make the shared connection internal to the db module

This should make it easier to refactor the code for removing the
databases package.

tests/conftest.py

@@ -17,7 +17,7 @@ def event_loop():
 
 @pytest_asyncio.fixture(scope="session")
 async def shared_conn():
-    c = db.shared_connection()
+    c = db._shared_connection()
     await c.connect()
 
     await db.apply_db_patches(c)

unwind/db.py

@@ -31,7 +31,7 @@ from .types import ULID
 log = logging.getLogger(__name__)
 T = TypeVar("T")
 
-_shared_connection: Database | None = None
+_database: Database | None = None
 
 
 async def open_connection_pool() -> None:
@@ -39,7 +39,7 @@ async def open_connection_pool() -> None:
 
     This function needs to be called before any access to the database can happen.
     """
-    db = shared_connection()
+    db = _shared_connection()
     await db.connect()
 
     await db.execute(sa.text("PRAGMA journal_mode=WAL"))
@@ -53,7 +53,7 @@ async def close_connection_pool() -> None:
     This function should be called before the app shuts down to ensure all data
     has been flushed to the database.
     """
-    db = shared_connection()
+    db = _shared_connection()
 
     # Run automatic ANALYZE prior to closing the db,
     # see https://sqlite.com/lang_analyze.html.
@@ -205,23 +205,27 @@ async def single_threaded():
 
 
 @contextlib.asynccontextmanager
-async def locked_connection():
+async def _locked_connection():
     async with single_threaded():
-        yield shared_connection()
+        yield _shared_connection()
 
 
-def shared_connection() -> Database:
+def _shared_connection() -> Database:
-    global _shared_connection
+    global _database
 
-    if _shared_connection is None:
+    if _database is None:
         uri = f"sqlite:///{config.storage_path}"
         # uri = f"sqlite+aiosqlite:///{config.storage_path}"
-        _shared_connection = Database(uri)
+        _database = Database(uri)
 
         engine = sa.create_engine(uri, future=True)
         metadata.create_all(engine, tables=[db_patches])
 
-    return _shared_connection
+    return _database
+
+
+def transaction():
+    return _shared_connection().transaction()
 
 
 async def add(item: Model) -> None:
@@ -233,7 +237,7 @@ async def add(item: Model) -> None:
     table: sa.Table = item.__table__
     values = asplain(item, serialize=True)
     stmt = table.insert().values(values)
-    async with locked_connection() as conn:
+    async with _locked_connection() as conn:
         await conn.execute(stmt)
 
 
@@ -264,7 +268,7 @@ async def get(
         query = query.order_by(
             order_col.asc() if order_dir == "asc" else order_col.desc()
         )
-    async with locked_connection() as conn:
+    async with _locked_connection() as conn:
         row = await conn.fetch_one(query)
     return fromplain(model, row._mapping, serialized=True) if row else None
 
@@ -284,7 +288,7 @@ async def get_many(
 
     table: sa.Table = model.__table__
     query = sa.select(model).where(*(table.c[k].in_(v) for k, v in field_sets.items()))
-    async with locked_connection() as conn:
+    async with _locked_connection() as conn:
         rows = await conn.fetch_all(query)
     return (fromplain(model, row._mapping, serialized=True) for row in rows)
 
@@ -298,7 +302,7 @@ async def get_all(model: Type[ModelType], **field_values) -> Iterable[ModelType]
     query = sa.select(model).where(
         *(table.c[k] == v for k, v in field_values.items() if v is not None)
     )
-    async with locked_connection() as conn:
+    async with _locked_connection() as conn:
         rows = await conn.fetch_all(query)
     return (fromplain(model, row._mapping, serialized=True) for row in rows)
 
@@ -312,7 +316,7 @@ async def update(item: Model) -> None:
     table: sa.Table = item.__table__
     values = asplain(item, serialize=True)
     stmt = table.update().where(table.c.id == values["id"]).values(values)
-    async with locked_connection() as conn:
+    async with _locked_connection() as conn:
         await conn.execute(stmt)
 
 
@@ -320,7 +324,7 @@ async def remove(item: Model) -> None:
     table: sa.Table = item.__table__
     values = asplain(item, filter_fields={"id"}, serialize=True)
     stmt = table.delete().where(table.c.id == values["id"])
-    async with locked_connection() as conn:
+    async with _locked_connection() as conn:
         await conn.execute(stmt)
 
 
@@ -471,7 +475,7 @@ async def find_ratings(
         )
         .limit(limit_rows)
     )
-    async with locked_connection() as conn:
+    async with _locked_connection() as conn:
         rating_rows: AsyncGenerator[Rating, None] = conn.iterate(query)  # type: ignore
         movie_ids = [r.movie_id async for r in rating_rows]
 
@@ -487,7 +491,7 @@ async def find_ratings(
             )
             .limit(limit_rows - len(movie_ids))
         )
-        async with locked_connection() as conn:
+        async with _locked_connection() as conn:
             movie_rows: AsyncGenerator[Movie, None] = conn.iterate(query)  # type: ignore
             movie_ids += [r.id async for r in movie_rows]
 
@@ -523,7 +527,7 @@ async def ratings_for_movie_ids(
         .outerjoin_from(movies, ratings, movies.c.id == ratings.c.movie_id)
         .where(sa.or_(*conds))
     )
-    async with locked_connection() as conn:
+    async with _locked_connection() as conn:
         rows = await conn.fetch_all(query)
     return tuple(dict(r._mapping) for r in rows)
 
@@ -538,7 +542,7 @@ async def ratings_for_movies(
 
     query = sa.select(ratings).where(*conditions)
 
-    async with locked_connection() as conn:
+    async with _locked_connection() as conn:
         rows = await conn.fetch_all(query)
 
     return (fromplain(Rating, row._mapping, serialized=True) for row in rows)
@@ -602,7 +606,7 @@ async def find_movies(
         .offset(skip_rows)
     )
 
-    async with locked_connection() as conn:
+    async with _locked_connection() as conn:
         rows = await conn.fetch_all(query)
 
     movies_ = [fromplain(Movie, row._mapping, serialized=True) for row in rows]

unwind/web.py

@@ -445,7 +445,7 @@ async def remove_user(request):
     if not user:
         return not_found()
 
-    async with db.shared_connection().transaction():
+    async with db.transaction():
         # XXX remove user refs from groups and ratings
 
         await db.remove(user)