int32
runtime·semasleep(int64 ns)
{
Timespec ts;
int64 secs;
// spin-mutex lock
while(runtime·xchg(&m->waitsemalock, 1))
runtime·osyield();
for(;;) {
// lock held
if(m->waitsemacount == 0) {
// sleep until semaphore != 0 or timeout.
// thrsleep unlocks m->waitsemalock.
if(ns < 0)
runtime·thrsleep(&m->waitsemacount, 0, nil, &m->waitsemalock, nil);
else {
ns += runtime·nanotime();
secs = ns/1000000000LL;
// Avoid overflow
if(secs >= 1LL<<31)
secs = (1LL<<31) - 1;
ts.tv_sec = secs;
ts.tv_nsec = ns%1000000000LL;
runtime·thrsleep(&m->waitsemacount, CLOCK_REALTIME, &ts, &m->waitsemalock, nil);
}
// reacquire lock
while(runtime·xchg(&m->waitsemalock, 1))
runtime·osyield();
}
// lock held (again)
if(m->waitsemacount != 0) {
// semaphore is available.
m->waitsemacount--;
// spin-mutex unlock
runtime·atomicstore(&m->waitsemalock, 0);
return 0; // semaphore acquired
}
// semaphore not available.
// if there is a timeout, stop now.
// otherwise keep trying.
if(ns >= 0)
break;
}
// lock held but giving up
// spin-mutex unlock
runtime·atomicstore(&m->waitsemalock, 0);
return -1;
}
int32
runtime·semasleep(int64 ns)
{
Timespec ts;
// spin-mutex lock
while(runtime·xchg(&m->waitsemalock, 1))
runtime·osyield();
for(;;) {
// lock held
if(m->waitsemacount == 0) {
// sleep until semaphore != 0 or timeout.
// thrsleep unlocks m->waitsemalock.
if(ns < 0)
runtime·thrsleep(&m->waitsemacount, 0, nil, &m->waitsemalock, nil);
else {
ns += runtime·nanotime();
// NOTE: tv_nsec is int64 on amd64, so this assumes a little-endian system.
ts.tv_nsec = 0;
ts.tv_sec = runtime·timediv(ns, 1000000000, (int32*)&ts.tv_nsec);
runtime·thrsleep(&m->waitsemacount, CLOCK_MONOTONIC, &ts, &m->waitsemalock, nil);
}
// reacquire lock
while(runtime·xchg(&m->waitsemalock, 1))
runtime·osyield();
}
// lock held (again)
if(m->waitsemacount != 0) {
// semaphore is available.
m->waitsemacount--;
// spin-mutex unlock
runtime·atomicstore(&m->waitsemalock, 0);
return 0; // semaphore acquired
}
// semaphore not available.
// if there is a timeout, stop now.
// otherwise keep trying.
if(ns >= 0)
break;
}
// lock held but giving up
// spin-mutex unlock
runtime·atomicstore(&m->waitsemalock, 0);
return -1;
}
