bool lock(SessionId owner,bool exclusive, unsigned timeout)
{
CTimeMon tm(timeout);
sect.enter();
loop {
unsigned num = owners.ordinality();
if (exclusive) {
if (num==0) {
owners.append(owner);
exclusivenest = 1;
break;
}
else if (exclusivenest && (owners.item(0)==owner)) {
exclusivenest++;
break;
}
}
else if (!exclusivenest) {
owners.append(owner);
break;
}
waiting++;
sect.leave();
unsigned remaining;
if (tm.timedout(&remaining)||!sem.wait(remaining)) {
sect.enter();
if (!sem.wait(0)) {
waiting--;
sect.leave();
return false;
}
}
else
sect.enter();
}
sect.leave();
return true;
}
void unlock(SessionId owner)
{
sect.enter();
if (exclusivenest) {
exclusivenest--;
if (exclusivenest) { // still locked
assertex(owners.item(0)==owner);
sect.leave();
return;
}
}
verifyex(owners.zap(owner));
if (owners.ordinality()==0) {
exclusivenest = 0;
if (waiting) {
sem.signal(waiting);
waiting = 0;
}
}
else {
assertex(!exclusivenest);
}
sect.leave();
}