ref: 44a5f4d2eff13fd08a56da842b11e0dd85462055
dir: /sys/src/libc/port/lock.c/
#include <u.h> #include <libc.h> void lock(Lock *lk) { int i; /* once fast */ if(!_tas(&lk->val)) return; /* a thousand times pretty fast */ for(i=0; i<1000; i++){ if(!_tas(&lk->val)) return; sleep(0); } /* now nice and slow */ for(i=0; i<1000; i++){ if(!_tas(&lk->val)) return; sleep(100); } /* take your time */ while(_tas(&lk->val)) sleep(1000); } int canlock(Lock *lk) { if(_tas(&lk->val)) return 0; return 1; } void unlock(Lock *lk) { lk->val = 0; }