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/**
* Lightweight async mutex (~10 lines). Acquire returns a release function.
* When the mutex is free, acquire() resolves immediately. When held,
* callers are queued and execute serially in FIFO order.
*/
export type Mutex = {
acquire(): Promise<() => void>;
};
export const createMutex = (): Mutex => {
let queue = Promise.resolve<unknown>(undefined);
return {
async acquire(): Promise<() => void> {
let release = () => {};
const next = new Promise<void>((resolve) => {
release = resolve;
});
const prev = queue;
queue = prev.then(() => next);
await prev;
return release;
},
};
};
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