Harvey
97 lines
3.2 KiB
Python
97 lines
3.2 KiB
Python
import asyncio
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from enum import IntEnum
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from typing import Optional
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from datetime import datetime
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class RequestPriority(IntEnum):
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USER_INITIATED = 0
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IMAGE_FETCH = 1
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PREFETCH_VISIBLE = 2
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BACKGROUND_SYNC = 3
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OPPORTUNISTIC = 4
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class PriorityQueueManager:
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_instance: Optional['PriorityQueueManager'] = None
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def __new__(cls):
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if cls._instance is None:
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cls._instance = super().__new__(cls)
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cls._instance._initialized = False
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return cls._instance
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def __init__(self):
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if self._initialized:
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return
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self._user_semaphore = asyncio.Semaphore(20)
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self._image_semaphore = asyncio.Semaphore(10)
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self._background_semaphore = asyncio.Semaphore(5)
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self._user_activity_flag = False
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self._user_activity_timestamp = 0.0
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self._user_activity_timeout = 2.0
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self._user_activity_event = asyncio.Event()
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self._background_waiters = 0
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self._initialized = True
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async def acquire_slot(self, priority: RequestPriority) -> asyncio.Semaphore:
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if priority == RequestPriority.USER_INITIATED:
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self._mark_user_activity()
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return self._user_semaphore
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elif priority == RequestPriority.IMAGE_FETCH:
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return self._image_semaphore
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else:
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await self._wait_for_user_inactivity()
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return self._background_semaphore
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def _mark_user_activity(self):
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self._user_activity_flag = True
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self._user_activity_timestamp = datetime.now().timestamp()
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self._user_activity_event.clear()
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async def _wait_for_user_inactivity(self):
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self._background_waiters += 1
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try:
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while self._user_activity_flag:
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current = datetime.now().timestamp()
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elapsed = current - self._user_activity_timestamp
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if elapsed >= self._user_activity_timeout:
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self._user_activity_flag = False
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self._user_activity_event.set()
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break
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wait_time = self._user_activity_timeout - elapsed
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try:
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await asyncio.wait_for(
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self._user_activity_event.wait(),
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timeout=wait_time + 0.1
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)
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except asyncio.TimeoutError:
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pass
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finally:
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self._background_waiters -= 1
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def mark_user_activity(self):
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self._mark_user_activity()
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def is_user_active(self) -> bool:
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current = datetime.now().timestamp()
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if current - self._user_activity_timestamp > self._user_activity_timeout:
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self._user_activity_flag = False
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return self._user_activity_flag
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def get_stats(self) -> dict:
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return {
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'user_slots_available': self._user_semaphore._value,
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'image_slots_available': self._image_semaphore._value,
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'background_slots_available': self._background_semaphore._value,
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'user_active': self.is_user_active(),
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'background_waiters': self._background_waiters
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}
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def get_priority_queue() -> PriorityQueueManager:
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return PriorityQueueManager()
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