umzug/lib/file-locker.js

Framework-agnostic migration tool for Node

"use strict";
var __createBinding = (this && this.__createBinding) || (Object.create ? (function(o, m, k, k2) {
    if (k2 === undefined) k2 = k;
    var desc = Object.getOwnPropertyDescriptor(m, k);
    if (!desc || ("get" in desc ? !m.__esModule : desc.writable || desc.configurable)) {
      desc = { enumerable: true, get: function() { return m[k]; } };
    }
    Object.defineProperty(o, k2, desc);
}) : (function(o, m, k, k2) {
    if (k2 === undefined) k2 = k;
    o[k2] = m[k];
}));
var __setModuleDefault = (this && this.__setModuleDefault) || (Object.create ? (function(o, v) {
    Object.defineProperty(o, "default", { enumerable: true, value: v });
}) : function(o, v) {
    o["default"] = v;
});
var __importStar = (this && this.__importStar) || function (mod) {
    if (mod && mod.__esModule) return mod;
    var result = {};
    if (mod != null) for (var k in mod) if (k !== "default" && Object.prototype.hasOwnProperty.call(mod, k)) __createBinding(result, mod, k);
    __setModuleDefault(result, mod);
    return result;
};
Object.defineProperty(exports, "__esModule", { value: true });
exports.FileLocker = void 0;
const fs = __importStar(require("fs"));
const path = __importStar(require("path"));
/**
 * Simple locker using the filesystem. Only one lock can be held per file. An error will be thrown if the
 * lock file already exists.
 *
 * @example
 * const umzug = new Umzug({ ... })
 * FileLocker.attach(umzug, { path: 'path/to/lockfile' })
 *
 * @docs
 * To wait for the lock to be free instead of throwing, you could extend it (the below example uses `setInterval`,
 * but depending on your use-case, you may want to use a library with retry/backoff):
 *
 * @example
 * class WaitingFileLocker extends FileLocker {
 *   async getLock() {
 *     return new Promise(resolve => setInterval(
 *       () => super.getLock().then(resolve).catch(),
 *       500,
 *     )
 *   }
 * }
 *
 * const locker = new WaitingFileLocker({ path: 'path/to/lockfile' })
 * locker.attachTo(umzug)
 */
class FileLocker {
    constructor(params) {
        var _a;
        this.lockFile = params.path;
        this.fs = (_a = params.fs) !== null && _a !== void 0 ? _a : fs;
    }
    /** Attach `beforeAll` and `afterAll` events to an umzug instance which use the specified filepath */
    static attach(umzug, params) {
        const locker = new FileLocker(params);
        locker.attachTo(umzug);
    }
    /** Attach lock handlers to `beforeCommand` and `afterCommand` events on an umzug instance */
    attachTo(umzug) {
        umzug.on('beforeCommand', async () => this.getLock());
        umzug.on('afterCommand', async () => this.releaseLock());
    }
    async readFile(filepath) {
        return this.fs.promises.readFile(filepath).then(buf => buf.toString(), () => undefined);
    }
    async writeFile(filepath, content) {
        await this.fs.promises.mkdir(path.dirname(filepath), { recursive: true });
        await this.fs.promises.writeFile(filepath, content);
    }
    async removeFile(filepath) {
        await this.fs.promises.unlink(filepath);
    }
    async getLock() {
        const existing = await this.readFile(this.lockFile);
        if (existing) {
            throw new Error(`Can't acquire lock. ${this.lockFile} exists`);
        }
        await this.writeFile(this.lockFile, 'lock');
    }
    async releaseLock() {
        const existing = await this.readFile(this.lockFile);
        if (!existing) {
            throw new Error(`Nothing to unlock`);
        }
        await this.removeFile(this.lockFile);
    }
}
exports.FileLocker = FileLocker;
//# sourceMappingURL=file-locker.js.map