jau::latch Class Reference

Inspired by std::latch of C++20. More...

#include <latch.hpp>

Collaboration diagram for jau::latch:

Public Member Functions
	latch () noexcept=default
	Initialize instance with counter zero.
	latch (const latch &o)=delete
	No copy constructor nor move constructor.
	latch (const size_t count_) noexcept
	Initialize instance with given counter.
void	arrive_and_wait (const size_t n=1) noexcept
	Atomically decrements the internal counter by n and (if necessary) blocks the calling thread until the counter reaches zero.
bool	arrive_and_wait_for (const fraction_i64 &timeout_duration, const size_t n=1) noexcept
	Atomically decrements the internal counter by n and (if necessary) blocks the calling thread until the counter reaches zero or the given timeout duration has expired.
template<typename Rep, typename Period>
bool	arrive_and_wait_for (const std::chrono::duration< Rep, Period > &timeout_duration, const size_t n=1) noexcept
	Atomically decrements the internal counter by n and (if necessary) blocks the calling thread until the counter reaches zero or the given timeout duration has expired.
void	count_down (const size_t n=1) noexcept
	Atomically decrements the internal counter by n and notifies all blocked wait() threads if zero is reached.
void	count_up (const size_t n=1) noexcept
	Atomically increments the internal counter by n, i.e.
void	set (const size_t n) noexcept
	Atomically set the internal counter by n.
bool	try_wait () const noexcept
	Returns true only if the internal counter has reached zero.
size_t	value () const noexcept
	Return the current atomic internal counter.
void	wait () const noexcept
	Blocks the calling thread until the internal counter reaches 0.
bool	wait_for (const fraction_i64 &timeout_duration) const noexcept
	Blocks the calling thread until the internal counter reaches 0 or the given timeout duration has expired.
template<typename Rep, typename Period>
bool	wait_for (const std::chrono::duration< Rep, Period > &timeout_duration) const noexcept
	Blocks the calling thread until the internal counter reaches 0 or the given timeout duration has expired.

Static Public Member Functions
static constexpr size_t	max () noexcept
	Returns the maximum value of the internal counter supported by the implementation.

Detailed Description

Inspired by std::latch of C++20.

Adds count_up() as an extension, allowing to dynamically add events to required to complete.

See also

https://en.cppreference.com/w/cpp/thread/latch

Definition at line 50 of file latch.hpp.

Constructor & Destructor Documentation

latch() [1/3]

jau::latch::latch ( )

defaultnoexcept

Initialize instance with counter zero.

Useful for member instances in combination with count_up() or with set() before count_down().

Extension of std::latch.

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latch() [2/3]

jau::latch::latch ( const size_t count_ )

inlinenoexcept

Initialize instance with given counter.

Compatible with std::latch.

Parameters

count_

Definition at line 76 of file latch.hpp.

latch() [3/3]

jau::latch::latch ( const latch & o )

delete

No copy constructor nor move constructor.

Compatible with std::latch.

Parameters

o

Member Function Documentation

max()

static constexpr size_t jau::latch::max ( )

inlinestaticconstexprnoexcept

Returns the maximum value of the internal counter supported by the implementation.

Definition at line 58 of file latch.hpp.

value()

size_t jau::latch::value ( ) const

inlinenoexcept

Return the current atomic internal counter.

Extension of std::latch.

Definition at line 93 of file latch.hpp.

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count_down()

void jau::latch::count_down ( const size_t n = 1 )

inlinenoexcept

Atomically decrements the internal counter by n and notifies all blocked wait() threads if zero is reached.

If n is greater than the value of the internal counter, the counter is set to zero.

This operation strongly happens-before all calls that are unblocked on this latch.

Compatible with std::latch.

Parameters

n	the value by which the internal counter is decreased, defaults to 1

Definition at line 107 of file latch.hpp.

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count_up()

void jau::latch::count_up ( const size_t n = 1 )

inlinenoexcept

Atomically increments the internal counter by n, i.e.

adds value to count down.

If internal counter + n is greater than the maximum value of the internal counter, the counter is set to its maximum.

This operation strongly happens-before all calls that are unblocked on this latch.

Extension of std::latch.

Parameters

n	the value by which the internal counter is increased, defaults to 1

Definition at line 135 of file latch.hpp.

set()

void jau::latch::set ( const size_t n )

inlinenoexcept

Atomically set the internal counter by n.

This operation strongly happens-before all calls that are unblocked on this latch.

Extension of std::latch.

Parameters

n	the value to be assigned to the internal counter

Definition at line 153 of file latch.hpp.

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try_wait()

bool jau::latch::try_wait ( ) const

inlinenoexcept

Returns true only if the internal counter has reached zero.

Compatible with std::latch.

Definition at line 163 of file latch.hpp.

wait()

void jau::latch::wait ( ) const

inlinenoexcept

Blocks the calling thread until the internal counter reaches 0.

If the internal counter is zero already, returns immediately.

Compatible with std::latch.

Definition at line 174 of file latch.hpp.

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arrive_and_wait()

void jau::latch::arrive_and_wait ( const size_t n = 1 )

inlinenoexcept

Atomically decrements the internal counter by n and (if necessary) blocks the calling thread until the counter reaches zero.

Equivalent to count_down(n); wait();.

Compatible with std::latch.

Parameters

n	the value by which the internal counter is decreased, defaults to 1

Definition at line 192 of file latch.hpp.

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wait_for() [1/2]

bool jau::latch::wait_for ( const fraction_i64 & timeout_duration ) const

inlinenoexcept

Blocks the calling thread until the internal counter reaches 0 or the given timeout duration has expired.

If the internal counter is zero already, returns immediately.

Implementation uses wait_for() w/ a monotonic clock and fraction_i64.

Extension of std::latch.

Parameters

timeout_duration

maximum duration in fractions of seconds to wait

Returns

true if internal counter has reached zero, otherwise a timeout has occurred.

Definition at line 209 of file latch.hpp.

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arrive_and_wait_for() [1/2]

bool jau::latch::arrive_and_wait_for ( const fraction_i64 & timeout_duration, const size_t n = 1 )

inlinenoexcept

Atomically decrements the internal counter by n and (if necessary) blocks the calling thread until the counter reaches zero or the given timeout duration has expired.

Equivalent to count_down(n); wait(timeout_duration);.

Implementation uses std::chrono::steady_clock::now() and fraction_i64.

Extension of std::latch.

Parameters

timeout_duration	maximum duration in fractions of seconds to wait
n	the value by which the internal counter is decreased, defaults to 1

Returns

true if internal counter has reached zero, otherwise a timeout has occurred.

Definition at line 240 of file latch.hpp.

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wait_for() [2/2]

template<typename Rep, typename Period>

bool jau::latch::wait_for ( const std::chrono::duration< Rep, Period > & timeout_duration ) const

inlinenoexcept

Blocks the calling thread until the internal counter reaches 0 or the given timeout duration has expired.

If the internal counter is zero already, returns immediately.

Implementation uses std::chrono::steady_clock::now().

Extension of std::latch.

Template Parameters

Rep
Period

Parameters

timeout_duration

maximum duration to wait

Returns

true if internal counter has reached zero, otherwise a timeout has occurred.

Definition at line 260 of file latch.hpp.

arrive_and_wait_for() [2/2]

template<typename Rep, typename Period>

bool jau::latch::arrive_and_wait_for ( const std::chrono::duration< Rep, Period > & timeout_duration, const size_t n = 1 )

inlinenoexcept

Atomically decrements the internal counter by n and (if necessary) blocks the calling thread until the counter reaches zero or the given timeout duration has expired.

Equivalent to count_down(n); wait(timeout_duration);.

Implementation uses std::chrono::steady_clock::now().

Extension of std::latch.

Template Parameters

Rep
Period

Parameters

timeout_duration	maximum duration to wait
n	the value by which the internal counter is decreased, defaults to 1

Returns

true if internal counter has reached zero, otherwise a timeout has occurred.

Definition at line 294 of file latch.hpp.

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

• jaulib/include/jau/latch.hpp