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annotate src/share/vm/runtime/jniHandles.hpp @ 2904:1916da1d3e11
Merge.
author | Thomas Wuerthinger <thomas@wuerthinger.net> |
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date | Wed, 08 Jun 2011 17:26:49 +0200 |
parents | f95d63e2154a |
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0 | 1 /* |
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2 * Copyright (c) 1998, 2010, Oracle and/or its affiliates. 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 * | |
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
0 | 22 * |
23 */ | |
24 | |
1972 | 25 #ifndef SHARE_VM_RUNTIME_JNIHANDLES_HPP |
26 #define SHARE_VM_RUNTIME_JNIHANDLES_HPP | |
27 | |
28 #include "runtime/handles.hpp" | |
29 #include "utilities/top.hpp" | |
30 | |
0 | 31 class JNIHandleBlock; |
32 | |
33 | |
34 // Interface for creating and resolving local/global JNI handles | |
35 | |
36 class JNIHandles : AllStatic { | |
37 friend class VMStructs; | |
38 private: | |
39 static JNIHandleBlock* _global_handles; // First global handle block | |
40 static JNIHandleBlock* _weak_global_handles; // First weak global handle block | |
41 static oop _deleted_handle; // Sentinel marking deleted handles | |
42 | |
43 public: | |
44 // Resolve handle into oop | |
45 inline static oop resolve(jobject handle); | |
46 // Resolve externally provided handle into oop with some guards | |
47 inline static oop resolve_external_guard(jobject handle); | |
48 // Resolve handle into oop, result guaranteed not to be null | |
49 inline static oop resolve_non_null(jobject handle); | |
50 | |
51 // Local handles | |
52 static jobject make_local(oop obj); | |
53 static jobject make_local(JNIEnv* env, oop obj); // Fast version when env is known | |
54 static jobject make_local(Thread* thread, oop obj); // Even faster version when current thread is known | |
55 inline static void destroy_local(jobject handle); | |
56 | |
57 // Global handles | |
58 static jobject make_global(Handle obj); | |
59 static void destroy_global(jobject handle); | |
60 | |
61 // Weak global handles | |
62 static jobject make_weak_global(Handle obj); | |
63 static void destroy_weak_global(jobject handle); | |
64 | |
65 // jmethodID handling (as Weak global handles). | |
66 // Because the useful life-span of a jmethodID cannot be determined, once created they are | |
67 // never reclaimed. The methods to which they refer, however, can be GC'ed away if the class | |
68 // is unloaded or if the method is made obsolete or deleted -- in these cases, the jmethodID | |
69 // refers to NULL (as is the case for any weak reference). | |
70 static jmethodID make_jmethod_id(methodHandle mh); | |
71 static void destroy_jmethod_id(jmethodID mid); | |
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72 // Use resolve_jmethod_id() in situations where the caller is expected |
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73 // to provide a valid jmethodID; the only sanity checks are in asserts; |
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74 // result guaranteed not to be NULL. |
0 | 75 inline static methodOop resolve_jmethod_id(jmethodID mid); |
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76 // Use checked_resolve_jmethod_id() in situations where the caller |
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77 // should provide a valid jmethodID, but might not. NULL is returned |
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78 // when the jmethodID does not refer to a valid method. |
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79 inline static methodOop checked_resolve_jmethod_id(jmethodID mid); |
0 | 80 static void change_method_associated_with_jmethod_id(jmethodID jmid, methodHandle mh); |
81 | |
82 // Sentinel marking deleted handles in block. Note that we cannot store NULL as | |
83 // the sentinel, since clearing weak global JNI refs are done by storing NULL in | |
84 // the handle. The handle may not be reused before destroy_weak_global is called. | |
85 static oop deleted_handle() { return _deleted_handle; } | |
86 | |
87 // Initialization | |
88 static void initialize(); | |
89 | |
90 // Debugging | |
91 static void print_on(outputStream* st); | |
92 static void print() { print_on(tty); } | |
93 static void verify(); | |
94 static bool is_local_handle(Thread* thread, jobject handle); | |
95 static bool is_frame_handle(JavaThread* thr, jobject obj); | |
96 static bool is_global_handle(jobject handle); | |
97 static bool is_weak_global_handle(jobject handle); | |
98 static long global_handle_memory_usage(); | |
99 static long weak_global_handle_memory_usage(); | |
100 | |
101 // Garbage collection support(global handles only, local handles are traversed from thread) | |
102 // Traversal of regular global handles | |
103 static void oops_do(OopClosure* f); | |
104 // Traversal of weak global handles. Unreachable oops are cleared. | |
105 static void weak_oops_do(BoolObjectClosure* is_alive, OopClosure* f); | |
106 }; | |
107 | |
108 | |
109 | |
110 // JNI handle blocks holding local/global JNI handles | |
111 | |
112 class JNIHandleBlock : public CHeapObj { | |
113 friend class VMStructs; | |
1010 | 114 friend class CppInterpreter; |
115 | |
0 | 116 private: |
117 enum SomeConstants { | |
118 block_size_in_oops = 32 // Number of handles per handle block | |
119 }; | |
120 | |
121 oop _handles[block_size_in_oops]; // The handles | |
122 int _top; // Index of next unused handle | |
123 JNIHandleBlock* _next; // Link to next block | |
124 | |
125 // The following instance variables are only used by the first block in a chain. | |
126 // Having two types of blocks complicates the code and the space overhead in negligble. | |
127 JNIHandleBlock* _last; // Last block in use | |
128 JNIHandleBlock* _pop_frame_link; // Block to restore on PopLocalFrame call | |
129 oop* _free_list; // Handle free list | |
130 int _allocate_before_rebuild; // Number of blocks to allocate before rebuilding free list | |
131 | |
132 #ifndef PRODUCT | |
133 JNIHandleBlock* _block_list_link; // Link for list below | |
134 static JNIHandleBlock* _block_list; // List of all allocated blocks (for debugging only) | |
135 #endif | |
136 | |
137 static JNIHandleBlock* _block_free_list; // Free list of currently unused blocks | |
138 static int _blocks_allocated; // For debugging/printing | |
139 | |
140 // Fill block with bad_handle values | |
141 void zap(); | |
142 | |
1010 | 143 protected: |
0 | 144 // No more handles in the both the current and following blocks |
145 void clear() { _top = 0; } | |
146 | |
1010 | 147 private: |
0 | 148 // Free list computation |
149 void rebuild_free_list(); | |
150 | |
151 public: | |
152 // Handle allocation | |
153 jobject allocate_handle(oop obj); | |
154 | |
155 // Block allocation and block free list management | |
156 static JNIHandleBlock* allocate_block(Thread* thread = NULL); | |
157 static void release_block(JNIHandleBlock* block, Thread* thread = NULL); | |
158 | |
159 // JNI PushLocalFrame/PopLocalFrame support | |
160 JNIHandleBlock* pop_frame_link() const { return _pop_frame_link; } | |
161 void set_pop_frame_link(JNIHandleBlock* block) { _pop_frame_link = block; } | |
162 | |
163 // Stub generator support | |
164 static int top_offset_in_bytes() { return offset_of(JNIHandleBlock, _top); } | |
165 | |
166 // Garbage collection support | |
167 // Traversal of regular handles | |
168 void oops_do(OopClosure* f); | |
169 // Traversal of weak handles. Unreachable oops are cleared. | |
170 void weak_oops_do(BoolObjectClosure* is_alive, OopClosure* f); | |
171 | |
172 // Debugging | |
173 bool chain_contains(jobject handle) const; // Does this block or following blocks contain handle | |
174 bool contains(jobject handle) const; // Does this block contain handle | |
175 int length() const; // Length of chain starting with this block | |
176 long memory_usage() const; | |
177 #ifndef PRODUCT | |
178 static bool any_contains(jobject handle); // Does any block currently in use contain handle | |
179 static void print_statistics(); | |
180 #endif | |
181 }; | |
182 | |
183 | |
184 inline oop JNIHandles::resolve(jobject handle) { | |
185 oop result = (handle == NULL ? (oop)NULL : *(oop*)handle); | |
186 assert(result != NULL || (handle == NULL || !CheckJNICalls || is_weak_global_handle(handle)), "Invalid value read from jni handle"); | |
187 assert(result != badJNIHandle, "Pointing to zapped jni handle area"); | |
188 return result; | |
189 }; | |
190 | |
191 | |
192 inline oop JNIHandles::resolve_external_guard(jobject handle) { | |
193 if (handle == NULL) return NULL; | |
194 oop result = *(oop*)handle; | |
195 if (result == NULL || result == badJNIHandle) return NULL; | |
196 return result; | |
197 }; | |
198 | |
199 | |
200 inline oop JNIHandles::resolve_non_null(jobject handle) { | |
201 assert(handle != NULL, "JNI handle should not be null"); | |
202 oop result = *(oop*)handle; | |
203 assert(result != NULL, "Invalid value read from jni handle"); | |
204 assert(result != badJNIHandle, "Pointing to zapped jni handle area"); | |
205 // Don't let that private _deleted_handle object escape into the wild. | |
206 assert(result != deleted_handle(), "Used a deleted global handle."); | |
207 return result; | |
208 }; | |
209 | |
210 inline methodOop JNIHandles::resolve_jmethod_id(jmethodID mid) { | |
211 return (methodOop) resolve_non_null((jobject)mid); | |
212 }; | |
213 | |
214 inline methodOop JNIHandles::checked_resolve_jmethod_id(jmethodID mid) { | |
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215 oop o = resolve_external_guard((jobject) mid); |
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216 if (o == NULL || !o->is_method()) { |
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217 return (methodOop) NULL; |
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218 } |
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219 |
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220 return (methodOop) o; |
0 | 221 }; |
222 | |
223 | |
224 inline void JNIHandles::destroy_local(jobject handle) { | |
225 if (handle != NULL) { | |
226 *((oop*)handle) = deleted_handle(); // Mark the handle as deleted, allocate will reuse it | |
227 } | |
228 } | |
1972 | 229 |
230 #endif // SHARE_VM_RUNTIME_JNIHANDLES_HPP |