| 1 | #pragma once |
|---|
| 2 | |
|---|
| 3 | #include <mbgl/util/work_task.hpp> |
|---|
| 4 | #include <mbgl/util/run_loop.hpp> |
|---|
| 5 | |
|---|
| 6 | #include <mutex> |
|---|
| 7 | |
|---|
| 8 | namespace mbgl { |
|---|
| 9 | |
|---|
| 10 | template <class F, class P> |
|---|
| 11 | class WorkTaskImpl : public WorkTask { |
|---|
| 12 | public: |
|---|
| 13 | WorkTaskImpl(F f, P p, std::shared_ptr<std::atomic<bool>> canceled_) |
|---|
| 14 | : canceled(std::move(canceled_)), |
|---|
| 15 | func(std::move(f)), |
|---|
| 16 | params(std::move(p)) { |
|---|
| 17 | } |
|---|
| 18 | |
|---|
| 19 | void operator()() override { |
|---|
| 20 | // Lock the mutex while processing so that cancel() will block. |
|---|
| 21 | std::lock_guard<std::recursive_mutex> lock(mutex); |
|---|
| 22 | if (!*canceled) { |
|---|
| 23 | invoke(std::make_index_sequence<std::tuple_size<P>::value>{}); |
|---|
| 24 | } |
|---|
| 25 | } |
|---|
| 26 | |
|---|
| 27 | // If the task has not yet begun, this will cancel it. |
|---|
| 28 | // If the task is in progress, this will block until it completed. (Currently |
|---|
| 29 | // necessary because of shared state, but should be removed.) It will also |
|---|
| 30 | // cancel the after callback. |
|---|
| 31 | // If the task has completed, but the after callback has not executed, this |
|---|
| 32 | // will cancel the after callback. |
|---|
| 33 | // If the task has completed and the after callback has executed, this will |
|---|
| 34 | // do nothing. |
|---|
| 35 | void cancel() override { |
|---|
| 36 | std::lock_guard<std::recursive_mutex> lock(mutex); |
|---|
| 37 | *canceled = true; |
|---|
| 38 | } |
|---|
| 39 | |
|---|
| 40 | private: |
|---|
| 41 | template <std::size_t... I> |
|---|
| 42 | void invoke(std::index_sequence<I...>) { |
|---|
| 43 | func(std::move(std::get<I>(std::forward<P>(params)))...); |
|---|
| 44 | } |
|---|
| 45 | |
|---|
| 46 | std::recursive_mutex mutex; |
|---|
| 47 | std::shared_ptr<std::atomic<bool>> canceled; |
|---|
| 48 | |
|---|
| 49 | F func; |
|---|
| 50 | P params; |
|---|
| 51 | }; |
|---|
| 52 | |
|---|
| 53 | template <class Fn, class... Args> |
|---|
| 54 | std::shared_ptr<WorkTask> WorkTask::make(Fn&& fn, Args&&... args) { |
|---|
| 55 | auto flag = std::make_shared<std::atomic<bool>>(); |
|---|
| 56 | *flag = false; |
|---|
| 57 | |
|---|
| 58 | auto tuple = std::make_tuple(std::forward<Args>(args)...); |
|---|
| 59 | return std::make_shared<WorkTaskImpl<std::decay_t<Fn>, decltype(tuple)>>( |
|---|
| 60 | std::forward<Fn>(fn), |
|---|
| 61 | std::move(tuple), |
|---|
| 62 | flag); |
|---|
| 63 | } |
|---|
| 64 | |
|---|
| 65 | } // namespace mbgl |
|---|
| 66 | |
|---|
