ripple::ClosureCounter< Ret_t, Args_t > Class Template Reference

The role of a ClosureCounter is to assist in shutdown by letting callers wait for the completion of closures (of a specific type signature) that they previously registered. More...

Collaboration diagram for ripple::ClosureCounter< Ret_t, Args_t >:

Classes
class	Substitute

Public Member Functions
	ClosureCounter ()=default
	ClosureCounter (ClosureCounter const &)=delete
ClosureCounter &	operator= (ClosureCounter const &)=delete
	~ClosureCounter ()
	Destructor verifies all in-flight closures are complete. More...
void	join (char const *name, std::chrono::milliseconds wait, beast::Journal j)
	Returns once all counted in-flight closures are destroyed. More...
template<class Closure >
std::optional< Substitute< Closure > >	wrap (Closure &&closure)
	Wrap the passed closure with a reference counter. More...
int	count () const
	Current number of Closures outstanding. More...
bool	joined () const
	Returns true if this has been joined. More...

Private Member Functions
ClosureCounter &	operator++ ()
ClosureCounter &	operator-- ()

Private Attributes
std::mutex	mutex_ {}
std::condition_variable	allClosuresDoneCond_ {}
bool	waitForClosures_ {false}
std::atomic< int >	closureCount_ {0}

Detailed Description

template<typename Ret_t, typename... Args_t>
class ripple::ClosureCounter< Ret_t, Args_t >

The role of a ClosureCounter is to assist in shutdown by letting callers wait for the completion of closures (of a specific type signature) that they previously registered.

These closures are typically callbacks for asynchronous operations. The lifetime of a ClosureCounter consists of two phases: the initial expanding "fork" phase, and the subsequent shrinking "join" phase.

In the fork phase, callers register a closure by passing the closure and receiving a substitute in return. The substitute has the same callable interface as the closure, and it informs the ClosureCounter whenever it is copied or destroyed, so that it can keep an accurate count of copies.

The transition to the join phase is made by a call to join. In this phase, every substitute returned going forward will be null, signaling to the caller that they should drop the closure and cancel their operation. join blocks until all existing closure substitutes are destroyed.

Template Parameters

Ret_t	The return type of the closure.
Args_t	The argument types of the closure.

Definition at line 54 of file ClosureCounter.h.

Constructor & Destructor Documentation

ClosureCounter() [1/2]

template<typename Ret_t , typename... Args_t>

ripple::ClosureCounter< Ret_t, Args_t >::ClosureCounter ( )

default

ClosureCounter() [2/2]

template<typename Ret_t , typename... Args_t>

ripple::ClosureCounter< Ret_t, Args_t >::ClosureCounter ( ClosureCounter< Ret_t, Args_t > const &  )

delete

~ClosureCounter()

template<typename Ret_t , typename... Args_t>

ripple::ClosureCounter< Ret_t, Args_t >::~ClosureCounter

(

)

Destructor verifies all in-flight closures are complete.

Definition at line 153 of file ClosureCounter.h.

Member Function Documentation

operator++()

template<typename Ret_t , typename... Args_t>

ClosureCounter& ripple::ClosureCounter< Ret_t, Args_t >::operator++ ( )

private

Definition at line 64 of file ClosureCounter.h.

operator--()

template<typename Ret_t , typename... Args_t>

ClosureCounter& ripple::ClosureCounter< Ret_t, Args_t >::operator-- ( )

private

Definition at line 73 of file ClosureCounter.h.

operator=()

template<typename Ret_t , typename... Args_t>

ClosureCounter& ripple::ClosureCounter< Ret_t, Args_t >::operator= ( ClosureCounter< Ret_t, Args_t > const &  )

delete

join()

template<typename Ret_t , typename... Args_t>

void ripple::ClosureCounter< Ret_t, Args_t >::join	(	char const *	name,
		std::chrono::milliseconds	wait,
		beast::Journal	j
	)

Returns once all counted in-flight closures are destroyed.

Parameters

name	Name reported if join time exceeds wait.
wait	If join() exceeds this duration report to Journal.
j	Journal written to if wait is exceeded.

Definition at line 166 of file ClosureCounter.h.

wrap()

template<typename Ret_t , typename... Args_t>

template<class Closure >

std::optional<Substitute<Closure> > ripple::ClosureCounter< Ret_t, Args_t >::wrap

(

Closure &&

closure

)

Wrap the passed closure with a reference counter.

Parameters

closure

Closure that accepts Args_t parameters and returns Ret_t.

Returns

If join() has been called returns std::nullopt. Otherwise returns a std::optional that wraps closure with a reference counter.

Definition at line 192 of file ClosureCounter.h.

count()

template<typename Ret_t , typename... Args_t>

int ripple::ClosureCounter< Ret_t, Args_t >::count

(

)

const

Current number of Closures outstanding.

Only useful for testing.

Definition at line 205 of file ClosureCounter.h.

joined()

template<typename Ret_t , typename... Args_t>

bool ripple::ClosureCounter< Ret_t, Args_t >::joined

(

)

const

Returns true if this has been joined.

Even if true is returned, counted closures may still be in flight. However if (joined() && (count() == 0)) there should be no more counted closures in flight.

Definition at line 217 of file ClosureCounter.h.

Member Data Documentation

mutex_

template<typename Ret_t , typename... Args_t>

std::mutex ripple::ClosureCounter< Ret_t, Args_t >::mutex_ {}

mutableprivate

Definition at line 57 of file ClosureCounter.h.

allClosuresDoneCond_

template<typename Ret_t , typename... Args_t>

std::condition_variable ripple::ClosureCounter< Ret_t, Args_t >::allClosuresDoneCond_ {}

private

Definition at line 58 of file ClosureCounter.h.

waitForClosures_

template<typename Ret_t , typename... Args_t>

bool ripple::ClosureCounter< Ret_t, Args_t >::waitForClosures_ {false}

private

Definition at line 59 of file ClosureCounter.h.

closureCount_

template<typename Ret_t , typename... Args_t>

std::atomic<int> ripple::ClosureCounter< Ret_t, Args_t >::closureCount_ {0}

private

Definition at line 60 of file ClosureCounter.h.