1 /* 2 * Copyright (c) 2001, 2018, 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 "gc/g1/g1BarrierSet.inline.hpp" 27 #include "gc/g1/g1CardTable.inline.hpp" 28 #include "gc/g1/g1CollectedHeap.inline.hpp" 29 #include "gc/g1/heapRegion.hpp" 30 #include "gc/g1/satbMarkQueue.hpp" 31 #include "logging/log.hpp" 32 #include "oops/oop.inline.hpp" 33 #include "runtime/mutexLocker.hpp" 34 #include "runtime/thread.inline.hpp" 35 36 G1BarrierSet::G1BarrierSet(G1CardTable* card_table) : 37 CardTableBarrierSet(card_table, BarrierSet::FakeRtti(BarrierSet::G1BarrierSet)), 38 _dcqs(JavaThread::dirty_card_queue_set()) 39 { } 40 41 void G1BarrierSet::enqueue(oop pre_val) { 42 // Nulls should have been already filtered. 43 assert(oopDesc::is_oop(pre_val, true), "Error"); 44 45 if (!JavaThread::satb_mark_queue_set().is_active()) return; 46 Thread* thr = Thread::current(); 47 if (thr->is_Java_thread()) { 48 JavaThread* jt = (JavaThread*)thr; 49 jt->satb_mark_queue().enqueue(pre_val); 50 } else { 51 MutexLockerEx x(Shared_SATB_Q_lock, Mutex::_no_safepoint_check_flag); 52 JavaThread::satb_mark_queue_set().shared_satb_queue()->enqueue(pre_val); 53 } 54 } 55 56 template <class T> void 57 G1BarrierSet::write_ref_array_pre_work(T* dst, int count) { 58 if (!JavaThread::satb_mark_queue_set().is_active()) return; 59 T* elem_ptr = dst; 60 for (int i = 0; i < count; i++, elem_ptr++) { 61 T heap_oop = oopDesc::load_heap_oop(elem_ptr); 62 if (!oopDesc::is_null(heap_oop)) { 63 enqueue(oopDesc::decode_heap_oop_not_null(heap_oop)); 64 } 65 } 66 } 67 68 void G1BarrierSet::write_ref_array_pre(oop* dst, int count, bool dest_uninitialized) { 69 if (!dest_uninitialized) { 70 write_ref_array_pre_work(dst, count); 71 } 72 } 73 74 void G1BarrierSet::write_ref_array_pre(narrowOop* dst, int count, bool dest_uninitialized) { 75 if (!dest_uninitialized) { 76 write_ref_array_pre_work(dst, count); 77 } 78 } 79 80 void G1BarrierSet::write_ref_field_post_slow(volatile jbyte* byte) { 81 // In the slow path, we know a card is not young 82 assert(*byte != G1CardTable::g1_young_card_val(), "slow path invoked without filtering"); 83 OrderAccess::storeload(); 84 if (*byte != G1CardTable::dirty_card_val()) { 85 *byte = G1CardTable::dirty_card_val(); 86 Thread* thr = Thread::current(); 87 if (thr->is_Java_thread()) { 88 JavaThread* jt = (JavaThread*)thr; 89 jt->dirty_card_queue().enqueue(byte); 90 } else { 91 MutexLockerEx x(Shared_DirtyCardQ_lock, 92 Mutex::_no_safepoint_check_flag); 93 _dcqs.shared_dirty_card_queue()->enqueue(byte); 94 } 95 } 96 } 97 98 void G1BarrierSet::invalidate(MemRegion mr) { 99 if (mr.is_empty()) { 100 return; 101 } 102 volatile jbyte* byte = _card_table->byte_for(mr.start()); 103 jbyte* last_byte = _card_table->byte_for(mr.last()); 104 Thread* thr = Thread::current(); 105 // skip all consecutive young cards 106 for (; byte <= last_byte && *byte == G1CardTable::g1_young_card_val(); byte++); 107 108 if (byte <= last_byte) { 109 OrderAccess::storeload(); 110 // Enqueue if necessary. 111 if (thr->is_Java_thread()) { 112 JavaThread* jt = (JavaThread*)thr; 113 for (; byte <= last_byte; byte++) { 114 if (*byte == G1CardTable::g1_young_card_val()) { 115 continue; 116 } 117 if (*byte != G1CardTable::dirty_card_val()) { 118 *byte = G1CardTable::dirty_card_val(); 119 jt->dirty_card_queue().enqueue(byte); 120 } 121 } 122 } else { 123 MutexLockerEx x(Shared_DirtyCardQ_lock, 124 Mutex::_no_safepoint_check_flag); 125 for (; byte <= last_byte; byte++) { 126 if (*byte == G1CardTable::g1_young_card_val()) { 127 continue; 128 } 129 if (*byte != G1CardTable::dirty_card_val()) { 130 *byte = G1CardTable::dirty_card_val(); 131 _dcqs.shared_dirty_card_queue()->enqueue(byte); 132 } 133 } 134 } 135 } 136 } 137 138 void G1BarrierSet::on_thread_attach(JavaThread* thread) { 139 // This method initializes the SATB and dirty card queues before a 140 // JavaThread is added to the Java thread list. Right now, we don't 141 // have to do anything to the dirty card queue (it should have been 142 // activated when the thread was created), but we have to activate 143 // the SATB queue if the thread is created while a marking cycle is 144 // in progress. The activation / de-activation of the SATB queues at 145 // the beginning / end of a marking cycle is done during safepoints 146 // so we have to make sure this method is called outside one to be 147 // able to safely read the active field of the SATB queue set. Right 148 // now, it is called just before the thread is added to the Java 149 // thread list in the Threads::add() method. That method is holding 150 // the Threads_lock which ensures we are outside a safepoint. We 151 // cannot do the obvious and set the active field of the SATB queue 152 // when the thread is created given that, in some cases, safepoints 153 // might happen between the JavaThread constructor being called and the 154 // thread being added to the Java thread list (an example of this is 155 // when the structure for the DestroyJavaVM thread is created). 156 assert(!SafepointSynchronize::is_at_safepoint(), "We should not be at a safepoint"); 157 assert(!thread->satb_mark_queue().is_active(), "SATB queue should not be active"); 158 assert(thread->satb_mark_queue().is_empty(), "SATB queue should be empty"); 159 assert(thread->dirty_card_queue().is_active(), "Dirty card queue should be active"); 160 161 // If we are creating the thread during a marking cycle, we should 162 // set the active field of the SATB queue to true. 163 if (thread->satb_mark_queue_set().is_active()) { 164 thread->satb_mark_queue().set_active(true); 165 } 166 } 167 168 void G1BarrierSet::on_thread_detach(JavaThread* thread) { 169 // Flush any deferred card marks, SATB buffers and dirty card queue buffers 170 CardTableBarrierSet::on_thread_detach(thread); 171 thread->satb_mark_queue().flush(); 172 thread->dirty_card_queue().flush(); 173 }