// placeholder used to track class loading internal states // placeholder existence now for loading superclass/superinterface // superthreadQ tracks class circularity, while loading superclass/superinterface // loadInstanceThreadQ tracks load_instance_class calls // definer() tracks the single thread that owns define token // defineThreadQ tracks waiters on defining thread's results // 1st claimant creates placeholder // find_and_add adds SeenThread entry for appropriate queue // All claimants remove SeenThread after completing action // On removal: if definer and all queues empty, remove entry // Note: you can be in both placeholders and systemDictionary // see parse_stream for redefine classes // Therefore - must always check SD first // Ignores the case where entry is not found void PlaceholderTable::find_and_remove(int index, unsigned int hash, symbolHandle name, Handle loader, Thread* thread) { assert_locked_or_safepoint(SystemDictionary_lock); PlaceholderEntry *probe = get_entry(index, hash, name, loader); if (probe != NULL) { // No other threads using this entry if ((probe->superThreadQ() == NULL) && (probe->loadInstanceThreadQ() == NULL) && (probe->defineThreadQ() == NULL) && (probe->definer() == NULL)) { remove_entry(index, hash, name, loader); } } }
// placeholder is used to track class loading internal states // placeholder existence now for loading superclass/superinterface // superthreadQ tracks class circularity, while loading superclass/superinterface // loadInstanceThreadQ tracks load_instance_class calls // definer() tracks the single thread that owns define token // defineThreadQ tracks waiters on defining thread's results // 1st claimant creates placeholder // find_and_add adds SeenThread entry for appropriate queue // All claimants remove SeenThread after completing action // On removal: if definer and all queues empty, remove entry // Note: you can be in both placeholders and systemDictionary // Therefore - must always check SD first // Ignores the case where entry is not found void PlaceholderTable::find_and_remove(int index, unsigned int hash, Symbol* name, ClassLoaderData* loader_data, classloadAction action, Thread* thread) { assert_locked_or_safepoint(SystemDictionary_lock); PlaceholderEntry *probe = get_entry(index, hash, name, loader_data); if (probe != NULL) { probe->remove_seen_thread(thread, action); // If no other threads using this entry, and this thread is not using this entry for other states if ((probe->superThreadQ() == NULL) && (probe->loadInstanceThreadQ() == NULL) && (probe->defineThreadQ() == NULL) && (probe->definer() == NULL)) { remove_entry(index, hash, name, loader_data); } } }