diff options
Diffstat (limited to 'tests')
| -rw-r--r-- | tests/util/test_rwlock.py | 30 |
1 files changed, 30 insertions, 0 deletions
diff --git a/tests/util/test_rwlock.py b/tests/util/test_rwlock.py index a10071c70f..0774625b85 100644 --- a/tests/util/test_rwlock.py +++ b/tests/util/test_rwlock.py @@ -13,6 +13,7 @@ # limitations under the License. from twisted.internet import defer +from twisted.internet.defer import Deferred from synapse.util.async_helpers import ReadWriteLock @@ -83,3 +84,32 @@ class ReadWriteLockTestCase(unittest.TestCase): self.assertTrue(d.called) with d.result: pass + + def test_lock_handoff_to_nonblocking_writer(self): + """Test a writer handing the lock to another writer that completes instantly.""" + rwlock = ReadWriteLock() + key = "key" + + unblock: "Deferred[None]" = Deferred() + + async def blocking_write(): + with await rwlock.write(key): + await unblock + + async def nonblocking_write(): + with await rwlock.write(key): + pass + + d1 = defer.ensureDeferred(blocking_write()) + d2 = defer.ensureDeferred(nonblocking_write()) + 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 = defer.ensureDeferred(nonblocking_write()) + self.assertTrue(d3.called) |