1 #ifndef JEMALLOC_INTERNAL_SPIN_H
2 #define JEMALLOC_INTERNAL_SPIN_H
3 
4 #define SPIN_INITIALIZER {0U}
5 
6 typedef struct {
7 	unsigned iteration;
8 } spin_t;
9 
10 static inline void
11 spin_cpu_spinwait() {
12 #  if HAVE_CPU_SPINWAIT
13 	CPU_SPINWAIT;
14 #  else
15 	volatile int x = 0;
16 	x = x;
17 #  endif
18 }
19 
20 static inline void
21 spin_adaptive(spin_t *spin) {
22 	volatile uint32_t i;
23 
24 	if (spin->iteration < 5) {
25 		for (i = 0; i < (1U << spin->iteration); i++) {
26 			spin_cpu_spinwait();
27 		}
28 		spin->iteration++;
29 	} else {
30 #ifdef _WIN32
31 		SwitchToThread();
32 #else
33 		sched_yield();
34 #endif
35 	}
36 }
37 
38 #undef SPIN_INLINE
39 
40 #endif /* JEMALLOC_INTERNAL_SPIN_H */
41