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Fix task cancelling

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This commit is contained in:
Nikita Lisitsa 2021-03-04 20:30:12 +03:00
parent 8091183375
commit 104ecb528a
1 changed files with 79 additions and 31 deletions
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110
libs/async/include/psemek/async/future.hpp
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@ -50,24 +50,22 @@ namespace psemek::async
using type = util::function<void()>;
};
struct cancel_token
{};
template <typename T>
struct task_state
{
std::atomic<bool> canceled = false;
bool const auto_cancel;
std::mutex value_mutex;
typename task_value_container<T>::type value{};
std::exception_ptr exception;
std::condition_variable value_cv;
std::shared_ptr<cancel_token> shared_cancel;
std::weak_ptr<cancel_token> weak_cancel;
std::mutex then_mutex;
typename then_function<T>::type then_func;
task_state(bool auto_cancel)
: auto_cancel{auto_cancel}
{}
};
}
@ -95,8 +93,9 @@ namespace psemek::async
future() = default;
future(future&&) = default;
future(std::shared_ptr<detail::task_state<T>> state)
future(std::shared_ptr<detail::task_state<T>> state, std::shared_ptr<detail::cancel_token> cancel)
: state_(std::move(state))
, cancel_(std::move(cancel))
{}
future & operator = (future&&) = default;
@ -108,10 +107,8 @@ namespace psemek::async
void reset()
{
if (state_ && state_->auto_cancel)
cancel();
state_.reset();
cancel_.reset();
}
explicit operator bool() const
@ -149,7 +146,7 @@ namespace psemek::async
{
if (!state_)
throw empty_future_error{};
if (state_->canceled)
if (!state_->weak_cancel.lock())
throw canceled_task_error{};
wait();
if (state_->value)
@ -165,8 +162,9 @@ namespace psemek::async
void cancel()
{
if (state_)
state_->canceled = true;
if (!state_) throw empty_future_error{};
cancel_.reset();
}
bool ready() const
@ -179,6 +177,7 @@ namespace psemek::async
private:
std::shared_ptr<detail::task_state<T>> state_;
std::shared_ptr<detail::cancel_token> cancel_;
bool has_value_unsafe() const
{
@ -205,12 +204,26 @@ namespace psemek::async
{}
promise()
: state_{std::make_shared<detail::task_state<T>>(false)}
{}
: state_{std::make_shared<detail::task_state<T>>()}
, cancel_{std::make_shared<detail::cancel_token>()}
{
state_->shared_cancel = cancel_;
state_->weak_cancel = cancel_;
}
promise(auto_cancel_tag tag)
: state_{std::make_shared<detail::task_state<T>>(true)}
{}
promise(auto_cancel_tag)
: state_{std::make_shared<detail::task_state<T>>()}
, cancel_{std::make_shared<detail::cancel_token>()}
{
state_->weak_cancel = cancel_;
}
promise(std::shared_ptr<detail::cancel_token> cancel)
: state_{std::make_shared<detail::task_state<T>>()}
, cancel_{cancel}
{
state_->weak_cancel = cancel_;
}
explicit operator bool() const
{
@ -249,13 +262,19 @@ namespace psemek::async
state_->exception = std::move(e);
}
future<T> get_future() const
future<T> get_future()
{
return future<T>(state_);
return future<T>(state_, std::move(cancel_));
}
bool canceled() const
{
return !state_->weak_cancel.lock();
}
private:
std::shared_ptr<detail::task_state<T>> state_;
std::shared_ptr<detail::cancel_token> cancel_;
};
template <>
@ -265,12 +284,26 @@ namespace psemek::async
{}
promise()
: state_{std::make_shared<detail::task_state<void>>(false)}
{}
: state_{std::make_shared<detail::task_state<void>>()}
, cancel_{std::make_shared<detail::cancel_token>()}
{
state_->shared_cancel = cancel_;
state_->weak_cancel = cancel_;
}
promise(auto_cancel_tag)
: state_{std::make_shared<detail::task_state<void>>(true)}
{}
: state_{std::make_shared<detail::task_state<void>>()}
, cancel_{std::make_shared<detail::cancel_token>()}
{
state_->weak_cancel = cancel_;
}
promise(std::shared_ptr<detail::cancel_token> cancel)
: state_{std::make_shared<detail::task_state<void>>()}
, cancel_{cancel}
{
state_->weak_cancel = cancel_;
}
explicit operator bool() const
{
@ -297,13 +330,19 @@ namespace psemek::async
state_->exception = std::move(e);
}
future<void> get_future() const
future<void> get_future()
{
return future<void>(state_);
return future<void>(state_, std::move(cancel_));
}
bool canceled() const
{
return !state_->weak_cancel.lock();
}
private:
std::shared_ptr<detail::task_state<void>> state_;
std::shared_ptr<detail::cancel_token> cancel_;
};
template <typename T>
@ -335,12 +374,18 @@ namespace psemek::async
, func_(std::forward<F>(f))
{}
template <typename F>
packaged_task(std::shared_ptr<detail::cancel_token> cancel, F && f)
: promise_(cancel)
, func_(std::forward<F>(f))
{}
explicit operator bool() const
{
return static_cast<bool>(promise_);
}
future<R> get_future() const
future<R> get_future()
{
return promise_.get_future();
}
@ -348,6 +393,9 @@ namespace psemek::async
template <typename ... Args1>
void operator() (Args1 && ... args)
{
if (promise_.canceled())
return;
try
{
if constexpr (std::is_same_v<R, void>)
@ -427,7 +475,7 @@ namespace psemek::async
if constexpr (std::is_same_v<T, void>)
{
using R = decltype(f());
packaged_task<R()> t(std::forward<F>(f));
packaged_task<R()> t(cancel_, std::forward<F>(f));
auto fut = t.get_future();
std::lock_guard lock{state_->then_mutex};
@ -437,7 +485,7 @@ namespace psemek::async
else
{
using R = decltype(f(*(state_->value)));
packaged_task<R(T &)> t(std::forward<F>(f));
packaged_task<R(T &)> t(cancel_, std::forward<F>(f));
auto fut = t.get_future();
std::lock_guard lock{state_->then_mutex};