diff options
Diffstat (limited to '3rdparty/asio/src/examples/cpp14/executors/priority_scheduler.cpp')
-rw-r--r-- | 3rdparty/asio/src/examples/cpp14/executors/priority_scheduler.cpp | 167 |
1 files changed, 167 insertions, 0 deletions
diff --git a/3rdparty/asio/src/examples/cpp14/executors/priority_scheduler.cpp b/3rdparty/asio/src/examples/cpp14/executors/priority_scheduler.cpp new file mode 100644 index 00000000000..3b28af1eec0 --- /dev/null +++ b/3rdparty/asio/src/examples/cpp14/executors/priority_scheduler.cpp @@ -0,0 +1,167 @@ +#include <asio/ts/executor.hpp> +#include <condition_variable> +#include <iostream> +#include <memory> +#include <mutex> +#include <queue> + +using asio::dispatch; +using asio::execution_context; + +class priority_scheduler : public execution_context +{ +public: + // A class that satisfies the Executor requirements. + class executor_type + { + public: + executor_type(priority_scheduler& ctx, int pri) noexcept + : context_(ctx), priority_(pri) + { + } + + priority_scheduler& context() const noexcept + { + return context_; + } + + void on_work_started() const noexcept + { + // This executor doesn't count work. Instead, the scheduler simply runs + // until explicitly stopped. + } + + void on_work_finished() const noexcept + { + // This executor doesn't count work. Instead, the scheduler simply runs + // until explicitly stopped. + } + + template <class Func, class Alloc> + void dispatch(Func&& f, const Alloc& a) const + { + post(std::forward<Func>(f), a); + } + + template <class Func, class Alloc> + void post(Func f, const Alloc& a) const + { + auto p(std::allocate_shared<item<Func>>( + typename std::allocator_traits< + Alloc>::template rebind_alloc<char>(a), + priority_, std::move(f))); + std::lock_guard<std::mutex> lock(context_.mutex_); + context_.queue_.push(p); + context_.condition_.notify_one(); + } + + template <class Func, class Alloc> + void defer(Func&& f, const Alloc& a) const + { + post(std::forward<Func>(f), a); + } + + friend bool operator==(const executor_type& a, + const executor_type& b) noexcept + { + return &a.context_ == &b.context_; + } + + friend bool operator!=(const executor_type& a, + const executor_type& b) noexcept + { + return &a.context_ != &b.context_; + } + + private: + priority_scheduler& context_; + int priority_; + }; + + executor_type get_executor(int pri = 0) noexcept + { + return executor_type(*const_cast<priority_scheduler*>(this), pri); + } + + void run() + { + std::unique_lock<std::mutex> lock(mutex_); + for (;;) + { + condition_.wait(lock, [&]{ return stopped_ || !queue_.empty(); }); + if (stopped_) + return; + auto p(queue_.top()); + queue_.pop(); + lock.unlock(); + p->execute_(p); + lock.lock(); + } + } + + void stop() + { + std::lock_guard<std::mutex> lock(mutex_); + stopped_ = true; + condition_.notify_all(); + } + +private: + struct item_base + { + int priority_; + void (*execute_)(std::shared_ptr<item_base>&); + }; + + template <class Func> + struct item : item_base + { + item(int pri, Func f) : function_(std::move(f)) + { + priority_ = pri; + execute_ = [](std::shared_ptr<item_base>& p) + { + Func tmp(std::move(static_cast<item*>(p.get())->function_)); + p.reset(); + tmp(); + }; + } + + Func function_; + }; + + struct item_comp + { + bool operator()( + const std::shared_ptr<item_base>& a, + const std::shared_ptr<item_base>& b) + { + return a->priority_ < b->priority_; + } + }; + + std::mutex mutex_; + std::condition_variable condition_; + std::priority_queue< + std::shared_ptr<item_base>, + std::vector<std::shared_ptr<item_base>>, + item_comp> queue_; + bool stopped_ = false; +}; + +int main() +{ + priority_scheduler sched; + auto low = sched.get_executor(0); + auto med = sched.get_executor(1); + auto high = sched.get_executor(2); + dispatch(low, []{ std::cout << "1\n"; }); + dispatch(low, []{ std::cout << "11\n"; }); + dispatch(med, []{ std::cout << "2\n"; }); + dispatch(med, []{ std::cout << "22\n"; }); + dispatch(high, []{ std::cout << "3\n"; }); + dispatch(high, []{ std::cout << "33\n"; }); + dispatch(high, []{ std::cout << "333\n"; }); + dispatch(sched.get_executor(-1), [&]{ sched.stop(); }); + sched.run(); +} |