import pytest
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import weakref
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from ..testing import wait_all_tasks_blocked, assert_checkpoints
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from .. import _core
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from .. import _timeouts
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from .._timeouts import sleep_forever, move_on_after
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from .._sync import *
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async def test_Event():
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e = Event()
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assert not e.is_set()
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assert e.statistics().tasks_waiting == 0
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e.set()
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assert e.is_set()
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with assert_checkpoints():
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await e.wait()
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e = Event()
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record = []
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async def child():
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record.append("sleeping")
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await e.wait()
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record.append("woken")
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async with _core.open_nursery() as nursery:
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nursery.start_soon(child)
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nursery.start_soon(child)
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await wait_all_tasks_blocked()
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assert record == ["sleeping", "sleeping"]
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assert e.statistics().tasks_waiting == 2
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e.set()
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await wait_all_tasks_blocked()
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assert record == ["sleeping", "sleeping", "woken", "woken"]
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async def test_CapacityLimiter():
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with pytest.raises(TypeError):
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CapacityLimiter(1.0)
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with pytest.raises(ValueError):
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CapacityLimiter(-1)
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c = CapacityLimiter(2)
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repr(c) # smoke test
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assert c.total_tokens == 2
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assert c.borrowed_tokens == 0
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assert c.available_tokens == 2
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with pytest.raises(RuntimeError):
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c.release()
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assert c.borrowed_tokens == 0
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c.acquire_nowait()
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assert c.borrowed_tokens == 1
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assert c.available_tokens == 1
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stats = c.statistics()
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assert stats.borrowed_tokens == 1
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assert stats.total_tokens == 2
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assert stats.borrowers == [_core.current_task()]
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assert stats.tasks_waiting == 0
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# Can't re-acquire when we already have it
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with pytest.raises(RuntimeError):
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c.acquire_nowait()
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assert c.borrowed_tokens == 1
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with pytest.raises(RuntimeError):
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await c.acquire()
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assert c.borrowed_tokens == 1
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# We can acquire on behalf of someone else though
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with assert_checkpoints():
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await c.acquire_on_behalf_of("someone")
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# But then we've run out of capacity
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assert c.borrowed_tokens == 2
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with pytest.raises(_core.WouldBlock):
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c.acquire_on_behalf_of_nowait("third party")
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assert set(c.statistics().borrowers) == {_core.current_task(), "someone"}
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# Until we release one
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c.release_on_behalf_of(_core.current_task())
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assert c.statistics().borrowers == ["someone"]
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c.release_on_behalf_of("someone")
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assert c.borrowed_tokens == 0
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with assert_checkpoints():
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async with c:
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assert c.borrowed_tokens == 1
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async with _core.open_nursery() as nursery:
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await c.acquire_on_behalf_of("value 1")
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await c.acquire_on_behalf_of("value 2")
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nursery.start_soon(c.acquire_on_behalf_of, "value 3")
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await wait_all_tasks_blocked()
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assert c.borrowed_tokens == 2
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assert c.statistics().tasks_waiting == 1
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c.release_on_behalf_of("value 2")
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# Fairness:
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assert c.borrowed_tokens == 2
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with pytest.raises(_core.WouldBlock):
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c.acquire_nowait()
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c.release_on_behalf_of("value 3")
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c.release_on_behalf_of("value 1")
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async def test_CapacityLimiter_inf():
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from math import inf
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c = CapacityLimiter(inf)
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repr(c) # smoke test
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assert c.total_tokens == inf
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assert c.borrowed_tokens == 0
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assert c.available_tokens == inf
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with pytest.raises(RuntimeError):
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c.release()
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assert c.borrowed_tokens == 0
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c.acquire_nowait()
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assert c.borrowed_tokens == 1
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assert c.available_tokens == inf
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async def test_CapacityLimiter_change_total_tokens():
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c = CapacityLimiter(2)
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with pytest.raises(TypeError):
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c.total_tokens = 1.0
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with pytest.raises(ValueError):
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c.total_tokens = 0
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with pytest.raises(ValueError):
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c.total_tokens = -10
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assert c.total_tokens == 2
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async with _core.open_nursery() as nursery:
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for i in range(5):
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nursery.start_soon(c.acquire_on_behalf_of, i)
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await wait_all_tasks_blocked()
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assert set(c.statistics().borrowers) == {0, 1}
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assert c.statistics().tasks_waiting == 3
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c.total_tokens += 2
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assert set(c.statistics().borrowers) == {0, 1, 2, 3}
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assert c.statistics().tasks_waiting == 1
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c.total_tokens -= 3
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assert c.borrowed_tokens == 4
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assert c.total_tokens == 1
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c.release_on_behalf_of(0)
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c.release_on_behalf_of(1)
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c.release_on_behalf_of(2)
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assert set(c.statistics().borrowers) == {3}
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assert c.statistics().tasks_waiting == 1
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c.release_on_behalf_of(3)
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assert set(c.statistics().borrowers) == {4}
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assert c.statistics().tasks_waiting == 0
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# regression test for issue #548
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async def test_CapacityLimiter_memleak_548():
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limiter = CapacityLimiter(total_tokens=1)
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await limiter.acquire()
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async with _core.open_nursery() as n:
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n.start_soon(limiter.acquire)
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await wait_all_tasks_blocked() # give it a chance to run the task
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n.cancel_scope.cancel()
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# if this is 1, the acquire call (despite being killed) is still there in the task, and will
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# leak memory all the while the limiter is active
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assert len(limiter._pending_borrowers) == 0
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async def test_Semaphore():
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with pytest.raises(TypeError):
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Semaphore(1.0)
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with pytest.raises(ValueError):
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Semaphore(-1)
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s = Semaphore(1)
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repr(s) # smoke test
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assert s.value == 1
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assert s.max_value is None
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s.release()
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assert s.value == 2
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assert s.statistics().tasks_waiting == 0
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s.acquire_nowait()
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assert s.value == 1
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with assert_checkpoints():
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await s.acquire()
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assert s.value == 0
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with pytest.raises(_core.WouldBlock):
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s.acquire_nowait()
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s.release()
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assert s.value == 1
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with assert_checkpoints():
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async with s:
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assert s.value == 0
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assert s.value == 1
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s.acquire_nowait()
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record = []
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async def do_acquire(s):
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record.append("started")
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await s.acquire()
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record.append("finished")
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async with _core.open_nursery() as nursery:
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nursery.start_soon(do_acquire, s)
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await wait_all_tasks_blocked()
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assert record == ["started"]
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assert s.value == 0
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s.release()
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# Fairness:
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assert s.value == 0
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with pytest.raises(_core.WouldBlock):
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s.acquire_nowait()
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assert record == ["started", "finished"]
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async def test_Semaphore_bounded():
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with pytest.raises(TypeError):
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Semaphore(1, max_value=1.0)
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with pytest.raises(ValueError):
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Semaphore(2, max_value=1)
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bs = Semaphore(1, max_value=1)
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assert bs.max_value == 1
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repr(bs) # smoke test
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with pytest.raises(ValueError):
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bs.release()
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assert bs.value == 1
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bs.acquire_nowait()
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assert bs.value == 0
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bs.release()
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assert bs.value == 1
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@pytest.mark.parametrize("lockcls", [Lock, StrictFIFOLock], ids=lambda fn: fn.__name__)
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async def test_Lock_and_StrictFIFOLock(lockcls):
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l = lockcls() # noqa
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assert not l.locked()
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# make sure locks can be weakref'ed (gh-331)
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r = weakref.ref(l)
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assert r() is l
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repr(l) # smoke test
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# make sure repr uses the right name for subclasses
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assert lockcls.__name__ in repr(l)
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with assert_checkpoints():
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async with l:
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assert l.locked()
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repr(l) # smoke test (repr branches on locked/unlocked)
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assert not l.locked()
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l.acquire_nowait()
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assert l.locked()
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l.release()
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assert not l.locked()
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with assert_checkpoints():
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await l.acquire()
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assert l.locked()
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l.release()
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assert not l.locked()
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l.acquire_nowait()
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with pytest.raises(RuntimeError):
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# Error out if we already own the lock
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l.acquire_nowait()
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l.release()
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with pytest.raises(RuntimeError):
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# Error out if we don't own the lock
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l.release()
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holder_task = None
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async def holder():
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nonlocal holder_task
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holder_task = _core.current_task()
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async with l:
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await sleep_forever()
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async with _core.open_nursery() as nursery:
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assert not l.locked()
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nursery.start_soon(holder)
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await wait_all_tasks_blocked()
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assert l.locked()
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# WouldBlock if someone else holds the lock
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with pytest.raises(_core.WouldBlock):
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l.acquire_nowait()
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# Can't release a lock someone else holds
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with pytest.raises(RuntimeError):
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l.release()
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statistics = l.statistics()
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print(statistics)
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assert statistics.locked
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assert statistics.owner is holder_task
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assert statistics.tasks_waiting == 0
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nursery.start_soon(holder)
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await wait_all_tasks_blocked()
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statistics = l.statistics()
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print(statistics)
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assert statistics.tasks_waiting == 1
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nursery.cancel_scope.cancel()
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statistics = l.statistics()
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assert not statistics.locked
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assert statistics.owner is None
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assert statistics.tasks_waiting == 0
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async def test_Condition():
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with pytest.raises(TypeError):
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Condition(Semaphore(1))
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with pytest.raises(TypeError):
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Condition(StrictFIFOLock)
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l = Lock() # noqa
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c = Condition(l)
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assert not l.locked()
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assert not c.locked()
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with assert_checkpoints():
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await c.acquire()
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assert l.locked()
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assert c.locked()
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c = Condition()
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assert not c.locked()
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c.acquire_nowait()
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assert c.locked()
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with pytest.raises(RuntimeError):
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c.acquire_nowait()
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c.release()
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with pytest.raises(RuntimeError):
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# Can't wait without holding the lock
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await c.wait()
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with pytest.raises(RuntimeError):
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# Can't notify without holding the lock
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c.notify()
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with pytest.raises(RuntimeError):
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# Can't notify without holding the lock
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c.notify_all()
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finished_waiters = set()
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async def waiter(i):
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async with c:
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await c.wait()
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finished_waiters.add(i)
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async with _core.open_nursery() as nursery:
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for i in range(3):
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nursery.start_soon(waiter, i)
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await wait_all_tasks_blocked()
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async with c:
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c.notify()
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assert c.locked()
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await wait_all_tasks_blocked()
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assert finished_waiters == {0}
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async with c:
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c.notify_all()
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await wait_all_tasks_blocked()
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assert finished_waiters == {0, 1, 2}
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finished_waiters = set()
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async with _core.open_nursery() as nursery:
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for i in range(3):
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nursery.start_soon(waiter, i)
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await wait_all_tasks_blocked()
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async with c:
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c.notify(2)
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statistics = c.statistics()
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print(statistics)
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assert statistics.tasks_waiting == 1
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assert statistics.lock_statistics.tasks_waiting == 2
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# exiting the context manager hands off the lock to the first task
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assert c.statistics().lock_statistics.tasks_waiting == 1
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await wait_all_tasks_blocked()
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assert finished_waiters == {0, 1}
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async with c:
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c.notify_all()
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# After being cancelled still hold the lock (!)
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# (Note that c.__aexit__ checks that we hold the lock as well)
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with _core.CancelScope() as scope:
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async with c:
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scope.cancel()
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try:
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await c.wait()
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finally:
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assert c.locked()
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from .._sync import AsyncContextManagerMixin
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from .._channel import open_memory_channel
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# Three ways of implementing a Lock in terms of a channel. Used to let us put
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# the channel through the generic lock tests.
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class ChannelLock1(AsyncContextManagerMixin):
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def __init__(self, capacity):
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self.s, self.r = open_memory_channel(capacity)
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for _ in range(capacity - 1):
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self.s.send_nowait(None)
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def acquire_nowait(self):
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self.s.send_nowait(None)
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async def acquire(self):
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await self.s.send(None)
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def release(self):
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self.r.receive_nowait()
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class ChannelLock2(AsyncContextManagerMixin):
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def __init__(self):
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self.s, self.r = open_memory_channel(10)
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self.s.send_nowait(None)
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def acquire_nowait(self):
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self.r.receive_nowait()
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async def acquire(self):
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await self.r.receive()
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def release(self):
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self.s.send_nowait(None)
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class ChannelLock3(AsyncContextManagerMixin):
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def __init__(self):
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self.s, self.r = open_memory_channel(0)
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# self.acquired is true when one task acquires the lock and
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# only becomes false when it's released and no tasks are
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# waiting to acquire.
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self.acquired = False
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def acquire_nowait(self):
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assert not self.acquired
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self.acquired = True
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async def acquire(self):
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if self.acquired:
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await self.s.send(None)
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else:
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self.acquired = True
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await _core.checkpoint()
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def release(self):
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try:
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self.r.receive_nowait()
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except _core.WouldBlock:
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assert self.acquired
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self.acquired = False
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lock_factories = [
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lambda: CapacityLimiter(1),
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lambda: Semaphore(1),
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Lock,
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StrictFIFOLock,
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lambda: ChannelLock1(10),
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lambda: ChannelLock1(1),
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ChannelLock2,
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ChannelLock3,
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]
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lock_factory_names = [
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"CapacityLimiter(1)",
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"Semaphore(1)",
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"Lock",
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"StrictFIFOLock",
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"ChannelLock1(10)",
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"ChannelLock1(1)",
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"ChannelLock2",
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"ChannelLock3",
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]
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generic_lock_test = pytest.mark.parametrize(
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"lock_factory", lock_factories, ids=lock_factory_names
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)
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# Spawn a bunch of workers that take a lock and then yield; make sure that
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# only one worker is ever in the critical section at a time.
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@generic_lock_test
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async def test_generic_lock_exclusion(lock_factory):
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LOOPS = 10
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WORKERS = 5
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in_critical_section = False
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acquires = 0
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async def worker(lock_like):
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nonlocal in_critical_section, acquires
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for _ in range(LOOPS):
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async with lock_like:
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acquires += 1
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assert not in_critical_section
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in_critical_section = True
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await _core.checkpoint()
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await _core.checkpoint()
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assert in_critical_section
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in_critical_section = False
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async with _core.open_nursery() as nursery:
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lock_like = lock_factory()
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for _ in range(WORKERS):
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nursery.start_soon(worker, lock_like)
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assert not in_critical_section
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assert acquires == LOOPS * WORKERS
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# Several workers queue on the same lock; make sure they each get it, in
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# order.
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@generic_lock_test
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async def test_generic_lock_fifo_fairness(lock_factory):
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initial_order = []
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record = []
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LOOPS = 5
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async def loopy(name, lock_like):
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# Record the order each task was initially scheduled in
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initial_order.append(name)
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for _ in range(LOOPS):
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async with lock_like:
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record.append(name)
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lock_like = lock_factory()
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async with _core.open_nursery() as nursery:
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nursery.start_soon(loopy, 1, lock_like)
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nursery.start_soon(loopy, 2, lock_like)
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nursery.start_soon(loopy, 3, lock_like)
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# The first three could be in any order due to scheduling randomness,
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# but after that they should repeat in the same order
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for i in range(LOOPS):
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assert record[3 * i : 3 * (i + 1)] == initial_order
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@generic_lock_test
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async def test_generic_lock_acquire_nowait_blocks_acquire(lock_factory):
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lock_like = lock_factory()
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record = []
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async def lock_taker():
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record.append("started")
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async with lock_like:
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pass
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record.append("finished")
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async with _core.open_nursery() as nursery:
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lock_like.acquire_nowait()
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nursery.start_soon(lock_taker)
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await wait_all_tasks_blocked()
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assert record == ["started"]
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lock_like.release()
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