uvco::MultiPromiseCore< T > Class Template Reference

#include <multipromise.h>

Inheritance diagram for uvco::MultiPromiseCore< T >:

Collaboration diagram for uvco::MultiPromiseCore< T >:

Public Member Functions
	MultiPromiseCore ()=default
	MultiPromiseCore (const MultiPromiseCore &)=delete
	MultiPromiseCore (MultiPromiseCore &&)=delete
MultiPromiseCore &	operator= (const MultiPromiseCore &)=delete
MultiPromiseCore &	operator= (MultiPromiseCore &&)=delete
	~MultiPromiseCore () override=default
void	setHandle (std::coroutine_handle<> handle) override
void	resume () override
void	resumeGenerator ()
void	suspendGenerator (std::coroutine_handle<> handle)
void	cancelGenerator ()
void	terminated ()
bool	isTerminated () const
	Check if the generator has been cancelled or has returned.
Public Member Functions inherited from uvco::PromiseCore< T >
	PromiseCore ()=default
	PromiseCore (const PromiseCore &)=delete
	PromiseCore (PromiseCore &&)=delete
PromiseCore &	operator= (const PromiseCore &)=delete
PromiseCore &	operator= (PromiseCore &&)=delete
	PromiseCore (T &&value)
void	resetHandle ()
void	cancel ()
bool	willResume ()
	Checks if a coroutine is waiting on a promise belonging to this core.
bool	ready () const
	Checks if a value is present in the slot.
bool	stale () const
virtual	~PromiseCore ()
void	except (const std::exception_ptr &exc)
Public Member Functions inherited from uvco::RefCounted< PromiseCore< T > >
	RefCounted (const RefCounted &other)=default
	RefCounted (RefCounted &&other) noexcept
RefCounted &	operator= (const RefCounted &other)=default
RefCounted &	operator= (RefCounted &&other) noexcept
virtual	~RefCounted ()=default
virtual T *	addRef ()
virtual void	delRef ()

Private Attributes
std::optional< std::coroutine_handle<> >	generatorHandle_
	Coroutine handle referring to the suspended generator.
bool	terminated_ = false

Additional Inherited Members
Public Attributes inherited from uvco::PromiseCore< T >
std::optional< std::variant< T, std::exception_ptr > >	slot
	The slot contains the result once obtained.
Protected Member Functions inherited from uvco::RefCounted< PromiseCore< T > >
	RefCounted ()=default
Protected Attributes inherited from uvco::PromiseCore< T >
std::optional< std::coroutine_handle<> >	handle_
PromiseState	state_ = PromiseState::init

Detailed Description

template<typename T>
class uvco::MultiPromiseCore< T >

A MultiPromiseCore works like a PromiseCore, but with an adapted state machine: it can transition from finished back to waitedOn, and therefore yield more than one value. It is used by MultiPromise, a generator-like type.

Constructor & Destructor Documentation

MultiPromiseCore() [1/3]

template<typename T >

uvco::MultiPromiseCore< T >::MultiPromiseCore ( )

default

MultiPromiseCore() [2/3]

template<typename T >

uvco::MultiPromiseCore< T >::MultiPromiseCore ( const MultiPromiseCore< T > &  )

delete

MultiPromiseCore() [3/3]

template<typename T >

uvco::MultiPromiseCore< T >::MultiPromiseCore ( MultiPromiseCore< T > &&  )

delete

~MultiPromiseCore()

template<typename T >

uvco::MultiPromiseCore< T >::~MultiPromiseCore ( )

overridedefault

Member Function Documentation

cancelGenerator()

template<typename T >

void uvco::MultiPromiseCore< T >::cancelGenerator ( )

inline

Cancel the generator coroutine. This will drop all stack variables inside the generator (and run their destructors), and ensure that the generatorHandle_ will never resume from the currently yielded value.

Called by tje MultiPromise destructor and MultiPromise::cancel().

                         {
    terminated();
    if (generatorHandle_) {
      const std::coroutine_handle<> generatorHandle = generatorHandle_.value();
      generatorHandle_.reset();
      // Careful: within this function, this class' dtor is called!
      generatorHandle.destroy();
    }
  }

isTerminated()

template<typename T >

bool uvco::MultiPromiseCore< T >::isTerminated ( ) const

inline

Check if the generator has been cancelled or has returned.

{ return terminated_; }

operator=() [1/2]

template<typename T >

MultiPromiseCore & uvco::MultiPromiseCore< T >::operator= ( const MultiPromiseCore< T > &  )

delete

operator=() [2/2]

template<typename T >

MultiPromiseCore & uvco::MultiPromiseCore< T >::operator= ( MultiPromiseCore< T > &&  )

delete

resume()

template<typename T >

void uvco::MultiPromiseCore< T >::resume ( )

inlineoverridevirtual

See Promise::resume. Implemented here to provide a distinction in stack traces.

Reimplemented from uvco::PromiseCore< T >.

{ PromiseCore<T>::resume(); }

resumeGenerator()

template<typename T >

void uvco::MultiPromiseCore< T >::resumeGenerator ( )

inline

Resume the generator from its last co_yield point, so it can yield the next value.

Called by a MultiPromiseAwaiter_ when the MultiPromise is co_awaited, after a value has been successfully awaited.

                         {
    BOOST_ASSERT(PromiseCore<T>::state_ != PromiseState::finished);
    if (generatorHandle_) {
      const auto generatorHandle = generatorHandle_.value();
      generatorHandle_.reset();
      Loop::enqueue(generatorHandle);
    }
  }

setHandle()

template<typename T >

void uvco::MultiPromiseCore< T >::setHandle ( std::coroutine_handle<>  handle )

inlineoverridevirtual

See PromiseCore::setHandle. Called by a MultiPromise when it is co_awaited.

In contrast to a PromiseCore, a finished multipromise core can be reset to the waiting state, in order to yield the next value, when the MultiPromise is co_awaited again.

Reimplemented from uvco::PromiseCore< T >.

                                                        {
    // Once an external scheduler works, Promises will not be nested anymore
    // (resume called by resume down in the stack)
    //
    // BOOST_ASSERT(PromiseCore<T>::state_
    // == PromiseState::init || PromiseCore<T>::state_ ==
    // PromiseState::finished);
    //
    // state is init or running (latter can occur if setHandle is called from a
    // stack originating at resume()).
    BOOST_ASSERT_MSG(PromiseCore<T>::state_ != PromiseState::waitedOn,
                     "MultiPromise must be co_awaited before next yield");
    BOOST_ASSERT_MSG(!PromiseCore<T>::handle_,
                     "MultiPromise must be co_awaited before next yield");
    PromiseCore<T>::handle_ = handle;
    PromiseCore<T>::state_ = PromiseState::waitedOn;
  }

suspendGenerator()

template<typename T >

void uvco::MultiPromiseCore< T >::suspendGenerator ( std::coroutine_handle<>  handle )

inline

Suspend the generator coroutine at the current co_yield point by storing the handle for a later resumption.

Called by the MultiPromise<...>::yield_value method when co_yield is invoked inside the generator.

                                                      {
    BOOST_ASSERT_MSG(!generatorHandle_,
                     "MultiPromiseCore::suspendGenerator: generatorHandle_ is "
                     "already set");
    generatorHandle_ = handle;
  }

terminated()

template<typename T >

void uvco::MultiPromiseCore< T >::terminated ( )

inline

Mark generator as finished, yielding no more values. Called from within the MultiPromise upon return_value and unhandled_exception. From hereon awaiting the generator will either rethrow the thrown exception, or yield nullopt.

{ terminated_ = true; }

Member Data Documentation

generatorHandle_

template<typename T >

std::optional<std::coroutine_handle<> > uvco::MultiPromiseCore< T >::generatorHandle_

private

Coroutine handle referring to the suspended generator.

terminated_

template<typename T >

bool uvco::MultiPromiseCore< T >::terminated_ = false

private

Set to true once the generator coroutine has returned or has been cancelled.

---

The documentation for this class was generated from the following file:

• uvco/promise/multipromise.h