1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/src/share/vm/classfile/placeholders.hpp Wed Apr 27 01:25:04 2016 +0800
1.3 @@ -0,0 +1,341 @@
1.4 +/*
1.5 + * Copyright (c) 2003, 2013, Oracle and/or its affiliates. All rights reserved.
1.6 + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
1.7 + *
1.8 + * This code is free software; you can redistribute it and/or modify it
1.9 + * under the terms of the GNU General Public License version 2 only, as
1.10 + * published by the Free Software Foundation.
1.11 + *
1.12 + * This code is distributed in the hope that it will be useful, but WITHOUT
1.13 + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
1.14 + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
1.15 + * version 2 for more details (a copy is included in the LICENSE file that
1.16 + * accompanied this code).
1.17 + *
1.18 + * You should have received a copy of the GNU General Public License version
1.19 + * 2 along with this work; if not, write to the Free Software Foundation,
1.20 + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
1.21 + *
1.22 + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
1.23 + * or visit www.oracle.com if you need additional information or have any
1.24 + * questions.
1.25 + *
1.26 + */
1.27 +
1.28 +#ifndef SHARE_VM_CLASSFILE_PLACEHOLDERS_HPP
1.29 +#define SHARE_VM_CLASSFILE_PLACEHOLDERS_HPP
1.30 +
1.31 +#include "runtime/thread.hpp"
1.32 +#include "utilities/hashtable.hpp"
1.33 +
1.34 +class PlaceholderEntry;
1.35 +
1.36 +// Placeholder objects. These represent classes currently
1.37 +// being loaded, as well as arrays of primitives.
1.38 +//
1.39 +
1.40 +class PlaceholderTable : public TwoOopHashtable<Symbol*, mtClass> {
1.41 + friend class VMStructs;
1.42 +
1.43 +public:
1.44 + PlaceholderTable(int table_size);
1.45 +
1.46 + PlaceholderEntry* new_entry(int hash, Symbol* name, ClassLoaderData* loader_data, bool havesupername, Symbol* supername);
1.47 + void free_entry(PlaceholderEntry* entry);
1.48 +
1.49 + PlaceholderEntry* bucket(int i) {
1.50 + return (PlaceholderEntry*)Hashtable<Symbol*, mtClass>::bucket(i);
1.51 + }
1.52 +
1.53 + PlaceholderEntry** bucket_addr(int i) {
1.54 + return (PlaceholderEntry**)Hashtable<Symbol*, mtClass>::bucket_addr(i);
1.55 + }
1.56 +
1.57 + void add_entry(int index, PlaceholderEntry* new_entry) {
1.58 + Hashtable<Symbol*, mtClass>::add_entry(index, (HashtableEntry<Symbol*, mtClass>*)new_entry);
1.59 + }
1.60 +
1.61 + void add_entry(int index, unsigned int hash, Symbol* name,
1.62 + ClassLoaderData* loader_data, bool havesupername, Symbol* supername);
1.63 +
1.64 + // This returns a Symbol* to match type for SystemDictionary
1.65 + Symbol* find_entry(int index, unsigned int hash,
1.66 + Symbol* name, ClassLoaderData* loader_data);
1.67 +
1.68 + PlaceholderEntry* get_entry(int index, unsigned int hash,
1.69 + Symbol* name, ClassLoaderData* loader_data);
1.70 +
1.71 +// caller to create a placeholder entry must enumerate an action
1.72 +// caller claims ownership of that action
1.73 +// For parallel classloading:
1.74 +// multiple LOAD_INSTANCE threads can proceed in parallel
1.75 +// multiple LOAD_SUPER threads can proceed in parallel
1.76 +// LOAD_SUPER needed to check for class circularity
1.77 +// DEFINE_CLASS: ultimately define class must be single threaded
1.78 +// on a class/classloader basis
1.79 +// so the head of that queue owns the token
1.80 +// and the rest of the threads return the result the first thread gets
1.81 + enum classloadAction {
1.82 + LOAD_INSTANCE = 1, // calling load_instance_class
1.83 + LOAD_SUPER = 2, // loading superclass for this class
1.84 + DEFINE_CLASS = 3 // find_or_define class
1.85 + };
1.86 +
1.87 + // find_and_add returns probe pointer - old or new
1.88 + // If no entry exists, add a placeholder entry and push SeenThread for classloadAction
1.89 + // If entry exists, reuse entry and push SeenThread for classloadAction
1.90 + PlaceholderEntry* find_and_add(int index, unsigned int hash,
1.91 + Symbol* name, ClassLoaderData* loader_data,
1.92 + classloadAction action, Symbol* supername,
1.93 + Thread* thread);
1.94 +
1.95 + void remove_entry(int index, unsigned int hash,
1.96 + Symbol* name, ClassLoaderData* loader_data);
1.97 +
1.98 + // find_and_remove first removes SeenThread for classloadAction
1.99 + // If all queues are empty and definer is null, remove the PlacheholderEntry completely
1.100 + void find_and_remove(int index, unsigned int hash,
1.101 + Symbol* name, ClassLoaderData* loader_data,
1.102 + classloadAction action, Thread* thread);
1.103 +
1.104 + // GC support.
1.105 + void classes_do(KlassClosure* f);
1.106 +
1.107 + // JVMTI support
1.108 + void entries_do(void f(Symbol*));
1.109 +
1.110 +#ifndef PRODUCT
1.111 + void print();
1.112 +#endif
1.113 + void verify();
1.114 +};
1.115 +
1.116 +// SeenThread objects represent list of threads that are
1.117 +// currently performing a load action on a class.
1.118 +// For class circularity, set before loading a superclass.
1.119 +// For bootclasssearchpath, set before calling load_instance_class.
1.120 +// Defining must be single threaded on a class/classloader basis
1.121 +// For DEFINE_CLASS, the head of the queue owns the
1.122 +// define token and the rest of the threads wait to return the
1.123 +// result the first thread gets.
1.124 +class SeenThread: public CHeapObj<mtInternal> {
1.125 +private:
1.126 + Thread *_thread;
1.127 + SeenThread* _stnext;
1.128 + SeenThread* _stprev;
1.129 +public:
1.130 + SeenThread(Thread *thread) {
1.131 + _thread = thread;
1.132 + _stnext = NULL;
1.133 + _stprev = NULL;
1.134 + }
1.135 + Thread* thread() const { return _thread;}
1.136 + void set_thread(Thread *thread) { _thread = thread; }
1.137 +
1.138 + SeenThread* next() const { return _stnext;}
1.139 + void set_next(SeenThread *seen) { _stnext = seen; }
1.140 + void set_prev(SeenThread *seen) { _stprev = seen; }
1.141 +
1.142 +#ifndef PRODUCT
1.143 + void printActionQ() {
1.144 + SeenThread* seen = this;
1.145 + while (seen != NULL) {
1.146 + seen->thread()->print_value();
1.147 + tty->print(", ");
1.148 + seen = seen->next();
1.149 + }
1.150 + }
1.151 +#endif // PRODUCT
1.152 +};
1.153 +
1.154 +// Placeholder objects represent classes currently being loaded.
1.155 +// All threads examining the placeholder table must hold the
1.156 +// SystemDictionary_lock, so we don't need special precautions
1.157 +// on store ordering here.
1.158 +// The system dictionary is the only user of this class.
1.159 +
1.160 +class PlaceholderEntry : public HashtableEntry<Symbol*, mtClass> {
1.161 + friend class VMStructs;
1.162 +
1.163 +
1.164 + private:
1.165 + ClassLoaderData* _loader_data; // initiating loader
1.166 + bool _havesupername; // distinguish between null supername, and unknown
1.167 + Symbol* _supername;
1.168 + Thread* _definer; // owner of define token
1.169 + Klass* _instanceKlass; // InstanceKlass from successful define
1.170 + SeenThread* _superThreadQ; // doubly-linked queue of Threads loading a superclass for this class
1.171 + SeenThread* _loadInstanceThreadQ; // loadInstance thread
1.172 + // can be multiple threads if classloader object lock broken by application
1.173 + // or if classloader supports parallel classloading
1.174 +
1.175 + SeenThread* _defineThreadQ; // queue of Threads trying to define this class
1.176 + // including _definer
1.177 + // _definer owns token
1.178 + // queue waits for and returns results from _definer
1.179 +
1.180 + public:
1.181 + // Simple accessors, used only by SystemDictionary
1.182 + Symbol* klassname() const { return literal(); }
1.183 +
1.184 + ClassLoaderData* loader_data() const { return _loader_data; }
1.185 + void set_loader_data(ClassLoaderData* loader_data) { _loader_data = loader_data; }
1.186 +
1.187 + bool havesupername() const { return _havesupername; }
1.188 + void set_havesupername(bool havesupername) { _havesupername = havesupername; }
1.189 +
1.190 + Symbol* supername() const { return _supername; }
1.191 + void set_supername(Symbol* supername) {
1.192 + _supername = supername;
1.193 + if (_supername != NULL) _supername->increment_refcount();
1.194 + }
1.195 +
1.196 + Thread* definer() const {return _definer; }
1.197 + void set_definer(Thread* definer) { _definer = definer; }
1.198 +
1.199 + Klass* instance_klass() const {return _instanceKlass; }
1.200 + void set_instance_klass(Klass* ik) { _instanceKlass = ik; }
1.201 +
1.202 + SeenThread* superThreadQ() const { return _superThreadQ; }
1.203 + void set_superThreadQ(SeenThread* SeenThread) { _superThreadQ = SeenThread; }
1.204 +
1.205 + SeenThread* loadInstanceThreadQ() const { return _loadInstanceThreadQ; }
1.206 + void set_loadInstanceThreadQ(SeenThread* SeenThread) { _loadInstanceThreadQ = SeenThread; }
1.207 +
1.208 + SeenThread* defineThreadQ() const { return _defineThreadQ; }
1.209 + void set_defineThreadQ(SeenThread* SeenThread) { _defineThreadQ = SeenThread; }
1.210 +
1.211 + PlaceholderEntry* next() const {
1.212 + return (PlaceholderEntry*)HashtableEntry<Symbol*, mtClass>::next();
1.213 + }
1.214 +
1.215 + PlaceholderEntry** next_addr() {
1.216 + return (PlaceholderEntry**)HashtableEntry<Symbol*, mtClass>::next_addr();
1.217 + }
1.218 +
1.219 + // Test for equality
1.220 + // Entries are unique for class/classloader name pair
1.221 + bool equals(Symbol* class_name, ClassLoaderData* loader) const {
1.222 + return (klassname() == class_name && loader_data() == loader);
1.223 + }
1.224 +
1.225 + SeenThread* actionToQueue(PlaceholderTable::classloadAction action) {
1.226 + SeenThread* queuehead;
1.227 + switch (action) {
1.228 + case PlaceholderTable::LOAD_INSTANCE:
1.229 + queuehead = _loadInstanceThreadQ;
1.230 + break;
1.231 + case PlaceholderTable::LOAD_SUPER:
1.232 + queuehead = _superThreadQ;
1.233 + break;
1.234 + case PlaceholderTable::DEFINE_CLASS:
1.235 + queuehead = _defineThreadQ;
1.236 + break;
1.237 + default: Unimplemented();
1.238 + }
1.239 + return queuehead;
1.240 + }
1.241 +
1.242 + void set_threadQ(SeenThread* seenthread, PlaceholderTable::classloadAction action) {
1.243 + switch (action) {
1.244 + case PlaceholderTable::LOAD_INSTANCE:
1.245 + _loadInstanceThreadQ = seenthread;
1.246 + break;
1.247 + case PlaceholderTable::LOAD_SUPER:
1.248 + _superThreadQ = seenthread;
1.249 + break;
1.250 + case PlaceholderTable::DEFINE_CLASS:
1.251 + _defineThreadQ = seenthread;
1.252 + break;
1.253 + default: Unimplemented();
1.254 + }
1.255 + return;
1.256 + }
1.257 +
1.258 + bool super_load_in_progress() {
1.259 + return (_superThreadQ != NULL);
1.260 + }
1.261 +
1.262 + bool instance_load_in_progress() {
1.263 + return (_loadInstanceThreadQ != NULL);
1.264 + }
1.265 +
1.266 + bool define_class_in_progress() {
1.267 + return (_defineThreadQ != NULL);
1.268 + }
1.269 +
1.270 +// Doubly-linked list of Threads per action for class/classloader pair
1.271 +// Class circularity support: links in thread before loading superclass
1.272 +// bootstrapsearchpath support: links in a thread before load_instance_class
1.273 +// definers: use as queue of define requestors, including owner of
1.274 +// define token. Appends for debugging of requestor order
1.275 + void add_seen_thread(Thread* thread, PlaceholderTable::classloadAction action) {
1.276 + assert_lock_strong(SystemDictionary_lock);
1.277 + SeenThread* threadEntry = new SeenThread(thread);
1.278 + SeenThread* seen = actionToQueue(action);
1.279 +
1.280 + if (seen == NULL) {
1.281 + set_threadQ(threadEntry, action);
1.282 + return;
1.283 + }
1.284 + SeenThread* next;
1.285 + while ((next = seen->next()) != NULL) {
1.286 + seen = next;
1.287 + }
1.288 + seen->set_next(threadEntry);
1.289 + threadEntry->set_prev(seen);
1.290 + return;
1.291 + }
1.292 +
1.293 + bool check_seen_thread(Thread* thread, PlaceholderTable::classloadAction action) {
1.294 + assert_lock_strong(SystemDictionary_lock);
1.295 + SeenThread* threadQ = actionToQueue(action);
1.296 + SeenThread* seen = threadQ;
1.297 + while (seen) {
1.298 + if (thread == seen->thread()) {
1.299 + return true;
1.300 + }
1.301 + seen = seen->next();
1.302 + }
1.303 + return false;
1.304 + }
1.305 +
1.306 + // returns true if seenthreadQ is now empty
1.307 + // Note, caller must ensure probe still exists while holding
1.308 + // SystemDictionary_lock
1.309 + // ignores if cleanup has already been done
1.310 + // if found, deletes SeenThread
1.311 + bool remove_seen_thread(Thread* thread, PlaceholderTable::classloadAction action) {
1.312 + assert_lock_strong(SystemDictionary_lock);
1.313 + SeenThread* threadQ = actionToQueue(action);
1.314 + SeenThread* seen = threadQ;
1.315 + SeenThread* prev = NULL;
1.316 + while (seen) {
1.317 + if (thread == seen->thread()) {
1.318 + if (prev) {
1.319 + prev->set_next(seen->next());
1.320 + } else {
1.321 + set_threadQ(seen->next(), action);
1.322 + }
1.323 + if (seen->next()) {
1.324 + seen->next()->set_prev(prev);
1.325 + }
1.326 + delete seen;
1.327 + break;
1.328 + }
1.329 + prev = seen;
1.330 + seen = seen->next();
1.331 + }
1.332 + return (actionToQueue(action) == NULL);
1.333 + }
1.334 +
1.335 + // GC support
1.336 + // Applies "f->do_oop" to all root oops in the placeholder table.
1.337 + void classes_do(KlassClosure* closure);
1.338 +
1.339 + // Print method doesn't append a cr
1.340 + void print() const PRODUCT_RETURN;
1.341 + void verify() const;
1.342 +};
1.343 +
1.344 +#endif // SHARE_VM_CLASSFILE_PLACEHOLDERS_HPP
