dpp::async< R > Class Template Reference

A co_await-able object handling an API call in parallel with the caller. More...

Inheritance diagram for dpp::async< R >:

Collaboration diagram for dpp::async< R >:

Public Types
using	result_type = R
	The return type of the API call. Defaults to confirmation_callback_t. More...

Public Member Functions
template<typename Obj , typename Fun , typename... Args>
	async (Obj &&obj, Fun &&fun, Args &&... args)
	Construct an async object wrapping an object method, the call is made immediately by forwarding to std::invoke and can be awaited later to retrieve the result. More...
template<typename Fun , typename... Args>
	async (Fun &&fun, Args &&... args)
	Construct an async object wrapping an invokeable object, the call is made immediately by forwarding to std::invoke and can be awaited later to retrieve the result. More...
	async (const async &)=delete
	Copy constructor is disabled. More...
	async (async &&)=default
	Move constructor, moves the awaitable async object. More...
async &	operator= (const async &)=delete
	Copy assignment operator is disabled. More...
async &	operator= (async &&)=default
	Move assignment operator, moves the awaitable async object. More...
	~async ()
	Destructor, signals to the callback that the async object is gone and shouldn't be notified of the result. More...
void	if_this_causes_an_invalid_read_your_promise_was_destroyed_before_your_awaitable____check_your_promise_lifetime ()
	Title :) More...
bool	valid () const noexcept
	Check whether this awaitable refers to a valid promise. More...
bool	await_ready () const
	Check whether or not co_await-ing this would suspend the caller, i.e. if we have the result or not. More...
	requires (std::is_base_of_v< awaitable, std::remove_cv_t< Derived >>) friend awaiter< Derived & > operator co_await(Derived &obj) noexcept
	Overload of the co_await operator. More...
	requires (std::is_base_of_v< awaitable, std::remove_cv_t< Derived >>) friend awaiter< Derived && > operator co_await(Derived &&obj) noexcept
	Overload of the co_await operator. Returns an awaiter referencing this awaitable. More...
auto	sync_wait ()
	Blocks this thread and waits for the awaitable to finish. More...
auto	sync_wait_for (const std::chrono::duration< Rep, Period > &duration)
	Blocks this thread and waits for the awaitable to finish. More...
auto	sync_wait_until (const std::chrono::time_point< Clock, Duration > &time)
	Blocks this thread and waits for the awaitable to finish. More...

Protected Types
using	shared_state = detail::promise::promise_base< R >
using	state_flags = detail::promise::state_flags

Protected Member Functions
uint8_t	abandon ()
	Abandons the promise. More...
auto	sync_wait_impl (auto &&do_wait)
	Implementation for sync_wait. This is code used by sync_wait, sync_wait_for, sync_wait_until. More...

Protected Attributes
shared_state *	state_ptr
	Non-owning pointer to the promise, which must be kept alive for the entire lifetime of the awaitable. More...

Detailed Description

template<typename R>
class dpp::async< R >

A co_await-able object handling an API call in parallel with the caller.

This class is the return type of the dpp::cluster::co_* methods, but it can also be created manually to wrap any async call.

Remarks

- The coroutine may be resumed in another thread, do not rely on thread_local variables.

Warning

- This feature is EXPERIMENTAL. The API may change at any time and there may be bugs. Please report any to GitHub issues or to the D++ Discord server.

Template Parameters

R	The return type of the API call. Defaults to confirmation_callback_t

Member Typedef Documentation

result_type

template<typename R >

using dpp::async< R >::result_type = R

The return type of the API call. Defaults to confirmation_callback_t.

shared_state

using dpp::awaitable< R >::shared_state = detail::promise::promise_base<R >

protectedinherited

state_flags

using dpp::awaitable< R >::state_flags = detail::promise::state_flags

protectedinherited

Constructor & Destructor Documentation

async() [1/4]

template<typename R >

template<typename Obj , typename Fun , typename... Args>

dpp::async< R >::async ( Obj &&  obj, Fun &&  fun, Args &&...  args  )

inlineexplicit

Construct an async object wrapping an object method, the call is made immediately by forwarding to std::invoke and can be awaited later to retrieve the result.

Parameters

obj	The object to call the method on
fun	The method of the object to call. Its last parameter must be a callback taking a parameter of type R
args	Parameters to pass to the method, excluding the callback

async() [2/4]

template<typename R >

template<typename Fun , typename... Args>

dpp::async< R >::async ( Fun &&  fun, Args &&...  args  )

inlineexplicit

Construct an async object wrapping an invokeable object, the call is made immediately by forwarding to std::invoke and can be awaited later to retrieve the result.

Parameters

fun	The object to call using std::invoke. Its last parameter must be a callable taking a parameter of type R
args	Parameters to pass to the object, excluding the callback

async() [3/4]

template<typename R >

dpp::async< R >::async ( const async< R > &  )

delete

Copy constructor is disabled.

async() [4/4]

template<typename R >

dpp::async< R >::async ( async< R > &&  )

default

Move constructor, moves the awaitable async object.

~async()

template<typename R >

dpp::async< R >::~async ( )

inline

Destructor, signals to the callback that the async object is gone and shouldn't be notified of the result.

Member Function Documentation

abandon()

auto dpp::awaitable< R >::abandon

protectedinherited

Abandons the promise.

Set the promise's state to broken and unlinks this awaitable.

Returns

uint8_t Flags previously held before setting them to broken

await_ready()

bool dpp::awaitable< R >::await_ready

inherited

Check whether or not co_await-ing this would suspend the caller, i.e. if we have the result or not.

Returns

bool Whether we already have the result or not

if_this_causes_an_invalid_read_your_promise_was_destroyed_before_your_awaitable____check_your_promise_lifetime()

void dpp::awaitable< R >::if_this_causes_an_invalid_read_your_promise_was_destroyed_before_your_awaitable____check_your_promise_lifetime

inlineinherited

Title :)

We use this in the destructor

operator=() [1/2]

template<typename R >

async& dpp::async< R >::operator= ( async< R > &&  )

default

Move assignment operator, moves the awaitable async object.

operator=() [2/2]

template<typename R >

async& dpp::async< R >::operator= ( const async< R > &  )

delete

Copy assignment operator is disabled.

requires() [1/2]

dpp::awaitable< R >::requires ( std::is_base_of_v< awaitable< R >, std::remove_cv_t< Derived >>  ) &

inlinenoexceptinherited

Overload of the co_await operator.

Returns

Returns an awaiter referencing this awaitable.

requires() [2/2]

dpp::awaitable< R >::requires ( std::is_base_of_v< awaitable< R >, std::remove_cv_t< Derived >>  ) &&

inlinenoexceptinherited

Overload of the co_await operator. Returns an awaiter referencing this awaitable.

Returns

Returns an awaiter referencing this awaitable.

sync_wait()

auto dpp::basic_awaitable< awaitable< R > >::sync_wait

inlineinherited

Blocks this thread and waits for the awaitable to finish.

Attention

This will BLOCK THE THREAD. It is likely you want to use co_await instead.

Returns

If T is void, returns a boolean for which true means the awaitable completed, false means it timed out.

If T is non-void, returns a std::optional<T> for which an absence of value means timed out.

sync_wait_for()

auto dpp::basic_awaitable< awaitable< R > >::sync_wait_for ( const std::chrono::duration< Rep, Period > &  duration )

inlineinherited

Blocks this thread and waits for the awaitable to finish.

Attention

This will BLOCK THE THREAD. It is likely you want to use co_await instead.

Parameters

duration

Maximum duration to wait for

Returns

If T is void, returns a boolean for which true means the awaitable completed, false means it timed out.

If T is non-void, returns a std::optional<T> for which an absence of value means timed out.

sync_wait_impl()

auto dpp::basic_awaitable< awaitable< R > >::sync_wait_impl ( auto &&  do_wait )

inlineprotectedinherited

Implementation for sync_wait. This is code used by sync_wait, sync_wait_for, sync_wait_until.

Template Parameters

Timed

Whether the wait function times out or not

Parameters

do_wait

Function to do the actual wait on the cv

Returns

If T is void, returns a boolean for which true means the awaitable completed, false means it timed out.

If T is non-void, returns a std::optional<T> for which an absence of value means timed out.

sync_wait_until()

auto dpp::basic_awaitable< awaitable< R > >::sync_wait_until ( const std::chrono::time_point< Clock, Duration > &  time )

inlineinherited

Blocks this thread and waits for the awaitable to finish.

Attention

This will BLOCK THE THREAD. It is likely you want to use co_await instead.

Parameters

time	Maximum time point to wait for

Returns

If T is void, returns a boolean for which true means the awaitable completed, false means it timed out.

If T is non-void, returns a std::optional<T> for which an absence of value means timed out.

valid()

bool dpp::awaitable< R >::valid

noexceptinherited

Check whether this awaitable refers to a valid promise.

Returns

bool Whether this awaitable refers to a valid promise or not

Member Data Documentation

state_ptr

shared_state* dpp::awaitable< R >::state_ptr

protectedinherited

Non-owning pointer to the promise, which must be kept alive for the entire lifetime of the awaitable.