ai-showcase-platform/lib/database-monitor.ts

// =====================================================
// 資料庫連線監控工具
// =====================================================

import { db } from './database';

export class DatabaseMonitor {
  private static instance: DatabaseMonitor;
  private connectionCount = 0;
  private maxConnections = 0;
  private isMonitoring = false;
  private monitorInterval: NodeJS.Timeout | null = null;

  private constructor() {}

  public static getInstance(): DatabaseMonitor {
    if (!DatabaseMonitor.instance) {
      DatabaseMonitor.instance = new DatabaseMonitor();
    }
    return DatabaseMonitor.instance;
  }

  // 開始監控
  public startMonitoring(intervalMs: number = 30000) {
    if (this.isMonitoring) {
      console.log('⚠️ 資料庫監控已在運行中');
      return;
    }

    this.isMonitoring = true;
    console.log('🔍 開始監控資料庫連線狀態...');

    this.monitorInterval = setInterval(async () => {
      await this.checkConnectionStatus();
    }, intervalMs);

    // 立即執行一次檢查
    this.checkConnectionStatus();
  }

  // 停止監控
  public stopMonitoring() {
    if (this.monitorInterval) {
      clearInterval(this.monitorInterval);
      this.monitorInterval = null;
    }
    this.isMonitoring = false;
    console.log('⏹️ 資料庫監控已停止');
  }

  // 檢查連線狀態
  private async checkConnectionStatus() {
    try {
      // 檢查當前連線數
      const statusResult = await db.queryOne(`
        SHOW STATUS LIKE 'Threads_connected'
      `);
      
      const currentConnections = statusResult?.Value || 0;
      this.connectionCount = parseInt(currentConnections);

      // 檢查最大連線數
      const maxConnResult = await db.queryOne(`
        SHOW VARIABLES LIKE 'max_connections'
      `);
      
      this.maxConnections = parseInt(maxConnResult?.Value || '100');

      // 檢查連線使用率
      const usagePercentage = (this.connectionCount / this.maxConnections) * 100;

      // 記錄狀態
      console.log(`📊 資料庫連線狀態: ${this.connectionCount}/${this.maxConnections} (${usagePercentage.toFixed(1)}%)`);

      // 警告檢查
      if (usagePercentage > 80) {
        console.warn(`⚠️ 資料庫連線使用率過高: ${usagePercentage.toFixed(1)}%`);
      } else if (usagePercentage > 60) {
        console.log(`⚠️ 資料庫連線使用率較高: ${usagePercentage.toFixed(1)}%`);
      }

      // 檢查長時間運行的查詢
      await this.checkLongRunningQueries();

    } catch (error) {
      console.error('❌ 資料庫監控錯誤:', error);
    }
  }

  // 檢查長時間運行的查詢
  private async checkLongRunningQueries() {
    try {
      const longQueries = await db.query(`
        SELECT 
          ID,
          USER,
          HOST,
          DB,
          COMMAND,
          TIME,
          STATE,
          INFO
        FROM information_schema.PROCESSLIST 
        WHERE TIME > 30 
        AND COMMAND != 'Sleep'
        ORDER BY TIME DESC
        LIMIT 5
      `);

      if (longQueries.length > 0) {
        console.warn(`⚠️ 發現 ${longQueries.length} 個長時間運行的查詢:`);
        longQueries.forEach((query, index) => {
          console.warn(`  ${index + 1}. 用戶: ${query.USER}, 時間: ${query.TIME}s, 狀態: ${query.STATE}`);
          if (query.INFO && query.INFO.length > 100) {
            console.warn(`     查詢: ${query.INFO.substring(0, 100)}...`);
          } else if (query.INFO) {
            console.warn(`     查詢: ${query.INFO}`);
          }
        });
      }
    } catch (error) {
      console.error('❌ 檢查長時間查詢時發生錯誤:', error);
    }
  }

  // 獲取連線統計
  public getConnectionStats() {
    return {
      currentConnections: this.connectionCount,
      maxConnections: this.maxConnections,
      usagePercentage: (this.connectionCount / this.maxConnections) * 100,
      isMonitoring: this.isMonitoring
    };
  }

  // 強制釋放空閒連線
  public async releaseIdleConnections() {
    try {
      const result = await db.query(`
        KILL 
        (SELECT GROUP_CONCAT(ID) 
         FROM information_schema.PROCESSLIST 
         WHERE COMMAND = 'Sleep' 
         AND TIME > 300)
      `);
      
      console.log('🔄 已嘗試釋放空閒連線');
      return true;
    } catch (error) {
      console.error('❌ 釋放空閒連線失敗:', error);
      return false;
    }
  }

  // 獲取連線池狀態
  public getPoolStatus() {
    // 這裡可以添加更多連線池狀態信息
    return {
      isMonitoring: this.isMonitoring,
      lastCheck: new Date().toISOString()
    };
  }
}

// 導出單例實例
export const dbMonitor = DatabaseMonitor.getInstance();