void Monitor::lock (Thread * Self) {
#ifdef CHECK_UNHANDLED_OOPS
// Clear unhandled oops so we get a crash right away. Only clear for non-vm
// or GC threads.
if (Self->is_Java_thread()) {
Self->clear_unhandled_oops();
}
#endif // CHECK_UNHANDLED_OOPS
debug_only(check_prelock_state(Self));
assert (_owner != Self , "invariant") ;
assert (_OnDeck != Self->_MutexEvent, "invariant") ;
if (TryFast()) {
Exeunt:
assert (ILocked(), "invariant") ;
assert (owner() == NULL, "invariant");
set_owner (Self);
return ;
}
// The lock is contended ...
bool can_sneak = Self->is_VM_thread() && SafepointSynchronize::is_at_safepoint();
if (can_sneak && _owner == NULL) {
// a java thread has locked the lock but has not entered the
// critical region -- let's just pretend we've locked the lock
// and go on. we note this with _snuck so we can also
// pretend to unlock when the time comes.
_snuck = true;
goto Exeunt ;
}
// Try a brief spin to avoid passing thru thread state transition ...
if (TrySpin (Self)) goto Exeunt ;
check_block_state(Self);
if (Self->is_Java_thread()) {
// Horribile dictu - we suffer through a state transition
assert(rank() > Mutex::special, "Potential deadlock with special or lesser rank mutex");
ThreadBlockInVM tbivm ((JavaThread *) Self) ;
ILock (Self) ;
} else {
// Mirabile dictu
ILock (Self) ;
}
goto Exeunt ;
}