Mercurial > hg > truffle
view src/share/vm/classfile/placeholders.hpp @ 4877:c03e06373b47
Merge
author | stefank |
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date | Sat, 28 Jan 2012 01:15:34 -0800 |
parents | 1d1603768966 |
children | d2a62e0f25eb |
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/* * Copyright (c) 2003, 2011, 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*> { friend class VMStructs; public: PlaceholderTable(int table_size); PlaceholderEntry* new_entry(int hash, Symbol* name, oop loader, bool havesupername, Symbol* supername); void free_entry(PlaceholderEntry* entry); PlaceholderEntry* bucket(int i) { return (PlaceholderEntry*)Hashtable<Symbol*>::bucket(i); } PlaceholderEntry** bucket_addr(int i) { return (PlaceholderEntry**)Hashtable<Symbol*>::bucket_addr(i); } void add_entry(int index, PlaceholderEntry* new_entry) { Hashtable<Symbol*>::add_entry(index, (HashtableEntry<Symbol*>*)new_entry); } void add_entry(int index, unsigned int hash, Symbol* name, Handle loader, bool havesupername, Symbol* supername); // This returns a Symbol* to match type for SystemDictionary Symbol* find_entry(int index, unsigned int hash, Symbol* name, Handle loader); PlaceholderEntry* get_entry(int index, unsigned int hash, Symbol* name, Handle loader); // 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 // If entry exists, reuse entry and push SeenThread for classloadAction PlaceholderEntry* find_and_add(int index, unsigned int hash, Symbol* name, Handle loader, classloadAction action, Symbol* supername, Thread* thread); void remove_entry(int index, unsigned int hash, Symbol* name, Handle loader); // Remove placeholder information void find_and_remove(int index, unsigned int hash, Symbol* name, Handle loader, Thread* thread); // GC support. void oops_do(OopClosure* f); // JVMTI support void entries_do(void f(Symbol*, oop)); #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 { 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*> { friend class VMStructs; private: oop _loader; // initiating loader bool _havesupername; // distinguish between null supername, and unknown Symbol* _supername; Thread* _definer; // owner of define token klassOop _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(); } oop loader() const { return _loader; } void set_loader(oop loader) { _loader = loader; } oop* loader_addr() { return &_loader; } 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; } klassOop instanceKlass() const {return _instanceKlass; } void set_instanceKlass(klassOop instanceKlass) { _instanceKlass = instanceKlass; } klassOop* instanceKlass_addr() { return &_instanceKlass; } 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*>::next(); } PlaceholderEntry** next_addr() { return (PlaceholderEntry**)HashtableEntry<Symbol*>::next_addr(); } // Test for equality // Entries are unique for class/classloader name pair bool equals(Symbol* class_name, oop class_loader) const { return (klassname() == class_name && loader() == class_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 oops_do(OopClosure* blk); // Print method doesn't append a cr void print() const PRODUCT_RETURN; void verify() const; }; #endif // SHARE_VM_CLASSFILE_PLACEHOLDERS_HPP