1 /*
  2  * Copyright (c) 2013, 2021, Red Hat, Inc. All rights reserved.
  3  * Copyright Amazon.com Inc. or its affiliates. All Rights Reserved.
  4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  5  *
  6  * This code is free software; you can redistribute it and/or modify it
  7  * under the terms of the GNU General Public License version 2 only, as
  8  * published by the Free Software Foundation.
  9  *
 10  * This code is distributed in the hope that it will be useful, but WITHOUT
 11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 13  * version 2 for more details (a copy is included in the LICENSE file that
 14  * accompanied this code).
 15  *
 16  * You should have received a copy of the GNU General Public License version
 17  * 2 along with this work; if not, write to the Free Software Foundation,
 18  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 19  *
 20  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 21  * or visit www.oracle.com if you need additional information or have any
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 25 
 26 #ifndef SHARE_GC_SHENANDOAH_SHENANDOAHCOLLECTORPOLICY_HPP
 27 #define SHARE_GC_SHENANDOAH_SHENANDOAHCOLLECTORPOLICY_HPP
 28 
 29 #include "gc/shared/gcTrace.hpp"
 30 #include "gc/shenandoah/shenandoahGC.hpp"
 31 #include "gc/shenandoah/shenandoahSharedVariables.hpp"
 32 #include "memory/allocation.hpp"
 33 #include "utilities/ostream.hpp"
 34 
 35 class ShenandoahTracer : public GCTracer, public CHeapObj<mtGC> {
 36 public:
 37   ShenandoahTracer() : GCTracer(Shenandoah) {}
 38 };
 39 
 40 class ShenandoahCollectorPolicy : public CHeapObj<mtGC> {
 41 private:
 42   size_t _success_concurrent_gcs;
 43   size_t _abbreviated_concurrent_gcs;
 44   size_t _success_degenerated_gcs;
 45   size_t _abbreviated_degenerated_gcs;
 46   // Written by control thread, read by mutators
 47   volatile size_t _success_full_gcs;
 48   uint _consecutive_degenerated_gcs;
 49   volatile size_t _consecutive_young_gcs;
 50   size_t _mixed_gcs;
 51   size_t _success_old_gcs;
 52   size_t _interrupted_old_gcs;
 53   size_t _alloc_failure_degenerated;
 54   size_t _alloc_failure_degenerated_upgrade_to_full;
 55   size_t _alloc_failure_full;
 56   size_t _collection_cause_counts[GCCause::_last_gc_cause];
 57   size_t _degen_point_counts[ShenandoahGC::_DEGENERATED_LIMIT];
 58 
 59   ShenandoahSharedFlag _in_shutdown;
 60   ShenandoahTracer* _tracer;
 61 
 62 
 63 public:
 64   ShenandoahCollectorPolicy();
 65 
 66   void record_mixed_cycle();
 67   void record_success_old();
 68   void record_interrupted_old();
 69 
 70   // A collection cycle may be "abbreviated" if Shenandoah finds a sufficient percentage
 71   // of regions that contain no live objects (ShenandoahImmediateThreshold). These cycles
 72   // end after final mark, skipping the evacuation and reference-updating phases. Such
 73   // cycles are very efficient and are worth tracking. Note that both degenerated and
 74   // concurrent cycles can be abbreviated.
 75   void record_success_concurrent(bool is_young, bool is_abbreviated);
 76   void record_success_degenerated(bool is_young, bool is_abbreviated);
 77   void record_success_full();
 78   void record_alloc_failure_to_degenerated(ShenandoahGC::ShenandoahDegenPoint point);
 79   void record_alloc_failure_to_full();
 80   void record_degenerated_upgrade_to_full();
 81   void record_collection_cause(GCCause::Cause cause);
 82 
 83   void record_shutdown();
 84   bool is_at_shutdown();
 85 
 86   ShenandoahTracer* tracer() {return _tracer;}
 87 
 88   void print_gc_stats(outputStream* out) const;
 89 
 90   size_t full_gc_count() const {
 91     return _success_full_gcs + _alloc_failure_degenerated_upgrade_to_full;
 92   }
 93 
 94   // If the heuristics find that the number of consecutive degenerated cycles is above
 95   // ShenandoahFullGCThreshold, then they will initiate a Full GC upon an allocation
 96   // failure.
 97   inline size_t consecutive_degenerated_gc_count() const {
 98     return _consecutive_degenerated_gcs;
 99   }
100 
101   static bool is_requested_gc(GCCause::Cause cause);
102   static bool should_run_full_gc(GCCause::Cause cause);
103   static bool should_handle_requested_gc(GCCause::Cause cause);
104 
105   inline size_t consecutive_young_gc_count() const {
106     return _consecutive_young_gcs;
107   }
108 
109 private:
110   void update_young(bool is_young);
111 };
112 
113 #endif // SHARE_GC_SHENANDOAH_SHENANDOAHCOLLECTORPOLICY_HPP