sequelize/lib/dialects/abstract/connection-manager.js

Sequelize is a promise-based Node.js ORM tool for Postgres, MySQL, MariaDB, SQLite, Microsoft SQL Server, Amazon Redshift and Snowflake’s Data Cloud. It features solid transaction support, relations, eager and lazy loading, read replication and more.

'use strict';

const { Pool, TimeoutError } = require('sequelize-pool');
const _ = require('lodash');
const semver = require('semver');
const errors = require('../../errors');
const { logger } = require('../../utils/logger');
const deprecations = require('../../utils/deprecations');
const debug = logger.debugContext('pool');

/**
 * Abstract Connection Manager
 *
 * Connection manager which handles pooling & replication.
 * Uses sequelize-pool for pooling
 *
 * @private
 */
class ConnectionManager {
  constructor(dialect, sequelize) {
    const config = _.cloneDeep(sequelize.config);

    this.sequelize = sequelize;
    this.config = config;
    this.dialect = dialect;
    this.versionPromise = null;
    this.dialectName = this.sequelize.options.dialect;

    if (config.pool === false) {
      throw new Error('Support for pool:false was removed in v4.0');
    }

    config.pool = _.defaults(config.pool || {}, {
      max: 5,
      min: 0,
      idle: 10000,
      acquire: 60000,
      evict: 1000,
      validate: this._validate.bind(this)
    });

    this.initPools();
  }

  refreshTypeParser(dataTypes) {
    _.each(dataTypes, dataType => {
      if (Object.prototype.hasOwnProperty.call(dataType, 'parse')) {
        if (dataType.types[this.dialectName]) {
          this._refreshTypeParser(dataType);
        } else {
          throw new Error(`Parse function not supported for type ${dataType.key} in dialect ${this.dialectName}`);
        }
      }
    });
  }

  /**
   * Try to load dialect module from various configured options.
   * Priority goes like dialectModulePath > dialectModule > require(default)
   *
   * @param {string} moduleName Name of dialect module to lookup
   *
   * @private
   * @returns {object}
   */
  _loadDialectModule(moduleName) {
    try {
      if (this.sequelize.config.dialectModulePath) {
        return require(this.sequelize.config.dialectModulePath);
      }
      if (this.sequelize.config.dialectModule) {
        return this.sequelize.config.dialectModule;
      }
      return require(moduleName);

    } catch (err) {
      if (err.code === 'MODULE_NOT_FOUND') {
        if (this.sequelize.config.dialectModulePath) {
          throw new Error(`Unable to find dialect at ${this.sequelize.config.dialectModulePath}`);
        }
        throw new Error(`Please install ${moduleName} package manually`);
      }

      throw err;
    }
  }

  /**
   * Handler which executes on process exit or connection manager shutdown
   *
   * @private
   * @returns {Promise}
   */
  async _onProcessExit() {
    if (!this.pool) {
      return;
    }

    await this.pool.drain();
    debug('connection drain due to process exit');

    return await this.pool.destroyAllNow();
  }

  /**
   * Drain the pool and close it permanently
   *
   * @returns {Promise}
   */
  async close() {
    // Mark close of pool
    this.getConnection = async function getConnection() {
      throw new Error('ConnectionManager.getConnection was called after the connection manager was closed!');
    };

    return await this._onProcessExit();
  }

  /**
   * Initialize connection pool. By default pool autostart is set to false, so no connection will be
   * be created unless `pool.acquire` is called.
   */
  initPools() {
    const config = this.config;

    if (!config.replication) {
      this.pool = new Pool({
        name: 'sequelize',
        create: () => this._connect(config),
        destroy: async connection => {
          const result = await this._disconnect(connection);
          debug('connection destroy');
          return result;
        },
        validate: config.pool.validate,
        max: config.pool.max,
        min: config.pool.min,
        acquireTimeoutMillis: config.pool.acquire,
        idleTimeoutMillis: config.pool.idle,
        reapIntervalMillis: config.pool.evict,
        maxUses: config.pool.maxUses
      });

      debug(`pool created with max/min: ${config.pool.max}/${config.pool.min}, no replication`);

      return;
    }

    if (!Array.isArray(config.replication.read)) {
      config.replication.read = [config.replication.read];
    }

    // Map main connection config
    config.replication.write = _.defaults(config.replication.write, _.omit(config, 'replication'));

    // Apply defaults to each read config
    config.replication.read = config.replication.read.map(readConfig =>
      _.defaults(readConfig, _.omit(this.config, 'replication'))
    );

    // custom pooling for replication (original author @janmeier)
    let reads = 0;
    this.pool = {
      release: client => {
        if (client.queryType === 'read') {
          this.pool.read.release(client);
        } else {
          this.pool.write.release(client);
        }
      },
      acquire: (queryType, useMaster) => {
        useMaster = useMaster === undefined ? false : useMaster;
        if (queryType === 'SELECT' && !useMaster) {
          return this.pool.read.acquire();
        }
        return this.pool.write.acquire();
      },
      destroy: connection => {
        this.pool[connection.queryType].destroy(connection);
        debug('connection destroy');
      },
      destroyAllNow: async () => {
        await Promise.all([
          this.pool.read.destroyAllNow(),
          this.pool.write.destroyAllNow()
        ]);

        debug('all connections destroyed');
      },
      drain: async () => Promise.all([
        this.pool.write.drain(),
        this.pool.read.drain()
      ]),
      read: new Pool({
        name: 'sequelize:read',
        create: async () => {
          // round robin config
          const nextRead = reads++ % config.replication.read.length;
          const connection = await this._connect(config.replication.read[nextRead]);
          connection.queryType = 'read';
          return connection;
        },
        destroy: connection => this._disconnect(connection),
        validate: config.pool.validate,
        max: config.pool.max,
        min: config.pool.min,
        acquireTimeoutMillis: config.pool.acquire,
        idleTimeoutMillis: config.pool.idle,
        reapIntervalMillis: config.pool.evict,
        maxUses: config.pool.maxUses
      }),
      write: new Pool({
        name: 'sequelize:write',
        create: async () => {
          const connection = await this._connect(config.replication.write);
          connection.queryType = 'write';
          return connection;
        },
        destroy: connection => this._disconnect(connection),
        validate: config.pool.validate,
        max: config.pool.max,
        min: config.pool.min,
        acquireTimeoutMillis: config.pool.acquire,
        idleTimeoutMillis: config.pool.idle,
        reapIntervalMillis: config.pool.evict,
        maxUses: config.pool.maxUses
      })
    };

    debug(`pool created with max/min: ${config.pool.max}/${config.pool.min}, with replication`);
  }

  /**
   * Get connection from pool. It sets database version if it's not already set.
   * Call pool.acquire to get a connection
   *
   * @param {object}   [options]                 Pool options
   * @param {string}   [options.type]            Set which replica to use. Available options are `read` and `write`
   * @param {boolean}  [options.useMaster=false] Force master or write replica to get connection from
   *
   * @returns {Promise<Connection>}
   */
  async getConnection(options) {
    options = options || {};

    if (this.sequelize.options.databaseVersion === 0) {
      if (!this.versionPromise) {
        this.versionPromise = (async () => {
          try {
            const connection = await this._connect(this.config.replication.write || this.config);
            const _options = {};

            _options.transaction = { connection }; // Cheat .query to use our private connection
            _options.logging = () => {};
            _options.logging.__testLoggingFn = true;

            //connection might have set databaseVersion value at initialization,
            //avoiding a useless round trip
            if (this.sequelize.options.databaseVersion === 0) {
              const version = await this.sequelize.databaseVersion(_options);
              const parsedVersion = _.get(semver.coerce(version), 'version') || version;
              this.sequelize.options.databaseVersion = semver.valid(parsedVersion)
                ? parsedVersion
                : this.dialect.defaultVersion;
            }

            if (semver.lt(this.sequelize.options.databaseVersion, this.dialect.defaultVersion)) {
              deprecations.unsupportedEngine();
              debug(`Unsupported database engine version ${this.sequelize.options.databaseVersion}`);
            }

            this.versionPromise = null;
            return await this._disconnect(connection);
          } catch (err) {
            this.versionPromise = null;
            throw err;
          }
        })();
      }
      await this.versionPromise;
    }

    let result;

    try {
      result = await this.pool.acquire(options.type, options.useMaster);
    } catch (error) {
      if (error instanceof TimeoutError) throw new errors.ConnectionAcquireTimeoutError(error);
      throw error;
    }

    debug('connection acquired');

    return result;
  }

  /**
   * Release a pooled connection so it can be utilized by other connection requests
   *
   * @param {Connection} connection
   *
   * @returns {Promise}
   */
  async releaseConnection(connection) {
    this.pool.release(connection);
    debug('connection released');
  }

  /**
   * Call dialect library to get connection
   *
   * @param {*} config Connection config
   * @private
   * @returns {Promise<Connection>}
   */
  async _connect(config) {
    await this.sequelize.runHooks('beforeConnect', config);
    const connection = await this.dialect.connectionManager.connect(config);
    await this.sequelize.runHooks('afterConnect', connection, config);
    return connection;
  }

  /**
   * Call dialect library to disconnect a connection
   *
   * @param {Connection} connection
   * @private
   * @returns {Promise}
   */
  async _disconnect(connection) {
    await this.sequelize.runHooks('beforeDisconnect', connection);
    await this.dialect.connectionManager.disconnect(connection);
    return this.sequelize.runHooks('afterDisconnect', connection);
  }

  /**
   * Determine if a connection is still valid or not
   *
   * @param {Connection} connection
   *
   * @returns {boolean}
   */
  _validate(connection) {
    if (!this.dialect.connectionManager.validate) {
      return true;
    }

    return this.dialect.connectionManager.validate(connection);
  }
}

module.exports = ConnectionManager;
module.exports.ConnectionManager = ConnectionManager;
module.exports.default = ConnectionManager;