void Dictionary::verify() {
guarantee(number_of_entries() >= 0, "Verify of system dictionary failed");
int element_count = 0;
for (int index = 0; index < table_size(); index++) {
for (DictionaryEntry* probe = bucket(index);
probe != NULL;
probe = probe->next()) {
Klass* e = probe->klass();
ClassLoaderData* loader_data = probe->loader_data();
guarantee(e->oop_is_instance(),
"Verify of system dictionary failed");
// class loader must be present; a null class loader is the
// boostrap loader
guarantee(loader_data != NULL || DumpSharedSpaces ||
loader_data->class_loader() == NULL ||
loader_data->class_loader()->is_instance(),
"checking type of class_loader");
e->verify();
probe->verify_protection_domain_set();
element_count++;
}
}
guarantee(number_of_entries() == element_count,
"Verify of system dictionary failed");
debug_only(verify_lookup_length((double)number_of_entries() / table_size()));
_pd_cache_table->verify();
}
void Dictionary::reorder_dictionary() {
// Copy all the dictionary entries into a single master list.
DictionaryEntry* master_list = NULL;
for (int i = 0; i < table_size(); ++i) {
DictionaryEntry* p = bucket(i);
while (p != NULL) {
DictionaryEntry* tmp;
tmp = p->next();
p->set_next(master_list);
master_list = p;
p = tmp;
}
set_entry(i, NULL);
}
// Add the dictionary entries back to the list in the correct buckets.
while (master_list != NULL) {
DictionaryEntry* p = master_list;
master_list = master_list->next();
p->set_next(NULL);
Symbol* class_name = InstanceKlass::cast((Klass*)(p->klass()))->name();
// Since the null class loader data isn't copied to the CDS archive,
// compute the hash with NULL for loader data.
unsigned int hash = compute_hash(class_name, NULL);
int index = hash_to_index(hash);
p->set_hash(hash);
p->set_loader_data(NULL); // loader_data isn't copied to CDS
p->set_next(bucket(index));
set_entry(index, p);
}
}
void Dictionary::print() {
ResourceMark rm;
HandleMark hm;
tty->print_cr("Java system dictionary (table_size=%d, classes=%d)",
table_size(), number_of_entries());
tty->print_cr("^ indicates that initiating loader is different from "
"defining loader");
for (int index = 0; index < table_size(); index++) {
for (DictionaryEntry* probe = bucket(index);
probe != NULL;
probe = probe->next()) {
if (Verbose) tty->print("%4d: ", index);
Klass* e = probe->klass();
ClassLoaderData* loader_data = probe->loader_data();
bool is_defining_class =
(loader_data == InstanceKlass::cast(e)->class_loader_data());
tty->print("%s%s", is_defining_class ? " " : "^",
e->external_name());
tty->print(", loader ");
loader_data->print_value();
tty->cr();
}
}
tty->cr();
_pd_cache_table->print();
tty->cr();
}
// All classes, and their class loaders
// Don't iterate over placeholders
void Dictionary::classes_do(void f(Klass*, ClassLoaderData*)) {
for (int index = 0; index < table_size(); index++) {
for (DictionaryEntry* probe = bucket(index);
probe != NULL;
probe = probe->next()) {
Klass* k = probe->klass();
f(k, probe->loader_data());
}
}
}
// Added for initialize_itable_for_klass to handle exceptions
// Just the classes from defining class loaders
void Dictionary::classes_do(void f(Klass*, TRAPS), TRAPS) {
for (int index = 0; index < table_size(); index++) {
for (DictionaryEntry* probe = bucket(index);
probe != NULL;
probe = probe->next()) {
Klass* k = probe->klass();
if (probe->loader_data() == InstanceKlass::cast(k)->class_loader_data()) {
f(k, CHECK);
}
}
}
}
void Dictionary::methods_do(void f(Method*)) {
for (int index = 0; index < table_size(); index++) {
for (DictionaryEntry* probe = bucket(index);
probe != NULL;
probe = probe->next()) {
Klass* k = probe->klass();
if (probe->loader_data() == InstanceKlass::cast(k)->class_loader_data()) {
// only take klass is we have the entry with the defining class loader
InstanceKlass::cast(k)->methods_do(f);
}
}
}
}
// This routine does not lock the system dictionary.
//
// Since readers don't hold a lock, we must make sure that system
// dictionary entries are only removed at a safepoint (when only one
// thread is running), and are added to in a safe way (all links must
// be updated in an MT-safe manner).
//
// Callers should be aware that an entry could be added just after
// _buckets[index] is read here, so the caller will not see the new entry.
DictionaryEntry* Dictionary::get_entry(int index, unsigned int hash,
Symbol* class_name,
ClassLoaderData* loader_data) {
debug_only(_lookup_count++);
for (DictionaryEntry* entry = bucket(index);
entry != NULL;
entry = entry->next()) {
if (entry->hash() == hash && entry->equals(class_name, loader_data)) {
return entry;
}
debug_only(_lookup_length++);
}
return NULL;
}
void Dictionary::always_strong_classes_do(KlassClosure* closure) {
// Follow all system classes and temporary placeholders in dictionary
for (int index = 0; index < table_size(); index++) {
for (DictionaryEntry* probe = bucket(index);
probe != NULL;
probe = probe->next()) {
Klass* e = probe->klass();
ClassLoaderData* loader_data = probe->loader_data();
if (is_strongly_reachable(loader_data, e)) {
closure->do_klass(e);
}
}
}
}
void Dictionary::always_strong_oops_do(OopClosure* blk) {
// Follow all system classes and temporary placeholders in dictionary; only
// protection domain oops contain references into the heap. In a first
// pass over the system dictionary determine which need to be treated as
// strongly reachable and mark them as such.
for (int index = 0; index < table_size(); index++) {
for (DictionaryEntry *probe = bucket(index);
probe != NULL;
probe = probe->next()) {
Klass* e = probe->klass();
ClassLoaderData* loader_data = probe->loader_data();
if (is_strongly_reachable(loader_data, e)) {
probe->set_strongly_reachable();
}
}
}
// Then iterate over the protection domain cache to apply the closure on the
// previously marked ones.
_pd_cache_table->always_strong_oops_do(blk);
}
bool Dictionary::do_unloading() {
assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
bool class_was_unloaded = false;
int index = 0; // Defined here for portability! Do not move
// Remove unloadable entries and classes from system dictionary
// The placeholder array has been handled in always_strong_oops_do.
DictionaryEntry* probe = NULL;
for (index = 0; index < table_size(); index++) {
for (DictionaryEntry** p = bucket_addr(index); *p != NULL; ) {
probe = *p;
Klass* e = probe->klass();
ClassLoaderData* loader_data = probe->loader_data();
InstanceKlass* ik = InstanceKlass::cast(e);
// Non-unloadable classes were handled in always_strong_oops_do
if (!is_strongly_reachable(loader_data, e)) {
// Entry was not visited in phase1 (negated test from phase1)
assert(!loader_data->is_the_null_class_loader_data(), "unloading entry with null class loader");
ClassLoaderData* k_def_class_loader_data = ik->class_loader_data();
// Do we need to delete this system dictionary entry?
bool purge_entry = false;
// Do we need to delete this system dictionary entry?
if (loader_data->is_unloading()) {
// If the loader is not live this entry should always be
// removed (will never be looked up again). Note that this is
// not the same as unloading the referred class.
if (k_def_class_loader_data == loader_data) {
// This is the defining entry, so the referred class is about
// to be unloaded.
class_was_unloaded = true;
}
// Also remove this system dictionary entry.
purge_entry = true;
} else {
// The loader in this entry is alive. If the klass is dead,
// (determined by checking the defining class loader)
// the loader must be an initiating loader (rather than the
// defining loader). Remove this entry.
if (k_def_class_loader_data->is_unloading()) {
// If we get here, the class_loader_data must not be the defining
// loader, it must be an initiating one.
assert(k_def_class_loader_data != loader_data,
"cannot have live defining loader and unreachable klass");
// Loader is live, but class and its defining loader are dead.
// Remove the entry. The class is going away.
purge_entry = true;
}
}
if (purge_entry) {
*p = probe->next();
if (probe == _current_class_entry) {
_current_class_entry = NULL;
}
free_entry(probe);
continue;
}
}
p = probe->next_addr();
}
}
return class_was_unloaded;
}
