Method createConnection

src/cmap/connection_pool.ts:603–685

(callback: Callback<Connection>)

  }

  private createConnection(callback: Callback<Connection>) {
    // Note that metadata may have changed on the client but have
    // been frozen here, so we pull the metadata promise always from the client
    // no matter what options were set at the construction of the pool.
    const connectOptions: ConnectionOptions = {
      ...this.options,
      id: this.connectionCounter.next().value,
      generation: this.generation,
      cancellationToken: this.cancellationToken,
      mongoLogger: this.mongoLogger,
      authProviders: this.server.topology.client.s.authProviders,
      metadata: this.server.topology.client.options.metadata
    };

    this.pending++;
    // This is our version of a "virtual" no-I/O connection as the spec requires
    const connectionCreatedTime = processTimeMS();
    this.emitAndLog(
      ConnectionPool.CONNECTION_CREATED,
      new ConnectionCreatedEvent(this, { id: connectOptions.id })
    );

    connect(connectOptions).then(
      connection => {
        // The pool might have closed since we started trying to create a connection
        if (this.poolState !== PoolState.ready) {
          this.pending--;
          connection.destroy();
          callback(this.closed ? new PoolClosedError(this) : new PoolClearedError(this));
          return;
        }

        // forward all events from the connection to the pool
        for (const event of [...APM_EVENTS, Connection.CLUSTER_TIME_RECEIVED]) {
          connection.on(event, (e: any) => this.emit(event, e));
        }

        if (this.loadBalanced) {
          connection.on(Connection.PINNED, pinType => this.metrics.markPinned(pinType));
          connection.on(Connection.UNPINNED, pinType => this.metrics.markUnpinned(pinType));

          const serviceId = connection.serviceId;
          if (serviceId) {
            let generation;
            const sid = serviceId.toHexString();
            if ((generation = this.serviceGenerations.get(sid))) {
              connection.generation = generation;
            } else {
              this.serviceGenerations.set(sid, 0);
              connection.generation = 0;
            }
          }
        }

        connection.markAvailable();
        this.emitAndLog(
          ConnectionPool.CONNECTION_READY,
          new ConnectionReadyEvent(this, connection, connectionCreatedTime)