examples/session-pool.ts

/**
 * SessionPool Example
 * 
 * This example demonstrates how to use SessionPool for efficient connection
 * management in high-concurrency scenarios, including explicit session management.
 */

import { SessionPool, PoolConfigBuilder } from '../src';

async function main() {
  console.log('=== SessionPool Example ===\n');

  // Method 1: Traditional constructor (backward compatible)
  console.log('Creating session pool using traditional constructor...');
  const pool1 = new SessionPool('localhost', 6667, {
    username: 'root',
    password: 'root',
    maxPoolSize: 10,
    minPoolSize: 2,
    maxIdleTime: 60000,
    waitTimeout: 60000,
  });

  // Method 2: Using Builder pattern (recommended)
  console.log('Creating session pool using Builder pattern...');
  const pool2 = new SessionPool(
    new PoolConfigBuilder()
      .host('localhost')
      .port(6667)
      .username('root')
      .password('root')
      .maxPoolSize(10)
      .minPoolSize(2)
      .maxIdleTime(60000)
      .waitTimeout(60000)
      .build()
  );

  // For demo purposes, we'll use pool1
  const pool = pool1;

  try {
    // Initialize the pool
    console.log('\nInitializing session pool...');
    await pool.init();
    console.log('Pool initialized with', pool.getPoolSize(), 'connections');

    // Create database
    console.log('\nCreating database...');
    await pool.executeNonQueryStatement('CREATE DATABASE root.pool_example');

    // Create timeseries
    console.log('Creating timeseries...');
    await pool.executeNonQueryStatement(
      'CREATE TIMESERIES root.pool_example.sensor1.value WITH DATATYPE=FLOAT'
    );

    // Approach 1: Using pool methods directly (automatic session management)
    console.log('\n--- Approach 1: Automatic session management ---');
    console.log('Executing concurrent queries...');
    const promises = [];
    
    for (let i = 0; i < 20; i++) {
      promises.push(
        pool.executeQueryStatement('SHOW DATABASES').then(() => {
          console.log(`Query ${i + 1} completed`);
        })
      );
    }

    await Promise.all(promises);
    console.log('All concurrent queries completed');

    // Approach 2: Explicit session management (new API)
    console.log('\n--- Approach 2: Explicit session management ---');
    console.log('Getting a session from the pool...');
    const session = await pool.getSession();
    
    try {
      console.log('Executing operations with explicit session...');
      
      // Insert data
      await session.insertTablet({
        deviceId: 'root.pool_example.sensor1',
        measurements: ['value'],
        dataTypes: [3], // FLOAT
        timestamps: [Date.now()],
        values: [[42.5]],
      });
      console.log('Data inserted via explicit session');
      
      // Query data
      const result = await session.executeQueryStatement(
        'SELECT * FROM root.pool_example.sensor1'
      );
      console.log('Query result:', result.rows.length, 'rows');
      
    } finally {
      // Always release the session back to the pool
      pool.releaseSession(session);
      console.log('Session released back to the pool');
    }

    // Check pool statistics
    console.log('\nPool statistics:');
    console.log('Total connections:', pool.getPoolSize());
    console.log('Available connections:', pool.getAvailableSize());
    console.log('In-use connections:', pool.getInUseSize());

  } catch (error) {
    console.error('Error:', error);
  } finally {
    // Close the pool
    console.log('\nClosing session pool...');
    await pool.close();
    console.log('Pool closed');
  }
}

main().catch(console.error);