1 /* 2 * Copyright (c) 2018, Red Hat, Inc. and/or its affiliates. 3 * 4 * This code is free software; you can redistribute it and/or modify it 5 * under the terms of the GNU General Public License version 2 only, as 6 * published by the Free Software Foundation. 7 * 8 * This code is distributed in the hope that it will be useful, but WITHOUT 9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 11 * version 2 for more details (a copy is included in the LICENSE file that 12 * accompanied this code). 13 * 14 * You should have received a copy of the GNU General Public License version 15 * 2 along with this work; if not, write to the Free Software Foundation, 16 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 17 * 18 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 19 * or visit www.oracle.com if you need additional information or have any 20 * questions. 21 * 22 */ 23 24 #ifndef SHARE_VM_GC_SHENANDOAH_SHENANDOAHTRAVERSALGC_HPP 25 #define SHARE_VM_GC_SHENANDOAH_SHENANDOAHTRAVERSALGC_HPP 26 27 #include "memory/allocation.hpp" 28 #include "gc/shenandoah/shenandoahTaskqueue.hpp" 29 30 class Thread; 31 class ShenandoahHeapRegionSet; 32 class ShenandoahHeap; 33 class ShenandoahStrDedupQueue; 34 35 class ShenandoahTraversalGC : public CHeapObj<mtGC> { 36 private: 37 ShenandoahHeap* _heap; 38 ShenandoahObjToScanQueueSet* _task_queues; 39 40 // Used for buffering per-region liveness data. 41 // Needed since ShenandoahHeapRegion uses atomics to update liveness. 42 // 43 // The array has max-workers elements, each of which is an array of 44 // jushort * max_regions. The choice of jushort is not accidental: 45 // there is a tradeoff between static/dynamic footprint that translates 46 // into cache pressure (which is already high during marking), and 47 // too many atomic updates. size_t/jint is too large, jbyte is too small. 48 jushort** _liveness_local; 49 50 public: 51 ShenandoahTraversalGC(ShenandoahHeap* heap, size_t num_regions); 52 ~ShenandoahTraversalGC(); 53 54 void reset(); 55 void prepare(); 56 void init_traversal_collection(); 57 void concurrent_traversal_collection(); 58 void final_traversal_collection(); 59 60 template <class T, bool STRING_DEDUP, bool DEGEN> 61 inline void process_oop(T* p, Thread* thread, ShenandoahObjToScanQueue* queue, ShenandoahStrDedupQueue* dq = NULL); 62 63 bool check_and_handle_cancelled_gc(ParallelTaskTerminator* terminator); 64 65 ShenandoahObjToScanQueueSet* task_queues(); 66 67 jushort* get_liveness(uint worker_id); 68 void flush_liveness(uint worker_id); 69 70 void main_loop(uint worker_id, ParallelTaskTerminator* terminator, bool do_satb); 71 72 private: 73 74 template <bool DO_SATB> 75 void main_loop_prework(uint w, ParallelTaskTerminator* t); 76 77 template <class T, bool DO_SATB> 78 void main_loop_work(T* cl, jushort* live_data, uint worker_id, ParallelTaskTerminator* terminator); 79 80 void preclean_weak_refs(); 81 void weak_refs_work(); 82 void weak_refs_work_doit(); 83 84 void fixup_roots(); 85 }; 86 87 #endif // SHARE_VM_GC_SHENANDOAH_SHENANDOAHTRAVERSALGC_HPP