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https://github.com/Garmelon/PFERD.git
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2034c9d426
This commit moves exceptions and some other things into utils.py and renames files according to python's file naming guides (kinda). It also adds a new example config using the new FfM downloader.
81 lines
2.2 KiB
Python
81 lines
2.2 KiB
Python
# From https://charemza.name/blog/posts/python/asyncio/read-write-lock/
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# https://gist.github.com/michalc/ab9bd571cfab09216c0316f2302a76b0#file-asyncio_read_write_lock-py
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import asyncio
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import collections
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import contextlib
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class _ReadWaiter(asyncio.Future):
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pass
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class _WriteWaiter(asyncio.Future):
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pass
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class ReadWriteLock():
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def __init__(self):
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self._waiters = collections.deque()
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self._reads_held = 0
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self._write_held = False
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def _pop_queued_waiters(self, waiter_type):
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while True:
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correct_type = self._waiters and isinstance(self._waiters[0], waiter_type)
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cancelled = self._waiters and self._waiters[0].cancelled()
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if correct_type or cancelled:
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waiter = self._waiters.popleft()
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if correct_type and not cancelled:
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yield waiter
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if not correct_type and not cancelled:
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break
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def _resolve_queued_waiters(self):
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if not self._write_held:
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for waiter in self._pop_queued_waiters(_ReadWaiter):
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self._reads_held += 1
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waiter.set_result(None)
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if not self._write_held and not self._reads_held:
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for waiter in self._pop_queued_waiters(_WriteWaiter):
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self._write_held = True
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waiter.set_result(None)
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break
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def _on_read_release(self):
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self._reads_held -= 1
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def _on_write_release(self):
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self._write_held = False
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@contextlib.asynccontextmanager
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async def _acquire(self, waiter_type, on_release):
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waiter = waiter_type()
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self._waiters.append(waiter)
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self._resolve_queued_waiters()
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try:
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await waiter
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except asyncio.CancelledError:
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self._resolve_queued_waiters()
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raise
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try:
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yield
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finally:
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on_release()
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self._resolve_queued_waiters()
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@contextlib.asynccontextmanager
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async def read(self):
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async with self._acquire(_ReadWaiter, self._on_read_release):
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yield
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@contextlib.asynccontextmanager
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async def write(self):
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async with self._acquire(_WriteWaiter, self._on_write_release):
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yield
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