SDL::Semaphore Struct Reference

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

Inheritance diagram for SDL::Semaphore:

Public Member Functions
constexpr	Semaphore (SemaphoreRaw resource) noexcept
	Constructs from raw Semaphore.
constexpr	Semaphore (const Semaphore &other)=delete
	Copy constructor.
constexpr	Semaphore (Semaphore &&other) noexcept
	Move constructor.
constexpr	Semaphore (const SemaphoreRef &other)=delete
constexpr	Semaphore (SemaphoreRef &&other)=delete
	Semaphore (Uint32 initial_value)
	Create a semaphore.
	~Semaphore ()
	Destructor.
constexpr Semaphore &	operator= (Semaphore &&other) noexcept
	Assignment operator.
Semaphore &	operator= (const Semaphore &other)=delete
	Assignment operator.
void	Destroy ()
	Destroy a semaphore.
void	Wait ()
	Wait until a semaphore has a positive value and then decrements it.
bool	TryWait ()
	See if a semaphore has a positive value and decrement it if it does.
bool	WaitTimeout (std::chrono::milliseconds timeout)
	Wait until a semaphore has a positive value and then decrements it.
void	Signal ()
	Atomically increment a semaphore's value and wake waiting threads.
Uint32	GetValue () const
	Get the current value of a semaphore.
constexpr	ResourceBase (RawPointer resource)
	Constructs from resource pointer.
constexpr	ResourceBase (std::nullptr_t=nullptr)
	Constructs null/invalid.
Public Member Functions inherited from SDL::ResourceBase< SemaphoreRaw >
constexpr	ResourceBase (RawPointer resource)
	Constructs from resource pointer.
constexpr	operator bool () const
	Converts to bool.
constexpr auto	operator<=> (const ResourceBase &other) const=default
	Comparison.
constexpr RawConstPointer	operator-> () const noexcept
	member access to underlying resource pointer.
constexpr RawPointer	get () const noexcept
	Retrieves underlying resource pointer.
constexpr RawPointer	release () noexcept
	Retrieves underlying resource pointer and clear this.

Additional Inherited Members
Public Types inherited from SDL::ResourceBase< SemaphoreRaw >
using	RawPointer
	The underlying raw pointer type.
using	RawConstPointer
	The underlying const raw pointer type.

Detailed Description

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

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()

SDL::Semaphore::Semaphore ( SemaphoreRaw resource )

inlineexplicitconstexprnoexcept

Constructs from raw Semaphore.

Parameters

resource

a SemaphoreRaw to be wrapped.

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

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

• SDL3pp/SDL3pp_mutex.h