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nodejs-performance-project

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const express = require('express');
const path = require('path');
const fs = require('fs');
const { exec } = require('child_process');
const LargeFileHandler = require('./src/largeFile');
const xmlJsonHandler = require('./src/xmlJson');
const performanceMonitor = require('./src/performance');
const CoreApiDemo = require('./src/coreApiDemo');

const app = express();
const PORT = 7860;

const DATA_DIR = path.join(__dirname, 'data');

// Ensure data directory exists
if (!fs.existsSync(DATA_DIR)) {
    fs.mkdirSync(DATA_DIR);
}

const LARGE_FILE_PATH = path.join(DATA_DIR, 'large_data.csv');
const XML_FILE_PATH = path.join(DATA_DIR, 'data.xml');
const LARGE_JSON_PATH = path.join(DATA_DIR, 'large_data.json');

// Global lock to prevent concurrent demos
global.isDemoRunning = false;

// Feature 1: Large File Stream
async function runLargeFileDemo() {
    console.log('=== 1. 大文件流式处理演示 ===');
    try {
        const largeFileHandler = new LargeFileHandler(LARGE_FILE_PATH);
        const lineCount = 100000;
        console.log(`正在生成测试数据 (${lineCount} 行)...`);
        await largeFileHandler.generateTestFile(lineCount);
        console.log('开始流式处理...');
        await largeFileHandler.processFileStream();
        logMemoryUsage();
    } catch (err) {
        console.error('发生错误:', err);
    }
}

// Feature 2: XML Processing
async function runXmlDemo() {
    console.log('=== 2. XML 处理演示 ===');
    try {
        const xmlContent = xmlJsonHandler.generateXml(1000);
        fs.writeFileSync(XML_FILE_PATH, xmlContent);
        console.log(`XML 文件已保存: ${XML_FILE_PATH}`);
        const parsedXml = xmlJsonHandler.parseXml(xmlContent);
        console.log('XML 解析完成');
        logMemoryUsage();
    } catch (err) {
        console.error('发生错误:', err);
    }
}

// Feature 3: JSON Stream
async function runJsonDemo() {
    console.log('=== 3. JSON 大文件流式处理演示 ===');
    try {
        console.log('正在生成 JSON 数据...');
        await xmlJsonHandler.generateLargeJson(LARGE_JSON_PATH, 10000);
        console.log('开始流式解析 JSON...');
        await xmlJsonHandler.processLargeJsonStream(LARGE_JSON_PATH);
        logMemoryUsage();
    } catch (err) {
        console.error('发生错误:', err);
    }
}

// Feature 4: Core APIs Demo
async function runCoreApiDemo() {
    const coreDemo = new CoreApiDemo(DATA_DIR);
    await coreDemo.run();
}

function logMemoryUsage() {
    const used = process.memoryUsage();
    console.log('Memory Usage:');
    for (let key in used) {
        console.log(`${key}: ${Math.round(used[key] / 1024 / 1024 * 100) / 100} MB`);
    }
}

// Serve the main page
app.get('/', (req, res) => {
    res.send(`
        <!DOCTYPE html>
        <html>
            <head>
                <title>Node.js Performance Demo</title>
                <meta charset="utf-8">
                <style>
                    body { font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif; background: #f0f2f5; padding: 40px; color: #333; }
                    .container { max-width: 900px; margin: 0 auto; background: #fff; padding: 30px; border-radius: 8px; box-shadow: 0 4px 12px rgba(0,0,0,0.1); }
                    h1 { color: #2c3e50; margin-bottom: 20px; border-bottom: 2px solid #eee; padding-bottom: 10px; }
                    .controls { margin-bottom: 20px; display: grid; grid-template-columns: repeat(2, 1fr); gap: 15px; }
                    button { padding: 15px; font-size: 16px; cursor: pointer; background: #007bff; color: white; border: none; border-radius: 5px; transition: background 0.3s; font-weight: bold; }
                    button:hover { background: #0056b3; }
                    button:disabled { background: #ccc; cursor: not-allowed; }
                    .btn-core { background: #6610f2; }
                    .btn-core:hover { background: #520dc2; }
                    .btn-system { background: #28a745; }
                    .btn-system:hover { background: #218838; }
                    .btn-clear { background: #6c757d; }
                    .btn-clear:hover { background: #5a6268; }
                    #output { background: #1e1e1e; color: #d4d4d4; padding: 20px; border-radius: 5px; font-family: "Menlo", "Monaco", "Courier New", monospace; height: 500px; overflow-y: auto; white-space: pre-wrap; font-size: 14px; line-height: 1.5; border: 1px solid #333; }
                    .status { margin-top: 10px; font-style: italic; color: #666; }
                </style>
            </head>
            <body>
                <div class="container">
                    <h1>Node.js Performance Demo</h1>
                    <div class="controls">
                        <button onclick="runDemo('large-file')">📄 1. 大文件流式处理</button>
                        <button onclick="runDemo('xml')">🏷️ 2. XML 解析处理</button>
                        <button onclick="runDemo('json')">📦 3. JSON 流式解析</button>
                        <button onclick="getSystemInfo()" class="btn-system">🖥️ 4. 系统信息 (child_process)</button>
                        <button onclick="runDemo('core-api')" class="btn-core">🛠️ 5. 核心 API 综合演示</button>
                        <button onclick="clearOutput()" class="btn-clear">🗑 清空输出</button>
                    </div>
                    <div id="output">点击上方按钮开始测试...</div>
                    <div id="status" class="status"></div>
                </div>

                <script>
                    const outputDiv = document.getElementById('output');
                    const statusDiv = document.getElementById('status');
                    let isRunning = false;

                    function log(msg, isError = false) {
                        if (outputDiv.innerHTML === '点击上方按钮开始测试...') {
                            outputDiv.innerHTML = '';
                        }
                        const span = document.createElement('div');
                        span.textContent = msg;
                        if (isError) span.style.color = '#ff6b6b';
                        outputDiv.appendChild(span);
                        outputDiv.scrollTop = outputDiv.scrollHeight;
                    }

                    function clearOutput() {
                        outputDiv.innerHTML = '点击上方按钮开始测试...';
                        statusDiv.textContent = '';
                    }

                    function runDemo(type) {
                        if (isRunning) return;
                        
                        isRunning = true;
                        updateButtons(true);
                        statusDiv.textContent = '正在运行演示...';
                        
                        const eventSource = new EventSource('/api/run-demo?type=' + type);
                        
                        eventSource.onmessage = function(event) {
                            try {
                                const data = JSON.parse(event.data);
                                if (data.type === 'log') {
                                    log(data.message);
                                } else if (data.type === 'error') {
                                    log(data.message, true);
                                } else if (data.type === 'end') {
                                    eventSource.close();
                                    isRunning = false;
                                    updateButtons(false);
                                    statusDiv.textContent = '演示完成';
                                }
                            } catch (e) {
                                console.error('Error parsing SSE data', e);
                            }
                        };

                        eventSource.onerror = function(err) {
                            console.error('EventSource failed:', err);
                            eventSource.close();
                            isRunning = false;
                            updateButtons(false);
                            statusDiv.textContent = '连接中断';
                            log('Error: Connection to server lost.', true);
                        };
                    }

                    function updateButtons(disabled) {
                        const btns = document.querySelectorAll('button:not(.btn-clear)');
                        btns.forEach(btn => btn.disabled = disabled);
                    }

                    async function getSystemInfo() {
                        if (isRunning) return;
                        statusDiv.textContent = '正在获取系统信息...';
                        try {
                            const res = await fetch('/api/system-info');
                            const text = await res.text();
                            log('\\n=== 4. 系统信息 ===');
                            log(text);
                            statusDiv.textContent = '获取成功';
                        } catch (e) {
                            log('Error fetching system info: ' + e.message, true);
                        }
                    }
                </script>
            </body>
        </html>
    `);
});

// SSE Endpoint for running the demo
app.get('/api/run-demo', async (req, res) => {
    const type = req.query.type;

    if (global.isDemoRunning) {
        res.writeHead(200, {
            'Content-Type': 'text/event-stream',
            'Cache-Control': 'no-cache',
            'Connection': 'keep-alive'
        });
        res.write(`data: ${JSON.stringify({ type: 'error', message: 'Demo is already running. Please wait.' })}\n\n`);
        res.write(`data: ${JSON.stringify({ type: 'end' })}\n\n`);
        return res.end();
    }

    res.writeHead(200, {
        'Content-Type': 'text/event-stream',
        'Cache-Control': 'no-cache',
        'Connection': 'keep-alive'
    });

    global.isDemoRunning = true;

    // Helper to send SSE messages
    const send = (type, message) => {
        res.write(`data: ${JSON.stringify({ type, message })}\n\n`);
    };

    // Override console methods
    const originalConsoleLog = console.log;
    const originalConsoleError = console.error;

    console.log = (...args) => {
        const msg = args.map(arg => (typeof arg === 'object' ? JSON.stringify(arg, null, 2) : String(arg))).join(' ');
        send('log', msg);
        originalConsoleLog.apply(console, args);
    };

    console.error = (...args) => {
        const msg = args.map(arg => (typeof arg === 'object' ? JSON.stringify(arg, null, 2) : String(arg))).join(' ');
        send('error', msg);
        originalConsoleError.apply(console, args);
    };

    try {
        switch (type) {
            case 'large-file':
                await runLargeFileDemo();
                break;
            case 'xml':
                await runXmlDemo();
                break;
            case 'json':
                await runJsonDemo();
                break;
            case 'core-api':
                await runCoreApiDemo();
                break;
            default:
                console.log('未知的任务类型');
        }
    } catch (e) {
        console.error('Unhandled error:', e);
    } finally {
        // Restore console
        console.log = originalConsoleLog;
        console.error = originalConsoleError;
        global.isDemoRunning = false;
        
        send('end', 'Done');
        res.end();
    }
});

// API for system info
app.get('/api/system-info', (req, res) => {
    exec('uname -a && echo "\\nDisk Usage:" && df -h | head -n 5', (error, stdout, stderr) => {
        if (error) {
            res.status(500).send(`Error: ${error.message}`);
            return;
        }
        res.send(stdout);
    });
});

app.listen(PORT, () => {
    console.log(`Server is running on http://localhost:${PORT}`);
});