1 /*
  2  * Copyright (c) 2021, Red Hat, Inc. 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 
 26 #include "precompiled.hpp"
 27 
 28 #include "gc/shared/strongRootsScope.hpp"
 29 #include "gc/shared/taskTerminator.hpp"
 30 #include "gc/shared/workgroup.hpp"
 31 #include "gc/shenandoah/shenandoahClosures.inline.hpp"
 32 #include "gc/shenandoah/shenandoahMark.inline.hpp"
 33 #include "gc/shenandoah/shenandoahOopClosures.inline.hpp"
 34 #include "gc/shenandoah/shenandoahReferenceProcessor.hpp"
 35 #include "gc/shenandoah/shenandoahRootProcessor.inline.hpp"
 36 #include "gc/shenandoah/shenandoahSTWMark.hpp"
 37 #include "gc/shenandoah/shenandoahVerifier.hpp"
 38 
 39 class ShenandoahInitMarkRootsClosure : public OopClosure {
 40 private:
 41   ShenandoahObjToScanQueue* const _queue;
 42   ShenandoahMarkingContext* const _mark_context;
 43 
 44   template <class T>
 45   inline void do_oop_work(T* p);
 46 public:
 47   ShenandoahInitMarkRootsClosure(ShenandoahObjToScanQueue* q);
 48 
 49   void do_oop(narrowOop* p) { do_oop_work(p); }
 50   void do_oop(oop* p)       { do_oop_work(p); }
 51 };
 52 
 53 ShenandoahInitMarkRootsClosure::ShenandoahInitMarkRootsClosure(ShenandoahObjToScanQueue* q) :
 54   _queue(q),
 55   _mark_context(ShenandoahHeap::heap()->marking_context()) {
 56 }
 57 
 58 template <class T>
 59 void ShenandoahInitMarkRootsClosure::do_oop_work(T* p) {
 60   ShenandoahMark::mark_through_ref<T>(p, _queue, _mark_context, false);
 61 }
 62 
 63 class ShenandoahSTWMarkTask : public AbstractGangTask {
 64 private:
 65   ShenandoahSTWMark* const _mark;
 66 
 67 public:
 68   ShenandoahSTWMarkTask(ShenandoahSTWMark* mark);
 69   void work(uint worker_id);
 70 };
 71 
 72 ShenandoahSTWMarkTask::ShenandoahSTWMarkTask(ShenandoahSTWMark* mark) :
 73   AbstractGangTask("Shenandoah STW mark"),
 74   _mark(mark) {
 75 }
 76 
 77 void ShenandoahSTWMarkTask::work(uint worker_id) {
 78   ShenandoahParallelWorkerSession worker_session(worker_id);
 79   _mark->mark_roots(worker_id);
 80   _mark->finish_mark(worker_id);
 81 }
 82 
 83 ShenandoahSTWMark::ShenandoahSTWMark(bool full_gc) :
 84   ShenandoahMark(),
 85   _root_scanner(full_gc ? ShenandoahPhaseTimings::full_gc_mark : ShenandoahPhaseTimings::degen_gc_stw_mark),
 86   _terminator(ShenandoahHeap::heap()->workers()->active_workers(), ShenandoahHeap::heap()->marking_context()->task_queues()),
 87   _full_gc(full_gc) {
 88   assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Must be at a Shenandoah safepoint");
 89 }
 90 
 91 void ShenandoahSTWMark::mark() {
 92   // Weak reference processing
 93   ShenandoahHeap* const heap = ShenandoahHeap::heap();
 94   ShenandoahReferenceProcessor* rp = heap->ref_processor();
 95   rp->reset_thread_locals();
 96   rp->set_soft_reference_policy(heap->soft_ref_policy()->should_clear_all_soft_refs());
 97 
 98   // Init mark, do not expect forwarded pointers in roots
 99   if (ShenandoahVerify) {
100     assert(Thread::current()->is_VM_thread(), "Must be");
101     heap->verifier()->verify_roots_no_forwarded();
102   }
103 
104   uint nworkers = heap->workers()->active_workers();
105   task_queues()->reserve(nworkers);
106 
107   TASKQUEUE_STATS_ONLY(task_queues()->reset_taskqueue_stats());
108 
109   {
110     // Mark
111     StrongRootsScope scope(nworkers);
112     ShenandoahSTWMarkTask task(this);
113     heap->workers()->run_task(&task);
114 
115     assert(task_queues()->is_empty(), "Should be empty");
116   }
117 
118   heap->mark_complete_marking_context();
119 
120   assert(task_queues()->is_empty(), "Should be empty");
121   TASKQUEUE_STATS_ONLY(task_queues()->print_taskqueue_stats());
122   TASKQUEUE_STATS_ONLY(task_queues()->reset_taskqueue_stats());
123 }
124 
125 void ShenandoahSTWMark::mark_roots(uint worker_id) {
126   ShenandoahInitMarkRootsClosure  init_mark(task_queues()->queue(worker_id));
127   _root_scanner.roots_do(&init_mark, worker_id);
128 }
129 
130 void ShenandoahSTWMark::finish_mark(uint worker_id) {
131   ShenandoahPhaseTimings::Phase phase = _full_gc ? ShenandoahPhaseTimings::full_gc_mark : ShenandoahPhaseTimings::degen_gc_stw_mark;
132   ShenandoahWorkerTimingsTracker timer(phase, ShenandoahPhaseTimings::ParallelMark, worker_id);
133   ShenandoahReferenceProcessor* rp = ShenandoahHeap::heap()->ref_processor();
134   StringDedup::Requests requests;
135 
136   mark_loop(worker_id, &_terminator, rp,
137             false /* not cancellable */,
138             ShenandoahStringDedup::is_enabled() ? ALWAYS_DEDUP : NO_DEDUP, &requests);
139 }
140