1 /* 2 * Copyright (c) 2014, 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 #include "precompiled.hpp" 26 #include "classfile/javaClasses.inline.hpp" 27 #include "gc/g1/g1CollectedHeap.inline.hpp" 28 #include "gc/g1/g1GCPhaseTimes.hpp" 29 #include "gc/g1/g1StringDedup.hpp" 30 #include "gc/g1/g1StringDedupQueue.hpp" 31 #include "gc/g1/g1StringDedupStat.hpp" 32 #include "gc/shared/stringdedup/stringDedup.inline.hpp" 33 #include "gc/shared/stringdedup/stringDedupQueue.hpp" 34 #include "gc/shared/stringdedup/stringDedupTable.hpp" 35 #include "gc/shared/stringdedup/stringDedupThread.inline.hpp" 36 #include "oops/oop.inline.hpp" 37 #include "runtime/atomic.hpp" 38 39 void G1StringDedup::initialize() { 40 assert(UseG1GC, "String deduplication available with G1"); 41 StringDedup::initialize_impl<G1StringDedupQueue, G1StringDedupStat>(); 42 } 43 44 bool G1StringDedup::is_candidate_from_mark(oop obj) { 45 if (java_lang_String::is_instance_inlined(obj)) { 46 bool from_young = G1CollectedHeap::heap()->heap_region_containing(obj)->is_young(); 47 if (from_young && obj->age() < StringDeduplicationAgeThreshold) { 48 // Candidate found. String is being evacuated from young to old but has not 49 // reached the deduplication age threshold, i.e. has not previously been a 50 // candidate during its life in the young generation. 51 return true; 52 } 53 } 54 55 // Not a candidate 56 return false; 57 } 58 59 void G1StringDedup::enqueue_from_mark(oop java_string, uint worker_id) { 60 assert(is_enabled(), "String deduplication not enabled"); 61 if (is_candidate_from_mark(java_string)) { 62 G1StringDedupQueue::push(worker_id, java_string); 63 } 64 } 65 66 bool G1StringDedup::is_candidate_from_evacuation(bool from_young, bool to_young, oop obj) { 67 if (from_young && java_lang_String::is_instance_inlined(obj)) { 68 if (to_young && obj->age() == StringDeduplicationAgeThreshold) { 69 // Candidate found. String is being evacuated from young to young and just 70 // reached the deduplication age threshold. 71 return true; 72 } 73 if (!to_young && obj->age() < StringDeduplicationAgeThreshold) { 74 // Candidate found. String is being evacuated from young to old but has not 75 // reached the deduplication age threshold, i.e. has not previously been a 76 // candidate during its life in the young generation. 77 return true; 78 } 79 } 80 81 // Not a candidate 82 return false; 83 } 84 85 void G1StringDedup::enqueue_from_evacuation(bool from_young, bool to_young, uint worker_id, oop java_string) { 86 assert(is_enabled(), "String deduplication not enabled"); 87 if (is_candidate_from_evacuation(from_young, to_young, java_string)) { 88 G1StringDedupQueue::push(worker_id, java_string); 89 } 90 } 91