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Add types to async_helpers (#8260)

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Patrick Cloke 2020-09-08 16:50:51 -04:00 • committed by GitHub
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3 changed files with 88 additions and 51 deletions
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1
changelog.d/8260.misc Normal file
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@ -0,0 +1 @@
Add type hints to `synapse.util.async_helpers`.

3
mypy.ini
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@ -34,7 +34,7 @@ files =
synapse/http/federation/well_known_resolver.py,
synapse/http/server.py,
synapse/http/site.py,
synapse/logging/,
synapse/logging,
synapse/metrics,
synapse/module_api,
synapse/notifier.py,
@ -54,6 +54,7 @@ files =
synapse/storage/util,
synapse/streams,
synapse/types.py,
synapse/util/async_helpers.py,
synapse/util/caches/descriptors.py,
synapse/util/caches/stream_change_cache.py,
synapse/util/metrics.py,

135
synapse/util/async_helpers.py
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@ -17,13 +17,25 @@
import collections
import logging
from contextlib import contextmanager
from typing import Dict, Sequence, Set, Union
from typing import (
Any,
Callable,
Dict,
Hashable,
Iterable,
List,
Optional,
Set,
TypeVar,
Union,
)
import attr
from typing_extensions import ContextManager
from twisted.internet import defer
from twisted.internet.defer import CancelledError
from twisted.internet.interfaces import IReactorTime
from twisted.python import failure
from synapse.logging.context import (
@ -54,7 +66,7 @@ class ObservableDeferred:
__slots__ = ["_deferred", "_observers", "_result"]
def __init__(self, deferred, consumeErrors=False):
def __init__(self, deferred: defer.Deferred, consumeErrors: bool = False):
object.__setattr__(self, "_deferred", deferred)
object.__setattr__(self, "_result", None)
object.__setattr__(self, "_observers", set())
@ -111,25 +123,25 @@ class ObservableDeferred:
success, res = self._result
return defer.succeed(res) if success else defer.fail(res)
def observers(self):
def observers(self) -> List[defer.Deferred]:
return self._observers
def has_called(self):
def has_called(self) -> bool:
return self._result is not None
def has_succeeded(self):
def has_succeeded(self) -> bool:
return self._result is not None and self._result[0] is True
def get_result(self):
def get_result(self) -> Any:
return self._result[1]
def __getattr__(self, name):
def __getattr__(self, name: str) -> Any:
return getattr(self._deferred, name)
def __setattr__(self, name, value):
def __setattr__(self, name: str, value: Any) -> None:
setattr(self._deferred, name, value)
def __repr__(self):
def __repr__(self) -> str:
return "<ObservableDeferred object at %s, result=%r, _deferred=%r>" % (
id(self),
self._result,
@ -137,18 +149,20 @@ class ObservableDeferred:
)
def concurrently_execute(func, args, limit):
"""Executes the function with each argument conncurrently while limiting
def concurrently_execute(
func: Callable, args: Iterable[Any], limit: int
) -> defer.Deferred:
"""Executes the function with each argument concurrently while limiting
the number of concurrent executions.
Args:
func (func): Function to execute, should return a deferred or coroutine.
args (Iterable): List of arguments to pass to func, each invocation of func
func: Function to execute, should return a deferred or coroutine.
args: List of arguments to pass to func, each invocation of func
gets a single argument.
limit (int): Maximum number of conccurent executions.
limit: Maximum number of conccurent executions.
Returns:
deferred: Resolved when all function invocations have finished.
Deferred[list]: Resolved when all function invocations have finished.
"""
it = iter(args)
@ -167,14 +181,17 @@ def concurrently_execute(func, args, limit):
).addErrback(unwrapFirstError)
def yieldable_gather_results(func, iter, *args, **kwargs):
def yieldable_gather_results(
func: Callable, iter: Iterable, *args: Any, **kwargs: Any
) -> defer.Deferred:
"""Executes the function with each argument concurrently.
Args:
func (func): Function to execute that returns a Deferred
iter (iter): An iterable that yields items that get passed as the first
func: Function to execute that returns a Deferred
iter: An iterable that yields items that get passed as the first
argument to the function
*args: Arguments to be passed to each call to func
**kwargs: Keyword arguments to be passed to each call to func
Returns
Deferred[list]: Resolved when all functions have been invoked, or errors if
@ -188,24 +205,37 @@ def yieldable_gather_results(func, iter, *args, **kwargs):
).addErrback(unwrapFirstError)
@attr.s(slots=True)
class _LinearizerEntry:
# The number of things executing.
count = attr.ib(type=int)
# Deferreds for the things blocked from executing.
deferreds = attr.ib(type=collections.OrderedDict)
class Linearizer:
"""Limits concurrent access to resources based on a key. Useful to ensure
only a few things happen at a time on a given resource.
Example:
with (yield limiter.queue("test_key")):
with await limiter.queue("test_key"):
# do some work.
"""
def __init__(self, name=None, max_count=1, clock=None):
def __init__(
self,
name: Optional[str] = None,
max_count: int = 1,
clock: Optional[Clock] = None,
):
"""
Args:
max_count(int): The maximum number of concurrent accesses
max_count: The maximum number of concurrent accesses
"""
if name is None:
self.name = id(self)
self.name = id(self) # type: Union[str, int]
else:
self.name = name
@ -216,15 +246,10 @@ class Linearizer:
self._clock = clock
self.max_count = max_count
# key_to_defer is a map from the key to a 2 element list where
# the first element is the number of things executing, and
# the second element is an OrderedDict, where the keys are deferreds for the
# things blocked from executing.
self.key_to_defer = (
{}
) # type: Dict[str, Sequence[Union[int, Dict[defer.Deferred, int]]]]
# key_to_defer is a map from the key to a _LinearizerEntry.
self.key_to_defer = {} # type: Dict[Hashable, _LinearizerEntry]
def is_queued(self, key) -> bool:
def is_queued(self, key: Hashable) -> bool:
"""Checks whether there is a process queued up waiting
"""
entry = self.key_to_defer.get(key)
@ -234,25 +259,27 @@ class Linearizer:
# There are waiting deferreds only in the OrderedDict of deferreds is
# non-empty.
return bool(entry[1])
return bool(entry.deferreds)
def queue(self, key):
def queue(self, key: Hashable) -> defer.Deferred:
# we avoid doing defer.inlineCallbacks here, so that cancellation works correctly.
# (https://twistedmatrix.com/trac/ticket/4632 meant that cancellations were not
# propagated inside inlineCallbacks until Twisted 18.7)
entry = self.key_to_defer.setdefault(key, [0, collections.OrderedDict()])
entry = self.key_to_defer.setdefault(
key, _LinearizerEntry(0, collections.OrderedDict())
)
# If the number of things executing is greater than the maximum
# then add a deferred to the list of blocked items
# When one of the things currently executing finishes it will callback
# this item so that it can continue executing.
if entry[0] >= self.max_count:
if entry.count >= self.max_count:
res = self._await_lock(key)
else:
logger.debug(
"Acquired uncontended linearizer lock %r for key %r", self.name, key
)
entry[0] += 1
entry.count += 1
res = defer.succeed(None)
# once we successfully get the lock, we need to return a context manager which
@ -267,15 +294,15 @@ class Linearizer:
# We've finished executing so check if there are any things
# blocked waiting to execute and start one of them
entry[0] -= 1
entry.count -= 1
if entry[1]:
(next_def, _) = entry[1].popitem(last=False)
if entry.deferreds:
(next_def, _) = entry.deferreds.popitem(last=False)
# we need to run the next thing in the sentinel context.
with PreserveLoggingContext():
next_def.callback(None)
elif entry[0] == 0:
elif entry.count == 0:
# We were the last thing for this key: remove it from the
# map.
del self.key_to_defer[key]
@ -283,7 +310,7 @@ class Linearizer:
res.addCallback(_ctx_manager)
return res
def _await_lock(self, key):
def _await_lock(self, key: Hashable) -> defer.Deferred:
"""Helper for queue: adds a deferred to the queue
Assumes that we've already checked that we've reached the limit of the number
@ -298,11 +325,11 @@ class Linearizer:
logger.debug("Waiting to acquire linearizer lock %r for key %r", self.name, key)
new_defer = make_deferred_yieldable(defer.Deferred())
entry[1][new_defer] = 1
entry.deferreds[new_defer] = 1
def cb(_r):
logger.debug("Acquired linearizer lock %r for key %r", self.name, key)
entry[0] += 1
entry.count += 1
# if the code holding the lock completes synchronously, then it
# will recursively run the next claimant on the list. That can
@ -331,7 +358,7 @@ class Linearizer:
)
# we just have to take ourselves back out of the queue.
del entry[1][new_defer]
del entry.deferreds[new_defer]
return e
new_defer.addCallbacks(cb, eb)
@ -419,14 +446,22 @@ class ReadWriteLock:
return _ctx_manager()
def _cancelled_to_timed_out_error(value, timeout):
R = TypeVar("R")
def _cancelled_to_timed_out_error(value: R, timeout: float) -> R:
if isinstance(value, failure.Failure):
value.trap(CancelledError)
raise defer.TimeoutError(timeout, "Deferred")
return value
def timeout_deferred(deferred, timeout, reactor, on_timeout_cancel=None):
def timeout_deferred(
deferred: defer.Deferred,
timeout: float,
reactor: IReactorTime,
on_timeout_cancel: Optional[Callable[[Any, float], Any]] = None,
) -> defer.Deferred:
"""The in built twisted `Deferred.addTimeout` fails to time out deferreds
that have a canceller that throws exceptions. This method creates a new
deferred that wraps and times out the given deferred, correctly handling
@ -437,10 +472,10 @@ def timeout_deferred(deferred, timeout, reactor, on_timeout_cancel=None):
NOTE: Unlike `Deferred.addTimeout`, this function returns a new deferred
Args:
deferred (Deferred)
timeout (float): Timeout in seconds
reactor (twisted.interfaces.IReactorTime): The twisted reactor to use
on_timeout_cancel (callable): A callable which is called immediately
deferred: The Deferred to potentially timeout.
timeout: Timeout in seconds
reactor: The twisted reactor to use
on_timeout_cancel: A callable which is called immediately
after the deferred times out, and not if this deferred is
otherwise cancelled before the timeout.
@ -452,7 +487,7 @@ def timeout_deferred(deferred, timeout, reactor, on_timeout_cancel=None):
CancelledError Failure into a defer.TimeoutError.
Returns:
Deferred
A new Deferred.
"""
new_d = defer.Deferred()