1 /*
2 * Copyright (c) 2017, 2018, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/javaClasses.hpp"
27 #include "memory/allocation.hpp"
28 #include "memory/resourceArea.hpp"
29 #include "oops/access.inline.hpp"
30 #include "oops/oop.inline.hpp"
31 #include "oops/method.hpp"
32 #include "oops/symbol.hpp"
33 #include "oops/weakHandle.inline.hpp"
34 #include "prims/resolvedMethodTable.hpp"
35 #include "runtime/handles.inline.hpp"
36 #include "runtime/mutexLocker.hpp"
37 #include "runtime/safepointVerifiers.hpp"
38 #include "utilities/hashtable.inline.hpp"
39 #include "utilities/macros.hpp"
40
41
42 oop ResolvedMethodEntry::object() {
43 return literal().resolve();
44 }
45
46 oop ResolvedMethodEntry::object_no_keepalive() {
47 // The AS_NO_KEEPALIVE peeks at the oop without keeping it alive.
48 // This is dangerous in general but is okay if the loaded oop does
49 // not leak out past a thread transition where a safepoint can happen.
50 // A subsequent oop_load without AS_NO_KEEPALIVE (the object() accessor)
51 // keeps the oop alive before doing so.
52 return literal().peek();
53 }
54
55 ResolvedMethodTable::ResolvedMethodTable()
56 : Hashtable<ClassLoaderWeakHandle, mtClass>(_table_size, sizeof(ResolvedMethodEntry)) { }
57
58 oop ResolvedMethodTable::lookup(int index, unsigned int hash, Method* method) {
59 for (ResolvedMethodEntry* p = bucket(index); p != NULL; p = p->next()) {
60 if (p->hash() == hash) {
61
62 // Peek the object to check if it is the right target.
63 oop target = p->object_no_keepalive();
64
65 // The method is in the table as a target already
66 if (target != NULL && java_lang_invoke_ResolvedMethodName::vmtarget(target) == method) {
67 ResourceMark rm;
68 log_debug(membername, table) ("ResolvedMethod entry found for %s index %d",
69 method->name_and_sig_as_C_string(), index);
70 // The object() accessor makes sure the target object is kept alive before
71 // leaking out.
72 return p->object();
73 }
74 }
75 }
76 return NULL;
77 }
78
79 unsigned int ResolvedMethodTable::compute_hash(Method* method) {
80 unsigned int name_hash = method->name()->identity_hash();
81 unsigned int signature_hash = method->signature()->identity_hash();
82 return name_hash ^ signature_hash;
83 }
84
85
86 oop ResolvedMethodTable::lookup(Method* method) {
87 unsigned int hash = compute_hash(method);
88 int index = hash_to_index(hash);
89 return lookup(index, hash, method);
90 }
91
92 oop ResolvedMethodTable::basic_add(Method* method, Handle rmethod_name) {
93 assert_locked_or_safepoint(ResolvedMethodTable_lock);
94
95 unsigned int hash = compute_hash(method);
96 int index = hash_to_index(hash);
97
98 // One was added while aquiring the lock
99 oop entry = lookup(index, hash, method);
100 if (entry != NULL) {
101 return entry;
102 }
103
104 ClassLoaderWeakHandle w = ClassLoaderWeakHandle::create(rmethod_name);
105 ResolvedMethodEntry* p = (ResolvedMethodEntry*) Hashtable<ClassLoaderWeakHandle, mtClass>::new_entry(hash, w);
106 Hashtable<ClassLoaderWeakHandle, mtClass>::add_entry(index, p);
107 ResourceMark rm;
108 log_debug(membername, table) ("ResolvedMethod entry added for %s index %d",
109 method->name_and_sig_as_C_string(), index);
110 return rmethod_name();
111 }
112
113 ResolvedMethodTable* ResolvedMethodTable::_the_table = NULL;
114
115 oop ResolvedMethodTable::find_method(Method* method) {
116 oop entry = _the_table->lookup(method);
117 return entry;
118 }
119
120 oop ResolvedMethodTable::add_method(Handle resolved_method_name) {
121 MutexLocker ml(ResolvedMethodTable_lock);
122 DEBUG_ONLY(NoSafepointVerifier nsv);
123
124 // Check if method has been redefined while taking out ResolvedMethodTable_lock, if so
125 // use new method.
126 Method* method = (Method*)java_lang_invoke_ResolvedMethodName::vmtarget(resolved_method_name());
127 assert(method->is_method(), "must be method");
128 if (method->is_old()) {
129 // Replace method with redefined version
130 InstanceKlass* holder = method->method_holder();
131 method = holder->method_with_idnum(method->method_idnum());
132 java_lang_invoke_ResolvedMethodName::set_vmtarget(resolved_method_name(), method);
133 }
134 // Set flag in class to indicate this InstanceKlass has entries in the table
135 // to avoid walking table during redefinition if none of the redefined classes
136 // have any membernames in the table.
137 method->method_holder()->set_has_resolved_methods();
138
139 return _the_table->basic_add(method, resolved_method_name);
140 }
141
142 // Removing entries
143 int ResolvedMethodTable::_oops_removed = 0;
144 int ResolvedMethodTable::_oops_counted = 0;
145
146 // Serially invoke removed unused oops from the table.
147 // This is done late during GC.
148 void ResolvedMethodTable::unlink() {
149 _oops_removed = 0;
150 _oops_counted = 0;
151 for (int i = 0; i < _the_table->table_size(); ++i) {
152 ResolvedMethodEntry** p = _the_table->bucket_addr(i);
153 ResolvedMethodEntry* entry = _the_table->bucket(i);
154 while (entry != NULL) {
155 _oops_counted++;
156 oop l = entry->object_no_keepalive();
157 if (l != NULL) {
158 p = entry->next_addr();
159 } else {
160 // Entry has been removed.
161 _oops_removed++;
162 if (log_is_enabled(Debug, membername, table)) {
163 log_debug(membername, table) ("ResolvedMethod entry removed for index %d", i);
164 }
165 entry->literal().release();
166 *p = entry->next();
167 _the_table->free_entry(entry);
168 }
169 // get next entry
170 entry = (ResolvedMethodEntry*)HashtableEntry<ClassLoaderWeakHandle, mtClass>::make_ptr(*p);
171 }
172 }
173 log_debug(membername, table) ("ResolvedMethod entries counted %d removed %d",
174 _oops_counted, _oops_removed);
175 }
176
177 #ifndef PRODUCT
178 void ResolvedMethodTable::print() {
179 for (int i = 0; i < table_size(); ++i) {
180 ResolvedMethodEntry* entry = bucket(i);
181 while (entry != NULL) {
182 tty->print("%d : ", i);
183 oop rmethod_name = entry->object_no_keepalive();
184 if (rmethod_name != NULL) {
185 rmethod_name->print();
186 Method* m = (Method*)java_lang_invoke_ResolvedMethodName::vmtarget(rmethod_name);
187 m->print();
188 }
189 entry = entry->next();
190 }
191 }
192 }
193 #endif // PRODUCT
194
195 #if INCLUDE_JVMTI
196 // It is called at safepoint only for RedefineClasses
197 void ResolvedMethodTable::adjust_method_entries(bool * trace_name_printed) {
198 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
199 // For each entry in RMT, change to new method
200 for (int i = 0; i < _the_table->table_size(); ++i) {
201 for (ResolvedMethodEntry* entry = _the_table->bucket(i);
202 entry != NULL;
203 entry = entry->next()) {
204
205 oop mem_name = entry->object_no_keepalive();
206 // except ones removed
207 if (mem_name == NULL) {
208 continue;
209 }
210 Method* old_method = (Method*)java_lang_invoke_ResolvedMethodName::vmtarget(mem_name);
211
212 if (old_method->is_old()) {
213
214 if (old_method->is_deleted()) {
215 // leave deleted method in ResolvedMethod for now (this is a bug that we don't mark
216 // these on_stack)
217 continue;
218 }
219
220 InstanceKlass* holder = old_method->method_holder();
221 Method* new_method = holder->method_with_idnum(old_method->orig_method_idnum());
222 assert(holder == new_method->method_holder(), "call after swapping redefined guts");
223 assert(new_method != NULL, "method_with_idnum() should not be NULL");
224 assert(old_method != new_method, "sanity check");
225
226 java_lang_invoke_ResolvedMethodName::set_vmtarget(mem_name, new_method);
227
228 ResourceMark rm;
229 if (!(*trace_name_printed)) {
230 log_info(redefine, class, update)("adjust: name=%s", old_method->method_holder()->external_name());
231 *trace_name_printed = true;
232 }
233 log_debug(redefine, class, update, constantpool)
234 ("ResolvedMethod method update: %s(%s)",
235 new_method->name()->as_C_string(), new_method->signature()->as_C_string());
236 }
237 }
238 }
239 }
240 #endif // INCLUDE_JVMTI