1 /*
2 * Copyright (c) 2003, 2011, Oracle and/or its affiliates. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 *
8 * - Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 *
11 * - Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 *
15 * - Neither the name of Oracle nor the names of its
16 * contributors may be used to endorse or promote products derived
17 * from this software without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
20 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
21 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
23 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
24 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
25 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
26 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
27 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
28 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
29 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30 */
31
32 /*
33 * This source code is provided to illustrate the usage of a given feature
34 * or technique and has been deliberately simplified. Additional steps
35 * required for a production-quality application, such as security checks,
36 * input validation and proper error handling, might not be present in
37 * this sample code.
38 */
39
40
41 /* The Class Loader table. */
42
43 /*
44 * The Class Loader objects show up so early in the VM process that a
45 * separate table was designated for Class Loaders.
46 *
47 * The Class Loader is unique by way of it's jobject uniqueness, unfortunately
48 * use of JNI too early for jobject comparisons is problematic.
49 * It is assumed that the number of class loaders will be limited, and
50 * a simple linear search will be performed for now.
51 * That logic is isolated here and can be changed to use the standard
52 * table hash table search once we know JNI can be called safely.
53 *
54 * A weak global reference is created to keep tabs on loaders, and as
55 * each search for a loader happens, NULL weak global references will
56 * trigger the freedom of those entries.
57 *
58 */
59
60 #include "hprof.h"
61
62 typedef struct {
63 jobject globalref; /* Weak Global reference for object */
64 ObjectIndex object_index;
65 } LoaderInfo;
66
67 static LoaderInfo *
68 get_info(LoaderIndex index)
69 {
70 return (LoaderInfo*)table_get_info(gdata->loader_table, index);
71 }
72
73 static void
74 delete_globalref(JNIEnv *env, LoaderInfo *info)
75 {
76 jobject ref;
77
78 HPROF_ASSERT(env!=NULL);
79 HPROF_ASSERT(info!=NULL);
80 ref = info->globalref;
81 info->globalref = NULL;
82 if ( ref != NULL ) {
83 deleteWeakGlobalReference(env, ref);
84 }
85 info->object_index = 0;
86 }
87
88 static void
89 cleanup_item(TableIndex index, void *key_ptr, int key_len,
90 void *info_ptr, void *arg)
91 {
92 }
93
94 static void
95 delete_ref_item(TableIndex index, void *key_ptr, int key_len,
96 void *info_ptr, void *arg)
97 {
98 delete_globalref((JNIEnv*)arg, (LoaderInfo*)info_ptr);
99 }
100
101 static void
102 list_item(TableIndex index, void *key_ptr, int key_len,
103 void *info_ptr, void *arg)
104 {
105 LoaderInfo *info;
106
107 HPROF_ASSERT(info_ptr!=NULL);
108
109 info = (LoaderInfo*)info_ptr;
110 debug_message( "Loader 0x%08x: globalref=%p, object_index=%d\n",
111 index, (void*)info->globalref, info->object_index);
112 }
113
114 static void
115 free_entry(JNIEnv *env, LoaderIndex index)
116 {
117 LoaderInfo *info;
118
119 info = get_info(index);
120 delete_globalref(env, info);
121 table_free_entry(gdata->loader_table, index);
122 }
123
124 typedef struct SearchData {
125 JNIEnv *env;
126 jobject loader;
127 LoaderIndex found;
128 } SearchData;
129
130 static void
131 search_item(TableIndex index, void *key_ptr, int key_len, void *info_ptr, void *arg)
132 {
133 LoaderInfo *info;
134 SearchData *data;
135
136 HPROF_ASSERT(info_ptr!=NULL);
137 HPROF_ASSERT(arg!=NULL);
138 info = (LoaderInfo*)info_ptr;
139 data = (SearchData*)arg;
140 if ( data->loader == info->globalref ) {
141 /* Covers when looking for NULL too. */
142 HPROF_ASSERT(data->found==0); /* Did we find more than one? */
143 data->found = index;
144 } else if ( data->env != NULL && data->loader != NULL &&
145 info->globalref != NULL ) {
146 jobject lref;
147
148 lref = newLocalReference(data->env, info->globalref);
149 if ( lref == NULL ) {
150 /* Object went away, free reference and entry */
151 free_entry(data->env, index);
152 } else if ( isSameObject(data->env, data->loader, lref) ) {
153 HPROF_ASSERT(data->found==0); /* Did we find more than one? */
154 data->found = index;
155 }
156 if ( lref != NULL ) {
157 deleteLocalReference(data->env, lref);
158 }
159 }
160
161 }
162
163 static LoaderIndex
164 search(JNIEnv *env, jobject loader)
165 {
166 SearchData data;
167
168 data.env = env;
169 data.loader = loader;
170 data.found = 0;
171 table_walk_items(gdata->loader_table, &search_item, (void*)&data);
172 return data.found;
173 }
174
175 LoaderIndex
176 loader_find_or_create(JNIEnv *env, jobject loader)
177 {
178 LoaderIndex index;
179
180 /* See if we remembered the system loader */
181 if ( loader==NULL && gdata->system_loader != 0 ) {
182 return gdata->system_loader;
183 }
184 if ( loader==NULL ) {
185 env = NULL;
186 }
187 index = search(env, loader);
188 if ( index == 0 ) {
189 static LoaderInfo empty_info;
190 LoaderInfo info;
191
192 info = empty_info;
193 if ( loader != NULL ) {
194 HPROF_ASSERT(env!=NULL);
195 info.globalref = newWeakGlobalReference(env, loader);
196 info.object_index = 0;
197 }
198 index = table_create_entry(gdata->loader_table, NULL, 0, (void*)&info);
199 }
200 HPROF_ASSERT(search(env,loader)==index);
201 /* Remember the system loader */
202 if ( loader==NULL && gdata->system_loader == 0 ) {
203 gdata->system_loader = index;
204 }
205 return index;
206 }
207
208 void
209 loader_init(void)
210 {
211 gdata->loader_table = table_initialize("Loader",
212 16, 16, 0, (int)sizeof(LoaderInfo));
213 }
214
215 void
216 loader_list(void)
217 {
218 debug_message(
219 "--------------------- Loader Table ------------------------\n");
220 table_walk_items(gdata->loader_table, &list_item, NULL);
221 debug_message(
222 "----------------------------------------------------------\n");
223 }
224
225 void
226 loader_cleanup(void)
227 {
228 table_cleanup(gdata->loader_table, &cleanup_item, NULL);
229 gdata->loader_table = NULL;
230 }
231
232 void
233 loader_delete_global_references(JNIEnv *env)
234 {
235 table_walk_items(gdata->loader_table, &delete_ref_item, (void*)env);
236 }
237
238 /* Get the object index for a class loader */
239 ObjectIndex
240 loader_object_index(JNIEnv *env, LoaderIndex index)
241 {
242 LoaderInfo *info;
243 ObjectIndex object_index;
244 jobject wref;
245
246 /* Assume no object index at first (default class loader) */
247 info = get_info(index);
248 object_index = info->object_index;
249 wref = info->globalref;
250 if ( wref != NULL && object_index == 0 ) {
251 jobject lref;
252
253 object_index = 0;
254 lref = newLocalReference(env, wref);
255 if ( lref != NULL && !isSameObject(env, lref, NULL) ) {
256 jlong tag;
257
258 /* Get the tag on the object and extract the object_index */
259 tag = getTag(lref);
260 if ( tag != (jlong)0 ) {
261 object_index = tag_extract(tag);
262 }
263 }
264 if ( lref != NULL ) {
265 deleteLocalReference(env, lref);
266 }
267 info->object_index = object_index;
268 }
269 return object_index;
270 }