Daemon-MCP

# daem0nmcp/rwlock.py """Async read-write lock for concurrent context access.""" import asyncio from contextlib import asynccontextmanager from typing import AsyncIterator class RWLock: """ Async read-write lock implementation. Multiple readers can hold the lock simultaneously. Writers have exclusive access. This implementation uses asyncio.Condition for coordination: - Readers wait while a writer is active - Writers wait while readers are active or another writer is active - When a writer releases, all waiting readers and one waiting writer are notified Example usage: lock = RWLock() # Multiple readers can access concurrently async with lock.read(): data = await read_shared_resource() # Writer gets exclusive access async with lock.write(): await modify_shared_resource() """ def __init__(self): self._read_ready = asyncio.Condition() self._readers = 0 self._writer = False @asynccontextmanager async def read(self) -> AsyncIterator[None]: """ Acquire read lock. Multiple readers can hold the lock simultaneously. Blocks while a writer holds the lock. """ async with self._read_ready: while self._writer: await self._read_ready.wait() self._readers += 1 try: yield finally: async with self._read_ready: self._readers -= 1 if self._readers == 0: self._read_ready.notify_all() @asynccontextmanager async def write(self) -> AsyncIterator[None]: """ Acquire write lock (exclusive). Only one writer can hold the lock. Blocks while any readers or another writer holds the lock. """ async with self._read_ready: while self._writer or self._readers > 0: await self._read_ready.wait() self._writer = True try: yield finally: async with self._read_ready: self._writer = False self._read_ready.notify_all() @property def readers(self) -> int: """Current number of active readers.""" return self._readers @property def writing(self) -> bool: """Whether a writer currently holds the lock.""" return self._writer