def test_demotion_with_blocked_writer(self):
lock = RWLock()
writer = LockingThread(lock.exclusive)
try:
with lock.exclusive:
writer.start()
writer.ready.wait()
# Ensure that writer is blocked
if writer.acquired.wait(0.5):
raise RuntimeError("Writer could acquire the lock while "
"holding a write lock")
lock.acquireRead()
# I hold both a read lock and a write lock now
# I release the write lock. Having read lock, writer must block
self.assertFalse(
writer.acquired.wait(0.5),
"Writer acquired the lock while holding a read "
"lock")
finally:
lock.release()
try:
# Writer must acquire now
self.assertTrue(writer.acquired.wait(0.5))
finally:
writer.stop()
def test_demotion_no_waiters(self):
lock = RWLock()
try:
with lock.exclusive:
lock.acquireRead()
finally:
lock.release()
def test_demotion_no_waiters(self):
lock = RWLock()
try:
with lock.exclusive:
lock.acquireRead()
finally:
lock.release()
def test_demotion_with_blocked_reader(self):
lock = RWLock()
reader = LockingThread(lock.shared)
try:
with lock.exclusive:
reader.start()
reader.ready.wait()
# Ensure that reader is blocked
if reader.acquired.wait(0.5):
raise RuntimeError("Reader could acquire the lock while "
"holding a write lock")
lock.acquireRead()
# I hold both a read lock and a write lock now
# I released the write lock. Having read lock, reader shold get the
# lock.
self.assertTrue(reader.acquired.wait(0.5),
"Reader could not acuire the lock")
finally:
lock.release()
reader.stop()
def test_demotion_with_blocked_reader(self):
lock = RWLock()
reader = LockingThread(lock.shared)
try:
with lock.exclusive:
reader.start()
reader.ready.wait()
# Ensure that reader is blocked
if reader.acquired.wait(0.5):
raise RuntimeError("Reader could acquire the lock while "
"holding a write lock")
lock.acquireRead()
# I hold both a read lock and a write lock now
# I released the write lock. Having read lock, reader should get
# the lock.
self.assertTrue(reader.acquired.wait(0.5),
"Reader could not acuire the lock")
finally:
lock.release()
reader.stop()
def test_demotion_with_blocked_writer(self):
lock = RWLock()
writer = LockingThread(lock.exclusive)
try:
with lock.exclusive:
writer.start()
writer.ready.wait()
# Ensure that writer is blocked
if writer.acquired.wait(0.5):
raise RuntimeError("Writer could acquire the lock while "
"holding a write lock")
lock.acquireRead()
# I hold both a read lock and a write lock now
# I release the write lock. Having read lock, writer must block
self.assertFalse(writer.acquired.wait(0.5),
"Writer acquired the lock while holding a read "
"lock")
finally:
lock.release()
try:
# Writer must acquire now
self.assertTrue(writer.acquired.wait(0.5))
finally:
writer.stop()
