349 lines
9.6 KiB
JavaScript
349 lines
9.6 KiB
JavaScript
// named-pipe-server.js
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const net = require('net');
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const fs = require('fs');
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const path = require('path');
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const { EventEmitter } = require('events');
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const async_hooks = require('async_hooks');
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const { v4: uuidv4 } = require('uuid');
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const DEFAULT_PIPE_PATH = process.platform === 'win32'? '\\\\.\\pipe\\rwlock' : '/tmp/rwlock.sock';
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/**
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* 基于命名管道的读写锁服务器
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* 提供跨进程的读写锁功能，支持多个客户端同时请求对同一资源的读锁或写锁
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* 实现读写锁的基本语义：
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* 1. 多个读操作可以同时进行
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* 2. 写操作是独占的，不允许同时进行读或其他写操作
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* 3. 锁请求按先进先出(FIFO)方式处理
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*/
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class NamedPipeLockServer extends EventEmitter {
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/**
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* 创建一个NamedPipeLockServer实例
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* @param {string} pipePath - 命名管道路径，默认值根据操作系统确定
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*/
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constructor(pipePath = DEFAULT_PIPE_PATH) {
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super();
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this.pipePath = pipePath;
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this.server = null;
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this.locks = new Map(); // resource -> { readers: Set, writer: null, queue: [] }
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this.clients = new Map(); // clientId -> socket
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}
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/**
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* 启动服务器
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* 创建并监听命名管道，处理客户端连接和消息
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*/
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start() {
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// 确保管道文件不存在（Windows）
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if (process.platform === 'win32') {
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try {
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if (fs.existsSync(this.pipePath)) {
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fs.unlinkSync(this.pipePath);
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}
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} catch (error) {
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// 忽略错误，可能管道正在使用
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}
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}
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this.server = net.createServer(socket => {
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const clientId = uuidv4();
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socket.clientId = clientId;
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this.clients.set(clientId, socket);
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console.log(`Client connected: ${clientId}`);
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socket.on('data', data => {
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try {
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const messageStrs = data.toString().split('\n');
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messageStrs.forEach(messageStr => {
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if (messageStr) {
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const message = JSON.parse(messageStr);
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this.handleMessage(clientId, message);
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}
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});
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// const message = JSON.parse();
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// this.handleMessage(clientId, message);
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} catch (error) {
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console.error('Error parsing message:', error);
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this.sendError(clientId, 'Invalid message format');
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}
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});
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socket.on('close', () => {
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this.handleClientDisconnect(clientId);
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this.clients.delete(clientId);
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console.log(`Client disconnected: ${clientId}`);
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});
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socket.on('error', error => {
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console.error(`Client error (${clientId}):`, error);
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this.handleClientDisconnect(clientId);
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this.clients.delete(clientId);
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});
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});
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// 启动命名管道服务器
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this.server.listen(this.pipePath, () => {
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console.log(`Lock server listening on named pipe: ${this.pipePath}`);
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});
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this.server.on('error', error => {
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console.error('Server error:', error);
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});
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}
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/**
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* 处理来自客户端的消息
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* @param {string} clientId - 客户端标识符
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* @param {Object} message - 消息对象
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*/
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handleMessage(clientId, message) {
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const { type, resource, requestId } = message;
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if (!this.locks.has(resource)) {
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this.locks.set(resource, {
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readers: new Set(),
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writer: null,
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queue: []
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});
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}
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const lock = this.locks.get(resource);
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switch (type) {
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case 'readLock':
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this.handleReadLock(clientId, resource, requestId, lock);
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break;
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case 'writeLock':
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this.handleWriteLock(clientId, resource, requestId, lock);
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break;
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case 'unlock':
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this.handleUnlock(clientId, resource, lock);
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break;
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default:
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this.sendError(clientId, `Unknown message type: ${type}`);
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}
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}
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/**
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* 处理读锁请求
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* @param {string} clientId - 客户端标识符
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* @param {string} resource - 资源名称
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* @param {string} requestId - 请求ID
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* @param {Object} lock - 锁对象
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*/
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handleReadLock(clientId, resource, requestId, lock) {
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if (!lock.writer) {
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// 可以立即获取读锁
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lock.readers.add(clientId);
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this.sendToClient(clientId, {
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type: 'lockGranted',
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requestId,
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resource,
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lockType: 'read'
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});
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console.log(`Read lock granted to ${clientId} for ${resource}`);
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} else {
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// 加入等待队列
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lock.queue.push({ clientId, type: 'read', requestId });
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console.log(`Read lock queued for ${clientId} for ${resource}`);
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}
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}
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/**
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* 处理写锁请求
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* @param {string} clientId - 客户端标识符
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* @param {string} resource - 资源名称
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* @param {string} requestId - 请求ID
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* @param {Object} lock - 锁对象
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*/
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handleWriteLock(clientId, resource, requestId, lock) {
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if (lock.readers.size === 0 && !lock.writer) {
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// 可以立即获取写锁
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lock.writer = clientId;
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this.sendToClient(clientId, {
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type: 'lockGranted',
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requestId,
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resource,
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lockType: 'write'
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});
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console.log(`Write lock granted to ${clientId} for ${resource}`);
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} else {
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// 加入等待队列
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lock.queue.push({ clientId, type: 'write', requestId });
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console.log(`Write lock queued for ${clientId} for ${resource}`);
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}
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}
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/**
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* 处理解锁请求
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* @param {string} clientId - 客户端标识符
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* @param {string} resource - 资源名称
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* @param {Object} lock - 锁对象
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*/
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handleUnlock(clientId, resource, lock) {
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let released = false;
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// 移除读锁
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if (lock.readers.has(clientId)) {
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lock.readers.delete(clientId);
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released = true;
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console.log(`Read lock released by ${clientId} for ${resource}`);
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}
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// 移除写锁
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if (lock.writer === clientId) {
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lock.writer = null;
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released = true;
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console.log(`Write lock released by ${clientId} for ${resource}`);
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}
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if (released) {
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// 处理等待队列
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this.processQueue(resource, lock);
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}
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}
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/**
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* 处理等待队列中的锁请求
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* 根据读写锁规则，尽可能多地授权锁请求
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* @param {string} resource - 资源名称
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* @param {Object} lock - 锁对象
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*/
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processQueue(resource, lock) {
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const granted = [];
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for (let i = 0; i < lock.queue.length; i++) {
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const request = lock.queue[i];
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if (request.type === 'read') {
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if (!lock.writer) {
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// 可以授予读锁
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lock.readers.add(request.clientId);
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this.sendToClient(request.clientId, {
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type: 'lockGranted',
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requestId: request.requestId,
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resource,
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lockType: 'read'
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});
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granted.push(i);
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console.log(`Queued read lock granted to ${request.clientId} for ${resource}`);
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} else {
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// 有写锁等待，读锁必须等待
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break;
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}
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} else { // write
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if (lock.readers.size === 0 && !lock.writer) {
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// 可以授予写锁
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lock.writer = request.clientId;
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this.sendToClient(request.clientId, {
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type: 'lockGranted',
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requestId: request.requestId,
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resource,
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lockType: 'write'
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});
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granted.push(i);
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console.log(`Queued write lock granted to ${request.clientId} for ${resource}`);
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} else {
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// 写锁必须等待前面的锁释放
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break;
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}
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}
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}
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// 移除已处理的请求
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if (granted.length > 0) {
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lock.queue = lock.queue.filter((_, index) => !granted.includes(index));
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}
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}
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/**
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* 处理客户端断开连接
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* 释放该客户端持有的所有锁，并处理相关队列
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* @param {string} clientId - 客户端标识符
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*/
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handleClientDisconnect(clientId) {
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console.log(`Processing disconnect for client: ${clientId}`);
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// 释放该客户端持有的所有锁
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for (const [resource, lock] of this.locks) {
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let released = false;
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if (lock.readers.has(clientId)) {
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lock.readers.delete(clientId);
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released = true;
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}
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if (lock.writer === clientId) {
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lock.writer = null;
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released = true;
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}
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// 如果释放了锁，重新处理队列
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if (released) {
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this.processQueue(resource, lock);
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}
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}
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}
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/**
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* 向指定客户端发送消息
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* @param {string} clientId - 客户端标识符
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* @param {Object} message - 要发送的消息对象
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*/
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sendToClient(clientId, message) {
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const socket = this.clients.get(clientId);
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if (socket && !socket.destroyed) {
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try {
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socket.write(JSON.stringify(message));
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} catch (error) {
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console.error(`Error sending to client ${clientId}:`, error);
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}
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}
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}
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/**
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* 向客户端发送错误消息
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* @param {string} clientId - 客户端标识符
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* @param {string} errorMessage - 错误信息
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*/
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sendError(clientId, errorMessage) {
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this.sendToClient(clientId, {
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type: 'error',
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message: errorMessage
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});
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}
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/**
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* 停止服务器
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*/
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stop() {
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if (this.server) {
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this.server.close();
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console.log('Lock server stopped');
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}
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}
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}
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// // 启动服务器
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// const pipePath = process.platform === 'win32'
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// ? '\\\\.\\pipe\\rwlock-server'
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// : '/tmp/rwlock.sock';
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// const server = new NamedPipeLockServer(pipePath);
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// server.start();
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// // 优雅关闭
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// process.on('SIGINT', () => {
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// console.log('Shutting down lock server...');
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// server.stop();
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// process.exit(0);
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// });
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// process.on('SIGTERM', () => {
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// console.log('Shutting down lock server...');
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// server.stop();
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// process.exit(0);
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// });
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module.exports = NamedPipeLockServer; |