Add types to synapse.util. (#10601)

synapse/util/__init__.py

@@ -15,27 +15,35 @@
 import json
 import logging
 import re
-from typing import Pattern
+import typing
+from typing import Any, Callable, Dict, Generator, Pattern
 
 import attr
 from frozendict import frozendict
 
 from twisted.internet import defer, task
+from twisted.internet.defer import Deferred
+from twisted.internet.interfaces import IDelayedCall, IReactorTime
+from twisted.internet.task import LoopingCall
+from twisted.python.failure import Failure
 
 from synapse.logging import context
 
+if typing.TYPE_CHECKING:
+    pass
+
 logger = logging.getLogger(__name__)
 
 
 _WILDCARD_RUN = re.compile(r"([\?\*]+)")
 
 
-def _reject_invalid_json(val):
+def _reject_invalid_json(val: Any) -> None:
     """Do not allow Infinity, -Infinity, or NaN values in JSON."""
     raise ValueError("Invalid JSON value: '%s'" % val)
 
 
-def _handle_frozendict(obj):
+def _handle_frozendict(obj: Any) -> Dict[Any, Any]:
     """Helper for json_encoder. Makes frozendicts serializable by returning
     the underlying dict
     """
@@ -60,10 +68,10 @@ json_encoder = json.JSONEncoder(
 json_decoder = json.JSONDecoder(parse_constant=_reject_invalid_json)
 
 
-def unwrapFirstError(failure):
+def unwrapFirstError(failure: Failure) -> Failure:
     # defer.gatherResults and DeferredLists wrap failures.
     failure.trap(defer.FirstError)
-    return failure.value.subFailure
+    return failure.value.subFailure  # type: ignore[union-attr]  # Issue in Twisted's annotations
 
 
 @attr.s(slots=True)
@@ -75,25 +83,25 @@ class Clock:
         reactor: The Twisted reactor to use.
     """
 
-    _reactor = attr.ib()
+    _reactor: IReactorTime = attr.ib()
 
-    @defer.inlineCallbacks
-    def sleep(self, seconds):
-        d = defer.Deferred()
+    @defer.inlineCallbacks  # type: ignore[arg-type]  # Issue in Twisted's type annotations
+    def sleep(self, seconds: float) -> "Generator[Deferred[float], Any, Any]":
+        d: defer.Deferred[float] = defer.Deferred()
         with context.PreserveLoggingContext():
             self._reactor.callLater(seconds, d.callback, seconds)
             res = yield d
         return res
 
-    def time(self):
+    def time(self) -> float:
         """Returns the current system time in seconds since epoch."""
         return self._reactor.seconds()
 
-    def time_msec(self):
+    def time_msec(self) -> int:
         """Returns the current system time in milliseconds since epoch."""
         return int(self.time() * 1000)
 
-    def looping_call(self, f, msec, *args, **kwargs):
+    def looping_call(self, f: Callable, msec: float, *args, **kwargs) -> LoopingCall:
         """Call a function repeatedly.
 
         Waits `msec` initially before calling `f` for the first time.
@@ -102,8 +110,8 @@ class Clock:
         other than trivial, you probably want to wrap it in run_as_background_process.
 
         Args:
-            f(function): The function to call repeatedly.
-            msec(float): How long to wait between calls in milliseconds.
+            f: The function to call repeatedly.
+            msec: How long to wait between calls in milliseconds.
             *args: Postional arguments to pass to function.
             **kwargs: Key arguments to pass to function.
         """
@@ -113,7 +121,7 @@ class Clock:
         d.addErrback(log_failure, "Looping call died", consumeErrors=False)
         return call
 
-    def call_later(self, delay, callback, *args, **kwargs):
+    def call_later(self, delay, callback, *args, **kwargs) -> IDelayedCall:
         """Call something later
 
         Note that the function will be called with no logcontext, so if it is anything
@@ -133,7 +141,7 @@ class Clock:
         with context.PreserveLoggingContext():
             return self._reactor.callLater(delay, wrapped_callback, *args, **kwargs)
 
-    def cancel_call_later(self, timer, ignore_errs=False):
+    def cancel_call_later(self, timer: IDelayedCall, ignore_errs: bool = False) -> None:
         try:
             timer.cancel()
         except Exception: