Method _connect

src/sdam/topology.ts:409–491

(options?: ConnectOptions)

  }

  private async _connect(options?: ConnectOptions): Promise<Topology> {
    options = options ?? {};
    if (this.s.state === STATE_CONNECTED) {
      return this;
    }

    stateTransition(this, STATE_CONNECTING);

    // emit SDAM monitoring events
    this.emitAndLog(Topology.TOPOLOGY_OPENING, new TopologyOpeningEvent(this.s.id));

    // emit an event for the topology change
    this.emitAndLog(
      Topology.TOPOLOGY_DESCRIPTION_CHANGED,
      new TopologyDescriptionChangedEvent(
        this.s.id,
        new TopologyDescription(TopologyType.Unknown), // initial is always Unknown
        this.s.description
      )
    );

    // connect all known servers, then attempt server selection to connect
    const serverDescriptions = Array.from(this.s.description.servers.values());
    this.s.servers = new Map(
      serverDescriptions.map(serverDescription => [
        serverDescription.address,
        createAndConnectServer(this, serverDescription)
      ])
    );

    // In load balancer mode we need to fake a server description getting
    // emitted from the monitor, since the monitor doesn't exist.
    if (this.s.options.loadBalanced) {
      for (const description of serverDescriptions) {
        const newDescription = new ServerDescription(description.hostAddress, undefined, {
          loadBalanced: this.s.options.loadBalanced
        });
        this.serverUpdateHandler(newDescription);
      }
    }

    const serverSelectionTimeoutMS = this.client.s.options.serverSelectionTimeoutMS;
    const readPreference = options.readPreference ?? ReadPreference.primary;
    const timeoutContext = TimeoutContext.create({
      // TODO(NODE-6448): auto-connect ignores timeoutMS; potential future feature
      timeoutMS: undefined,
      serverSelectionTimeoutMS,
      waitQueueTimeoutMS: this.client.s.options.waitQueueTimeoutMS
    });
    const selectServerOptions = {
      operationName: 'handshake',
      ...options,
      timeoutContext,
      deprioritizedServers: new DeprioritizedServers()
    };

    try {
      const server = await this.selectServer(