1 /*
 2  * Copyright (c) 2013, 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 #ifndef SHARE_GC_SHENANDOAH_SHENANDOAHCOLLECTORPOLICY_HPP
26 #define SHARE_GC_SHENANDOAH_SHENANDOAHCOLLECTORPOLICY_HPP
27 
28 #include "gc/shared/gcTrace.hpp"
29 #include "gc/shenandoah/shenandoahGC.hpp"
30 #include "gc/shenandoah/shenandoahSharedVariables.hpp"
31 #include "memory/allocation.hpp"
32 #include "utilities/ostream.hpp"
33 
34 class ShenandoahTracer : public GCTracer, public CHeapObj<mtGC> {
35 public:
36   ShenandoahTracer() : GCTracer(Shenandoah) {}
37 };
38 
39 class ShenandoahCollectorPolicy : public CHeapObj<mtGC> {
40 private:
41   size_t _success_concurrent_gcs;
42   size_t _abbreviated_concurrent_gcs;
43   size_t _success_degenerated_gcs;
44   size_t _abbreviated_degenerated_gcs;
45   // Written by control thread, read by mutators
46   volatile size_t _success_full_gcs;
47   uint _consecutive_degenerated_gcs;
48   size_t _alloc_failure_degenerated;
49   size_t _alloc_failure_degenerated_upgrade_to_full;
50   size_t _alloc_failure_full;
51   size_t _collection_cause_counts[GCCause::_last_gc_cause];
52   size_t _degen_point_counts[ShenandoahGC::_DEGENERATED_LIMIT];
53 
54   ShenandoahSharedFlag _in_shutdown;
55   ShenandoahTracer* _tracer;
56 
57 
58 public:
59   ShenandoahCollectorPolicy();
60 
61   // A collection cycle may be "abbreviated" if Shenandoah finds a sufficient percentage
62   // of regions that contain no live objects (ShenandoahImmediateThreshold). These cycles
63   // end after final mark, skipping the evacuation and reference-updating phases. Such
64   // cycles are very efficient and are worth tracking. Note that both degenerated and
65   // concurrent cycles can be abbreviated.
66   void record_success_concurrent(bool is_abbreviated);
67   void record_success_degenerated(bool is_abbreviated);
68   void record_success_full();
69   void record_alloc_failure_to_degenerated(ShenandoahGC::ShenandoahDegenPoint point);
70   void record_alloc_failure_to_full();
71   void record_degenerated_upgrade_to_full();
72   void record_collection_cause(GCCause::Cause cause);
73 
74   void record_shutdown();
75   bool is_at_shutdown();
76 
77   ShenandoahTracer* tracer() {return _tracer;}
78 
79   void print_gc_stats(outputStream* out) const;
80 
81   size_t full_gc_count() const {
82     return _success_full_gcs + _alloc_failure_degenerated_upgrade_to_full;
83   }
84 
85   // If the heuristics find that the number of consecutive degenerated cycles is above
86   // ShenandoahFullGCThreshold, then they will initiate a Full GC upon an allocation
87   // failure.
88   inline size_t consecutive_degenerated_gc_count() const {
89     return _consecutive_degenerated_gcs;
90   }
91 
92   static bool should_run_full_gc(GCCause::Cause cause);
93   static bool should_handle_requested_gc(GCCause::Cause cause);
94 };
95 
96 #endif // SHARE_GC_SHENANDOAH_SHENANDOAHCOLLECTORPOLICY_HPP