Extend RedisSettings to include redis Retry Helper settings (#387)

* extend RedisSettings retry settings

* fix type and settings test

* add redis.Retry type

* fix test to allow arbitrary types

* add testing for retry settings

* update tests

* granular patch handling

* update comment

* stop patch when exists

* update retry type to asyncio

* chore: test cleanup

* fix exception type

---------

Co-authored-by: Samuel Colvin <s@muelcolvin.com>

Author: mernmic

arq/connections.py

@@ -9,6 +9,7 @@
 from uuid import uuid4
 
 from redis.asyncio import ConnectionPool, Redis
+from redis.asyncio.retry import Retry
 from redis.asyncio.sentinel import Sentinel
 from redis.exceptions import RedisError, WatchError
 
@@ -47,6 +48,10 @@ class RedisSettings:
     sentinel: bool = False
     sentinel_master: str = 'mymaster'
 
+    retry_on_timeout: bool = False
+    retry_on_error: Optional[List[Exception]] = None
+    retry: Optional[Retry] = None
+
     @classmethod
     def from_dsn(cls, dsn: str) -> 'RedisSettings':
         conf = urlparse(dsn)
@@ -254,6 +259,9 @@ def pool_factory(*args: Any, **kwargs: Any) -> ArqRedis:
             ssl_ca_certs=settings.ssl_ca_certs,
             ssl_ca_data=settings.ssl_ca_data,
             ssl_check_hostname=settings.ssl_check_hostname,
+            retry=settings.retry,
+            retry_on_timeout=settings.retry_on_timeout,
+            retry_on_error=settings.retry_on_error,
         )
 
     while True:

tests/conftest.py

@@ -5,6 +5,9 @@
 
 import msgpack
 import pytest
+import redis.exceptions
+from redis.asyncio.retry import Retry
+from redis.backoff import NoBackoff
 
 from arq.connections import ArqRedis, create_pool
 from arq.worker import Worker
@@ -44,6 +47,21 @@ async def arq_redis_msgpack(loop):
     await redis_.close(close_connection_pool=True)
 
 
+@pytest.fixture
+async def arq_redis_retry(loop):
+    redis_ = ArqRedis(
+        host='localhost',
+        port=6379,
+        encoding='utf-8',
+        retry=Retry(backoff=NoBackoff(), retries=3),
+        retry_on_timeout=True,
+        retry_on_error=[redis.exceptions.ConnectionError],
+    )
+    await redis_.flushall()
+    yield redis_
+    await redis_.close(close_connection_pool=True)
+
+
 @pytest.fixture
 async def worker(arq_redis):
     worker_: Worker = None
@@ -61,6 +79,28 @@ def create(functions=[], burst=True, poll_delay=0, max_jobs=10, arq_redis=arq_re
         await worker_.close()
 
 
+@pytest.fixture
+async def worker_retry(arq_redis_retry):
+    worker_retry_: Worker = None
+
+    def create(functions=[], burst=True, poll_delay=0, max_jobs=10, arq_redis=arq_redis_retry, **kwargs):
+        nonlocal worker_retry_
+        worker_retry_ = Worker(
+            functions=functions,
+            redis_pool=arq_redis,
+            burst=burst,
+            poll_delay=poll_delay,
+            max_jobs=max_jobs,
+            **kwargs,
+        )
+        return worker_retry_
+
+    yield create
+
+    if worker_retry_:
+        await worker_retry_.close()
+
+
 @pytest.fixture(name='create_pool')
 async def fix_create_pool(loop):
     pools = []

tests/test_utils.py

@@ -21,7 +21,7 @@ def test_settings_changed():
         "RedisSettings(host='localhost', port=123, unix_socket_path=None, database=0, username=None, password=None, "
         "ssl=False, ssl_keyfile=None, ssl_certfile=None, ssl_cert_reqs='required', ssl_ca_certs=None, "
         'ssl_ca_data=None, ssl_check_hostname=False, conn_timeout=1, conn_retries=5, conn_retry_delay=1, '
-        "sentinel=False, sentinel_master='mymaster')"
+        "sentinel=False, sentinel_master='mymaster', retry_on_timeout=False, retry_on_error=None, retry=None)"
     ) == str(settings)
 
 
@@ -109,7 +109,7 @@ def test_typing():
 
 
 def test_redis_settings_validation():
-    class Settings(BaseModel):
+    class Settings(BaseModel, arbitrary_types_allowed=True):
         redis_settings: RedisSettings
 
         @field_validator('redis_settings', mode='before')

tests/test_worker.py

@@ -5,10 +5,11 @@
 import signal
 import sys
 from datetime import datetime, timedelta, timezone
-from unittest.mock import MagicMock
+from unittest.mock import MagicMock, patch
 
 import msgpack
 import pytest
+import redis.exceptions
 
 from arq.connections import ArqRedis, RedisSettings
 from arq.constants import abort_jobs_ss, default_queue_name, expires_extra_ms, health_check_key_suffix, job_key_prefix
@@ -1024,3 +1025,79 @@ async def test_worker_timezone_defaults_to_system_timezone(worker):
     worker = worker(functions=[func(foobar)])
     assert worker.timezone is not None
     assert worker.timezone == datetime.now().astimezone().tzinfo
+
+
+@pytest.mark.parametrize(
+    'exception_thrown',
+    [
+        redis.exceptions.ConnectionError('Error while reading from host'),
+        redis.exceptions.TimeoutError('Timeout reading from host'),
+    ],
+)
+async def test_worker_retry(mocker, worker_retry, exception_thrown):
+    # Testing redis exceptions, with retry settings specified
+    worker = worker_retry(functions=[func(foobar)])
+
+    # patch db read_response to mimic connection exceptions
+    p = patch.object(worker.pool.connection_pool.connection_class, 'read_response', side_effect=exception_thrown)
+
+    # baseline
+    await worker.main()
+    await worker._poll_iteration()
+
+    # spy method handling call_with_retry failure
+    spy = mocker.spy(worker.pool, '_disconnect_raise')
+
+    try:
+        # start patch
+        p.start()
+
+        # assert exception thrown
+        with pytest.raises(type(exception_thrown)):
+            await worker._poll_iteration()
+
+        # assert retry counts and no exception thrown during '_disconnect_raise'
+        assert spy.call_count == 4  # retries setting + 1
+        assert spy.spy_exception is None
+
+    finally:
+        # stop patch to allow worker cleanup
+        p.stop()
+
+
+@pytest.mark.parametrize(
+    'exception_thrown',
+    [
+        redis.exceptions.ConnectionError('Error while reading from host'),
+        redis.exceptions.TimeoutError('Timeout reading from host'),
+    ],
+)
+async def test_worker_crash(mocker, worker, exception_thrown):
+    # Testing redis exceptions, no retry settings specified
+    worker = worker(functions=[func(foobar)])
+
+    # patch db read_response to mimic connection exceptions
+    p = patch.object(worker.pool.connection_pool.connection_class, 'read_response', side_effect=exception_thrown)
+
+    # baseline
+    await worker.main()
+    await worker._poll_iteration()
+
+    # spy method handling call_with_retry failure
+    spy = mocker.spy(worker.pool, '_disconnect_raise')
+
+    try:
+        # start patch
+        p.start()
+
+        # assert exception thrown
+        with pytest.raises(type(exception_thrown)):
+            await worker._poll_iteration()
+
+        # assert no retry counts and exception thrown during '_disconnect_raise'
+        assert spy.call_count == 1
+        assert spy.spy_exception == exception_thrown
+
+    finally:
+        # stop patch to allow worker cleanup
+        p.stop()