void Operation::cancel()

in squangle/mysql_client/Operation.cpp [153:184]

• 19 lines of code
• 5 McCabe index (conditional complexity)

void Operation::cancel() {
  folly::RequestContextScopeGuard guard(std::move(request_context_));

  {
    // This code competes with `run()` to see who changes `state_` first,
    // since they both have the combination `check and change` this must
    // be locked
    std::unique_lock<std::mutex> l(run_state_mutex_);

    if (state_ == OperationState::Cancelling ||
        state_ == OperationState::Completed) {
      // If the cancel was already called we dont do the cancelling
      // process again
      return;
    }

    if (state_ == OperationState::Unstarted) {
      cancel_on_run_ = true;
      // wait the user to call "run()" to run the completeOperation
      // otherwise we will throw exception
      return;
    }

    state_ = OperationState::Cancelling;
  }

  if (!connection()->runInThread(
          this, &Operation::completeOperation, OperationResult::Cancelled)) {
    // if a strange error happen in EventBase , mark it cancelled now
    completeOperationInner(OperationResult::Cancelled);
  }
}