SDL::AtomicInt Class Reference

A type representing an atomic integer value. More...

Public Member Functions
constexpr	AtomicInt (int value=0)
	Constructor.
	AtomicInt (const AtomicInt &value)=delete
AtomicInt &	operator= (const AtomicInt &value)=delete
constexpr	operator SDL_AtomicInt * ()
	Convert to underlying type.
bool	CompareAndSwap (int oldval, int newval)
	Set an atomic variable to a new value if it is currently an old value.
int	Set (int v)
	Set an atomic variable to a value.
int	Get ()
	Get the value of an atomic variable.
int	Add (int v)
	Add to an atomic variable.
bool	AtomicIncRef ()
	Increment an atomic variable used as a reference count.
bool	AtomicDecRef ()
	Decrement an atomic variable used as a reference count.

Detailed Description

This can be used to manage a value that is synchronized across multiple CPUs without a race condition; when an app sets a value with AtomicInt.Set all other threads, regardless of the CPU it is running on, will see that value when retrieved with AtomicInt.Get, regardless of CPU caches, etc.

This is also useful for atomic compare-and-swap operations: a thread can change the value as long as its current value matches expectations. When done in a loop, one can guarantee data consistency across threads without a lock (but the usual warnings apply: if you don't know what you're doing, or you don't do it carefully, you can confidently cause any number of disasters with this, so in most cases, you should use a mutex instead of this!).

This is a struct so people don't accidentally use numeric operations on it directly. You have to use SDL atomic functions.

Since

This struct is available since SDL 3.2.0.

See also

AtomicInt.CompareAndSwap

AtomicInt.Get

AtomicInt.Set

AtomicInt.Add

Member Function Documentation

Add()

int SDL::AtomicInt::Add ( int  v )

inline

This function also acts as a full memory barrier.

Note: If you don't know what this function is for, you shouldn't use it!

Parameters

v	the desired value to add.

Returns

the previous value of the atomic variable.

Thread safety:

It is safe to call this function from any thread.

Since

This function is available since SDL 3.2.0.

See also

AtomicInt.AtomicDecRef

AtomicInt.AtomicIncRef

AtomicDecRef()

bool SDL::AtomicInt::AtomicDecRef ( )

inline

Note: If you don't know what this macro is for, you shouldn't use it!

Returns

true if the variable reached zero after decrementing, false otherwise.

Thread safety:

It is safe to call this macro from any thread.

Since

This macro is available since SDL 3.2.0.

See also

AtomicInt.AtomicIncRef

AtomicIncRef()

bool SDL::AtomicInt::AtomicIncRef ( )

inline

Note: If you don't know what this macro is for, you shouldn't use it!

Returns

the previous value of the atomic variable.

Thread safety:

It is safe to call this macro from any thread.

Since

This macro is available since SDL 3.2.0.

See also

AtomicInt.AtomicDecRef

CompareAndSwap()

bool SDL::AtomicInt::CompareAndSwap ( int  oldval, int  newval  )

inline

Note: If you don't know what this function is for, you shouldn't use it!

Parameters

oldval	the old value.
newval	the new value.

Returns

true if the atomic variable was set, false otherwise.

Thread safety:

It is safe to call this function from any thread.

Since

This function is available since SDL 3.2.0.

See also

AtomicInt.Get

AtomicInt.Set

Get()

int SDL::AtomicInt::Get ( )

inline

Note: If you don't know what this function is for, you shouldn't use it!

Returns

the current value of an atomic variable.

Thread safety:

It is safe to call this function from any thread.

Since

This function is available since SDL 3.2.0.

See also

AtomicInt.Set

Set()

int SDL::AtomicInt::Set ( int  v )

inline

This function also acts as a full memory barrier.

Note: If you don't know what this function is for, you shouldn't use it!

Parameters

v	the desired value.

Returns

the previous value of the atomic variable.

Thread safety:

It is safe to call this function from any thread.

Since

This function is available since SDL 3.2.0.

See also

AtomicInt.Get

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

• SDL3pp/SDL3pp_atomic.h