Error Handling Operators

Operators that help to recover from error notifications from an Observable. More...

Functions
template<typename Selector> requires rpp::constraint::observable<std::invoke_result_t<Selector, std::exception_ptr>>
auto	rpp::operators::on_error_resume_next (Selector &&selector)
	If an error occurs, take the result from the Selector and subscribe to that instead.
auto	rpp::operators::retry (size_t count)
	The retry operator attempts to resubscribe to the observable when an error occurs, up to the specified number of retries.
auto	rpp::operators::retry ()
	The infinite retry operator continuously attempts to resubscribe to the observable upon error, without a retry limit.
template<typename TNotifier> requires rpp::constraint::observable<std::invoke_result_t<TNotifier, std::exception_ptr>>
auto	rpp::operators::retry_when (TNotifier &&notifier)
	If an error occurs, invoke notifier and when returned observable emits a value resubscribe to the source observable. If the notifier throws or returns an error/empty observable, then error/completed emission is forwarded to original subscription.

Detailed Description

Operators that help to recover from error notifications from an Observable.

See also

https://reactivex.io/documentation/operators.html#error

Function Documentation

on_error_resume_next()

template<typename Selector>
requires rpp::constraint::observable<std::invoke_result_t<Selector, std::exception_ptr>>

auto rpp::operators::on_error_resume_next

(

Selector &&

selector

)

If an error occurs, take the result from the Selector and subscribe to that instead.

Parameters

selector

callable taking a std::exception_ptr and returning observable to continue on

Note

#include <rpp/operators/on_error_resume_next.hpp>

See also

https://reactivex.io/documentation/operators/catch.html

retry() [1/2]

auto rpp::operators::retry ( )

inline

The infinite retry operator continuously attempts to resubscribe to the observable upon error, without a retry limit.

Note

#include <rpp/operators/retry.hpp>

Examples:

    rpp::source::concat(rpp::source::just(1, 2, 3), rpp::source::error<int>({}))
        | rpp::operators::retry()
        | rpp::operators::take(10)
        | rpp::operators::subscribe([](int v) { std::cout << v << " "; },
                                    [](const std::exception_ptr&) { std::cout << "error" << std::endl; },
                                    []() { std::cout << "completed" << std::endl; });
    // Output: 1 2 3 1 2 3 1 2 3 1 completed

See also

https://reactivex.io/documentation/operators/retry.html

retry() [2/2]

auto rpp::operators::retry ( size_t count )

inline

The retry operator attempts to resubscribe to the observable when an error occurs, up to the specified number of retries.

Parameters

count

is the number of retries

Note

#include <rpp/operators/retry.hpp>

Examples:

    rpp::source::concat(rpp::source::just(1, 2, 3), rpp::source::error<int>({}))
        | rpp::operators::retry(2)
        | rpp::operators::subscribe([](int v) { std::cout << v << " "; },
                                    [](const std::exception_ptr&) { std::cout << "error" << std::endl; },
                                    []() { std::cout << "completed" << std::endl; });
    // Output: 1 2 3 1 2 3 1 2 3 error

See also

https://reactivex.io/documentation/operators/retry.html

retry_when()

template<typename TNotifier>
requires rpp::constraint::observable<std::invoke_result_t<TNotifier, std::exception_ptr>>

auto rpp::operators::retry_when

(

TNotifier &&

notifier

)

If an error occurs, invoke notifier and when returned observable emits a value resubscribe to the source observable. If the notifier throws or returns an error/empty observable, then error/completed emission is forwarded to original subscription.

Parameters

notifier

callable taking a std::exception_ptr and returning observable notifying when to resubscribe

Warning

retry_when along with other re-subscribing operators needs to be carefully used with hot observables, as re-subscribing to a hot observable can have unwanted behaviors. For example, a hot observable behind a replay subject can indefinitely yield an error on each re-subscription and using retry_when on it would lead to an infinite execution.

Note

#include <rpp/operators/retry_when.hpp>

Examples:

    size_t retry_count = 0;
    rpp::source::create<std::string>([&retry_count](const auto& sub) {
        if (++retry_count != 4)
        {
            sub.on_error({});
        }
        else
        {
            sub.on_next(std::string{"success"});
            sub.on_completed();
        }
    })
        | rpp::operators::retry_when([](const std::exception_ptr&) {
              return rpp::source::timer(std::chrono::seconds{5}, rpp::schedulers::current_thread{});
          })
        | rpp::operators::subscribe([](const std::string& v) { std::cout << v << std::endl; });
    // Source observable is resubscribed after 5 seconds on each error emission

    retry_count = 0;
    rpp::source::create<std::string>([&retry_count](const auto& sub) {
        if (++retry_count != 4)
        {
            sub.on_error({});
        }
        else
        {
            sub.on_next(std::string{"success"});
            sub.on_completed();
        }
    })
        | rpp::operators::retry_when([](const std::exception_ptr& ep) {
              try
              {
                  std::rethrow_exception(ep);
              }
              catch (const std::runtime_error&)
              {
                  return rpp::source::timer(std::chrono::seconds{5}, rpp::schedulers::current_thread{});
              }
              catch (...)
              {
                  throw;
              }
          })
        | rpp::operators::subscribe([](const std::string& v) { std::cout << v << std::endl; });
    // Source observable is resubscribed after 5 seconds only on particular error emissions

See also

https://reactivex.io/documentation/operators/retry.html