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test_rwlock.py
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test_rwlock.py
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# Copyright (c) Meta Platforms, Inc. and affiliates.
# pyre-unsafe
import threading
import time
import unittest
from ft_utils.concurrent import AtomicFlag, AtomicInt64
from ft_utils.lock_test_utils import run_interrupt_handling
from ft_utils.synchronization import RWLock, RWReadContext, RWWriteContext
class TestRWLock(unittest.TestCase):
def execute(self, what):
def runnit():
for _ in range(5):
what()
threads = [threading.Thread(target=runnit) for _ in range(10)]
for t in threads:
t.start()
for t in threads:
t.join()
def test_simple_read_lock(self):
lock = RWLock()
lock.lock_read()
time.sleep(0.01)
lock.unlock_read()
lock.lock_read()
time.sleep(0.01)
lock.unlock_read()
def test_simple_write_lock(self):
lock = RWLock()
lock.lock_write()
time.sleep(0.01)
lock.unlock_write()
lock.lock_write()
time.sleep(0.01)
lock.unlock_write()
def test_lock_write(self):
lock = RWLock()
count = AtomicInt64()
ok = AtomicFlag(True)
ran = AtomicFlag(False)
def check_serialized():
try:
lock.lock_write()
count.incr()
if count > 1:
ok.set(False)
time.sleep(0.01)
count.decr()
finally:
lock.unlock_write()
ran.set(True)
self.execute(check_serialized)
self.assertTrue(ok)
self.assertTrue(ran)
def test_lock_read(self):
lock = RWLock()
count = AtomicInt64()
ok = AtomicFlag(False)
ran = AtomicFlag(False)
def check_notserialized():
try:
lock.lock_read()
count.incr()
if count > 1:
ok.set(True)
time.sleep(0.1)
count.decr()
finally:
lock.unlock_read()
ran.set(True)
self.execute(check_notserialized)
self.assertTrue(ok)
self.assertTrue(ran)
def test_lock_read_write(self):
lock = RWLock()
rcount = AtomicInt64()
wcount = AtomicInt64()
rok = AtomicFlag(False)
wokr = AtomicFlag(True)
wokw = AtomicFlag(True)
rran = AtomicFlag(False)
wran = AtomicFlag(False)
def check_both():
try:
lock.lock_read()
rcount.incr()
if rcount > 1:
rok.set(True)
if wcount > 0:
rok.set(True)
time.sleep(0.01)
rcount.decr()
rran.set(True)
finally:
lock.unlock_read()
time.sleep(0.01)
try:
lock.lock_write()
wcount.incr()
if wcount > 1:
wokw.set(False)
if rcount > 0:
wokr.set(False)
time.sleep(0.01)
wcount.decr()
wran.set(True)
finally:
lock.unlock_write()
self.execute(check_both)
self.assertTrue(rok)
self.assertTrue(wokr)
self.assertTrue(wokw)
self.assertTrue(rran)
self.assertTrue(wran)
def test_simple_context(self):
lock = RWLock()
with RWReadContext(lock):
pass
with RWWriteContext(lock):
pass
def test_lock_context(self):
lock = RWLock()
rcount = AtomicInt64()
wcount = AtomicInt64()
rok = AtomicFlag(False)
wokr = AtomicFlag(True)
wokw = AtomicFlag(True)
rran = AtomicFlag(False)
wran = AtomicFlag(False)
def check_both():
with RWReadContext(lock):
rcount.incr()
if rcount > 1:
rok.set(True)
if wcount > 0:
rok.set(False)
return
time.sleep(0.01)
rcount.decr()
rran.set(True)
time.sleep(0.01)
with RWWriteContext(lock):
wcount.incr()
if wcount > 1:
wokw.set(False)
return
if rcount > 0:
wokr.set(False)
return
time.sleep(0.01)
wcount.decr()
wran.set(True)
self.execute(check_both)
self.assertTrue(rok)
self.assertTrue(wokr)
self.assertTrue(wokw)
self.assertTrue(rran)
self.assertTrue(wran)
def test_readers(self):
lock = RWLock()
count = AtomicInt64()
done = AtomicFlag(False)
def read_wait():
with RWReadContext(lock):
count.incr()
while not done:
time.sleep(0.01)
threads = [threading.Thread(target=read_wait) for _ in range(10)]
for t in threads:
t.start()
while count < 10:
time.sleep(0.01)
readers = lock.readers()
writers_waiting = lock.writers_waiting()
writer_locked = lock.writer_locked()
done.set(True)
for t in threads:
t.join()
self.assertEqual(readers, 10)
self.assertEqual(writers_waiting, 0)
self.assertEqual(writer_locked, 0)
def test_writers_block_readers(self):
lock = RWLock()
done = AtomicFlag(False)
locked = AtomicFlag(False)
new_start = AtomicInt64()
started = AtomicFlag(False)
def read_wait1():
with RWReadContext(lock):
while not done:
time.sleep(0.01)
def read_wait2():
new_start.incr()
with RWReadContext(lock):
while not done:
time.sleep(0.01)
new_start.decr()
def write_wait():
started.set(True)
with RWWriteContext(lock):
pass
# Get 5 read locks
threads = [threading.Thread(target=read_wait1) for _ in range(5)]
for t in threads:
t.start()
while lock.readers() < 5:
time.sleep(0.01)
# Ask for a write lock even though read is held.
t = threading.Thread(target=write_wait)
t.start()
threads.append(t)
while not started:
time.sleep(0.01)
# Now start 5 new read threads which should not get the read lock as the write waiting blocks.
new_threads = [threading.Thread(target=read_wait2) for _ in range(5)]
for t in new_threads:
t.start()
threads.append(t)
while new_start < 5:
time.sleep(0.01)
readers = lock.readers()
locked = lock.writer_locked()
waiting = lock.writers_waiting()
done.set(True)
# Drain the second set of readers.
while new_start > 0:
time.sleep(0.01)
for t in threads:
t.join()
self.assertEqual(readers, 5)
self.assertEqual(waiting, 1)
self.assertFalse(locked)
self.assertEqual(lock.readers(), 0)
def test_writers_waiting(self):
lock = RWLock()
done = AtomicFlag(False)
started = AtomicFlag(False)
locked = AtomicFlag(False)
unlocked = AtomicFlag(True)
def read_wait():
with RWReadContext(lock):
while not done:
time.sleep(0.01)
def write_wait():
unlocked.set(not lock.writer_locked())
started.set(True)
with RWWriteContext(lock):
locked.set(lock.writer_locked())
threads = [threading.Thread(target=read_wait) for _ in range(10)]
for t in threads:
t.start()
while lock.readers() < 0:
time.sleep(0.01)
t = threading.Thread(target=write_wait)
t.start()
threads.append(t)
while lock.readers() < 10 or (not started):
time.sleep(0.01)
time.sleep(0.1)
writers_waiting = lock.writers_waiting()
done.set(True)
for t in threads:
t.join()
self.assertEqual(writers_waiting, 1)
self.assertTrue(locked)
self.assertTrue(unlocked)
class TestRWLockSignals(unittest.TestCase):
def test_interrupt_handling_write(self):
def acquire(lock):
lock.lock_write()
def release(lock):
lock.unlock_write()
run_interrupt_handling(self, RWLock(), acquire, release)
def test_interrupt_handling_read(self):
phase = AtomicInt64(0)
def acquire(lock):
if phase == 0:
lock.lock_write()
elif phase == 1:
lock.lock_read()
else:
raise RuntimeError("Acquire lock phase error")
phase.incr()
def release(lock):
if phase == 1:
lock.unlock_write()
if phase == 2:
lock.unlock_read()
else:
raise RuntimeError("Release lock phase error")
phase.incr()
run_interrupt_handling(self, RWLock(), acquire, release)
if __name__ == "__main__":
unittest.main()