Function canRetry

src/operations/execute_operation.ts:380–419

(operation: AbstractOperation, error: MongoError)

  );

  function canRetry(operation: AbstractOperation, error: MongoError) {
    // SystemOverloadedError is retryable, but must respect retryReads/retryWrites settings
    // Check topology options directly (not operation.canRetryRead/Write) because backpressure
    // expands retry support beyond traditional retryable reads/writes
    // NOTE: Unlike traditional retries, backpressure retries ARE allowed inside transactions
    if (
      error.hasErrorLabel(MongoErrorLabel.SystemOverloadedError) &&
      error.hasErrorLabel(MongoErrorLabel.RetryableError)
    ) {
      // runCommand requires BOTH retryReads and retryWrites to be enabled (per spec step 2.4)
      if (operation instanceof RunCommandOperation) {
        return topology.s.options.retryReads && topology.s.options.retryWrites;
      }

      // Write-stage aggregates ($out/$merge) require retryWrites
      if (operation instanceof AggregateOperation && operation.hasWriteStage) {
        return topology.s.options.retryWrites;
      }

      // For other operations, check if retries are enabled based on operation type
      const canRetryAsRead = hasReadAspect && topology.s.options.retryReads;
      const canRetryAsWrite = hasWriteAspect && topology.s.options.retryWrites;
      return canRetryAsRead || canRetryAsWrite;
    }

    // run command is only retryable if we get retryable overload errors
    if (operation instanceof RunCommandOperation) {
      return false;
    }

    // batch operations are only retryable if the batch is retryable
    if (operation.hasAspect(Aspect.COMMAND_BATCHING)) {
      return operation.canRetryWrite && isRetryableWriteError(error);
    }

    return (
      (hasWriteAspect && willRetryWrite && isRetryableWriteError(error)) ||
      (hasReadAspect && willRetryRead && isRetryableReadError(error))
    );
  }
}