I was looking at another fine example of modern programming from glibc
and just had to share it.
Where does the getpid happen? It's anyone's guess. This is just so
readable too ... I'm glad they want to such effort to optimize getpid.
ron
#ifndef NOT_IN_libc
static inline __attribute__((always_inline)) pid_t really_getpid (pid_t oldval);
static inline __attribute__((always_inline)) pid_t
really_getpid (pid_t oldval)
{
if (__builtin_expect (oldval == 0, 1))
{
pid_t selftid = THREAD_GETMEM (THREAD_SELF, tid);
if (__builtin_expect (selftid != 0, 1))
return selftid;
}
INTERNAL_SYSCALL_DECL (err);
pid_t result = INTERNAL_SYSCALL (getpid, err, 0);
/* We do not set the PID field in the TID here since we might be
called from a signal handler while the thread executes fork. */
if (oldval == 0)
THREAD_SETMEM (THREAD_SELF, tid, result);
return result;
}
#endif
pid_t
__getpid (void)
{
#ifdef NOT_IN_libc
INTERNAL_SYSCALL_DECL (err);
pid_t result = INTERNAL_SYSCALL (getpid, err, 0);
#else
pid_t result = THREAD_GETMEM (THREAD_SELF, pid);
if (__builtin_expect (result <= 0, 0))
result = really_getpid (result);
#endif
return result;
}
libc_hidden_def (__getpid)
weak_alias (__getpid, getpid)
libc_hidden_def (getpid)
