A means to manage access to a resource, by count, between threads. More...

Inheritance diagram for SDL::Semaphore:

Public Member Functions
constexpr	Semaphore ()=default
	Default ctor.

constexpr	Semaphore (const SemaphoreRaw resource)
	Constructs from SemaphoreParam. More...

constexpr	Semaphore (const Semaphore &other)=delete
	Copy constructor.

constexpr	Semaphore (Semaphore &&other)
	Move constructor.

constexpr	Semaphore (const SemaphoreRef &other)=delete

constexpr	Semaphore (SemaphoreRef &&other)=delete

	Semaphore (Uint32 initial_value)
	Create a semaphore. More...

	~Semaphore ()
	Destructor.

Semaphore &	operator= (Semaphore other)
	Assignment operator.

constexpr SemaphoreRaw	get () const
	Retrieves underlying SemaphoreRaw.

constexpr SemaphoreRaw	release ()
	Retrieves underlying SemaphoreRaw and clear this.

constexpr auto	operator<=> (const Semaphore &other) const =default
	Comparison.

constexpr bool	operator== (std::nullptr_t _) const
	Comparison.

constexpr	operator bool () const
	Converts to bool.

constexpr	operator SemaphoreParam () const
	Converts to SemaphoreParam.

void	Destroy ()
	Destroy a semaphore. More...

void	Wait ()
	Wait until a semaphore has a positive value and then decrements it. More...

bool	TryWait ()
	See if a semaphore has a positive value and decrement it if it does. More...

bool	WaitTimeout (std::chrono::milliseconds timeout)
	Wait until a semaphore has a positive value and then decrements it. More...

void	Signal ()
	Atomically increment a semaphore's value and wake waiting threads. More...

Uint32	GetValue () const
	Get the current value of a semaphore. More...

Detailed Description

Semaphores (specifically, "counting semaphores"), let X number of threads request access at the same time, each thread granted access decrementing a counter. When the counter reaches zero, future requests block until a prior thread releases their request, incrementing the counter again.

Wikipedia has a thorough explanation of the concept:

https://en.wikipedia.org/wiki/Semaphore_(programming)

Since: This struct is available since SDL 3.2.0.

Category:: Resource

Constructor & Destructor Documentation

◆ Semaphore() [1/2]

constexpr SDL::Semaphore::Semaphore ( const SemaphoreRaw resource )

inlineexplicitconstexpr

Parameters

resource a SemaphoreRaw to be wrapped.

This assumes the ownership, call release() if you need to take back.

◆ Semaphore() [2/2]

SDL::Semaphore::Semaphore ( Uint32 initial_value )

inline

This function creates a new semaphore and initializes it with the value initial_value. Each wait operation on the semaphore will atomically decrement the semaphore value and potentially block if the semaphore value is 0. Each post operation will atomically increment the semaphore value and wake waiting threads and allow them to retry the wait operation.

Parameters

initial_value the starting value of the semaphore.

Postcondition: a new semaphore or nullptr on failure; call GetError() for more information.

Since: This function is available since SDL 3.2.0.

See also: Semaphore.Destroy; Semaphore.Signal; Semaphore.TryWait; Semaphore.GetValue; Semaphore.Wait; Semaphore.WaitTimeout

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

SDL3pp/SDL3pp_mutex.h

Public Member Functions

Detailed Description

Constructor & Destructor Documentation

◆ Semaphore() [1/2]

◆ Semaphore() [2/2]