Add initial SQLmem package structure with SQL parser, cache manager, column registry, and tests

src/sqlmem/engine.py

@@ -0,0 +1,43 @@
+import sqlite3
+
+from loguru import logger
+from sqlalchemy.engine import Engine
+
+from .cache import CacheManager
+from .config import BACKUP_INTERVAL_SECONDS, CACHE_DB_PATH
+from .executor import QueryExecutor
+from .parser import parse
+from .registry import ColumnRegistry
+
+
+class CachingEngine:
+    """Transparent SQLAlchemy-compatible cache layer."""
+
+    def __init__(self, source_engine: Engine) -> None:
+        self._source_engine = source_engine
+        self._cache = CacheManager(CACHE_DB_PATH, BACKUP_INTERVAL_SECONDS)
+        self._registry = ColumnRegistry(self._cache.connection)
+        logger.info("CachingEngine initialized.")
+
+    def execute(self, sql: str) -> list[dict]:
+        parsed = parse(sql)
+        with self._source_engine.connect() as sa_conn:
+            raw_conn: sqlite3.Connection = sa_conn.connection.dbapi_connection
+            executor = QueryExecutor(self._cache, self._registry, raw_conn)
+            return executor.execute(parsed)
+
+    def invalidate(self, table: str) -> None:
+        logger.info(f"Manually invalidating cache for table {table!r}")
+        with self._cache._lock:
+            self._cache.connection.execute(f"DROP TABLE IF EXISTS {table}")
+            self._cache.connection.execute(
+                "DELETE FROM _sqlmem_tables WHERE table_name = ?", (table,)
+            )
+            self._cache.connection.execute(
+                "DELETE FROM _sqlmem_columns WHERE table_name = ?", (table,)
+            )
+            self._cache.connection.commit()
+
+    def close(self) -> None:
+        self._cache.close()
+        logger.info("CachingEngine closed.")