Question

我想在我的主index.js中优雅地停止process.on('SIGINT', handler)上的postgres数据库。

使用Node Postgres，我正在使用一个包含4个客户端的池。在阅读了标题为shut it down的文档以关闭池之后，我需要先发布客户端。

从导出的pool本身（module.exports.pool = pool;），如何访问池中的客户端来执行此操作？这就是我启动postgres db，创建池并将其导出到其他模块的方法。

const colors = require('colors');
const pg = require('pg');

if (process.env.DOLPHIN_TEST) {
  var dbName = 'test_dolphin_db';
  var maxCon = 1
} else {
  var dbName = 'dev_dolphin_db';
  var maxCon = 4
}

const config = {
  user: 'postgres',
  database: dbName,
  host: 'localhost',
  max: maxCon,
  idleTimeoutMillis: 30000
}

const pool = new pg.Pool(config);

function poolConnected(err, client, done, resolve) {
  if(err) {
    return promiseArgs.reject(`error fetching client from pool ${err}`);
  }
  client.query('SELECT $1::int AS number', ['1'], function(err, result) {
    //call `done()` to release the client back to the pool
    done();

    if(err) {
      return console.error('error running query', err);
    }

    console.log(colors.grey(
      `Postgres is online using ${client.database} as user ${client.user}\n` + 
      `and is listening on ${client.host}`));
    promiseArgs.resolve();
  });
}

var promiseArgs = { resolve: undefined, reject: undefined };  

function initDb() {
  var promise = new Promise(function(resolve, reject) {
    promiseArgs.resolve = resolve;
    promiseArgs.reject = reject;

    pool.connect(poolConnected);

    pool.on('error', function (err, client) {
      // if an error is encountered by a client while it sits idle in the pool
      // the pool itself will emit an error event with both the error and
      // the client which emitted the original error
      // this is a rare occurrence but can happen if there is a network partition
      // between your application and the database, the database restarts, etc.
      // and so you might want to handle it and at least log it out
      console.error('idle client error', err.message, err.stack)
    });
  });
  return promise;
}

module.exports.pool = pool;
module.exports.initDb = initDb;

Node Postgres - 在关闭池之前释放池中的客户端

0 个答案: