1 /* 2 * Copyright (c) 2001, 2019, 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_G1CONCURRENTHEAPRESIZETHREAD_HPP 26 #define SHARE_GC_G1_G1CONCURRENTHEAPRESIZETHREAD_HPP 27 28 #include "gc/shared/concurrentGCThread.hpp" 29 30 class G1Policy; 31 class G1ConcurrentHeapResize; 32 33 // The concurrent heap resize thread helps to commit/uncommit heap region memory 34 // to avoid the time spend in STW pause 35 class G1ConcurrentHeapResizeThread : public ConcurrentGCThread { 36 37 G1ConcurrentHeapResize* _concurrent_heap_resize; 38 39 // The concurrent resizing thread has 3 states: 40 // Idle: thread is waiting for start 41 // Working: thread has started and is doing the work of memory commit/uncommit 42 // Done: the work of memory commit/uncommit has finished but regions have not synchronized yet 43 enum State { 44 Idle, 45 Working, 46 Done, 47 }; 48 49 volatile State _state; 50 51 Monitor* _start_monitor; // used notify the start of resize thread 52 Monitor* _done_monitor; // used to notify concurrent resize is done 53 54 void sleep_before_next_cycle(); 55 56 void run_service(); 57 void stop_service(); 58 59 public: 60 // Constructor 61 G1ConcurrentHeapResizeThread(G1ConcurrentHeapResize* heap_resize); 62 63 G1ConcurrentHeapResize* concurrent_heap_resize() { return _concurrent_heap_resize; } 64 65 void set_idle() { assert(_state != Working, "must not be working"); _state = Idle; } 66 bool idle() const { return _state == Idle; } 67 void set_working() { assert(_state == Idle, "must be idle"); _state = Working; } 68 bool working() const { return _state == Working; } 69 void set_done() { assert(_state == Working, "must be working"); _state = Done; } 70 bool done() const { return _state == Done; } 71 72 // Returns true if a concurrent resizing cycle is in progress 73 bool during_cycle() { return !idle(); } 74 75 Monitor* start_monitor() { return _start_monitor; } 76 Monitor* done_monitor() { return _done_monitor; } 77 }; 78 79 #endif // SHARE_GC_G1_G1CONCURRENTHEAPRESIZETHREAD_HPP