nodedb-json/dist/esm/storage/file-lock.js

A lightweight JSON-based database for Node.js with TypeScript support, indexing, and complex query capabilities

import * as fs from 'fs';
import * as path from 'path';
import { FileLockError } from '../errors/file-lock-error.js';
import { ensureParentDirectory } from './atomic-writer.js';
const activeLocks = new Map();
let exitHookInstalled = false;
export class FileLock {
    constructor(options) {
        this.acquired = false;
        this.lockPath = options.lockPath;
        this.enabled = options.enabled;
        this.staleLockMs = options.staleLockMs;
        this.lockId = `${process.pid}:${Date.now()}:${Math.random().toString(16).slice(2)}`;
    }
    acquire() {
        if (!this.enabled || this.acquired) {
            return;
        }
        ensureParentDirectory(this.lockPath);
        this.removeStaleLock();
        try {
            fs.writeFileSync(this.lockPath, this.createLockPayload(), {
                encoding: 'utf-8',
                flag: 'wx'
            });
            this.acquired = true;
            activeLocks.set(this.lockPath, this.lockId);
            installExitHook();
        }
        catch (error) {
            if ((error === null || error === void 0 ? void 0 : error.code) === 'EEXIST') {
                throw new FileLockError(this.lockPath);
            }
            throw error;
        }
    }
    release() {
        if (!this.enabled || !this.acquired) {
            return;
        }
        this.acquired = false;
        activeLocks.delete(this.lockPath);
        unlinkLockFile(this.lockPath, this.lockId);
    }
    get path() {
        return this.lockPath;
    }
    removeStaleLock() {
        if (!this.staleLockMs || this.staleLockMs <= 0 || !fs.existsSync(this.lockPath)) {
            return;
        }
        const stat = fs.statSync(this.lockPath);
        if (Date.now() - stat.mtimeMs < this.staleLockMs) {
            return;
        }
        const lockOwnerPid = readLockOwnerPid(this.lockPath);
        if (lockOwnerPid === undefined || !isProcessAlive(lockOwnerPid)) {
            fs.unlinkSync(this.lockPath);
        }
    }
    createLockPayload() {
        return `${JSON.stringify({
            pid: process.pid,
            id: this.lockId,
            cwd: process.cwd(),
            file: path.resolve(this.lockPath),
            createdAt: new Date().toISOString()
        }, null, 2)}\n`;
    }
}
function readLockOwnerPid(lockPath) {
    try {
        const content = fs.readFileSync(lockPath, 'utf-8');
        const parsed = JSON.parse(content);
        return Number.isInteger(parsed.pid) && parsed.pid > 0 ? parsed.pid : undefined;
    }
    catch (_a) {
        return undefined;
    }
}
function isProcessAlive(pid) {
    try {
        process.kill(pid, 0);
        return true;
    }
    catch (error) {
        return (error === null || error === void 0 ? void 0 : error.code) === 'EPERM';
    }
}
function installExitHook() {
    if (exitHookInstalled) {
        return;
    }
    exitHookInstalled = true;
    process.once('exit', () => {
        for (const [lockPath, lockId] of activeLocks) {
            try {
                unlinkLockFile(lockPath, lockId);
            }
            catch (_a) {
                // Process exit cleanup is best-effort.
            }
        }
        activeLocks.clear();
    });
}
function unlinkLockFile(lockPath, expectedId) {
    try {
        const content = fs.readFileSync(lockPath, 'utf-8');
        const parsed = JSON.parse(content);
        if (parsed.id !== expectedId) {
            return;
        }
        fs.unlinkSync(lockPath);
    }
    catch (error) {
        if ((error === null || error === void 0 ? void 0 : error.code) !== 'ENOENT') {
            throw error;
        }
    }
}
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