Merge pull request '[patch] Align Redis and MinIO connect() idempotency' (#37) from cursor/connect-idempotency-alignment into main

Reviewed-on: brian/python-repositories#37

README.md

@@ -12,7 +12,7 @@ Subclass an adapter in your own repository to add domain-specific methods while
 | **Adapters**     | Technology-specific base classes (`RedisAdapter`, `MinioAdapter`) |
 | **Your project** | Subclass an adapter and add domain methods                        |
 
-Connection adapters expose `connect()`, `disconnect()`, and `is_connected()`. The latter verifies backend reachability with a cached health probe (default TTL: 1 second). Subclasses may override `health_check_ttl_seconds`.
+Connection adapters expose `connect()`, `disconnect()`, and `is_connected()`. The latter verifies backend reachability with a cached health probe (default TTL: 1 second). Subclasses may override `health_check_ttl_seconds`. `connect()` is idempotent: calling it while already connected and healthy is a no-op.
 
 ## Optional dependencies
 

python_repositories/adapters/connection_aware_adapter.py

@@ -22,6 +22,7 @@ class ConnectionAwareAdapter(ConnectionAwareInterface, ContextAwareInterface):
 
     def __init__(self) -> None:
         self.logger = structlog.get_logger(self.__class__.__name__)
+        self._client_injected = False
         self._health_check_at: float | None = None
         self._health_check_ok: bool = False
 
@@ -57,6 +58,27 @@ class ConnectionAwareAdapter(ConnectionAwareInterface, ContextAwareInterface):
     def _probe_connection(self) -> bool:
         """Backend-specific liveness check; called only when client is ready."""
 
+    @abstractmethod
+    def _validate_injected_client(self) -> None:
+        """Verify an injected client is reachable; raise ConnectionError on failure."""
+
+    @abstractmethod
+    def _establish_connection(self) -> None:
+        """Create a backend client and set internal connection state."""
+
+    def connect(self) -> None:
+        """Connect to the backend; idempotent when already connected and healthy."""
+        if self._client_injected:
+            self._validate_injected_client()
+            self._invalidate_health_cache()
+            return
+        if self._is_client_ready() and self.is_connected():
+            self.logger.info(f"Already connected to {self.connection_name}")
+            return
+        self.disconnect()
+        self._establish_connection()
+        self._invalidate_health_cache()
+
     def is_connected(self) -> bool:
         """Check if connected to the backend."""
         if not self._is_client_ready():

python_repositories/adapters/minio_adapter.py

@@ -58,23 +58,17 @@ class MinioAdapter(ObjectRepositoryInterface, ConnectionAwareAdapter):
     def _is_client_ready(self) -> bool:
         return self._client is not None and self._bucket_name is not None
 
-    def connect(self) -> None:
-        """Connect to the Minio server."""
-        if self._client_injected:
-            if self._client is not None:
+    def _validate_injected_client(self) -> None:
+        if self._client is None:
+            return
         try:
             _ = self._client.list_buckets()
         except Exception as exc:  # pylint: disable=broad-except
             raise ConnectionError(
                 f"Could not connect to Minio at {self._config.endpoint}"
             ) from exc
-            self._invalidate_health_cache()
-            return
-        if self._client is not None and self.is_connected():
-            self.logger.info("Already connected to Minio")
-            return
-        if self._client is not None:
-            self.disconnect()
+
+    def _establish_connection(self) -> None:
         endpoint = self._config.endpoint
         access_key = self._config.access_key
         secret_key = self._config.secret_key
@@ -98,7 +92,6 @@ class MinioAdapter(ObjectRepositoryInterface, ConnectionAwareAdapter):
             client.make_bucket(bucket)
         self._client = client
         self._bucket_name = bucket
-        self._invalidate_health_cache()
 
     def disconnect(self) -> None:
         """Disconnect from the Minio server."""

python_repositories/adapters/redis_adapter.py

@@ -49,10 +49,9 @@ class RedisAdapter(JsonRepositoryInterface, ConnectionAwareAdapter):
     def _is_client_ready(self) -> bool:
         return self._client is not None
 
-    def connect(self) -> None:
-        """Connect to the Redis server."""
-        if self._client_injected:
-            if self._client is not None:
+    def _validate_injected_client(self) -> None:
+        if self._client is None:
+            return
         try:
             if not self._client.ping():
                 raise ConnectionError(
@@ -62,12 +61,8 @@ class RedisAdapter(JsonRepositoryInterface, ConnectionAwareAdapter):
             raise ConnectionError(
                 f"Could not connect to Redis at {self._config.uri}"
             ) from exc
-            self._invalidate_health_cache()
-            return
-        if self._client is not None:
-            self._client.close()
-            self._client = None
-            self._invalidate_health_cache()
+
+    def _establish_connection(self) -> None:
         uri = self._config.uri
         try:
             client = redis.Redis.from_url(
@@ -79,7 +74,6 @@ class RedisAdapter(JsonRepositoryInterface, ConnectionAwareAdapter):
         except (redis.ConnectionError, redis.TimeoutError) as exc:
             raise ConnectionError(f"Could not connect to Redis at {uri}") from exc
         self._client = client
-        self._invalidate_health_cache()
 
     def disconnect(self) -> None:
         """Disconnect from the Redis server."""

python_repositories/interfaces/connection_aware_interface.py

@@ -8,7 +8,11 @@ class ConnectionAwareInterface(ABC):
 
     @abstractmethod
     def connect(self) -> None:
-        """Connect to resource."""
+        """Connect to resource.
+
+        Implementations should be idempotent: calling connect while already
+        connected and healthy is a no-op.
+        """
         ...
 
     @abstractmethod

tests/integration/redis_adapter_test.py

@@ -1,6 +1,7 @@
 """Integration tests for the RedisAdapter."""
 
 from collections.abc import Generator
+import logging
 
 import pytest
 import redis
@@ -48,6 +49,16 @@ def clear_redis(raw_redis_client: redis.Redis) -> None:
     raw_redis_client.flushall()
 
 
+def test_should_log_info_when_already_connected(
+    redis_adapter: RedisAdapter,
+    caplog: pytest.LogCaptureFixture,
+) -> None:
+    """Test that the RedisAdapter logs info when connect is called while already connected."""
+    with caplog.at_level(logging.INFO):
+        redis_adapter.connect()
+    assert "Already connected to Redis" in caplog.text
+
+
 def test_should_raise_connection_error_when_unable_to_connect() -> None:
     """Test that the RedisAdapter raises ConnectionError when unable to connect."""
     adapter = RedisAdapter(config=RedisConfig(uri="redis://invalid:6379"))

tests/unit/minio_adapter_test.py

@@ -75,6 +75,16 @@ def test_connect_with_injected_client_raises_on_failure() -> None:
         adapter.connect()
 
 
+def test_connect_with_injected_client_skips_validation_when_client_cleared() -> None:
+    mock_client = MagicMock(spec=Minio)
+    adapter = MinioAdapter(config=TEST_MINIO_CONFIG, client=mock_client)
+    adapter.disconnect()
+
+    adapter.connect()
+
+    mock_client.list_buckets.assert_not_called()
+
+
 def test_connect_disconnects_before_reconnect(
     monkeypatch: pytest.MonkeyPatch,
 ) -> None:
@@ -95,6 +105,27 @@ def test_connect_disconnects_before_reconnect(
     new_client.list_buckets.assert_called_once()
 
 
+def test_connect_skips_reconnect_when_already_connected(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    stale_client = MagicMock(spec=Minio)
+    stale_client.bucket_exists.return_value = True
+    adapter = MinioAdapter(config=TEST_MINIO_CONFIG)
+    adapter._client = stale_client
+    adapter._bucket_name = TEST_MINIO_CONFIG.bucket
+
+    minio_ctor = MagicMock()
+    monkeypatch.setattr(
+        "python_repositories.adapters.minio_adapter.minio.Minio",
+        minio_ctor,
+    )
+
+    adapter.connect()
+
+    minio_ctor.assert_not_called()
+    assert adapter._client is stale_client
+
+
 def test_connect_raises_when_bucket_missing(
     monkeypatch: pytest.MonkeyPatch,
 ) -> None:

tests/unit/redis_adapter_test.py

@@ -99,10 +99,21 @@ def test_connect_with_injected_client_raises_on_redis_error() -> None:
         adapter.connect()
 
 
-def test_connect_closes_existing_non_injected_client(
+def test_connect_with_injected_client_skips_validation_when_client_cleared() -> None:
+    mock_client = MagicMock(spec=redis.Redis)
+    adapter = RedisAdapter(config=TEST_REDIS_CONFIG, client=mock_client)
+    adapter.disconnect()
+
+    adapter.connect()
+
+    mock_client.ping.assert_not_called()
+
+
+def test_connect_reconnects_when_existing_client_unhealthy(
     monkeypatch: pytest.MonkeyPatch,
 ) -> None:
     stale_client = MagicMock(spec=redis.Redis)
+    stale_client.ping.side_effect = redis.ConnectionError("connection lost")
     new_client = MagicMock(spec=redis.Redis)
     new_client.ping.return_value = True
     adapter = RedisAdapter(config=TEST_REDIS_CONFIG)
@@ -116,6 +127,24 @@ def test_connect_closes_existing_non_injected_client(
     assert adapter._client is new_client
 
 
+def test_connect_skips_reconnect_when_already_connected(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    stale_client = MagicMock(spec=redis.Redis)
+    stale_client.ping.return_value = True
+    adapter = RedisAdapter(config=TEST_REDIS_CONFIG)
+    adapter._client = stale_client
+
+    from_url = MagicMock()
+    monkeypatch.setattr("redis.Redis.from_url", from_url)
+
+    adapter.connect()
+
+    stale_client.close.assert_not_called()
+    from_url.assert_not_called()
+    assert adapter._client is stale_client
+
+
 def test_scan_keys_yields_decoded_keys() -> None:
     mock_client = MagicMock(spec=redis.Redis)
     mock_client.scan_iter.return_value = iter([b"key1", b"key2"])