80 lines
2.5 KiB
JavaScript
80 lines
2.5 KiB
JavaScript
"use strict";
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Object.defineProperty(exports, "__esModule", { value: true });
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exports.Locks = void 0;
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const defaultStore = typeof window === 'object' && window && typeof window.localStorage === 'object' ? window.localStorage : null;
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let _locks;
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/**
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* Creates a lock manager, which can create exclusive locks across browser tabs.
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* Uses `window.localStorage` by default to lock across tabs.
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*
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* Below example, will wait for 5 seconds to acquire a lock, and then execute
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* the function once lock is acquired and release the lock after function
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* execution. It will fail with `LOCK_TIMEOUT` error if lock is not acquired
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* within the 5 seconds. The lock will acquired for 2 seconds (default 1000ms).
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*
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* ```ts
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* Locks.get().lock('my-lock', 2000, 5000)(async () => {
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* console.log('Lock acquired');
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* });
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* ```
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*/
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class Locks {
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constructor(store = defaultStore || {}, now = Date.now, pfx = 'lock-') {
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this.store = store;
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this.now = now;
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this.pfx = pfx;
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}
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acquire(id, ms = 1000) {
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if (ms <= 0)
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return;
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const key = this.pfx + id;
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const lockUntil = this.store[key];
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const now = this.now();
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const isLocked = lockUntil !== undefined && parseInt(lockUntil, 36) > now;
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if (isLocked)
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return;
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const lockUntilNex = (now + ms).toString(36);
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this.store[key] = lockUntilNex;
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const unlock = () => {
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if (this.store[key] === lockUntilNex)
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delete this.store[key];
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};
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return unlock;
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}
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isLocked(id) {
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const key = this.pfx + id;
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const lockUntil = this.store[key];
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if (lockUntil === undefined)
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return false;
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const now = this.now();
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const lockUntilNum = parseInt(lockUntil, 36);
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return lockUntilNum > now;
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}
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lock(id, ms, timeoutMs = 2 * 1000, checkMs = 10) {
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return async (fn) => {
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const timeout = this.now() + timeoutMs;
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let unlock;
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while (!unlock) {
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unlock = this.acquire(id, ms);
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if (unlock)
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break;
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await new Promise((r) => setTimeout(r, checkMs));
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if (this.now() > timeout)
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throw new Error('LOCK_TIMEOUT');
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}
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try {
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return await fn();
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}
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finally {
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unlock();
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}
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};
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}
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}
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exports.Locks = Locks;
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Locks.get = () => {
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if (!_locks)
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_locks = new Locks();
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return _locks;
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};
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