jdk8-mips64-public/hotspot: comparison src/share/vm/classfile/placeholders.hpp

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+/*
+* Copyright (c) 2003, 2013, Oracle and/or its affiliates. All rights reserved.
+* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+*
+* This code is free software; you can redistribute it and/or modify it
+* under the terms of the GNU General Public License version 2 only, as
+* published by the Free Software Foundation.
+*
+* This code is distributed in the hope that it will be useful, but WITHOUT
+* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+* FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+* version 2 for more details (a copy is included in the LICENSE file that
+* accompanied this code).
+*
+* You should have received a copy of the GNU General Public License version
+* 2 along with this work; if not, write to the Free Software Foundation,
+* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+*
+* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+* or visit www.oracle.com if you need additional information or have any
+* questions.
+*
+*/
+#ifndef SHARE_VM_CLASSFILE_PLACEHOLDERS_HPP
+#define SHARE_VM_CLASSFILE_PLACEHOLDERS_HPP
+#include "runtime/thread.hpp"
+#include "utilities/hashtable.hpp"
+class PlaceholderEntry;
+// Placeholder objects. These represent classes currently
+// being loaded, as well as arrays of primitives.
+//
+class PlaceholderTable : public TwoOopHashtable<Symbol*, mtClass> {
+friend class VMStructs;
+public:
+PlaceholderTable(int table_size);
+PlaceholderEntry* new_entry(int hash, Symbol* name, ClassLoaderData* loader_data, bool havesupername, Symbol* supername);
+void free_entry(PlaceholderEntry* entry);
+PlaceholderEntry* bucket(int i) {
+return (PlaceholderEntry*)Hashtable<Symbol*, mtClass>::bucket(i);
+}
+PlaceholderEntry** bucket_addr(int i) {
+return (PlaceholderEntry**)Hashtable<Symbol*, mtClass>::bucket_addr(i);
+}
+void add_entry(int index, PlaceholderEntry* new_entry) {
+Hashtable<Symbol*, mtClass>::add_entry(index, (HashtableEntry<Symbol*, mtClass>*)new_entry);
+}
+void add_entry(int index, unsigned int hash, Symbol* name,
+ClassLoaderData* loader_data, bool havesupername, Symbol* supername);
+// This returns a Symbol* to match type for SystemDictionary
+Symbol* find_entry(int index, unsigned int hash,
+Symbol* name, ClassLoaderData* loader_data);
+PlaceholderEntry* get_entry(int index, unsigned int hash,
+Symbol* name, ClassLoaderData* loader_data);
+// caller to create a placeholder entry must enumerate an action
+// caller claims ownership of that action
+// For parallel classloading:
+// multiple LOAD_INSTANCE threads can proceed in parallel
+// multiple LOAD_SUPER threads can proceed in parallel
+// LOAD_SUPER needed to check for class circularity
+// DEFINE_CLASS: ultimately define class must be single threaded
+// on a class/classloader basis
+// so the head of that queue owns the token
+// and the rest of the threads return the result the first thread gets
+enum classloadAction {
+LOAD_INSTANCE = 1,             // calling load_instance_class
+LOAD_SUPER = 2,                // loading superclass for this class
+DEFINE_CLASS = 3               // find_or_define class
+};
+// find_and_add returns probe pointer - old or new
+// If no entry exists, add a placeholder entry and push SeenThread for classloadAction
+// If entry exists, reuse entry and push SeenThread for classloadAction
+PlaceholderEntry* find_and_add(int index, unsigned int hash,
+Symbol* name, ClassLoaderData* loader_data,
+classloadAction action, Symbol* supername,
+Thread* thread);
+void remove_entry(int index, unsigned int hash,
+Symbol* name, ClassLoaderData* loader_data);
+// find_and_remove first removes SeenThread for classloadAction
+// If all queues are empty and definer is null, remove the PlacheholderEntry completely
+void find_and_remove(int index, unsigned int hash,
+Symbol* name, ClassLoaderData* loader_data,
+classloadAction action, Thread* thread);
+// GC support.
+void classes_do(KlassClosure* f);
+// JVMTI support
+void entries_do(void f(Symbol*));
+#ifndef PRODUCT
+void print();
+#endif
+void verify();
+};
+// SeenThread objects represent list of threads that are
+// currently performing a load action on a class.
+// For class circularity, set before loading a superclass.
+// For bootclasssearchpath, set before calling load_instance_class.
+// Defining must be single threaded on a class/classloader basis
+// For DEFINE_CLASS, the head of the queue owns the
+// define token and the rest of the threads wait to return the
+// result the first thread gets.
+class SeenThread: public CHeapObj<mtInternal> {
+private:
+Thread *_thread;
+SeenThread* _stnext;
+SeenThread* _stprev;
+public:
+SeenThread(Thread *thread) {
+_thread = thread;
+_stnext = NULL;
+_stprev = NULL;
+}
+Thread* thread()                const { return _thread;}
+void set_thread(Thread *thread) { _thread = thread; }
+SeenThread* next()              const { return _stnext;}
+void set_next(SeenThread *seen) { _stnext = seen; }
+void set_prev(SeenThread *seen) { _stprev = seen; }
+#ifndef PRODUCT
+void printActionQ() {
+SeenThread* seen = this;
+while (seen != NULL) {
+seen->thread()->print_value();
+tty->print(", ");
+seen = seen->next();
+}
+}
+#endif // PRODUCT
+};
+// Placeholder objects represent classes currently being loaded.
+// All threads examining the placeholder table must hold the
+// SystemDictionary_lock, so we don't need special precautions
+// on store ordering here.
+// The system dictionary is the only user of this class.
+class PlaceholderEntry : public HashtableEntry<Symbol*, mtClass> {
+friend class VMStructs;
+private:
+ClassLoaderData*  _loader_data;   // initiating loader
+bool              _havesupername; // distinguish between null supername, and unknown
+Symbol*           _supername;
+Thread*           _definer;       // owner of define token
+Klass*            _instanceKlass; // InstanceKlass from successful define
+SeenThread*       _superThreadQ;  // doubly-linked queue of Threads loading a superclass for this class
+SeenThread*       _loadInstanceThreadQ;  // loadInstance thread
+// can be multiple threads if classloader object lock broken by application
+// or if classloader supports parallel classloading
+SeenThread*       _defineThreadQ; // queue of Threads trying to define this class
+// including _definer
+// _definer owns token
+// queue waits for and returns results from _definer
+public:
+// Simple accessors, used only by SystemDictionary
+Symbol*            klassname()           const { return literal(); }
+ClassLoaderData*   loader_data()         const { return _loader_data; }
+void               set_loader_data(ClassLoaderData* loader_data) { _loader_data = loader_data; }
+bool               havesupername()       const { return _havesupername; }
+void               set_havesupername(bool havesupername) { _havesupername = havesupername; }
+Symbol*            supername()           const { return _supername; }
+void               set_supername(Symbol* supername) {
+_supername = supername;
+if (_supername != NULL) _supername->increment_refcount();
+}
+Thread*            definer()             const {return _definer; }
+void               set_definer(Thread* definer) { _definer = definer; }
+Klass*             instance_klass()      const {return _instanceKlass; }
+void               set_instance_klass(Klass* ik) { _instanceKlass = ik; }
+SeenThread*        superThreadQ()        const { return _superThreadQ; }
+void               set_superThreadQ(SeenThread* SeenThread) { _superThreadQ = SeenThread; }
+SeenThread*        loadInstanceThreadQ() const { return _loadInstanceThreadQ; }
+void               set_loadInstanceThreadQ(SeenThread* SeenThread) { _loadInstanceThreadQ = SeenThread; }
+SeenThread*        defineThreadQ()        const { return _defineThreadQ; }
+void               set_defineThreadQ(SeenThread* SeenThread) { _defineThreadQ = SeenThread; }
+PlaceholderEntry* next() const {
+return (PlaceholderEntry*)HashtableEntry<Symbol*, mtClass>::next();
+}
+PlaceholderEntry** next_addr() {
+return (PlaceholderEntry**)HashtableEntry<Symbol*, mtClass>::next_addr();
+}
+// Test for equality
+// Entries are unique for class/classloader name pair
+bool equals(Symbol* class_name, ClassLoaderData* loader) const {
+return (klassname() == class_name && loader_data() == loader);
+}
+SeenThread* actionToQueue(PlaceholderTable::classloadAction action) {
+SeenThread* queuehead;
+switch (action) {
+case PlaceholderTable::LOAD_INSTANCE:
+queuehead = _loadInstanceThreadQ;
+break;
+case PlaceholderTable::LOAD_SUPER:
+queuehead = _superThreadQ;
+break;
+case PlaceholderTable::DEFINE_CLASS:
+queuehead = _defineThreadQ;
+break;
+default: Unimplemented();
+}
+return queuehead;
+}
+void set_threadQ(SeenThread* seenthread, PlaceholderTable::classloadAction action) {
+switch (action) {
+case PlaceholderTable::LOAD_INSTANCE:
+_loadInstanceThreadQ = seenthread;
+break;
+case PlaceholderTable::LOAD_SUPER:
+_superThreadQ = seenthread;
+break;
+case PlaceholderTable::DEFINE_CLASS:
+_defineThreadQ = seenthread;
+break;
+default: Unimplemented();
+}
+return;
+}
+bool super_load_in_progress() {
+return (_superThreadQ != NULL);
+}
+bool instance_load_in_progress() {
+return (_loadInstanceThreadQ != NULL);
+}
+bool define_class_in_progress() {
+return (_defineThreadQ != NULL);
+}
+// Doubly-linked list of Threads per action for class/classloader pair
+// Class circularity support: links in thread before loading superclass
+// bootstrapsearchpath support: links in a thread before load_instance_class
+// definers: use as queue of define requestors, including owner of
+// define token. Appends for debugging of requestor order
+void add_seen_thread(Thread* thread, PlaceholderTable::classloadAction action) {
+assert_lock_strong(SystemDictionary_lock);
+SeenThread* threadEntry = new SeenThread(thread);
+SeenThread* seen = actionToQueue(action);
+if (seen == NULL) {
+set_threadQ(threadEntry, action);
+return;
+}
+SeenThread* next;
+while ((next = seen->next()) != NULL) {
+seen = next;
+}
+seen->set_next(threadEntry);
+threadEntry->set_prev(seen);
+return;
+}
+bool check_seen_thread(Thread* thread, PlaceholderTable::classloadAction action) {
+assert_lock_strong(SystemDictionary_lock);
+SeenThread* threadQ = actionToQueue(action);
+SeenThread* seen = threadQ;
+while (seen) {
+if (thread == seen->thread()) {
+return true;
+}
+seen = seen->next();
+}
+return false;
+}
+// returns true if seenthreadQ is now empty
+// Note, caller must ensure probe still exists while holding
+// SystemDictionary_lock
+// ignores if cleanup has already been done
+// if found, deletes SeenThread
+bool remove_seen_thread(Thread* thread, PlaceholderTable::classloadAction action) {
+assert_lock_strong(SystemDictionary_lock);
+SeenThread* threadQ = actionToQueue(action);
+SeenThread* seen = threadQ;
+SeenThread* prev = NULL;
+while (seen) {
+if (thread == seen->thread()) {
+if (prev) {
+prev->set_next(seen->next());
+} else {
+set_threadQ(seen->next(), action);
+}
+if (seen->next()) {
+seen->next()->set_prev(prev);
+}
+delete seen;
+break;
+}
+prev = seen;
+seen = seen->next();
+}
+return (actionToQueue(action) == NULL);
+}
+// GC support
+// Applies "f->do_oop" to all root oops in the placeholder table.
+void classes_do(KlassClosure* closure);
+// Print method doesn't append a cr
+void print() const  PRODUCT_RETURN;
+void verify() const;
+};
+#endif // SHARE_VM_CLASSFILE_PLACEHOLDERS_HPP

Mercurial > jdk8-mips64-public > hotspot / file comparison

comparison: src/share/vm/classfile/placeholders.hpp

src/share/vm/classfile/placeholders.hpp