Add some type annotations in synapse.storage (matrix-org#6987)

I cracked, and added some type definitions in synapse.storage.

changelog.d/6987.misc

@@ -0,0 +1 @@
+Add some type annotations to the database storage classes.

synapse/storage/database.py

@@ -15,9 +15,9 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 import logging
-import sys
 import time
-from typing import Iterable, Tuple
+from time import monotonic as monotonic_time
+from typing import Any, Callable, Dict, Iterable, Iterator, List, Optional, Tuple
 
 from six import iteritems, iterkeys, itervalues
 from six.moves import intern, range
@@ -32,24 +32,14 @@
 from synapse.logging.context import LoggingContext, make_deferred_yieldable
 from synapse.metrics.background_process_metrics import run_as_background_process
 from synapse.storage.background_updates import BackgroundUpdater
-from synapse.storage.engines import PostgresEngine, Sqlite3Engine
+from synapse.storage.engines import BaseDatabaseEngine, PostgresEngine, Sqlite3Engine
+from synapse.storage.types import Connection, Cursor
 from synapse.util.stringutils import exception_to_unicode
 
-# import a function which will return a monotonic time, in seconds
-try:
-    # on python 3, use time.monotonic, since time.clock can go backwards
-    from time import monotonic as monotonic_time
-except ImportError:
-    # ... but python 2 doesn't have it
-    from time import clock as monotonic_time
-
 logger = logging.getLogger(__name__)
 
-try:
-    MAX_TXN_ID = sys.maxint - 1
-except AttributeError:
-    # python 3 does not have a maximum int value
-    MAX_TXN_ID = 2 ** 63 - 1
+# python 3 does not have a maximum int value
+MAX_TXN_ID = 2 ** 63 - 1
 
 sql_logger = logging.getLogger("synapse.storage.SQL")
 transaction_logger = logging.getLogger("synapse.storage.txn")
@@ -77,7 +67,7 @@
 
 
 def make_pool(
-    reactor, db_config: DatabaseConnectionConfig, engine
+    reactor, db_config: DatabaseConnectionConfig, engine: BaseDatabaseEngine
 ) -> adbapi.ConnectionPool:
     """Get the connection pool for the database.
     """
@@ -90,7 +80,9 @@ def make_pool(
     )
 
 
-def make_conn(db_config: DatabaseConnectionConfig, engine):
+def make_conn(
+    db_config: DatabaseConnectionConfig, engine: BaseDatabaseEngine
+) -> Connection:
     """Make a new connection to the database and return it.
 
     Returns:
@@ -107,20 +99,27 @@ def make_conn(db_config: DatabaseConnectionConfig, engine):
     return db_conn
 
 
-class LoggingTransaction(object):
+# The type of entry which goes on our after_callbacks and exception_callbacks lists.
+#
+# Python 3.5.2 doesn't support Callable with an ellipsis, so we wrap it in quotes so
+# that mypy sees the type but the runtime python doesn't.
+_CallbackListEntry = Tuple["Callable[..., None]", Iterable[Any], Dict[str, Any]]
+
+
+class LoggingTransaction:
     """An object that almost-transparently proxies for the 'txn' object
     passed to the constructor. Adds logging and metrics to the .execute()
     method.
 
     Args:
         txn: The database transcation object to wrap.
-        name (str): The name of this transactions for logging.
-        database_engine (Sqlite3Engine|PostgresEngine)
-        after_callbacks(list|None): A list that callbacks will be appended to
+        name: The name of this transactions for logging.
+        database_engine
+        after_callbacks: A list that callbacks will be appended to
             that have been added by `call_after` which should be run on
             successful completion of the transaction. None indicates that no
             callbacks should be allowed to be scheduled to run.
-        exception_callbacks(list|None): A list that callbacks will be appended
+        exception_callbacks: A list that callbacks will be appended
             to that have been added by `call_on_exception` which should be run
             if transaction ends with an error. None indicates that no callbacks
             should be allowed to be scheduled to run.
@@ -135,46 +134,67 @@ class LoggingTransaction(object):
     ]
 
     def __init__(
-        self, txn, name, database_engine, after_callbacks=None, exception_callbacks=None
+        self,
+        txn: Cursor,
+        name: str,
+        database_engine: BaseDatabaseEngine,
+        after_callbacks: Optional[List[_CallbackListEntry]] = None,
+        exception_callbacks: Optional[List[_CallbackListEntry]] = None,
     ):
-        object.__setattr__(self, "txn", txn)
-        object.__setattr__(self, "name", name)
-        object.__setattr__(self, "database_engine", database_engine)
-        object.__setattr__(self, "after_callbacks", after_callbacks)
-        object.__setattr__(self, "exception_callbacks", exception_callbacks)
+        self.txn = txn
+        self.name = name
+        self.database_engine = database_engine
+        self.after_callbacks = after_callbacks
+        self.exception_callbacks = exception_callbacks
 
-    def call_after(self, callback, *args, **kwargs):
+    def call_after(self, callback: "Callable[..., None]", *args, **kwargs):
         """Call the given callback on the main twisted thread after the
         transaction has finished. Used to invalidate the caches on the
         correct thread.
         """
+        # if self.after_callbacks is None, that means that whatever constructed the
+        # LoggingTransaction isn't expecting there to be any callbacks; assert that
+        # is not the case.
+        assert self.after_callbacks is not None
         self.after_callbacks.append((callback, args, kwargs))
 
-    def call_on_exception(self, callback, *args, **kwargs):
+    def call_on_exception(self, callback: "Callable[..., None]", *args, **kwargs):
+        # if self.exception_callbacks is None, that means that whatever constructed the
+        # LoggingTransaction isn't expecting there to be any callbacks; assert that
+        # is not the case.
+        assert self.exception_callbacks is not None
         self.exception_callbacks.append((callback, args, kwargs))
 
-    def __getattr__(self, name):
-        return getattr(self.txn, name)
+    def fetchall(self) -> List[Tuple]:
+        return self.txn.fetchall()
 
-    def __setattr__(self, name, value):
-        setattr(self.txn, name, value)
+    def fetchone(self) -> Tuple:
+        return self.txn.fetchone()
 
-    def __iter__(self):
+    def __iter__(self) -> Iterator[Tuple]:
         return self.txn.__iter__()
 
+    @property
+    def rowcount(self) -> int:
+        return self.txn.rowcount
+
+    @property
+    def description(self) -> Any:
+        return self.txn.description
+
     def execute_batch(self, sql, args):
         if isinstance(self.database_engine, PostgresEngine):
-            from psycopg2.extras import execute_batch
+            from psycopg2.extras import execute_batch  # type: ignore
 
             self._do_execute(lambda *x: execute_batch(self.txn, *x), sql, args)
         else:
             for val in args:
                 self.execute(sql, val)
 
-    def execute(self, sql, *args):
+    def execute(self, sql: str, *args: Any):
         self._do_execute(self.txn.execute, sql, *args)
 
-    def executemany(self, sql, *args):
+    def executemany(self, sql: str, *args: Any):
         self._do_execute(self.txn.executemany, sql, *args)
 
     def _make_sql_one_line(self, sql):
@@ -207,6 +227,9 @@ def _do_execute(self, func, sql, *args):
             sql_logger.debug("[SQL time] {%s} %f sec", self.name, secs)
             sql_query_timer.labels(sql.split()[0]).observe(secs)
 
+    def close(self):
+        self.txn.close()
+
 
 class PerformanceCounters(object):
     def __init__(self):
@@ -251,17 +274,19 @@ class Database(object):
 
     _TXN_ID = 0
 
-    def __init__(self, hs, database_config: DatabaseConnectionConfig, engine):
+    def __init__(
+        self, hs, database_config: DatabaseConnectionConfig, engine: BaseDatabaseEngine
+    ):
         self.hs = hs
         self._clock = hs.get_clock()
         self._database_config = database_config
         self._db_pool = make_pool(hs.get_reactor(), database_config, engine)
 
         self.updates = BackgroundUpdater(hs, self)
 
-        self._previous_txn_total_time = 0
-        self._current_txn_total_time = 0
-        self._previous_loop_ts = 0
+        self._previous_txn_total_time = 0.0
+        self._current_txn_total_time = 0.0
+        self._previous_loop_ts = 0.0
 
         # TODO(paul): These can eventually be removed once the metrics code
         #   is running in mainline, and we have some nice monitoring frontends
@@ -463,23 +488,23 @@ def new_transaction(
             sql_txn_timer.labels(desc).observe(duration)
 
     @defer.inlineCallbacks
-    def runInteraction(self, desc, func, *args, **kwargs):
+    def runInteraction(self, desc: str, func: Callable, *args: Any, **kwargs: Any):
         """Starts a transaction on the database and runs a given function
 
         Arguments:
-            desc (str): description of the transaction, for logging and metrics
-            func (func): callback function, which will be called with a
+            desc: description of the transaction, for logging and metrics
+            func: callback function, which will be called with a
                 database transaction (twisted.enterprise.adbapi.Transaction) as
                 its first argument, followed by `args` and `kwargs`.
 
-            args (list): positional args to pass to `func`
-            kwargs (dict): named args to pass to `func`
+            args: positional args to pass to `func`
+            kwargs: named args to pass to `func`
 
         Returns:
             Deferred: The result of func
         """
-        after_callbacks = []
-        exception_callbacks = []
+        after_callbacks = []  # type: List[_CallbackListEntry]
+        exception_callbacks = []  # type: List[_CallbackListEntry]
 
         if LoggingContext.current_context() == LoggingContext.sentinel:
             logger.warning("Starting db txn '%s' from sentinel context", desc)
@@ -505,15 +530,15 @@ def runInteraction(self, desc, func, *args, **kwargs):
         return result
 
     @defer.inlineCallbacks
-    def runWithConnection(self, func, *args, **kwargs):
+    def runWithConnection(self, func: Callable, *args: Any, **kwargs: Any):
         """Wraps the .runWithConnection() method on the underlying db_pool.
 
         Arguments:
-            func (func): callback function, which will be called with a
+            func: callback function, which will be called with a
                 database connection (twisted.enterprise.adbapi.Connection) as
                 its first argument, followed by `args` and `kwargs`.
-            args (list): positional args to pass to `func`
-            kwargs (dict): named args to pass to `func`
+            args: positional args to pass to `func`
+            kwargs: named args to pass to `func`
 
         Returns:
             Deferred: The result of func
@@ -800,7 +825,7 @@ def _getwhere(key):
                 return False
 
         # We didn't find any existing rows, so insert a new one
-        allvalues = {}
+        allvalues = {}  # type: Dict[str, Any]
         allvalues.update(keyvalues)
         allvalues.update(values)
         allvalues.update(insertion_values)
@@ -829,7 +854,7 @@ def simple_upsert_txn_native_upsert(
         Returns:
             None
         """
-        allvalues = {}
+        allvalues = {}  # type: Dict[str, Any]
         allvalues.update(keyvalues)
         allvalues.update(insertion_values)
 
@@ -916,7 +941,7 @@ def simple_upsert_many_txn_native_upsert(
         Returns:
             None
         """
-        allnames = []
+        allnames = []  # type: List[str]
         allnames.extend(key_names)
         allnames.extend(value_names)
 
@@ -1100,7 +1125,7 @@ def simple_select_many_batch(
             keyvalues : dict of column names and values to select the rows with
             retcols : list of strings giving the names of the columns to return
         """
-        results = []
+        results = []  # type: List[Dict[str, Any]]
 
         if not iterable:
             return results
@@ -1439,7 +1464,7 @@ def simple_select_list_paginate_txn(
             raise ValueError("order_direction must be one of 'ASC' or 'DESC'.")
 
         where_clause = "WHERE " if filters or keyvalues else ""
-        arg_list = []
+        arg_list = []  # type: List[Any]
         if filters:
             where_clause += " AND ".join("%s LIKE ?" % (k,) for k in filters)
             arg_list += list(filters.values())

synapse/storage/engines/__init__.py

@@ -12,29 +12,31 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-
-import importlib
 import platform
 
-from ._base import IncorrectDatabaseSetup
+from ._base import BaseDatabaseEngine, IncorrectDatabaseSetup
 from .postgres import PostgresEngine
 from .sqlite import Sqlite3Engine
 
-SUPPORTED_MODULE = {"sqlite3": Sqlite3Engine, "psycopg2": PostgresEngine}
-
 
-def create_engine(database_config):
+def create_engine(database_config) -> BaseDatabaseEngine:
     name = database_config["name"]
-    engine_class = SUPPORTED_MODULE.get(name, None)
 
-    if engine_class:
+    if name == "sqlite3":
+        import sqlite3
+
+        return Sqlite3Engine(sqlite3, database_config)
+
+    if name == "psycopg2":
         # pypy requires psycopg2cffi rather than psycopg2
-        if name == "psycopg2" and platform.python_implementation() == "PyPy":
-            name = "psycopg2cffi"
-        module = importlib.import_module(name)
-        return engine_class(module, database_config)
+        if platform.python_implementation() == "PyPy":
+            import psycopg2cffi as psycopg2  # type: ignore
+        else:
+            import psycopg2  # type: ignore
+
+        return PostgresEngine(psycopg2, database_config)
 
     raise RuntimeError("Unsupported database engine '%s'" % (name,))
 
 
-__all__ = ["create_engine", "IncorrectDatabaseSetup"]
+__all__ = ["create_engine", "BaseDatabaseEngine", "IncorrectDatabaseSetup"]