feat: Implemented redis.asyncio.SentinelBlockingConnectionPool.

.github/wordlist.txt

@@ -44,6 +44,7 @@ RedisJSON
 RedisTimeSeries
 SHA
 SearchCommands
+SentinelBlockingConnectionPool
 SentinelCommands
 SentinelConnectionPool
 Sharded

CHANGES

@@ -1,3 +1,5 @@
+    * Add redis.asyncio.SentinelBlockingConnectionPool
+    * Use SentinelConnectionPoolProxy in asyncio.sentinel module
     * Move doctests (doc code examples) to main branch
     * Update `ResponseT` type hint
     * Allow to control the minimum SSL version

docs/connections.rst

@@ -63,6 +63,24 @@ This client is used for communicating with Redis, asynchronously.
     :members:
 
 
+Async Sentinel Client
+*********************
+
+Sentinel (Async)
+================
+.. autoclass:: redis.asyncio.sentinel.Sentinel
+    :members:
+
+SentinelConnectionPool (Async)
+==============================
+.. autoclass:: redis.asyncio.sentinel.SentinelConnectionPool
+    :members:
+
+SentinelBlockingConnectionPool (Async)
+======================================
+.. autoclass:: redis.asyncio.sentinel.SentinelBlockingConnectionPool
+    :members:
+
 Async Cluster Client
 ********************
 

docs/examples/asyncio_examples.ipynb

@@ -328,6 +328,29 @@
     "assert val == b\"value\""
    ]
   },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "import asyncio\n",
+    "\n",
+    "from redis.asyncio.sentinel import Sentinel, SentinelBlockingConnectionPool\n",
+    "\n",
+    "\n",
+    "sentinel = Sentinel([(\"localhost\", 26379), (\"sentinel2\", 26379)])\n",
+    "r = sentinel.master_for(\n",
+    "    \"mymaster\",\n",
+    "    connection_pool_class=SentinelBlockingConnectionPool,\n",
+    "    max_connections=5,  # Max connections in pool\n",
+    "    timeout=3,  # Connection acquiring timeout in seconds. To turn off the timeout, set None\n",
+    ")\n",
+    "\n",
+    "# This code doesn't raise a MaxConectionsError exception\n",
+    "await asyncio.gather(*[r.get(\"key\") for _ in range(10)])"
+   ]
+  },
   {
    "cell_type": "markdown",
    "metadata": {},

redis/asyncio/__init__.py

@@ -9,6 +9,7 @@
 )
 from redis.asyncio.sentinel import (
     Sentinel,
+    SentinelBlockingConnectionPool,
     SentinelConnectionPool,
     SentinelManagedConnection,
     SentinelManagedSSLConnection,
@@ -53,6 +54,7 @@
     "RedisError",
     "ResponseError",
     "Sentinel",
+    "SentinelBlockingConnectionPool",
     "SentinelConnectionPool",
     "SentinelManagedConnection",
     "SentinelManagedSSLConnection",

redis/asyncio/sentinel.py

@@ -1,10 +1,20 @@
 import asyncio
 import random
 import weakref
-from typing import AsyncIterator, Iterable, Mapping, Optional, Sequence, Tuple, Type
+from typing import (
+    AsyncIterator,
+    Iterable,
+    Mapping,
+    Optional,
+    Sequence,
+    Tuple,
+    Type,
+    Union,
+)
 
 from redis.asyncio.client import Redis
 from redis.asyncio.connection import (
+    BlockingConnectionPool,
     Connection,
     ConnectionPool,
     EncodableT,
@@ -97,6 +107,55 @@ class SentinelManagedSSLConnection(SentinelManagedConnection, SSLConnection):
     pass
 
 
+class SentinelConnectionPoolProxy:
+    def __init__(
+        self,
+        connection_pool,
+        is_master,
+        check_connection,
+        service_name,
+        sentinel_manager,
+    ):
+        self.connection_pool_ref = weakref.ref(connection_pool)
+        self.is_master = is_master
+        self.check_connection = check_connection
+        self.service_name = service_name
+        self.sentinel_manager = sentinel_manager
+        self.reset()
+
+    def reset(self):
+        self.master_address = None
+        self.slave_rr_counter = None
+
+    async def get_master_address(self):
+        master_address = await self.sentinel_manager.discover_master(self.service_name)
+        if self.is_master and self.master_address != master_address:
+            self.master_address = master_address
+            # disconnect any idle connections so that they reconnect
+            # to the new master the next time that they are used.
+            connection_pool = self.connection_pool_ref()
+            if connection_pool is not None:
+                await connection_pool.disconnect(inuse_connections=False)
+        return master_address
+
+    async def rotate_slaves(self) -> AsyncIterator:
+        """Round-robin slave balancer"""
+        slaves = await self.sentinel_manager.discover_slaves(self.service_name)
+        if slaves:
+            if self.slave_rr_counter is None:
+                self.slave_rr_counter = random.randint(0, len(slaves) - 1)
+            for _ in range(len(slaves)):
+                self.slave_rr_counter = (self.slave_rr_counter + 1) % len(slaves)
+                slave = slaves[self.slave_rr_counter]
+                yield slave
+        # Fallback to the master connection
+        try:
+            yield await self.get_master_address()
+        except MasterNotFoundError:
+            pass
+        raise SlaveNotFoundError(f"No slave found for {self.service_name!r}")
+
+
 class SentinelConnectionPool(ConnectionPool):
     """
     Sentinel backed connection pool.
@@ -116,12 +175,17 @@ def __init__(self, service_name, sentinel_manager, **kwargs):
         )
         self.is_master = kwargs.pop("is_master", True)
         self.check_connection = kwargs.pop("check_connection", False)
+        self.proxy = SentinelConnectionPoolProxy(
+            connection_pool=self,
+            is_master=self.is_master,
+            check_connection=self.check_connection,
+            service_name=service_name,
+            sentinel_manager=sentinel_manager,
+        )
         super().__init__(**kwargs)
-        self.connection_kwargs["connection_pool"] = weakref.proxy(self)
+        self.connection_kwargs["connection_pool"] = self.proxy
         self.service_name = service_name
         self.sentinel_manager = sentinel_manager
-        self.master_address = None
-        self.slave_rr_counter = None
 
     def __repr__(self):
         return (
@@ -131,8 +195,11 @@ def __repr__(self):
 
     def reset(self):
         super().reset()
-        self.master_address = None
-        self.slave_rr_counter = None
+        self.proxy.reset()
+
+    @property
+    def master_address(self):
+        return self.proxy.master_address
 
     def owns_connection(self, connection: Connection):
         check = not self.is_master or (
@@ -141,31 +208,70 @@ def owns_connection(self, connection: Connection):
         return check and super().owns_connection(connection)
 
     async def get_master_address(self):
-        master_address = await self.sentinel_manager.discover_master(self.service_name)
-        if self.is_master:
-            if self.master_address != master_address:
-                self.master_address = master_address
-                # disconnect any idle connections so that they reconnect
-                # to the new master the next time that they are used.
-                await self.disconnect(inuse_connections=False)
-        return master_address
+        return await self.proxy.get_master_address()
 
-    async def rotate_slaves(self) -> AsyncIterator:
+    def rotate_slaves(self) -> AsyncIterator:
         """Round-robin slave balancer"""
-        slaves = await self.sentinel_manager.discover_slaves(self.service_name)
-        if slaves:
-            if self.slave_rr_counter is None:
-                self.slave_rr_counter = random.randint(0, len(slaves) - 1)
-            for _ in range(len(slaves)):
-                self.slave_rr_counter = (self.slave_rr_counter + 1) % len(slaves)
-                slave = slaves[self.slave_rr_counter]
-                yield slave
-        # Fallback to the master connection
-        try:
-            yield await self.get_master_address()
-        except MasterNotFoundError:
-            pass
-        raise SlaveNotFoundError(f"No slave found for {self.service_name!r}")
+        return self.proxy.rotate_slaves()
+
+
+class SentinelBlockingConnectionPool(BlockingConnectionPool):
+    """
+    Sentinel blocking connection pool.
+
+    If ``check_connection`` flag is set to True, SentinelManagedConnection
+    sends a PING command right after establishing the connection.
+    """
+
+    def __init__(self, service_name, sentinel_manager, **kwargs):
+        kwargs["connection_class"] = kwargs.get(
+            "connection_class",
+            (
+                SentinelManagedSSLConnection
+                if kwargs.pop("ssl", False)
+                else SentinelManagedConnection
+            ),
+        )
+        self.is_master = kwargs.pop("is_master", True)
+        self.check_connection = kwargs.pop("check_connection", False)
+        self.proxy = SentinelConnectionPoolProxy(
+            connection_pool=self,
+            is_master=self.is_master,
+            check_connection=self.check_connection,
+            service_name=service_name,
+            sentinel_manager=sentinel_manager,
+        )
+        super().__init__(**kwargs)
+        self.connection_kwargs["connection_pool"] = self.proxy
+        self.service_name = service_name
+        self.sentinel_manager = sentinel_manager
+
+    def __repr__(self):
+        return (
+            f"<{self.__class__.__module__}.{self.__class__.__name__}"
+            f"(service={self.service_name}({self.is_master and 'master' or 'slave'}))>"
+        )
+
+    def reset(self):
+        super().reset()
+        self.proxy.reset()
+
+    @property
+    def master_address(self):
+        return self.proxy.master_address
+
+    def owns_connection(self, connection: Connection):
+        check = not self.is_master or (
+            self.is_master and self.master_address == (connection.host, connection.port)
+        )
+        return check and super().owns_connection(connection)
+
+    async def get_master_address(self):
+        return await self.proxy.get_master_address()
+
+    def rotate_slaves(self) -> AsyncIterator:
+        """Round-robin slave balancer"""
+        return self.proxy.rotate_slaves()
 
 
 class Sentinel(AsyncSentinelCommands):
@@ -318,7 +424,10 @@ def master_for(
         self,
         service_name: str,
         redis_class: Type[Redis] = Redis,
-        connection_pool_class: Type[SentinelConnectionPool] = SentinelConnectionPool,
+        connection_pool_class: Union[
+            Type[SentinelConnectionPool],
+            Type[SentinelBlockingConnectionPool],
+        ] = SentinelConnectionPool,
         **kwargs,
     ):
         """
@@ -355,7 +464,10 @@ def slave_for(
         self,
         service_name: str,
         redis_class: Type[Redis] = Redis,
-        connection_pool_class: Type[SentinelConnectionPool] = SentinelConnectionPool,
+        connection_pool_class: Union[
+            Type[SentinelConnectionPool],
+            Type[SentinelBlockingConnectionPool],
+        ] = SentinelConnectionPool,
         **kwargs,
     ):
         """