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| ||'''lock'''||,,points to the lock,, ^the desired SDL_!SpinLock to lock^|| <<Color2(green,Should SDL_!SpinLock be changed to spin lock because it's a typedef with no page? Does this function change the setting of a lock struct (typedef?) to non-0 automatically when it is called? Unlock changes it back to 0?)>> |
||'''lock'''||a pointer to a lock variable|| |
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| The spin lock functions and type are required and can not be emulated because they are used in the emulation code. <<Color2(green,Would the following site be a relevant link here or perhaps in a more detailed section on this topic?)>> http://en.wikipedia.org/wiki/Spin_lock |
<<Include(CategoryAtomic, , , from="Start include here.", to="##The Include ends here")>> |
SDL_AtomicLock
Use this function to lock a spin lock by setting it to a non-zero value.
Contents
Syntax
void SDL_AtomicLock(SDL_SpinLock* lock)
Function Parameters
lock |
a pointer to a lock variable |
Code Examples
You can add your code example here
Remarks
Include: Nothing found for "Start include here."!
Include: Nothing found for "##The Include ends here"!
Atomic Operations
Include File(s): SDL_atomic.h
Introduction
This category contains functions for handling atomic operations.
![/!\](/moin_static198/fixedleft/img/alert.png "/!\"){kind=small}
IMPORTANT:
If you are not an expert in concurrent lockless programming, you should only be using the atomic lock and reference counting functions in this file. In all other cases you should be protecting your data structures with full mutexes. Seriously, here be dragons!
"Safe" functions to use are:
You can find out a little more about lockless programming and the subtle issues that can arise here:
There's also lots of good information here:
These operations may or may not actually be implemented using processor specific atomic operations. When possible they are implemented as true processor specific atomic operations. When that is not possible the are implemented using locks that do use the available atomic operations.
All of the atomic operations that modify memory are full memory barriers.
Atomic Locks
The atomic locks are efficient spinlocks using CPU instructions, but are vulnerable to starvation and can spin forever if a thread holding a lock has been terminated. For this reason you should minimize the code executed inside an atomic lock and never do expensive things like API or system calls while holding them.
The atomic locks are not safe to lock recursively.
Structures
Functions
