GLib: atomic integer operations

["Gustavo J. A. M. " Carneiro <gjc inescporto pt>]

  I would like to propose that a set of "atomic integer operations" be
included in a future glib. Something like this:

  http://www.mozilla.org/projects/nspr/reference/html/pratom.html#20841

  These functions are very useful for threaded programs. Advantages:
	1. These operations do not require any locking/mutexes, so they are
super fast!;
	2. Thread-safe reference counting of objects without any performance
penalty;
	3. They're very simple to implement; It takes only a few asm
instructions. Example (from NSPR):

/ PRInt32 _PR_x86_AtomicIncrement(PRInt32 *val)
/
/ Atomically increment the integer pointed to by 'val' and return
/ the result of the increment.
/
    .text
    .globl _PR_x86_AtomicIncrement
    .align 4
_PR_x86_AtomicIncrement:
    movl 4(%esp), %ecx
    movl $1, %eax
    lock
    xaddl %eax, (%ecx)
    incl %eax
    ret

  For unsupported platforms, the behaviour can be emulated with mutexes, of course.

  Let me know what you think.

-- 
Gustavo João Alves Marques Carneiro
<gjc inescporto pt> <gustavo users sourceforge net>