devilfish-dbms/client.js

a database that based on key-value map and is successful in deal with saved in disk and high-performance in select that act as a memory-based database

const worker = require('worker_threads');
const express = require('express');
const { spawn, exec } = require('child_process');
const app = express();
const port = 3125;
const bodyParser = require('body-parser');
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: true }));
exec('dir',{encoding: 'utf8'},(error,stdout,stderr)=>{ 
    if(error){
        console.log(`error:${error.message}`);
        return;
    }
    if(stderr){
        console.log(`stderr:${stderr}`);
        return;
    }
    console.log(`stdout:${stdout}`);
});
// 处理POST请求并执行命令
app.post('/execute', (req, res) => {
    console.log(req.body);
    console.log(__dirname);
    try {
        
        console.log('Received request:', req.body);
        // 验证请求体是否为有效的JSON
        if (!req.body || typeof req.body !== 'object') {
            return res.status(400).json({error: 'Invalid request body'});
        }
        
        const { command } = req.body;
        
        if (!command) {
            return res.status(400).json({error: 'Command is required'});
        }
        console.log('Received command:', command);
        console.log(req.body);
        
        // 使用spawn启动main_database.js
        // 全局变量保存子进程实例
let childProcess;

// 初始化子进程
function initChildProcess() {
    if (!childProcess) {
        childProcess = spawn('node', ['./main_database.js'], {
            cwd: __dirname,
            stdio: ['pipe', 'pipe', 'pipe']
        });
        
        // 错误处理
        childProcess.on('error', (err) => {
            console.error('Child process error:', err);
            childProcess = null;
        });
        
        // 进程退出处理
        childProcess.on('exit', (code) => {
            console.log(`Child process exited with code ${code}`);
            childProcess = null;
        });
    }
    return childProcess;
}

// 在请求处理中使用
const process = initChildProcess();
let output = '';

// 实时收集输出
let responseSent = false;
process.stdout.on('data', (data) => {
    output += data.toString();
    
    // 当检测到完整响应时返回结果
    if (output.includes('\n') && !responseSent) {
        res.status(200).json({result: output.trim()});
        output = '';
        responseSent = true;
    }
});

process.stderr.on('data', (data) => {
    console.error('Child process stderr:', data.toString());
    if (!responseSent) {
        res.status(500).json({error: data.toString()});
        responseSent = true;
    }
});

// 发送命令
process.stdin.write(command + '\n');

// 设置超时返回部分结果
setTimeout(() => {
    if (!responseSent) {
        res.status(200).json({result: output || 'No response from database process'});
        output = '';
        responseSent = true;
    }
}, 1000);
        
    } catch (err) {
        console.error('Error processing request:', err);
        res.status(500).json({error: 'Internal server error'});
    }
});

// 启动服务器
app.listen(port, () => {
    console.log(`Server running on port ${port}`);
});