Method writeCommand

src/cmap/connection.ts:690–746

* @internal * * Writes an OP_MSG or OP_QUERY request to the socket, optionally compressing the command. This method * waits until the socket's buffer has emptied (the Nodejs socket `drain` event has fired).

(
    command: WriteProtocolMessageType,
    options: {
      agreedCompressor?: CompressorName;
      zlibCompressionLevel?: number;
      timeoutContext?: TimeoutContext;
    } & Abortable
  )

   * waits until the socket's buffer has emptied (the Nodejs socket `drain` event has fired).
   */
  private async writeCommand(
    command: WriteProtocolMessageType,
    options: {
      agreedCompressor?: CompressorName;
      zlibCompressionLevel?: number;
      timeoutContext?: TimeoutContext;
    } & Abortable
  ): Promise<void> {
    const finalCommand =
      options.agreedCompressor === 'none' || !OpCompressedRequest.canCompress(command)
        ? command
        : new OpCompressedRequest(command, {
            agreedCompressor: options.agreedCompressor ?? 'none',
            zlibCompressionLevel: options.zlibCompressionLevel ?? 0
          });

    const buffer = ByteUtils.concat(await finalCommand.toBin());

    if (options.timeoutContext?.csotEnabled()) {
      if (
        options.timeoutContext.minRoundTripTime != null &&
        options.timeoutContext.remainingTimeMS < options.timeoutContext.minRoundTripTime
      ) {
        throw new MongoOperationTimeoutError(
          'Server roundtrip time is greater than the time remaining'
        );
      }
    }

    try {
      if (this.socket.write(buffer)) return;
    } catch (writeError) {
      const networkError = new MongoNetworkError('unexpected error writing to socket', {
        cause: writeError
      });
      this.onError(networkError);
      throw networkError;
    }

    const drainEvent = once<void>(this.socket, 'drain', options);
    const timeout = options?.timeoutContext?.timeoutForSocketWrite;
    const drained = timeout ? Promise.race([drainEvent, timeout]) : drainEvent;
    try {
      return await drained;
    } catch (writeError) {
      if (TimeoutError.is(writeError)) {
        const timeoutError = new MongoOperationTimeoutError('Timed out at socket write');
        this.onError(timeoutError);
        throw timeoutError;
      } else if (writeError === options.signal?.reason) {
        this.onError(writeError);
      }
      throw writeError;
    } finally {
      timeout?.clear();
    }
  }