annotate src/share/vm/runtime/jniHandles.cpp @ 196:d1605aabd0a1 jdk7-b30

6719955: Update copyright year Summary: Update copyright year for files that have been modified in 2008 Reviewed-by: ohair, tbell
author xdono
date Wed, 02 Jul 2008 12:55:16 -0700
parents ba764ed4b6f2
children 4ce7240d622c
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1 /*
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d1605aabd0a1 6719955: Update copyright year
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2 * Copyright 1998-2008 Sun Microsystems, Inc. All Rights Reserved.
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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4 *
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5 * This code is free software; you can redistribute it and/or modify it
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6 * under the terms of the GNU General Public License version 2 only, as
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7 * published by the Free Software Foundation.
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8 *
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9 * This code is distributed in the hope that it will be useful, but WITHOUT
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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12 * version 2 for more details (a copy is included in the LICENSE file that
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13 * accompanied this code).
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14 *
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15 * You should have received a copy of the GNU General Public License version
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16 * 2 along with this work; if not, write to the Free Software Foundation,
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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18 *
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19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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20 * CA 95054 USA or visit www.sun.com if you need additional information or
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21 * have any questions.
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22 *
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23 */
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24
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25 # include "incls/_precompiled.incl"
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26 # include "incls/_jniHandles.cpp.incl"
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27
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28
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29 JNIHandleBlock* JNIHandles::_global_handles = NULL;
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30 JNIHandleBlock* JNIHandles::_weak_global_handles = NULL;
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31 oop JNIHandles::_deleted_handle = NULL;
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32
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33
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34 jobject JNIHandles::make_local(oop obj) {
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35 if (obj == NULL) {
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36 return NULL; // ignore null handles
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37 } else {
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38 Thread* thread = Thread::current();
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39 assert(Universe::heap()->is_in_reserved(obj), "sanity check");
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40 return thread->active_handles()->allocate_handle(obj);
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41 }
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42 }
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43
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44
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45 // optimized versions
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46
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47 jobject JNIHandles::make_local(Thread* thread, oop obj) {
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48 if (obj == NULL) {
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49 return NULL; // ignore null handles
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50 } else {
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51 assert(Universe::heap()->is_in_reserved(obj), "sanity check");
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52 return thread->active_handles()->allocate_handle(obj);
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53 }
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54 }
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55
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56
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57 jobject JNIHandles::make_local(JNIEnv* env, oop obj) {
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58 if (obj == NULL) {
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59 return NULL; // ignore null handles
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60 } else {
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61 JavaThread* thread = JavaThread::thread_from_jni_environment(env);
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62 assert(Universe::heap()->is_in_reserved(obj), "sanity check");
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63 return thread->active_handles()->allocate_handle(obj);
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64 }
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65 }
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66
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67
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68 jobject JNIHandles::make_global(Handle obj) {
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69 jobject res = NULL;
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70 if (!obj.is_null()) {
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71 // ignore null handles
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72 MutexLocker ml(JNIGlobalHandle_lock);
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73 assert(Universe::heap()->is_in_reserved(obj()), "sanity check");
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74 res = _global_handles->allocate_handle(obj());
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75 } else {
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76 CHECK_UNHANDLED_OOPS_ONLY(Thread::current()->clear_unhandled_oops());
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77 }
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78
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79 return res;
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80 }
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81
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82
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83 jobject JNIHandles::make_weak_global(Handle obj) {
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84 jobject res = NULL;
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85 if (!obj.is_null()) {
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86 // ignore null handles
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87 MutexLocker ml(JNIGlobalHandle_lock);
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88 assert(Universe::heap()->is_in_reserved(obj()), "sanity check");
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89 res = _weak_global_handles->allocate_handle(obj());
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90 } else {
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91 CHECK_UNHANDLED_OOPS_ONLY(Thread::current()->clear_unhandled_oops());
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92 }
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93 return res;
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94 }
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95
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96 jmethodID JNIHandles::make_jmethod_id(methodHandle mh) {
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97 return (jmethodID) make_weak_global(mh);
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98 }
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99
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100
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101
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102 void JNIHandles::change_method_associated_with_jmethod_id(jmethodID jmid, methodHandle mh) {
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103 MutexLocker ml(JNIGlobalHandle_lock); // Is this necessary?
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104 Handle obj = (Handle)mh;
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105 oop* jobj = (oop*)jmid;
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106 *jobj = obj();
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107 }
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108
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109
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110 void JNIHandles::destroy_global(jobject handle) {
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111 if (handle != NULL) {
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112 assert(is_global_handle(handle), "Invalid delete of global JNI handle");
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113 *((oop*)handle) = deleted_handle(); // Mark the handle as deleted, allocate will reuse it
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114 }
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115 }
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116
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117
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118 void JNIHandles::destroy_weak_global(jobject handle) {
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119 if (handle != NULL) {
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120 assert(!CheckJNICalls || is_weak_global_handle(handle), "Invalid delete of weak global JNI handle");
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121 *((oop*)handle) = deleted_handle(); // Mark the handle as deleted, allocate will reuse it
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122 }
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123 }
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124
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125 void JNIHandles::destroy_jmethod_id(jmethodID mid) {
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126 destroy_weak_global((jobject)mid);
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127 }
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128
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129
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130 void JNIHandles::oops_do(OopClosure* f) {
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131 f->do_oop(&_deleted_handle);
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132 _global_handles->oops_do(f);
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133 }
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134
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135
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136 void JNIHandles::weak_oops_do(BoolObjectClosure* is_alive, OopClosure* f) {
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137 _weak_global_handles->weak_oops_do(is_alive, f);
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138 }
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139
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140
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141 void JNIHandles::initialize() {
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142 _global_handles = JNIHandleBlock::allocate_block();
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143 _weak_global_handles = JNIHandleBlock::allocate_block();
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144 EXCEPTION_MARK;
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145 // We will never reach the CATCH below since Exceptions::_throw will cause
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146 // the VM to exit if an exception is thrown during initialization
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147 klassOop k = SystemDictionary::object_klass();
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148 _deleted_handle = instanceKlass::cast(k)->allocate_permanent_instance(CATCH);
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149 }
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150
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151
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152 bool JNIHandles::is_local_handle(Thread* thread, jobject handle) {
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153 JNIHandleBlock* block = thread->active_handles();
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154
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155 // Look back past possible native calls to jni_PushLocalFrame.
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156 while (block != NULL) {
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157 if (block->chain_contains(handle)) {
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158 return true;
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159 }
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160 block = block->pop_frame_link();
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161 }
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162 return false;
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163 }
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164
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165
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166 // Determine if the handle is somewhere in the current thread's stack.
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167 // We easily can't isolate any particular stack frame the handle might
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168 // come from, so we'll check the whole stack.
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169
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170 bool JNIHandles::is_frame_handle(JavaThread* thr, jobject obj) {
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171 // If there is no java frame, then this must be top level code, such
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172 // as the java command executable, in which case, this type of handle
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173 // is not permitted.
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174 return (thr->has_last_Java_frame() &&
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175 (void*)obj < (void*)thr->stack_base() &&
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176 (void*)obj >= (void*)thr->last_Java_sp());
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177 }
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178
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179
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180 bool JNIHandles::is_global_handle(jobject handle) {
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181 return _global_handles->chain_contains(handle);
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182 }
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183
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184
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185 bool JNIHandles::is_weak_global_handle(jobject handle) {
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186 return _weak_global_handles->chain_contains(handle);
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187 }
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188
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189 long JNIHandles::global_handle_memory_usage() {
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190 return _global_handles->memory_usage();
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191 }
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192
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193 long JNIHandles::weak_global_handle_memory_usage() {
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194 return _weak_global_handles->memory_usage();
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195 }
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196
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197
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198 class AlwaysAliveClosure: public BoolObjectClosure {
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199 public:
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200 bool do_object_b(oop obj) { return true; }
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201 void do_object(oop obj) { assert(false, "Don't call"); }
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202 };
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203
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204 class CountHandleClosure: public OopClosure {
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205 private:
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206 int _count;
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207 public:
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208 CountHandleClosure(): _count(0) {}
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209 virtual void do_oop(oop* unused) {
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210 _count++;
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211 }
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212 virtual void do_oop(narrowOop* unused) { ShouldNotReachHere(); }
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213 int count() { return _count; }
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214 };
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215
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216 // We assume this is called at a safepoint: no lock is needed.
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217 void JNIHandles::print_on(outputStream* st) {
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218 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
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219 assert(_global_handles != NULL && _weak_global_handles != NULL,
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220 "JNIHandles not initialized");
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221
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222 CountHandleClosure global_handle_count;
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223 AlwaysAliveClosure always_alive;
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224 oops_do(&global_handle_count);
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225 weak_oops_do(&always_alive, &global_handle_count);
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226
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227 st->print_cr("JNI global references: %d", global_handle_count.count());
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228 st->cr();
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229 st->flush();
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diff changeset
230 }
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231
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232 class VerifyHandleClosure: public OopClosure {
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233 public:
113
ba764ed4b6f2 6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
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parents: 0
diff changeset
234 virtual void do_oop(oop* root) {
0
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parents:
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235 (*root)->verify();
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236 }
113
ba764ed4b6f2 6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
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parents: 0
diff changeset
237 virtual void do_oop(narrowOop* root) { ShouldNotReachHere(); }
0
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238 };
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239
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240 void JNIHandles::verify() {
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241 VerifyHandleClosure verify_handle;
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242 AlwaysAliveClosure always_alive;
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parents:
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243
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parents:
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244 oops_do(&verify_handle);
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parents:
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245 weak_oops_do(&always_alive, &verify_handle);
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parents:
diff changeset
246 }
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247
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248
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249
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250 void jni_handles_init() {
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251 JNIHandles::initialize();
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252 }
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253
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254
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255 int JNIHandleBlock::_blocks_allocated = 0;
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256 JNIHandleBlock* JNIHandleBlock::_block_free_list = NULL;
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diff changeset
257 #ifndef PRODUCT
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258 JNIHandleBlock* JNIHandleBlock::_block_list = NULL;
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259 #endif
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260
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261
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diff changeset
262 void JNIHandleBlock::zap() {
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263 // Zap block values
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264 _top = 0;
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265 for (int index = 0; index < block_size_in_oops; index++) {
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266 _handles[index] = badJNIHandle;
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267 }
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268 }
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269
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270 JNIHandleBlock* JNIHandleBlock::allocate_block(Thread* thread) {
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271 assert(thread == NULL || thread == Thread::current(), "sanity check");
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272 JNIHandleBlock* block;
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273 // Check the thread-local free list for a block so we don't
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274 // have to acquire a mutex.
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275 if (thread != NULL && thread->free_handle_block() != NULL) {
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276 block = thread->free_handle_block();
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277 thread->set_free_handle_block(block->_next);
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278 }
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279 else {
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280 // locking with safepoint checking introduces a potential deadlock:
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281 // - we would hold JNIHandleBlockFreeList_lock and then Threads_lock
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parents:
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282 // - another would hold Threads_lock (jni_AttachCurrentThread) and then
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parents:
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283 // JNIHandleBlockFreeList_lock (JNIHandleBlock::allocate_block)
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284 MutexLockerEx ml(JNIHandleBlockFreeList_lock,
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285 Mutex::_no_safepoint_check_flag);
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parents:
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286 if (_block_free_list == NULL) {
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287 // Allocate new block
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288 block = new JNIHandleBlock();
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289 _blocks_allocated++;
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290 if (TraceJNIHandleAllocation) {
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291 tty->print_cr("JNIHandleBlock " INTPTR_FORMAT " allocated (%d total blocks)",
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292 block, _blocks_allocated);
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293 }
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294 if (ZapJNIHandleArea) block->zap();
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295 #ifndef PRODUCT
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diff changeset
296 // Link new block to list of all allocated blocks
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297 block->_block_list_link = _block_list;
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298 _block_list = block;
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299 #endif
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300 } else {
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301 // Get block from free list
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302 block = _block_free_list;
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303 _block_free_list = _block_free_list->_next;
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304 }
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diff changeset
305 }
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306 block->_top = 0;
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307 block->_next = NULL;
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diff changeset
308 block->_pop_frame_link = NULL;
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parents:
diff changeset
309 // _last, _free_list & _allocate_before_rebuild initialized in allocate_handle
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310 debug_only(block->_last = NULL);
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311 debug_only(block->_free_list = NULL);
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312 debug_only(block->_allocate_before_rebuild = -1);
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313 return block;
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diff changeset
314 }
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diff changeset
315
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316
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diff changeset
317 void JNIHandleBlock::release_block(JNIHandleBlock* block, Thread* thread) {
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diff changeset
318 assert(thread == NULL || thread == Thread::current(), "sanity check");
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319 JNIHandleBlock* pop_frame_link = block->pop_frame_link();
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320 // Put returned block at the beginning of the thread-local free list.
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321 // Note that if thread == NULL, we use it as an implicit argument that
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parents:
diff changeset
322 // we _don't_ want the block to be kept on the free_handle_block.
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parents:
diff changeset
323 // See for instance JavaThread::exit().
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parents:
diff changeset
324 if (thread != NULL ) {
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parents:
diff changeset
325 if (ZapJNIHandleArea) block->zap();
a61af66fc99e Initial load
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parents:
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326 JNIHandleBlock* freelist = thread->free_handle_block();
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327 block->_pop_frame_link = NULL;
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328 thread->set_free_handle_block(block);
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329
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diff changeset
330 // Add original freelist to end of chain
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parents:
diff changeset
331 if ( freelist != NULL ) {
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parents:
diff changeset
332 while ( block->_next != NULL ) block = block->_next;
a61af66fc99e Initial load
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parents:
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333 block->_next = freelist;
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parents:
diff changeset
334 }
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diff changeset
335 block = NULL;
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diff changeset
336 }
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parents:
diff changeset
337 if (block != NULL) {
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parents:
diff changeset
338 // Return blocks to free list
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parents:
diff changeset
339 // locking with safepoint checking introduces a potential deadlock:
a61af66fc99e Initial load
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parents:
diff changeset
340 // - we would hold JNIHandleBlockFreeList_lock and then Threads_lock
a61af66fc99e Initial load
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parents:
diff changeset
341 // - another would hold Threads_lock (jni_AttachCurrentThread) and then
a61af66fc99e Initial load
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parents:
diff changeset
342 // JNIHandleBlockFreeList_lock (JNIHandleBlock::allocate_block)
a61af66fc99e Initial load
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parents:
diff changeset
343 MutexLockerEx ml(JNIHandleBlockFreeList_lock,
a61af66fc99e Initial load
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parents:
diff changeset
344 Mutex::_no_safepoint_check_flag);
a61af66fc99e Initial load
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parents:
diff changeset
345 while (block != NULL) {
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parents:
diff changeset
346 if (ZapJNIHandleArea) block->zap();
a61af66fc99e Initial load
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parents:
diff changeset
347 JNIHandleBlock* next = block->_next;
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parents:
diff changeset
348 block->_next = _block_free_list;
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parents:
diff changeset
349 _block_free_list = block;
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parents:
diff changeset
350 block = next;
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parents:
diff changeset
351 }
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parents:
diff changeset
352 }
a61af66fc99e Initial load
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parents:
diff changeset
353 if (pop_frame_link != NULL) {
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parents:
diff changeset
354 // As a sanity check we release blocks pointed to by the pop_frame_link.
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parents:
diff changeset
355 // This should never happen (only if PopLocalFrame is not called the
a61af66fc99e Initial load
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parents:
diff changeset
356 // correct number of times).
a61af66fc99e Initial load
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parents:
diff changeset
357 release_block(pop_frame_link, thread);
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parents:
diff changeset
358 }
a61af66fc99e Initial load
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parents:
diff changeset
359 }
a61af66fc99e Initial load
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parents:
diff changeset
360
a61af66fc99e Initial load
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parents:
diff changeset
361
a61af66fc99e Initial load
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parents:
diff changeset
362 void JNIHandleBlock::oops_do(OopClosure* f) {
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parents:
diff changeset
363 JNIHandleBlock* current_chain = this;
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parents:
diff changeset
364 // Iterate over chain of blocks, followed by chains linked through the
a61af66fc99e Initial load
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parents:
diff changeset
365 // pop frame links.
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parents:
diff changeset
366 while (current_chain != NULL) {
a61af66fc99e Initial load
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parents:
diff changeset
367 for (JNIHandleBlock* current = current_chain; current != NULL;
a61af66fc99e Initial load
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parents:
diff changeset
368 current = current->_next) {
a61af66fc99e Initial load
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parents:
diff changeset
369 assert(current == current_chain || current->pop_frame_link() == NULL,
a61af66fc99e Initial load
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parents:
diff changeset
370 "only blocks first in chain should have pop frame link set");
a61af66fc99e Initial load
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parents:
diff changeset
371 for (int index = 0; index < current->_top; index++) {
a61af66fc99e Initial load
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parents:
diff changeset
372 oop* root = &(current->_handles)[index];
a61af66fc99e Initial load
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parents:
diff changeset
373 oop value = *root;
a61af66fc99e Initial load
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parents:
diff changeset
374 // traverse heap pointers only, not deleted handles or free list
a61af66fc99e Initial load
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parents:
diff changeset
375 // pointers
a61af66fc99e Initial load
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parents:
diff changeset
376 if (value != NULL && Universe::heap()->is_in_reserved(value)) {
a61af66fc99e Initial load
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parents:
diff changeset
377 f->do_oop(root);
a61af66fc99e Initial load
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parents:
diff changeset
378 }
a61af66fc99e Initial load
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parents:
diff changeset
379 }
a61af66fc99e Initial load
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parents:
diff changeset
380 // the next handle block is valid only if current block is full
a61af66fc99e Initial load
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parents:
diff changeset
381 if (current->_top < block_size_in_oops) {
a61af66fc99e Initial load
duke
parents:
diff changeset
382 break;
a61af66fc99e Initial load
duke
parents:
diff changeset
383 }
a61af66fc99e Initial load
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parents:
diff changeset
384 }
a61af66fc99e Initial load
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parents:
diff changeset
385 current_chain = current_chain->pop_frame_link();
a61af66fc99e Initial load
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parents:
diff changeset
386 }
a61af66fc99e Initial load
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parents:
diff changeset
387 }
a61af66fc99e Initial load
duke
parents:
diff changeset
388
a61af66fc99e Initial load
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parents:
diff changeset
389
a61af66fc99e Initial load
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parents:
diff changeset
390 void JNIHandleBlock::weak_oops_do(BoolObjectClosure* is_alive,
a61af66fc99e Initial load
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parents:
diff changeset
391 OopClosure* f) {
a61af66fc99e Initial load
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parents:
diff changeset
392 for (JNIHandleBlock* current = this; current != NULL; current = current->_next) {
a61af66fc99e Initial load
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parents:
diff changeset
393 assert(current->pop_frame_link() == NULL,
a61af66fc99e Initial load
duke
parents:
diff changeset
394 "blocks holding weak global JNI handles should not have pop frame link set");
a61af66fc99e Initial load
duke
parents:
diff changeset
395 for (int index = 0; index < current->_top; index++) {
a61af66fc99e Initial load
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parents:
diff changeset
396 oop* root = &(current->_handles)[index];
a61af66fc99e Initial load
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parents:
diff changeset
397 oop value = *root;
a61af66fc99e Initial load
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parents:
diff changeset
398 // traverse heap pointers only, not deleted handles or free list pointers
a61af66fc99e Initial load
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parents:
diff changeset
399 if (value != NULL && Universe::heap()->is_in_reserved(value)) {
a61af66fc99e Initial load
duke
parents:
diff changeset
400 if (is_alive->do_object_b(value)) {
a61af66fc99e Initial load
duke
parents:
diff changeset
401 // The weakly referenced object is alive, update pointer
a61af66fc99e Initial load
duke
parents:
diff changeset
402 f->do_oop(root);
a61af66fc99e Initial load
duke
parents:
diff changeset
403 } else {
a61af66fc99e Initial load
duke
parents:
diff changeset
404 // The weakly referenced object is not alive, clear the reference by storing NULL
a61af66fc99e Initial load
duke
parents:
diff changeset
405 if (TraceReferenceGC) {
a61af66fc99e Initial load
duke
parents:
diff changeset
406 tty->print_cr("Clearing JNI weak reference (" INTPTR_FORMAT ")", root);
a61af66fc99e Initial load
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parents:
diff changeset
407 }
a61af66fc99e Initial load
duke
parents:
diff changeset
408 *root = NULL;
a61af66fc99e Initial load
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parents:
diff changeset
409 }
a61af66fc99e Initial load
duke
parents:
diff changeset
410 }
a61af66fc99e Initial load
duke
parents:
diff changeset
411 }
a61af66fc99e Initial load
duke
parents:
diff changeset
412 // the next handle block is valid only if current block is full
a61af66fc99e Initial load
duke
parents:
diff changeset
413 if (current->_top < block_size_in_oops) {
a61af66fc99e Initial load
duke
parents:
diff changeset
414 break;
a61af66fc99e Initial load
duke
parents:
diff changeset
415 }
a61af66fc99e Initial load
duke
parents:
diff changeset
416 }
a61af66fc99e Initial load
duke
parents:
diff changeset
417 }
a61af66fc99e Initial load
duke
parents:
diff changeset
418
a61af66fc99e Initial load
duke
parents:
diff changeset
419
a61af66fc99e Initial load
duke
parents:
diff changeset
420 jobject JNIHandleBlock::allocate_handle(oop obj) {
a61af66fc99e Initial load
duke
parents:
diff changeset
421 assert(Universe::heap()->is_in_reserved(obj), "sanity check");
a61af66fc99e Initial load
duke
parents:
diff changeset
422 if (_top == 0) {
a61af66fc99e Initial load
duke
parents:
diff changeset
423 // This is the first allocation or the initial block got zapped when
a61af66fc99e Initial load
duke
parents:
diff changeset
424 // entering a native function. If we have any following blocks they are
a61af66fc99e Initial load
duke
parents:
diff changeset
425 // not valid anymore.
a61af66fc99e Initial load
duke
parents:
diff changeset
426 for (JNIHandleBlock* current = _next; current != NULL;
a61af66fc99e Initial load
duke
parents:
diff changeset
427 current = current->_next) {
a61af66fc99e Initial load
duke
parents:
diff changeset
428 assert(current->_last == NULL, "only first block should have _last set");
a61af66fc99e Initial load
duke
parents:
diff changeset
429 assert(current->_free_list == NULL,
a61af66fc99e Initial load
duke
parents:
diff changeset
430 "only first block should have _free_list set");
a61af66fc99e Initial load
duke
parents:
diff changeset
431 current->_top = 0;
a61af66fc99e Initial load
duke
parents:
diff changeset
432 if (ZapJNIHandleArea) current->zap();
a61af66fc99e Initial load
duke
parents:
diff changeset
433 }
a61af66fc99e Initial load
duke
parents:
diff changeset
434 // Clear initial block
a61af66fc99e Initial load
duke
parents:
diff changeset
435 _free_list = NULL;
a61af66fc99e Initial load
duke
parents:
diff changeset
436 _allocate_before_rebuild = 0;
a61af66fc99e Initial load
duke
parents:
diff changeset
437 _last = this;
a61af66fc99e Initial load
duke
parents:
diff changeset
438 if (ZapJNIHandleArea) zap();
a61af66fc99e Initial load
duke
parents:
diff changeset
439 }
a61af66fc99e Initial load
duke
parents:
diff changeset
440
a61af66fc99e Initial load
duke
parents:
diff changeset
441 // Try last block
a61af66fc99e Initial load
duke
parents:
diff changeset
442 if (_last->_top < block_size_in_oops) {
a61af66fc99e Initial load
duke
parents:
diff changeset
443 oop* handle = &(_last->_handles)[_last->_top++];
a61af66fc99e Initial load
duke
parents:
diff changeset
444 *handle = obj;
a61af66fc99e Initial load
duke
parents:
diff changeset
445 return (jobject) handle;
a61af66fc99e Initial load
duke
parents:
diff changeset
446 }
a61af66fc99e Initial load
duke
parents:
diff changeset
447
a61af66fc99e Initial load
duke
parents:
diff changeset
448 // Try free list
a61af66fc99e Initial load
duke
parents:
diff changeset
449 if (_free_list != NULL) {
a61af66fc99e Initial load
duke
parents:
diff changeset
450 oop* handle = _free_list;
a61af66fc99e Initial load
duke
parents:
diff changeset
451 _free_list = (oop*) *_free_list;
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452 *handle = obj;
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453 return (jobject) handle;
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454 }
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455 // Check if unused block follow last
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456 if (_last->_next != NULL) {
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457 // update last and retry
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458 _last = _last->_next;
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459 return allocate_handle(obj);
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460 }
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461
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462 // No space available, we have to rebuild free list or expand
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463 if (_allocate_before_rebuild == 0) {
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464 rebuild_free_list(); // updates _allocate_before_rebuild counter
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465 } else {
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466 // Append new block
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467 Thread* thread = Thread::current();
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468 Handle obj_handle(thread, obj);
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469 // This can block, so we need to preserve obj accross call.
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470 _last->_next = JNIHandleBlock::allocate_block(thread);
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471 _last = _last->_next;
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472 _allocate_before_rebuild--;
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473 obj = obj_handle();
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474 }
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475 return allocate_handle(obj); // retry
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476 }
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477
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478
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479 void JNIHandleBlock::rebuild_free_list() {
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480 assert(_allocate_before_rebuild == 0 && _free_list == NULL, "just checking");
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481 int free = 0;
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482 int blocks = 0;
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483 for (JNIHandleBlock* current = this; current != NULL; current = current->_next) {
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484 for (int index = 0; index < current->_top; index++) {
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485 oop* handle = &(current->_handles)[index];
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486 if (*handle == JNIHandles::deleted_handle()) {
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487 // this handle was cleared out by a delete call, reuse it
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488 *handle = (oop) _free_list;
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489 _free_list = handle;
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490 free++;
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491 }
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492 }
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493 // we should not rebuild free list if there are unused handles at the end
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494 assert(current->_top == block_size_in_oops, "just checking");
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495 blocks++;
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496 }
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497 // Heuristic: if more than half of the handles are free we rebuild next time
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498 // as well, otherwise we append a corresponding number of new blocks before
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499 // attempting a free list rebuild again.
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500 int total = blocks * block_size_in_oops;
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501 int extra = total - 2*free;
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502 if (extra > 0) {
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503 // Not as many free handles as we would like - compute number of new blocks to append
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504 _allocate_before_rebuild = (extra + block_size_in_oops - 1) / block_size_in_oops;
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505 }
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506 if (TraceJNIHandleAllocation) {
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507 tty->print_cr("Rebuild free list JNIHandleBlock " INTPTR_FORMAT " blocks=%d used=%d free=%d add=%d",
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508 this, blocks, total-free, free, _allocate_before_rebuild);
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509 }
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510 }
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511
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512
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513 bool JNIHandleBlock::contains(jobject handle) const {
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514 return ((jobject)&_handles[0] <= handle && handle<(jobject)&_handles[_top]);
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515 }
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parents:
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516
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parents:
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517
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parents:
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518 bool JNIHandleBlock::chain_contains(jobject handle) const {
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519 for (JNIHandleBlock* current = (JNIHandleBlock*) this; current != NULL; current = current->_next) {
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parents:
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520 if (current->contains(handle)) {
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521 return true;
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522 }
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parents:
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523 }
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524 return false;
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parents:
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525 }
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parents:
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526
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parents:
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527
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528 int JNIHandleBlock::length() const {
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parents:
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529 int result = 1;
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parents:
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530 for (JNIHandleBlock* current = _next; current != NULL; current = current->_next) {
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531 result++;
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parents:
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532 }
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533 return result;
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parents:
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534 }
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parents:
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535
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parents:
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536 // This method is not thread-safe, i.e., must be called whule holding a lock on the
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parents:
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537 // structure.
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parents:
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538 long JNIHandleBlock::memory_usage() const {
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parents:
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539 return length() * sizeof(JNIHandleBlock);
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parents:
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540 }
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parents:
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541
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542
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543 #ifndef PRODUCT
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544
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parents:
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545 bool JNIHandleBlock::any_contains(jobject handle) {
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parents:
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546 for (JNIHandleBlock* current = _block_list; current != NULL; current = current->_block_list_link) {
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parents:
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547 if (current->contains(handle)) {
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parents:
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548 return true;
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parents:
diff changeset
549 }
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parents:
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550 }
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parents:
diff changeset
551 return false;
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parents:
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552 }
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parents:
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553
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parents:
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554 void JNIHandleBlock::print_statistics() {
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parents:
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555 int used_blocks = 0;
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parents:
diff changeset
556 int free_blocks = 0;
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parents:
diff changeset
557 int used_handles = 0;
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parents:
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558 int free_handles = 0;
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parents:
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559 JNIHandleBlock* block = _block_list;
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parents:
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560 while (block != NULL) {
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parents:
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561 if (block->_top > 0) {
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parents:
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562 used_blocks++;
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parents:
diff changeset
563 } else {
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parents:
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564 free_blocks++;
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parents:
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565 }
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parents:
diff changeset
566 used_handles += block->_top;
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parents:
diff changeset
567 free_handles += (block_size_in_oops - block->_top);
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parents:
diff changeset
568 block = block->_block_list_link;
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parents:
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569 }
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parents:
diff changeset
570 tty->print_cr("JNIHandleBlocks statistics");
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parents:
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571 tty->print_cr("- blocks allocated: %d", used_blocks + free_blocks);
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parents:
diff changeset
572 tty->print_cr("- blocks in use: %d", used_blocks);
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parents:
diff changeset
573 tty->print_cr("- blocks free: %d", free_blocks);
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parents:
diff changeset
574 tty->print_cr("- handles in use: %d", used_handles);
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parents:
diff changeset
575 tty->print_cr("- handles free: %d", free_handles);
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parents:
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576 }
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parents:
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577
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parents:
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578 #endif