Atomic Operations basic atomic integer and pointer operations The following functions can be used to atomically access integers and pointers. They are implemented as inline assembler function on most platforms and use slower fall-backs otherwise. Using them can sometimes save you from using a performance-expensive #GMutex to protect the integer or pointer. The most important usage is reference counting. Using g_atomic_int_inc() and g_atomic_int_dec_and_test() makes reference counting a very fast operation. You must not directly read integers or pointers concurrently accessed by other threads with with the following functions directly. Always use g_atomic_int_get() and g_atomic_pointer_get() respectively. They are acting as a memory barrier. If you are using those functions for anything apart from simple reference counting, you should really be aware of the implications of doing that. There are literally thousands of ways to shoot yourself in the foot. So if in doubt, use a #GMutex. If you don't know, what memory barriers are, do not use anything but g_atomic_int_inc() and g_atomic_int_dec_and_test(). It is not safe to set an integer or pointer just by assigning to it, when it is concurrently accessed by other threads with the following functions. Use g_atomic_int_compare_and_exchange() or g_atomic_pointer_compare_and_exchange() respectively. #GMutex GLib mutual exclusions. Reads the value of the integer pointed to by @atomic. Also acts as a memory barrier. @atomic: a pointer to an integer. @Returns: the value of *@atomic. @Since: 2.4 Atomically adds @val to the integer pointed to by @atomic. Also acts as a memory barrier. @atomic: a pointer to an integer. @val: the value to add to *@atomic. @Since: 2.4 Atomically adds @val to the integer pointed to by @atomic. It returns the value of *@atomic just before the addition took place. Also acts as a memory barrier. @atomic: a pointer to an integer. @val: the value to add to *@atomic. @Returns: the value of *@atomic before the addition. @Since: 2.4 Compares @oldval with the integer pointed to by @atomic and if they are equal, atomically exchanges *@atomic with @newval. Also acts as a memory barrier. @atomic: a pointer to an integer. @oldval: the assumed old value of *@atomic. @newval: the new value of *@atomic. @Returns: %TRUE, if *@atomic was equal @oldval. %FALSE otherwise. @Since: 2.4 Reads the value of the pointer pointed to by @atomic. Also acts as a memory barrier. @atomic: a pointer to a #gpointer. @Returns: the value to add to *@atomic. @Since: 2.4 Compares @oldval with the pointer pointed to by @atomic and if they are equal, atomically exchanges *@atomic with @newval. Also acts as a memory barrier. @atomic: a pointer to a #gpointer. @oldval: the assumed old value of *@atomic. @newval: the new value of *@atomic. @Returns: %TRUE, if *@atomic was equal @oldval. %FALSE otherwise. @Since: 2.4 Atomically increments the integer pointed to by @atomic by 1. @atomic: a pointer to an integer. @Since: 2.4 Atomically decrements the integer pointed to by @atomic by 1. @atomic: a pointer to an integer. @Returns: %TRUE, if the integer pointed to by @atomic is 0 after decrementing it. @Since: 2.4