cross-process-lock/lock.js

Cross-process file locking solution with lock-queue

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.lock = exports.LockError = void 0;
const tslib_1 = require("tslib");
const logger_1 = require("./logger");
const unlock_1 = require("./unlock");
const fs_1 = require("fs");
const metadata_1 = require("./metadata");
const DEFAULT_OPTIONS = {
    lockTimeout: 12e5,
    waitTimeout: 1e4,
};
const INTERVAL = 500;
class LockError extends Error {
}
exports.LockError = LockError;
/**
 * Creates a cross-process lock for the given file, for the actual process.
 *
 * Note, that it will be only a soft-lock, the file will be locked for other
 * instances of cross-process-lock, or processes using the same API for locking.
 *
 * @param file The path of the file to lock.
 * @param options The lock options/timeout.
 * @returns The function to unlock the file.
 */
function lock(file, options = {}) {
    return tslib_1.__awaiter(this, void 0, void 0, function* () {
        options = Object.assign(Object.assign({}, DEFAULT_OPTIONS), options);
        (0, logger_1.logger)("lock file:%s", file);
        (0, logger_1.logger)("lock options:%o", options);
        if (!(0, fs_1.existsSync)(file)) {
            (0, logger_1.logger)("lock file does not exist");
            throw new Error(`The given file (${file}) does not exist!`);
        }
        const lockTime = Date.now();
        const lockFile = `${file}.lock`;
        const tryToLock = () => new Promise((resolve, reject) => {
            const now = Date.now();
            (0, logger_1.logger)("lock now:%d", now);
            if (now - lockTime >= options.waitTimeout) {
                (0, logger_1.logger)("lock too many tries");
                return reject(new LockError(`Couldn't lock file (${file}) in the given timeout (${options.waitTimeout} ms)!`));
            }
            const done = () => resolve(unlock_1.unlock.bind(null, file));
            const next = () => {
                (0, logger_1.logger)("lock schedule");
                setTimeout(() => {
                    (0, logger_1.logger)("lock schedule called");
                    tryToLock().then(done, reject);
                }, INTERVAL);
            };
            let def = Promise.resolve(null);
            if ((0, fs_1.existsSync)(lockFile)) {
                (0, logger_1.logger)("lock read metadata");
                def = (0, metadata_1.readMetadata)(lockFile);
            }
            def.then((metadata) => {
                const actual = Date.now();
                const lockedTime = metadata ? actual - metadata.lockTime : -1;
                (0, logger_1.logger)("lock metadata:%o", metadata);
                (0, logger_1.logger)("lock actual:%d lockedTime:%d", actual, lockedTime);
                if (!metadata || metadata.pID === process.pid || lockedTime > options.lockTimeout) {
                    (0, logger_1.logger)("lock locking");
                    (0, metadata_1.saveMetadata)(lockFile, lockTime).then(done, next);
                }
                else {
                    (0, logger_1.logger)("lock next iteration");
                    next();
                }
            }, next);
        });
        return tryToLock();
    });
}
exports.lock = lock;
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