Are there functions for performing atomic operations (like increment / decrement of an integer) etc supported by C Run time library or any other utility libraries?
If yes, what all operations can be made atomic using such functions?
Will it be more beneficial to use such functions than the normal synchronization primitives like mutex etc?
OS : Windows, Linux, Solaris & VxWorks
The C library doesn't have any.
On Linux, gcc provides some -- look for
__sync_fetch_and_sub, and so on.
In the case of Windows, look for
InterlockedDecrement``,InterlockedExchange`, and so on. If you use gcc on Windows, I'd guess it also has the same built-ins as it does on Linux (though I haven't verified that).
On Solaris, it'll depend. Presumably if you use gcc, it'll probably (again) have the same built-ins it does under Linux. Otherwise, there are libraries floating around, but nothing really standardized.
C11 added a (reasonably) complete set of atomic operations and atomic types. The operations include things like
*_explicit versions of same that let you specify the ordering model you need, where the default ones always use
memory_order_seq_cst). There are also
fence functions, such as
The types correspond to each of the normal integer types--for example,
atomic_int8_t corresponding to
atomic_uint_least64_t corrsponding to
uint_least64_t. Those are
typedef names defined in
<stdatomic.h>. To avoid conflicts with any existing names, you can omit the header; the compiler itself uses names in the implementor's namespace (e.g.,
_Atomic_uint_least32_t instead of