Mercurial > hg > truffle
annotate src/share/vm/runtime/jniHandles.hpp @ 1288:c76ca382971b
Merge
author | johnc |
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date | Tue, 02 Mar 2010 13:59:37 -0800 |
parents | 354d3184f6b2 |
children | 892898e961c5 |
rev | line source |
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0 | 1 /* |
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2 * Copyright 1998-2009 Sun Microsystems, Inc. All Rights Reserved. |
0 | 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, | |
20 * CA 95054 USA or visit www.sun.com if you need additional information or | |
21 * have any questions. | |
22 * | |
23 */ | |
24 | |
25 class JNIHandleBlock; | |
26 | |
27 | |
28 // Interface for creating and resolving local/global JNI handles | |
29 | |
30 class JNIHandles : AllStatic { | |
31 friend class VMStructs; | |
32 private: | |
33 static JNIHandleBlock* _global_handles; // First global handle block | |
34 static JNIHandleBlock* _weak_global_handles; // First weak global handle block | |
35 static oop _deleted_handle; // Sentinel marking deleted handles | |
36 | |
37 public: | |
38 // Resolve handle into oop | |
39 inline static oop resolve(jobject handle); | |
40 // Resolve externally provided handle into oop with some guards | |
41 inline static oop resolve_external_guard(jobject handle); | |
42 // Resolve handle into oop, result guaranteed not to be null | |
43 inline static oop resolve_non_null(jobject handle); | |
44 | |
45 // Local handles | |
46 static jobject make_local(oop obj); | |
47 static jobject make_local(JNIEnv* env, oop obj); // Fast version when env is known | |
48 static jobject make_local(Thread* thread, oop obj); // Even faster version when current thread is known | |
49 inline static void destroy_local(jobject handle); | |
50 | |
51 // Global handles | |
52 static jobject make_global(Handle obj); | |
53 static void destroy_global(jobject handle); | |
54 | |
55 // Weak global handles | |
56 static jobject make_weak_global(Handle obj); | |
57 static void destroy_weak_global(jobject handle); | |
58 | |
59 // jmethodID handling (as Weak global handles). | |
60 // Because the useful life-span of a jmethodID cannot be determined, once created they are | |
61 // never reclaimed. The methods to which they refer, however, can be GC'ed away if the class | |
62 // is unloaded or if the method is made obsolete or deleted -- in these cases, the jmethodID | |
63 // refers to NULL (as is the case for any weak reference). | |
64 static jmethodID make_jmethod_id(methodHandle mh); | |
65 static void destroy_jmethod_id(jmethodID mid); | |
66 inline static methodOop resolve_jmethod_id(jmethodID mid); | |
67 inline static methodOop checked_resolve_jmethod_id(jmethodID mid); // NULL on invalid jmethodID | |
68 static void change_method_associated_with_jmethod_id(jmethodID jmid, methodHandle mh); | |
69 | |
70 // Sentinel marking deleted handles in block. Note that we cannot store NULL as | |
71 // the sentinel, since clearing weak global JNI refs are done by storing NULL in | |
72 // the handle. The handle may not be reused before destroy_weak_global is called. | |
73 static oop deleted_handle() { return _deleted_handle; } | |
74 | |
75 // Initialization | |
76 static void initialize(); | |
77 | |
78 // Debugging | |
79 static void print_on(outputStream* st); | |
80 static void print() { print_on(tty); } | |
81 static void verify(); | |
82 static bool is_local_handle(Thread* thread, jobject handle); | |
83 static bool is_frame_handle(JavaThread* thr, jobject obj); | |
84 static bool is_global_handle(jobject handle); | |
85 static bool is_weak_global_handle(jobject handle); | |
86 static long global_handle_memory_usage(); | |
87 static long weak_global_handle_memory_usage(); | |
88 | |
89 // Garbage collection support(global handles only, local handles are traversed from thread) | |
90 // Traversal of regular global handles | |
91 static void oops_do(OopClosure* f); | |
92 // Traversal of weak global handles. Unreachable oops are cleared. | |
93 static void weak_oops_do(BoolObjectClosure* is_alive, OopClosure* f); | |
94 }; | |
95 | |
96 | |
97 | |
98 // JNI handle blocks holding local/global JNI handles | |
99 | |
100 class JNIHandleBlock : public CHeapObj { | |
101 friend class VMStructs; | |
1010 | 102 friend class CppInterpreter; |
103 | |
0 | 104 private: |
105 enum SomeConstants { | |
106 block_size_in_oops = 32 // Number of handles per handle block | |
107 }; | |
108 | |
109 oop _handles[block_size_in_oops]; // The handles | |
110 int _top; // Index of next unused handle | |
111 JNIHandleBlock* _next; // Link to next block | |
112 | |
113 // The following instance variables are only used by the first block in a chain. | |
114 // Having two types of blocks complicates the code and the space overhead in negligble. | |
115 JNIHandleBlock* _last; // Last block in use | |
116 JNIHandleBlock* _pop_frame_link; // Block to restore on PopLocalFrame call | |
117 oop* _free_list; // Handle free list | |
118 int _allocate_before_rebuild; // Number of blocks to allocate before rebuilding free list | |
119 | |
120 #ifndef PRODUCT | |
121 JNIHandleBlock* _block_list_link; // Link for list below | |
122 static JNIHandleBlock* _block_list; // List of all allocated blocks (for debugging only) | |
123 #endif | |
124 | |
125 static JNIHandleBlock* _block_free_list; // Free list of currently unused blocks | |
126 static int _blocks_allocated; // For debugging/printing | |
127 | |
128 // Fill block with bad_handle values | |
129 void zap(); | |
130 | |
1010 | 131 protected: |
0 | 132 // No more handles in the both the current and following blocks |
133 void clear() { _top = 0; } | |
134 | |
1010 | 135 private: |
0 | 136 // Free list computation |
137 void rebuild_free_list(); | |
138 | |
139 public: | |
140 // Handle allocation | |
141 jobject allocate_handle(oop obj); | |
142 | |
143 // Block allocation and block free list management | |
144 static JNIHandleBlock* allocate_block(Thread* thread = NULL); | |
145 static void release_block(JNIHandleBlock* block, Thread* thread = NULL); | |
146 | |
147 // JNI PushLocalFrame/PopLocalFrame support | |
148 JNIHandleBlock* pop_frame_link() const { return _pop_frame_link; } | |
149 void set_pop_frame_link(JNIHandleBlock* block) { _pop_frame_link = block; } | |
150 | |
151 // Stub generator support | |
152 static int top_offset_in_bytes() { return offset_of(JNIHandleBlock, _top); } | |
153 | |
154 // Garbage collection support | |
155 // Traversal of regular handles | |
156 void oops_do(OopClosure* f); | |
157 // Traversal of weak handles. Unreachable oops are cleared. | |
158 void weak_oops_do(BoolObjectClosure* is_alive, OopClosure* f); | |
159 | |
160 // Debugging | |
161 bool chain_contains(jobject handle) const; // Does this block or following blocks contain handle | |
162 bool contains(jobject handle) const; // Does this block contain handle | |
163 int length() const; // Length of chain starting with this block | |
164 long memory_usage() const; | |
165 #ifndef PRODUCT | |
166 static bool any_contains(jobject handle); // Does any block currently in use contain handle | |
167 static void print_statistics(); | |
168 #endif | |
169 }; | |
170 | |
171 | |
172 inline oop JNIHandles::resolve(jobject handle) { | |
173 oop result = (handle == NULL ? (oop)NULL : *(oop*)handle); | |
174 assert(result != NULL || (handle == NULL || !CheckJNICalls || is_weak_global_handle(handle)), "Invalid value read from jni handle"); | |
175 assert(result != badJNIHandle, "Pointing to zapped jni handle area"); | |
176 return result; | |
177 }; | |
178 | |
179 | |
180 inline oop JNIHandles::resolve_external_guard(jobject handle) { | |
181 if (handle == NULL) return NULL; | |
182 oop result = *(oop*)handle; | |
183 if (result == NULL || result == badJNIHandle) return NULL; | |
184 return result; | |
185 }; | |
186 | |
187 | |
188 inline oop JNIHandles::resolve_non_null(jobject handle) { | |
189 assert(handle != NULL, "JNI handle should not be null"); | |
190 oop result = *(oop*)handle; | |
191 assert(result != NULL, "Invalid value read from jni handle"); | |
192 assert(result != badJNIHandle, "Pointing to zapped jni handle area"); | |
193 // Don't let that private _deleted_handle object escape into the wild. | |
194 assert(result != deleted_handle(), "Used a deleted global handle."); | |
195 return result; | |
196 }; | |
197 | |
198 inline methodOop JNIHandles::resolve_jmethod_id(jmethodID mid) { | |
199 return (methodOop) resolve_non_null((jobject)mid); | |
200 }; | |
201 | |
202 inline methodOop JNIHandles::checked_resolve_jmethod_id(jmethodID mid) { | |
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203 if (mid == NULL) { |
0 | 204 return (methodOop) NULL; |
205 } | |
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206 |
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207 oop o = resolve_non_null((jobject) mid); |
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208 if (!o->is_method()) { |
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209 return (methodOop) NULL; |
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210 } |
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211 |
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212 return (methodOop) o; |
0 | 213 }; |
214 | |
215 | |
216 inline void JNIHandles::destroy_local(jobject handle) { | |
217 if (handle != NULL) { | |
218 *((oop*)handle) = deleted_handle(); // Mark the handle as deleted, allocate will reuse it | |
219 } | |
220 } |