1 /* 2 * Copyright (c) 2001, 2020, 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 #ifndef SHARE_GC_G1_G1CONCURRENTMARKTHREAD_HPP 26 #define SHARE_GC_G1_G1CONCURRENTMARKTHREAD_HPP 27 28 #include "gc/shared/concurrentGCThread.hpp" 29 30 class G1ConcurrentMark; 31 class G1Policy; 32 33 // The concurrent mark thread triggers the various steps of the concurrent marking 34 // cycle, including various marking cleanup. 35 class G1ConcurrentMarkThread: public ConcurrentGCThread { 36 friend class VMStructs; 37 38 double _vtime_start; // Initial virtual time. 39 double _vtime_accum; // Accumulated virtual time. 40 41 G1ConcurrentMark* _cm; 42 43 enum ServiceState { 44 Idle, 45 Started, 46 InProgress 47 }; 48 49 volatile ServiceState _state; 50 51 // Wait for next cycle. Returns true if we should stop the service. 52 bool wait_for_next_cycle(); 53 54 // Phases for the full concurrent marking cycle in order. 55 // 56 // We have to ensure that we finish scanning the root regions 57 // before the next GC takes place. To ensure this we have to 58 // make sure that we do not join the STS until the root regions 59 // have been scanned. If we did then it's possible that a 60 // subsequent GC could block us from joining the STS and proceed 61 // without the root regions have been scanned which would be a 62 // correctness issue. 63 // ConcurrentGCBreakpoints must not be placed before the the root 64 // region scan phase too for this reason. 65 bool phase_concurrent_cycle_start(); 66 bool phase_clear_cld_claimed_marks(); 67 bool phase_scan_root_regions(); 68 bool phase_mark_from_roots(); 69 bool phase_preclean(); 70 bool phase_delay_to_keep_mmu_before_remark(); 71 bool phase_remark(bool& has_overflown); 72 bool phase_rebuild_remembered_sets(); 73 bool phase_delay_to_keep_mmu_before_cleanup(); 74 bool phase_cleanup(); 75 bool phase_clear_bitmap_for_next_mark(); 76 77 void concurrent_cycle_start(); 78 // Perform a full concurrent cycle. 79 void full_concurrent_cycle_do(); 80 void concurrent_cycle_end(); 81 82 // Delay pauses to meet MMU. 83 void delay_to_keep_mmu(bool remark); 84 double mmu_delay_end(G1Policy* policy, bool remark); 85 86 void run_service(); 87 void stop_service(); 88 89 public: 90 // Constructor 91 G1ConcurrentMarkThread(G1ConcurrentMark* cm); 92 93 // Total virtual time so far for this thread and concurrent marking tasks. 94 double vtime_accum(); 95 // Marking virtual time so far this thread and concurrent marking tasks. 96 double vtime_mark_accum(); 97 98 G1ConcurrentMark* cm() { return _cm; } 99 100 void set_idle() { assert(_state != Started, "must not be starting a new cycle"); _state = Idle; } 101 bool idle() { return _state == Idle; } 102 void set_started() { assert(_state == Idle, "cycle in progress"); _state = Started; } 103 bool started() { return _state == Started; } 104 void set_in_progress() { assert(_state == Started, "must be starting a cycle"); _state = InProgress; } 105 bool in_progress() { return _state == InProgress; } 106 107 // Returns true from the moment a marking cycle is 108 // initiated (during the concurrent start pause when started() is set) 109 // to the moment when the cycle completes (just after the next 110 // marking bitmap has been cleared and in_progress() is 111 // cleared). While during_cycle() is true we will not start another cycle 112 // so that cycles do not overlap. We cannot use just in_progress() 113 // as the CM thread might take some time to wake up before noticing 114 // that started() is set and set in_progress(). 115 bool during_cycle() { return !idle(); } 116 }; 117 118 #endif // SHARE_GC_G1_G1CONCURRENTMARKTHREAD_HPP