portable_concurrency
README.md
portable_concurrency
std::future
done right. Simple to use portable implementation of the future/promise API inspired by the
C++ Extensions for Concurrency TS and some parts of A Unified Executors Proposal for C++.
- Minimum requred C++ standard: C++14
- The only public dependency: standard library.
- The only build dependency: gtest
Key features
- Execcutor aware
pc::static_thread_pool pool{5};pc::future<int> answer = pc::async(pool.executor(), [] {return 42;});
- Designed to work with user provided executors
namespace portable_concurrency {template<> struct is_executor<QThreadPool*>: std::true_type {};}void post(QThreadPool*, pc::unique_function<void()>);pc::future<int> answer = pc::async(QThreadPool::globalInstance(), [] {return 42;});
- Continuations support
pc::static_thread_pool pool{5};asio::io_context io;pc::future<rapidjson::Document> res = pc::async(io.get_executor(), receive_document).next(pool.executor(), parse_document);
when_all
/when_any
composition of futurespc::future<rapidjson::Document> res = pc::when_any(pc::async(pool.executor(), fetch_from_cache),pc::async(io.get_executor(), receive_from_network)).next([](auto when_any_res) {switch(when_any_res.index) {case 0: return std::get<0>(when_any_res.futures);case 1: return std::get<1>(when_any_res.futures);}});future<future<T>>
transparently unwrapped tofuture<T>
future<shared_future<T>>
transparently unwrapped toshred_future<T>
- Automatic task cancelation:
- Not yet started functions passed to
pc::async
/pc::packaged_task
or attached to intermediate futures as continuations may not be executed at all iffuture
or allshared_future
's on the result of continuations chain are destroyed. future::detach()
andshared_future::detach()
functions allows to destroy future without cancelation of any tasks.auto future = pc::async(pool.executor(), important_calculation).next(io.get_executor(), important_io).detach().next(pool.executor(), not_so_important_calculations);important_calculation
andimportant_io
are guarantied to be executed even in case of premature future destruction.promise::is_awaiten()
allows to check if there is afuture
orshared_future
waiting for value to be set on thispromise
object.promise::promise(canceler_arg_t, CancelAction)
constructor allows to specify action which is called in case of cancelation via future destruction.- Additional
then
overload to check if task is canceled from the continuations functionpc::future<std::string> res = pc::async(pool.executor(), [] {return 42;}).then([](pc::promise<std::string> p, pc::future<int> f) {std::string res;while (has_work_to_do()) {do_next_step(res, f);if (!p.is_awaiten())return;}p.set_value(res);});
- Not yet started functions passed to
Build
mkdir -p build/debug
cd build/debug
conan install --build=missing ../..
cmake -G Ninja -DCMAKE_BUILD_TYPE=Debug ../..
ninja
ninja test
Языки
C++
- CMake
- Python
- C
- Shell
- Dockerfile