pw::async2::Selector< Pendables > Class Template Reference

Public Types
using	ResultVariant = typename internal::SelectVariantType< std::make_index_sequence< sizeof...(Pendables)>, Pendables... >::type

Public Member Functions
	Selector (Pendables &&... pendables)
	Creates a SingleSelector from a series of pendable values.
Poll< ResultVariant >	Pend (Context &cx)

Detailed Description

template<typename... Pendables>
class pw::async2::Selector< Pendables >

A pendable value which returns the result of the first of several pendable values to complete.

Each call to Selector::Pend polls its pendables until one returns Ready. If a Ready pendable is found, its value is returned as a SelectResult indicating the index of the completed pendable.

If no pendables are Ready, Selector::Pend returns a Pending.

If every pendable provided to the Selector has already completed, Pend will return an AllPendablesCompleted value indicating this.

Example usage:

Poll<int> TaskOne(Context&) { return Ready(3); }
Poll<char> TaskTwo(Context&) { return Ready('c'); }
 
Poll<> RaceTasks(Context& cx) {
  auto task_one = PendableFor<&TaskOne>();
  auto task_two = PendableFor<&TaskTwo>();
 
  Selector selector(std::move(task_one), std::move(task_two));
  auto result = selector.Pend(cx);
  if (result.IsPending()) {
    return Pending();
  }
 
  VisitSelectResult(
      *result,
      [](AllPendablesCompleted) { PW_LOG_INFO("Both tasks completed"); },
      [](int value) {
        PW_LOG_INFO("Task one completed with value %d", value);
      },
      [](char value) {
        PW_LOG_INFO("Task two completed with value %c", value);
      });
}

Member Function Documentation

Pend()

template<typename... Pendables>

Poll< ResultVariant > pw::async2::Selector< Pendables >::Pend ( Context &  cx )

inline

Attempts to complete the stored pendables, returning the first one which is ready.

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The documentation for this class was generated from the following file:

• pw_async2/public/pw_async2/select.h