Files
deer-flow/backend/packages/harness/deerflow/persistence/engine.py
T
rayhpeng 1ff6b5f7ab feat(persistence): add SQLAlchemy 2.0 async ORM scaffold
Introduce a unified database configuration (DatabaseConfig) that
controls both the LangGraph checkpointer and the DeerFlow application
persistence layer from a single `database:` config section.

New modules:
- deerflow.config.database_config — Pydantic config with memory/sqlite/postgres backends
- deerflow.persistence — async engine lifecycle, DeclarativeBase with to_dict mixin, Alembic skeleton
- deerflow.runtime.runs.store — RunStore ABC + MemoryRunStore implementation

Gateway integration initializes/tears down the persistence engine in
the existing langgraph_runtime() context manager. Legacy checkpointer
config is preserved for backward compatibility.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
2026-04-01 15:50:06 +08:00

117 lines
3.6 KiB
Python

"""Async SQLAlchemy engine lifecycle management.
Initializes at Gateway startup, provides session factory for
repositories, disposes at shutdown.
When database.backend="memory", init_engine is a no-op and
get_session_factory() returns None. Repositories must check for
None and fall back to in-memory implementations.
"""
from __future__ import annotations
import logging
from sqlalchemy.ext.asyncio import AsyncEngine, AsyncSession, async_sessionmaker, create_async_engine
logger = logging.getLogger(__name__)
_engine: AsyncEngine | None = None
_session_factory: async_sessionmaker[AsyncSession] | None = None
async def init_engine(
backend: str,
*,
url: str = "",
echo: bool = False,
pool_size: int = 5,
sqlite_dir: str = "",
) -> None:
"""Create the async engine and session factory, then auto-create tables.
Args:
backend: "memory", "sqlite", or "postgres".
url: SQLAlchemy async URL (for sqlite/postgres).
echo: Echo SQL to log.
pool_size: Postgres connection pool size.
sqlite_dir: Directory to create for SQLite (ensured to exist).
"""
global _engine, _session_factory
if backend == "memory":
logger.info("Persistence backend=memory -- ORM engine not initialized")
return
if backend == "postgres":
try:
import asyncpg # noqa: F401
except ImportError:
raise ImportError("database.backend is set to 'postgres' but asyncpg is not installed.\nInstall it with:\n uv sync --extra postgres\nOr switch to backend: sqlite in config.yaml for single-node deployment.") from None
if backend == "sqlite":
import os
os.makedirs(sqlite_dir or ".", exist_ok=True)
_engine = create_async_engine(url, echo=echo)
elif backend == "postgres":
_engine = create_async_engine(
url,
echo=echo,
pool_size=pool_size,
pool_pre_ping=True,
)
else:
raise ValueError(f"Unknown persistence backend: {backend!r}")
_session_factory = async_sessionmaker(_engine, expire_on_commit=False)
# Auto-create tables (dev convenience). Production should use Alembic.
from deerflow.persistence.base import Base
# Import all models so Base.metadata discovers them.
# When no models exist yet (scaffolding phase), this is a no-op.
try:
import deerflow.persistence.models # noqa: F401
except ImportError:
pass
async with _engine.begin() as conn:
await conn.run_sync(Base.metadata.create_all)
logger.info("Persistence engine initialized: backend=%s", backend)
async def init_engine_from_config(config) -> None:
"""Convenience: init engine from a DatabaseConfig object."""
if config.backend == "memory":
await init_engine("memory")
return
await init_engine(
backend=config.backend,
url=config.app_sqlalchemy_url,
echo=config.echo_sql,
pool_size=config.pool_size,
sqlite_dir=config.sqlite_dir if config.backend == "sqlite" else "",
)
def get_session_factory() -> async_sessionmaker[AsyncSession] | None:
"""Return the async session factory, or None if backend=memory."""
return _session_factory
def get_engine() -> AsyncEngine | None:
"""Return the async engine, or None if not initialized."""
return _engine
async def close_engine() -> None:
"""Dispose the engine, release all connections."""
global _engine, _session_factory
if _engine is not None:
await _engine.dispose()
logger.info("Persistence engine closed")
_engine = None
_session_factory = None