klassOop Klass::base_create_klass_oop(KlassHandle& klass, int size, const Klass_vtbl& vtbl, TRAPS) { size = align_object_size(size); // allocate and initialize vtable Klass* kl = (Klass*) vtbl.allocate_permanent(klass, size, CHECK_NULL); klassOop k = kl->as_klassOop(); { // Preinitialize supertype information. // A later call to initialize_supers() may update these settings: kl->set_super(NULL); for (juint i = 0; i < Klass::primary_super_limit(); i++) { kl->_primary_supers[i] = NULL; } kl->set_secondary_supers(NULL); oop_store_without_check((oop*) &kl->_primary_supers[0], k); kl->set_super_check_offset(in_bytes(primary_supers_offset())); } kl->set_java_mirror(NULL); kl->set_modifier_flags(0); kl->set_layout_helper(Klass::_lh_neutral_value); kl->set_name(NULL); AccessFlags af; af.set_flags(0); kl->set_access_flags(af); kl->set_subklass(NULL); kl->set_next_sibling(NULL); kl->set_alloc_count(0); kl->set_alloc_size(0); TRACE_SET_KLASS_TRACE_ID(kl, 0); kl->set_prototype_header(markOopDesc::prototype()); kl->set_biased_lock_revocation_count(0); kl->set_last_biased_lock_bulk_revocation_time(0); return k; }
static BiasedLocking::Condition bulk_revoke_or_rebias_at_safepoint(oop o, bool bulk_rebias, bool attempt_rebias_of_object, JavaThread* requesting_thread) { assert(SafepointSynchronize::is_at_safepoint(), "must be done at safepoint"); if (TraceBiasedLocking) { tty->print_cr("* Beginning bulk revocation (kind == %s) because of object " INTPTR_FORMAT " , mark " INTPTR_FORMAT " , type %s", (bulk_rebias ? "rebias" : "revoke"), p2i((void *) o), (intptr_t) o->mark(), o->klass()->external_name()); } jlong cur_time = os::javaTimeMillis(); o->klass()->set_last_biased_lock_bulk_revocation_time(cur_time); Klass* k_o = o->klass(); Klass* klass = k_o; if (bulk_rebias) { // Use the epoch in the klass of the object to implicitly revoke // all biases of objects of this data type and force them to be // reacquired. However, we also need to walk the stacks of all // threads and update the headers of lightweight locked objects // with biases to have the current epoch. // If the prototype header doesn't have the bias pattern, don't // try to update the epoch -- assume another VM operation came in // and reset the header to the unbiased state, which will // implicitly cause all existing biases to be revoked if (klass->prototype_header()->has_bias_pattern()) { int prev_epoch = klass->prototype_header()->bias_epoch(); klass->set_prototype_header(klass->prototype_header()->incr_bias_epoch()); int cur_epoch = klass->prototype_header()->bias_epoch(); // Now walk all threads' stacks and adjust epochs of any biased // and locked objects of this data type we encounter for (JavaThread* thr = Threads::first(); thr != NULL; thr = thr->next()) { GrowableArray<MonitorInfo*>* cached_monitor_info = get_or_compute_monitor_info(thr); for (int i = 0; i < cached_monitor_info->length(); i++) { MonitorInfo* mon_info = cached_monitor_info->at(i); oop owner = mon_info->owner(); markOop mark = owner->mark(); if ((owner->klass() == k_o) && mark->has_bias_pattern()) { // We might have encountered this object already in the case of recursive locking assert(mark->bias_epoch() == prev_epoch || mark->bias_epoch() == cur_epoch, "error in bias epoch adjustment"); owner->set_mark(mark->set_bias_epoch(cur_epoch)); } } } } // At this point we're done. All we have to do is potentially // adjust the header of the given object to revoke its bias. revoke_bias(o, attempt_rebias_of_object && klass->prototype_header()->has_bias_pattern(), true, requesting_thread); } else { if (TraceBiasedLocking) { ResourceMark rm; tty->print_cr("* Disabling biased locking for type %s", klass->external_name()); } // Disable biased locking for this data type. Not only will this // cause future instances to not be biased, but existing biased // instances will notice that this implicitly caused their biases // to be revoked. klass->set_prototype_header(markOopDesc::prototype()); // Now walk all threads' stacks and forcibly revoke the biases of // any locked and biased objects of this data type we encounter. for (JavaThread* thr = Threads::first(); thr != NULL; thr = thr->next()) { GrowableArray<MonitorInfo*>* cached_monitor_info = get_or_compute_monitor_info(thr); for (int i = 0; i < cached_monitor_info->length(); i++) { MonitorInfo* mon_info = cached_monitor_info->at(i); oop owner = mon_info->owner(); markOop mark = owner->mark(); if ((owner->klass() == k_o) && mark->has_bias_pattern()) { revoke_bias(owner, false, true, requesting_thread); } } } // Must force the bias of the passed object to be forcibly revoked // as well to ensure guarantees to callers revoke_bias(o, false, true, requesting_thread); } if (TraceBiasedLocking) { tty->print_cr("* Ending bulk revocation"); } BiasedLocking::Condition status_code = BiasedLocking::BIAS_REVOKED; if (attempt_rebias_of_object && o->mark()->has_bias_pattern() && klass->prototype_header()->has_bias_pattern()) { markOop new_mark = markOopDesc::encode(requesting_thread, o->mark()->age(), klass->prototype_header()->bias_epoch()); o->set_mark(new_mark); status_code = BiasedLocking::BIAS_REVOKED_AND_REBIASED; if (TraceBiasedLocking) { tty->print_cr(" Rebiased object toward thread " INTPTR_FORMAT, (intptr_t) requesting_thread); } } assert(!o->mark()->has_bias_pattern() || (attempt_rebias_of_object && (o->mark()->biased_locker() == requesting_thread)), "bug in bulk bias revocation"); return status_code; }