| 1 | // Copyright (c) 2022 Klemens D. Morgenstern |
|---|---|
| 2 | // |
| 3 | // Distributed under the Boost Software License, Version 1.0. (See accompanying |
| 4 | // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) |
| 5 | #ifndef BOOST_COBALT_WAIT_GROUP_HPP |
| 6 | #define BOOST_COBALT_WAIT_GROUP_HPP |
| 7 | |
| 8 | #include <boost/cobalt/detail/wait_group.hpp> |
| 9 | |
| 10 | namespace boost::cobalt |
| 11 | { |
| 12 | // tag::outline[] |
| 13 | struct wait_group |
| 14 | { |
| 15 | // create a wait_group |
| 16 | explicit |
| 17 | wait_group(asio::cancellation_type normal_cancel = asio::cancellation_type::none, |
| 18 | asio::cancellation_type exception_cancel = asio::cancellation_type::all); |
| 19 | |
| 20 | // insert a task into the group |
| 21 | void push_back(promise<void> p); |
| 22 | |
| 23 | // the number of tasks in the group |
| 24 | std::size_t size() const; |
| 25 | // remove completed tasks without waiting (i.e. zombie tasks) |
| 26 | std::size_t reap(); |
| 27 | // cancel all tasks |
| 28 | void cancel(asio::cancellation_type ct = asio::cancellation_type::all); |
| 29 | // end::outline[] |
| 30 | |
| 31 | /* tag::outline[] |
| 32 | // wait for one task to complete. |
| 33 | __wait_one_op__ wait_one(); |
| 34 | // wait for all tasks to complete |
| 35 | __wait_op__ wait(); |
| 36 | // wait for all tasks to complete |
| 37 | __wait_op__ operator co_await (); |
| 38 | // when used with `with` , this will receive the exception |
| 39 | // and wait for the completion |
| 40 | // if `ep` is set, this will use the `exception_cancel` level, |
| 41 | // otherwise the `normal_cancel` to cancel all promises. |
| 42 | __wait_op__ await_exit(std::exception_ptr ep); |
| 43 | end::outline[] */ |
| 44 | |
| 45 | auto wait_one() -> detail::race_wrapper |
| 46 | { |
| 47 | return detail::race_wrapper(waitables_); |
| 48 | } |
| 49 | |
| 50 | detail::gather_wrapper wait() |
| 51 | { |
| 52 | return detail::gather_wrapper(waitables_); |
| 53 | |
| 54 | } |
| 55 | detail::gather_wrapper::awaitable_type operator co_await () |
| 56 | { |
| 57 | return detail::gather_wrapper(waitables_).operator co_await(); |
| 58 | } |
| 59 | // swallow the exception here. |
| 60 | detail::gather_wrapper await_exit(std::exception_ptr ep) |
| 61 | { |
| 62 | auto ct = ep ? ct_except_ : ct_normal_; |
| 63 | if (ct != asio::cancellation_type::none) |
| 64 | for (auto & w : waitables_) |
| 65 | w.cancel(ct); |
| 66 | return detail::gather_wrapper(waitables_); |
| 67 | } |
| 68 | |
| 69 | |
| 70 | private: |
| 71 | std::list<promise<void>> waitables_; |
| 72 | asio::cancellation_type ct_normal_, ct_except_; |
| 73 | // tag::outline[] |
| 74 | }; |
| 75 | // end::outline[] |
| 76 | |
| 77 | inline wait_group::wait_group( |
| 78 | asio::cancellation_type normal_cancel, |
| 79 | asio::cancellation_type exception_cancel) |
| 80 | : ct_normal_(normal_cancel), ct_except_(exception_cancel) {} |
| 81 | |
| 82 | inline |
| 83 | std::size_t wait_group::size() const {return waitables_.size();} |
| 84 | |
| 85 | inline |
| 86 | std::size_t wait_group::reap() |
| 87 | { |
| 88 | return erase_if(cont&: waitables_, pred: [](promise<void> & p) { return p.ready() && p;}); |
| 89 | } |
| 90 | |
| 91 | inline |
| 92 | void wait_group::cancel(asio::cancellation_type ct) |
| 93 | { |
| 94 | for (auto & w : waitables_) |
| 95 | w.cancel(ct); |
| 96 | } |
| 97 | |
| 98 | inline |
| 99 | void wait_group::push_back(promise<void> p) { waitables_.push_back(x: std::move(p));} |
| 100 | |
| 101 | |
| 102 | } |
| 103 | |
| 104 | #endif //BOOST_COBALT_WAIT_GROUP_HPP |
| 105 |