_redis: Callable[..., RedisCluster]
     ) -> None:

tests/test_asyncio/test_connection.py

@@ -6,6 +6,7 @@
 import pytest
 
 import redis
+from redis.asyncio import Redis
 from redis.asyncio.connection import (
     BaseParser,
     Connection,
@@ -42,25 +43,47 @@ async def test_invalid_response(create_redis):
 
 
 @pytest.mark.onlynoncluster
-async def test_asynckills(create_redis):
-
-    for b in [True, False]:
-        r = await create_redis(single_connection_client=b)
-
-        await r.set("foo", "foo")
-        await r.set("bar", "bar")
-
-        t = asyncio.create_task(r.get("foo"))
-        await asyncio.sleep(1)
-        t.cancel()
-        try:
-            await t
-        except asyncio.CancelledError:
-            pytest.fail("connection left open with unread response")
-
-        assert await r.get("bar") == b"bar"
-        assert await r.ping()
-        assert await r.get("foo") == b"foo"
+async def test_single_connection():
+    """Test that concurrent requests on a single client are synchronised."""
+    r = Redis(single_connection_client=True)
+
+    init_call_count = 0
+    command_call_count = 0
+    in_use = False
+
+    class Retry_:
+        async def call_with_retry(self, _, __):
+            # If we remove the single-client lock, this error gets raised as two
+            # coroutines will be vying for the `in_use` flag due to the two
+            # asymmetric sleep calls
+            nonlocal command_call_count
+            nonlocal in_use
+            if in_use is True:
+                raise ValueError("Commands should be executed one at a time.")
+            in_use = True
+            await asyncio.sleep(0.01)
+            command_call_count += 1
+            await asyncio.sleep(0.03)
+            in_use = False
+            return "foo"
+
+    mock_conn = mock.MagicMock()
+    mock_conn.retry = Retry_()
+
+    async def get_conn(_):
+        # Validate only one client is created in single-client mode when
+        # concurrent requests are made
+        nonlocal init_call_count
+        await asyncio.sleep(0.01)
+        init_call_count += 1
+        return mock_conn
+
+    with mock.patch.object(r.connection_pool, "get_connection", get_conn):
+        with mock.patch.object(r.connection_pool, "release"):
+            await asyncio.gather(r.set("a", "b"), r.set("c", "d"))
+
+    assert init_call_count == 1
+    assert command_call_count == 2
 
 
 @skip_if_server_version_lt("4.0.0")