1 /* 2 * Copyright (c) 1997, 2015, 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 "classfile/systemDictionary.hpp" 28 #include "gc/shared/collectedHeap.inline.hpp" 29 #include "gc/shared/genCollectedHeap.hpp" 30 #include "gc/shared/specialized_oop_closures.hpp" 31 #include "oops/instanceRefKlass.inline.hpp" 32 #include "oops/oop.inline.hpp" 33 #include "utilities/macros.hpp" 34 #include "utilities/preserveException.hpp" 35 36 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC 37 38 void InstanceRefKlass::update_nonstatic_oop_maps(Klass* k) { 39 // Clear the nonstatic oop-map entries corresponding to referent 40 // and nextPending field. They are treated specially by the 41 // garbage collector. 42 // The discovered field is used only by the garbage collector 43 // and is also treated specially. 44 InstanceKlass* ik = InstanceKlass::cast(k); 45 46 // Check that we have the right class 47 debug_only(static bool first_time = true); 48 assert(k == SystemDictionary::Reference_klass() && first_time, 49 "Invalid update of maps"); 50 debug_only(first_time = false); 51 assert(ik->nonstatic_oop_map_count() == 1, "just checking"); 52 53 OopMapBlock* map = ik->start_of_nonstatic_oop_maps(); 54 55 // Check that the current map is (2,4) - currently points at field with 56 // offset 2 (words) and has 4 map entries. 57 debug_only(int offset = java_lang_ref_Reference::referent_offset); 58 debug_only(unsigned int count = ((java_lang_ref_Reference::discovered_offset - 59 java_lang_ref_Reference::referent_offset)/heapOopSize) + 1); 60 61 if (UseSharedSpaces) { 62 assert(map->offset() == java_lang_ref_Reference::queue_offset && 63 map->count() == 1, "just checking"); 64 } else { 65 assert(map->offset() == offset && map->count() == count, 66 "just checking"); 67 68 // Update map to (3,1) - point to offset of 3 (words) with 1 map entry. 69 map->set_offset(java_lang_ref_Reference::queue_offset); 70 map->set_count(1); 71 } 72 } 73 74 75 // Verification 76 77 void InstanceRefKlass::oop_verify_on(oop obj, outputStream* st) { 78 InstanceKlass::oop_verify_on(obj, st); 79 // Verify referent field 80 oop referent = java_lang_ref_Reference::referent(obj); 81 if (referent != NULL) { 82 guarantee(referent->is_oop(), "referent field heap failed"); 83 } 84 // Verify next field 85 oop next = java_lang_ref_Reference::next(obj); 86 if (next != NULL) { 87 guarantee(next->is_oop(), "next field verify failed"); 88 guarantee(next->is_instanceRef(), "next field verify failed"); 89 } 90 } 91 92 bool InstanceRefKlass::owns_pending_list_lock(JavaThread* thread) { 93 if (java_lang_ref_Reference::pending_list_lock() == NULL) return false; 94 Handle h_lock(thread, java_lang_ref_Reference::pending_list_lock()); 95 return ObjectSynchronizer::current_thread_holds_lock(thread, h_lock); 96 } 97 98 void InstanceRefKlass::acquire_pending_list_lock(BasicLock *pending_list_basic_lock) { 99 // we may enter this with pending exception set 100 PRESERVE_EXCEPTION_MARK; // exceptions are never thrown, needed for TRAPS argument 101 102 // Create a HandleMark in case we retry a GC multiple times. 103 // Each time we attempt the GC, we allocate the handle below 104 // to hold the pending list lock. We want to free this handle. 105 HandleMark hm; 106 107 Handle h_lock(THREAD, java_lang_ref_Reference::pending_list_lock()); 108 ObjectSynchronizer::fast_enter(h_lock, pending_list_basic_lock, false, THREAD); 109 assert(ObjectSynchronizer::current_thread_holds_lock( 110 JavaThread::current(), h_lock), 111 "Locking should have succeeded"); 112 if (HAS_PENDING_EXCEPTION) CLEAR_PENDING_EXCEPTION; 113 } 114 115 void InstanceRefKlass::release_and_notify_pending_list_lock( 116 BasicLock *pending_list_basic_lock) { 117 // we may enter this with pending exception set 118 PRESERVE_EXCEPTION_MARK; // exceptions are never thrown, needed for TRAPS argument 119 120 // Create a HandleMark in case we retry a GC multiple times. 121 // Each time we attempt the GC, we allocate the handle below 122 // to hold the pending list lock. We want to free this handle. 123 HandleMark hm; 124 125 Handle h_lock(THREAD, java_lang_ref_Reference::pending_list_lock()); 126 assert(ObjectSynchronizer::current_thread_holds_lock( 127 JavaThread::current(), h_lock), 128 "Lock should be held"); 129 // Notify waiters on pending lists lock if there is any reference. 130 if (java_lang_ref_Reference::pending_list() != NULL) { 131 ObjectSynchronizer::notifyall(h_lock, THREAD); 132 } 133 ObjectSynchronizer::fast_exit(h_lock(), pending_list_basic_lock, THREAD); 134 if (HAS_PENDING_EXCEPTION) CLEAR_PENDING_EXCEPTION; 135 }