Method prepareEnvironment

src/transaction.js:112–147

* Called to acquire a connection to use and set the correct options on the connection. * We should ensure all of the environment that's set up is cleaned up in `cleanup()` below. * * @param {boolean} useCLS Defaults to true: Use CLS (Continuation Local Storage) with Sequelize. With CLS, all

(useCLS = true)

   * @returns {Promise}
   */
  async prepareEnvironment(useCLS = true) {
    let connectionPromise;

    if (this.parent) {
      connectionPromise = Promise.resolve(this.parent.connection);
    } else {
      const acquireOptions = { uuid: this.id };
      if (this.options.readOnly) {
        acquireOptions.type = 'SELECT';
      }
      connectionPromise = this.sequelize.connectionManager.getConnection(acquireOptions);
    }

    let result;
    const connection = await connectionPromise;
    this.connection = connection;
    this.connection.uuid = this.id;

    try {
      await this.begin();
      result = await this.setDeferrable();
    } catch (setupErr) {
      try {
        result = await this.rollback();
      } finally {
        throw setupErr; // eslint-disable-line no-unsafe-finally
      }
    }

    // TODO (@ephys) [>=7.0.0]: move this inside of sequelize.transaction, remove parameter.
    if (useCLS && this.sequelize.constructor._cls) {
      this.sequelize.constructor._cls.set('transaction', this);
    }

    return result;
  }

  async setDeferrable() {
    if (this.options.deferrable) {