mirror of
https://git.anonymousland.org/anonymousland/synapse.git
synced 2024-12-11 06:44:19 -05:00
395 lines
16 KiB
Python
395 lines
16 KiB
Python
# Copyright 2016 OpenMarket Ltd
|
|
#
|
|
# Licensed under the Apache License, Version 2.0 (the "License");
|
|
# you may not use this file except in compliance with the License.
|
|
# You may obtain a copy of the License at
|
|
#
|
|
# http://www.apache.org/licenses/LICENSE-2.0
|
|
#
|
|
# Unless required by applicable law or agreed to in writing, software
|
|
# distributed under the License is distributed on an "AS IS" BASIS,
|
|
# 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.
|
|
|
|
from typing import AsyncContextManager, Callable, Sequence, Tuple
|
|
|
|
from twisted.internet import defer
|
|
from twisted.internet.defer import CancelledError, Deferred
|
|
|
|
from synapse.util.async_helpers import ReadWriteLock
|
|
|
|
from tests import unittest
|
|
|
|
|
|
class ReadWriteLockTestCase(unittest.TestCase):
|
|
def _start_reader_or_writer(
|
|
self,
|
|
read_or_write: Callable[[str], AsyncContextManager],
|
|
key: str,
|
|
return_value: str,
|
|
) -> Tuple["Deferred[str]", "Deferred[None]", "Deferred[None]"]:
|
|
"""Starts a reader or writer which acquires the lock, blocks, then completes.
|
|
|
|
Args:
|
|
read_or_write: A function returning a context manager for a lock.
|
|
Either a bound `ReadWriteLock.read` or `ReadWriteLock.write`.
|
|
key: The key to read or write.
|
|
return_value: A string that the reader or writer will resolve with when
|
|
done.
|
|
|
|
Returns:
|
|
A tuple of three `Deferred`s:
|
|
* A cancellable `Deferred` for the entire read or write operation that
|
|
resolves with `return_value` on successful completion.
|
|
* A `Deferred` that resolves once the reader or writer acquires the lock.
|
|
* A `Deferred` that blocks the reader or writer. Must be resolved by the
|
|
caller to allow the reader or writer to release the lock and complete.
|
|
"""
|
|
acquired_d: "Deferred[None]" = Deferred()
|
|
unblock_d: "Deferred[None]" = Deferred()
|
|
|
|
async def reader_or_writer():
|
|
async with read_or_write(key):
|
|
acquired_d.callback(None)
|
|
await unblock_d
|
|
return return_value
|
|
|
|
d = defer.ensureDeferred(reader_or_writer())
|
|
return d, acquired_d, unblock_d
|
|
|
|
def _start_blocking_reader(
|
|
self, rwlock: ReadWriteLock, key: str, return_value: str
|
|
) -> Tuple["Deferred[str]", "Deferred[None]", "Deferred[None]"]:
|
|
"""Starts a reader which acquires the lock, blocks, then releases the lock.
|
|
|
|
See the docstring for `_start_reader_or_writer` for details about the arguments
|
|
and return values.
|
|
"""
|
|
return self._start_reader_or_writer(rwlock.read, key, return_value)
|
|
|
|
def _start_blocking_writer(
|
|
self, rwlock: ReadWriteLock, key: str, return_value: str
|
|
) -> Tuple["Deferred[str]", "Deferred[None]", "Deferred[None]"]:
|
|
"""Starts a writer which acquires the lock, blocks, then releases the lock.
|
|
|
|
See the docstring for `_start_reader_or_writer` for details about the arguments
|
|
and return values.
|
|
"""
|
|
return self._start_reader_or_writer(rwlock.write, key, return_value)
|
|
|
|
def _start_nonblocking_reader(
|
|
self, rwlock: ReadWriteLock, key: str, return_value: str
|
|
) -> Tuple["Deferred[str]", "Deferred[None]"]:
|
|
"""Starts a reader which acquires the lock, then releases it immediately.
|
|
|
|
See the docstring for `_start_reader_or_writer` for details about the arguments.
|
|
|
|
Returns:
|
|
A tuple of two `Deferred`s:
|
|
* A cancellable `Deferred` for the entire read operation that resolves with
|
|
`return_value` on successful completion.
|
|
* A `Deferred` that resolves once the reader acquires the lock.
|
|
"""
|
|
d, acquired_d, unblock_d = self._start_reader_or_writer(
|
|
rwlock.read, key, return_value
|
|
)
|
|
unblock_d.callback(None)
|
|
return d, acquired_d
|
|
|
|
def _start_nonblocking_writer(
|
|
self, rwlock: ReadWriteLock, key: str, return_value: str
|
|
) -> Tuple["Deferred[str]", "Deferred[None]"]:
|
|
"""Starts a writer which acquires the lock, then releases it immediately.
|
|
|
|
See the docstring for `_start_reader_or_writer` for details about the arguments.
|
|
|
|
Returns:
|
|
A tuple of two `Deferred`s:
|
|
* A cancellable `Deferred` for the entire write operation that resolves
|
|
with `return_value` on successful completion.
|
|
* A `Deferred` that resolves once the writer acquires the lock.
|
|
"""
|
|
d, acquired_d, unblock_d = self._start_reader_or_writer(
|
|
rwlock.write, key, return_value
|
|
)
|
|
unblock_d.callback(None)
|
|
return d, acquired_d
|
|
|
|
def _assert_first_n_resolved(
|
|
self, deferreds: Sequence["defer.Deferred[None]"], n: int
|
|
) -> None:
|
|
"""Assert that exactly the first n `Deferred`s in the given list are resolved.
|
|
|
|
Args:
|
|
deferreds: The list of `Deferred`s to be checked.
|
|
n: The number of `Deferred`s at the start of `deferreds` that should be
|
|
resolved.
|
|
"""
|
|
for i, d in enumerate(deferreds[:n]):
|
|
self.assertTrue(d.called, msg="deferred %d was unexpectedly unresolved" % i)
|
|
|
|
for i, d in enumerate(deferreds[n:]):
|
|
self.assertFalse(
|
|
d.called, msg="deferred %d was unexpectedly resolved" % (i + n)
|
|
)
|
|
|
|
def test_rwlock(self):
|
|
rwlock = ReadWriteLock()
|
|
key = "key"
|
|
|
|
ds = [
|
|
self._start_blocking_reader(rwlock, key, "0"),
|
|
self._start_blocking_reader(rwlock, key, "1"),
|
|
self._start_blocking_writer(rwlock, key, "2"),
|
|
self._start_blocking_writer(rwlock, key, "3"),
|
|
self._start_blocking_reader(rwlock, key, "4"),
|
|
self._start_blocking_reader(rwlock, key, "5"),
|
|
self._start_blocking_writer(rwlock, key, "6"),
|
|
]
|
|
# `Deferred`s that resolve when each reader or writer acquires the lock.
|
|
acquired_ds = [acquired_d for _, acquired_d, _ in ds]
|
|
# `Deferred`s that will trigger the release of locks when resolved.
|
|
release_ds = [release_d for _, _, release_d in ds]
|
|
|
|
# The first two readers should acquire their locks.
|
|
self._assert_first_n_resolved(acquired_ds, 2)
|
|
|
|
# Release one of the read locks. The next writer should not acquire the lock,
|
|
# because there is another reader holding the lock.
|
|
self._assert_first_n_resolved(acquired_ds, 2)
|
|
release_ds[0].callback(None)
|
|
self._assert_first_n_resolved(acquired_ds, 2)
|
|
|
|
# Release the other read lock. The next writer should acquire the lock.
|
|
self._assert_first_n_resolved(acquired_ds, 2)
|
|
release_ds[1].callback(None)
|
|
self._assert_first_n_resolved(acquired_ds, 3)
|
|
|
|
# Release the write lock. The next writer should acquire the lock.
|
|
self._assert_first_n_resolved(acquired_ds, 3)
|
|
release_ds[2].callback(None)
|
|
self._assert_first_n_resolved(acquired_ds, 4)
|
|
|
|
# Release the write lock. The next two readers should acquire locks.
|
|
self._assert_first_n_resolved(acquired_ds, 4)
|
|
release_ds[3].callback(None)
|
|
self._assert_first_n_resolved(acquired_ds, 6)
|
|
|
|
# Release one of the read locks. The next writer should not acquire the lock,
|
|
# because there is another reader holding the lock.
|
|
self._assert_first_n_resolved(acquired_ds, 6)
|
|
release_ds[5].callback(None)
|
|
self._assert_first_n_resolved(acquired_ds, 6)
|
|
|
|
# Release the other read lock. The next writer should acquire the lock.
|
|
self._assert_first_n_resolved(acquired_ds, 6)
|
|
release_ds[4].callback(None)
|
|
self._assert_first_n_resolved(acquired_ds, 7)
|
|
|
|
# Release the write lock.
|
|
release_ds[6].callback(None)
|
|
|
|
# Acquire and release the write and read locks one last time for good measure.
|
|
_, acquired_d = self._start_nonblocking_writer(rwlock, key, "last writer")
|
|
self.assertTrue(acquired_d.called)
|
|
|
|
_, acquired_d = self._start_nonblocking_reader(rwlock, key, "last reader")
|
|
self.assertTrue(acquired_d.called)
|
|
|
|
def test_lock_handoff_to_nonblocking_writer(self):
|
|
"""Test a writer handing the lock to another writer that completes instantly."""
|
|
rwlock = ReadWriteLock()
|
|
key = "key"
|
|
|
|
d1, _, unblock = self._start_blocking_writer(rwlock, key, "write 1 completed")
|
|
d2, _ = self._start_nonblocking_writer(rwlock, key, "write 2 completed")
|
|
self.assertFalse(d1.called)
|
|
self.assertFalse(d2.called)
|
|
|
|
# Unblock the first writer. The second writer will complete without blocking.
|
|
unblock.callback(None)
|
|
self.assertTrue(d1.called)
|
|
self.assertTrue(d2.called)
|
|
|
|
# The `ReadWriteLock` should operate as normal.
|
|
d3, _ = self._start_nonblocking_writer(rwlock, key, "write 3 completed")
|
|
self.assertTrue(d3.called)
|
|
|
|
def test_cancellation_while_holding_read_lock(self):
|
|
"""Test cancellation while holding a read lock.
|
|
|
|
A waiting writer should be given the lock when the reader holding the lock is
|
|
cancelled.
|
|
"""
|
|
rwlock = ReadWriteLock()
|
|
key = "key"
|
|
|
|
# 1. A reader takes the lock and blocks.
|
|
reader_d, _, _ = self._start_blocking_reader(rwlock, key, "read completed")
|
|
|
|
# 2. A writer waits for the reader to complete.
|
|
writer_d, _ = self._start_nonblocking_writer(rwlock, key, "write completed")
|
|
self.assertFalse(writer_d.called)
|
|
|
|
# 3. The reader is cancelled.
|
|
reader_d.cancel()
|
|
self.failureResultOf(reader_d, CancelledError)
|
|
|
|
# 4. The writer should take the lock and complete.
|
|
self.assertTrue(
|
|
writer_d.called, "Writer is stuck waiting for a cancelled reader"
|
|
)
|
|
self.assertEqual("write completed", self.successResultOf(writer_d))
|
|
|
|
def test_cancellation_while_holding_write_lock(self):
|
|
"""Test cancellation while holding a write lock.
|
|
|
|
A waiting reader should be given the lock when the writer holding the lock is
|
|
cancelled.
|
|
"""
|
|
rwlock = ReadWriteLock()
|
|
key = "key"
|
|
|
|
# 1. A writer takes the lock and blocks.
|
|
writer_d, _, _ = self._start_blocking_writer(rwlock, key, "write completed")
|
|
|
|
# 2. A reader waits for the writer to complete.
|
|
reader_d, _ = self._start_nonblocking_reader(rwlock, key, "read completed")
|
|
self.assertFalse(reader_d.called)
|
|
|
|
# 3. The writer is cancelled.
|
|
writer_d.cancel()
|
|
self.failureResultOf(writer_d, CancelledError)
|
|
|
|
# 4. The reader should take the lock and complete.
|
|
self.assertTrue(
|
|
reader_d.called, "Reader is stuck waiting for a cancelled writer"
|
|
)
|
|
self.assertEqual("read completed", self.successResultOf(reader_d))
|
|
|
|
def test_cancellation_while_waiting_for_read_lock(self):
|
|
"""Test cancellation while waiting for a read lock.
|
|
|
|
Tests that cancelling a waiting reader:
|
|
* does not cancel the writer it is waiting on
|
|
* does not cancel the next writer waiting on it
|
|
* does not allow the next writer to acquire the lock before an earlier writer
|
|
has finished
|
|
* does not keep the next writer waiting indefinitely
|
|
|
|
These correspond to the asserts with explicit messages.
|
|
"""
|
|
rwlock = ReadWriteLock()
|
|
key = "key"
|
|
|
|
# 1. A writer takes the lock and blocks.
|
|
writer1_d, _, unblock_writer1 = self._start_blocking_writer(
|
|
rwlock, key, "write 1 completed"
|
|
)
|
|
|
|
# 2. A reader waits for the first writer to complete.
|
|
# This reader will be cancelled later.
|
|
reader_d, _ = self._start_nonblocking_reader(rwlock, key, "read completed")
|
|
self.assertFalse(reader_d.called)
|
|
|
|
# 3. A second writer waits for both the first writer and the reader to complete.
|
|
writer2_d, _ = self._start_nonblocking_writer(rwlock, key, "write 2 completed")
|
|
self.assertFalse(writer2_d.called)
|
|
|
|
# 4. The waiting reader is cancelled.
|
|
# Neither of the writers should be cancelled.
|
|
# The second writer should still be waiting, but only on the first writer.
|
|
reader_d.cancel()
|
|
self.failureResultOf(reader_d, CancelledError)
|
|
self.assertFalse(writer1_d.called, "First writer was unexpectedly cancelled")
|
|
self.assertFalse(
|
|
writer2_d.called,
|
|
"Second writer was unexpectedly cancelled or given the lock before the "
|
|
"first writer finished",
|
|
)
|
|
|
|
# 5. Unblock the first writer, which should complete.
|
|
unblock_writer1.callback(None)
|
|
self.assertEqual("write 1 completed", self.successResultOf(writer1_d))
|
|
|
|
# 6. The second writer should take the lock and complete.
|
|
self.assertTrue(
|
|
writer2_d.called, "Second writer is stuck waiting for a cancelled reader"
|
|
)
|
|
self.assertEqual("write 2 completed", self.successResultOf(writer2_d))
|
|
|
|
def test_cancellation_while_waiting_for_write_lock(self):
|
|
"""Test cancellation while waiting for a write lock.
|
|
|
|
Tests that cancelling a waiting writer:
|
|
* does not cancel the reader or writer it is waiting on
|
|
* does not cancel the next writer waiting on it
|
|
* does not allow the next writer to acquire the lock before an earlier reader
|
|
and writer have finished
|
|
* does not keep the next writer waiting indefinitely
|
|
|
|
These correspond to the asserts with explicit messages.
|
|
"""
|
|
rwlock = ReadWriteLock()
|
|
key = "key"
|
|
|
|
# 1. A reader takes the lock and blocks.
|
|
reader_d, _, unblock_reader = self._start_blocking_reader(
|
|
rwlock, key, "read completed"
|
|
)
|
|
|
|
# 2. A writer waits for the reader to complete.
|
|
writer1_d, _, unblock_writer1 = self._start_blocking_writer(
|
|
rwlock, key, "write 1 completed"
|
|
)
|
|
|
|
# 3. A second writer waits for both the reader and first writer to complete.
|
|
# This writer will be cancelled later.
|
|
writer2_d, _ = self._start_nonblocking_writer(rwlock, key, "write 2 completed")
|
|
self.assertFalse(writer2_d.called)
|
|
|
|
# 4. A third writer waits for the second writer to complete.
|
|
writer3_d, _ = self._start_nonblocking_writer(rwlock, key, "write 3 completed")
|
|
self.assertFalse(writer3_d.called)
|
|
|
|
# 5. The second writer is cancelled, but continues waiting for the lock.
|
|
# The reader, first writer and third writer should not be cancelled.
|
|
# The first writer should still be waiting on the reader.
|
|
# The third writer should still be waiting on the second writer.
|
|
writer2_d.cancel()
|
|
self.assertNoResult(writer2_d)
|
|
self.assertFalse(reader_d.called, "Reader was unexpectedly cancelled")
|
|
self.assertFalse(writer1_d.called, "First writer was unexpectedly cancelled")
|
|
self.assertFalse(
|
|
writer3_d.called,
|
|
"Third writer was unexpectedly cancelled or given the lock before the first "
|
|
"writer finished",
|
|
)
|
|
|
|
# 6. Unblock the reader, which should complete.
|
|
# The first writer should be given the lock and block.
|
|
# The third writer should still be waiting on the second writer.
|
|
unblock_reader.callback(None)
|
|
self.assertEqual("read completed", self.successResultOf(reader_d))
|
|
self.assertNoResult(writer2_d)
|
|
self.assertFalse(
|
|
writer3_d.called,
|
|
"Third writer was unexpectedly given the lock before the first writer "
|
|
"finished",
|
|
)
|
|
|
|
# 7. Unblock the first writer, which should complete.
|
|
unblock_writer1.callback(None)
|
|
self.assertEqual("write 1 completed", self.successResultOf(writer1_d))
|
|
|
|
# 8. The second writer should take the lock and release it immediately, since it
|
|
# has been cancelled.
|
|
self.failureResultOf(writer2_d, CancelledError)
|
|
|
|
# 9. The third writer should take the lock and complete.
|
|
self.assertTrue(
|
|
writer3_d.called, "Third writer is stuck waiting for a cancelled writer"
|
|
)
|
|
self.assertEqual("write 3 completed", self.successResultOf(writer3_d))
|