Add Redis scan_keys iterator API.

Provide a SCAN-based key iterator for Redis adapters so callers can enumerate large keyspaces without relying on blocking KEYS lookups.

Co-authored-by: Cursor <[email protected]>

python_repositories/adapters/redis_adapter.py

@@ -1,6 +1,7 @@
 """Definition of RedisAdapter class."""
 
 from __future__ import annotations
+from collections.abc import Iterator
 from typing import cast
 
 from python_repositories.adapters.connection_aware_adapter import (
@@ -136,11 +137,13 @@ class RedisAdapter(JsonRepositoryInterface, ConnectionAwareAdapter):
         self._client.json().delete(key)
         self.logger.debug(f"Deleted {key}")
 
-    def list_keys(self, pattern: str) -> list[str]:
-        """List keys in Redis matching a pattern."""
-        # Check input
+    def _validate_pattern(self, pattern: str) -> None:
         if not isinstance(pattern, str) or len(pattern) == 0:
             raise ValueError("Pattern must be a non-empty string")
+
+    def list_keys(self, pattern: str) -> list[str]:
+        """List keys in Redis using KEYS; may block on large datasets."""
+        self._validate_pattern(pattern)
         # Check connection
         self._require_connected()
         assert self._client is not None
@@ -152,3 +155,29 @@ class RedisAdapter(JsonRepositoryInterface, ConnectionAwareAdapter):
         keys: list[str] = [key.decode(self.encoding) for key in keys_raw]
         self.logger.debug(f"Got {keys} matching {pattern}")
         return keys
+
+    def scan_keys(
+        self,
+        pattern: str,
+        *,
+        count: int | None = None,
+    ) -> Iterator[str]:
+        """Yield keys in Redis using SCAN to avoid blocking large datasets."""
+        self._validate_pattern(pattern)
+        self._require_connected()
+        assert self._client is not None
+        client = self._client
+
+        def _decode(key: bytes | str) -> str:
+            return key if isinstance(key, str) else key.decode(self.encoding)
+
+        def _iter() -> Iterator[str]:
+            scan_iter = (
+                client.scan_iter(match=pattern, count=count)
+                if count is not None
+                else client.scan_iter(match=pattern)
+            )
+            for key_raw in scan_iter:
+                yield _decode(key_raw)
+
+        return _iter()