mirror of https://github.com/Garmelon/PFERD.git
98 lines
2.7 KiB
Python
98 lines
2.7 KiB
Python
import asyncio
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import time
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from contextlib import asynccontextmanager
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from dataclasses import dataclass
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from typing import AsyncIterator, Optional
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@dataclass
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class Slot:
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active: bool = False
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last_left: Optional[float] = None
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class Limiter:
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def __init__(
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self,
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task_limit: int,
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download_limit: int,
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task_delay: float
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):
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if task_limit <= 0:
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raise ValueError("task limit must be at least 1")
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if download_limit <= 0:
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raise ValueError("download limit must be at least 1")
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if download_limit > task_limit:
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raise ValueError("download limit can't be greater than task limit")
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if task_delay < 0:
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raise ValueError("Task delay must not be negative")
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self._slots = [Slot() for _ in range(task_limit)]
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self._downloads = download_limit
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self._delay = task_delay
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self._condition = asyncio.Condition()
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def _acquire_slot(self) -> Optional[Slot]:
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for slot in self._slots:
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if not slot.active:
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slot.active = True
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return slot
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return None
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async def _wait_for_slot_delay(self, slot: Slot) -> None:
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if slot.last_left is not None:
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delay = slot.last_left + self._delay - time.time()
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if delay > 0:
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await asyncio.sleep(delay)
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def _release_slot(self, slot: Slot) -> None:
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slot.last_left = time.time()
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slot.active = False
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@asynccontextmanager
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async def limit_crawl(self) -> AsyncIterator[None]:
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slot: Slot
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async with self._condition:
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while True:
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if found_slot := self._acquire_slot():
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slot = found_slot
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break
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await self._condition.wait()
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await self._wait_for_slot_delay(slot)
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try:
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yield
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finally:
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async with self._condition:
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self._release_slot(slot)
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self._condition.notify_all()
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@asynccontextmanager
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async def limit_download(self) -> AsyncIterator[None]:
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slot: Slot
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async with self._condition:
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while True:
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if self._downloads <= 0:
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await self._condition.wait()
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continue
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if found_slot := self._acquire_slot():
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slot = found_slot
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self._downloads -= 1
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break
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await self._condition.wait()
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await self._wait_for_slot_delay(slot)
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try:
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yield
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finally:
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async with self._condition:
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self._release_slot(slot)
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self._downloads += 1
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self._condition.notify_all()
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