seastar::coroutine::parallel_for_each< Func > Class Template Reference

Detailed Description

template<typename Func>
class seastar::coroutine::parallel_for_each< Func >

Invoke a function on all elements in a range in parallel and wait for all futures to complete in a coroutine.

parallel_for_each can be used to launch a function concurrently on all elements in a given range and wait for all of them to complete. Waiting is performend by co_await and returns a future.

If one or more of the function invocations resolve to an exception then the one of the exceptions is re-thrown. All of the futures are waited for, even in the case of exceptions.

Example

future<int> sum_of_squares(std::vector<int> v) {
    int sum = 0;
    return co_await parallel_for_each(v, [&sum] (int& x) {
        sum += x * x;
    });
    co_return sum;
};

Safe for use with lambda coroutines.

Note

parallel_for_each() schedules all invocations of func on the current shard. If you want to run a function on all shards in parallel, have a look at smp::invoke_on_all() instead.

#include <seastar/coroutine/parallel_for_each.hh>

Inheritance diagram for seastar::coroutine::parallel_for_each< Func >:

Public Member Functions
template<typename Iterator , typename Sentinel , typename Func1 > requires (std::same_as<Sentinel, Iterator> || std::sentinel_for<Sentinel, Iterator>) && std::same_as<future<>, futurize_t<std::invoke_result_t<Func, typename std::iterator_traits<Iterator>::reference>>>
	parallel_for_each (Iterator begin, Sentinel end, Func1 &&func) noexcept
template<std::ranges::range Range, typename Func1 > requires std::invocable<Func, std::ranges::range_reference_t<Range>>
	parallel_for_each (Range &&range, Func1 &&func) noexcept
bool	await_ready () const noexcept
template<typename T >
void	await_suspend (std::coroutine_handle< T > h)
void	await_resume () const
virtual void	run_and_dispose () noexcept override
virtual task *	waiting_task () noexcept override

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

• seastar/coroutine/parallel_for_each.hh