1 /*
2 * Copyright (c) 2013, 2018, Red Hat, Inc. All rights reserved.
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_SHENANDOAHCONCURRENTTHREAD_HPP
25 #define SHARE_VM_GC_SHENANDOAH_SHENANDOAHCONCURRENTTHREAD_HPP
26
27 #include "gc_interface/gcCause.hpp"
28 #include "gc_implementation/shared/concurrentGCThread.hpp"
29 #include "gc_implementation/shenandoah/shenandoahHeap.hpp"
30 #include "gc_implementation/shenandoah/shenandoahPadding.hpp"
31 #include "gc_implementation/shenandoah/shenandoahSharedVariables.hpp"
32 #include "runtime/task.hpp"
33 #include "utilities/ostream.hpp"
34
35 class ShenandoahControlThread;
36
37 // Periodic task is useful for doing asynchronous things that do not require (heap) locks,
38 // or synchronization with other parts of collector. These could run even when ShenandoahConcurrentThread
39 // is busy driving the GC cycle.
40 class ShenandoahPeriodicTask : public PeriodicTask {
41 private:
42 ShenandoahControlThread* _thread;
43 public:
44 ShenandoahPeriodicTask(ShenandoahControlThread* thread) :
45 PeriodicTask(100), _thread(thread) {}
46 virtual void task();
47 };
48
49 // Periodic task to flush SATB buffers periodically.
50 class ShenandoahPeriodicSATBFlushTask : public PeriodicTask {
51 public:
52 ShenandoahPeriodicSATBFlushTask() : PeriodicTask(ShenandoahSATBBufferFlushInterval) {}
53 virtual void task();
54 };
55
56 // Periodic task to notify blocked paced waiters.
57 class ShenandoahPeriodicPacerNotify : public PeriodicTask {
58 public:
59 ShenandoahPeriodicPacerNotify() : PeriodicTask(PeriodicTask::min_interval) {}
60 virtual void task();
61 };
62
63 class ShenandoahControlThread: public ConcurrentGCThread {
64 friend class VMStructs;
65
66 private:
67 typedef enum {
68 none,
69 concurrent_normal,
70 stw_degenerated,
71 stw_full
72 } GCMode;
73
74 // While we could have a single lock for these, it may risk unblocking
75 // GC waiters when alloc failure GC cycle finishes. We want instead
76 // to make complete explicit cycle for for demanding customers.
77 Monitor _alloc_failure_waiters_lock;
78 Monitor _gc_waiters_lock;
79 ShenandoahPeriodicTask _periodic_task;
80 ShenandoahPeriodicSATBFlushTask _periodic_satb_flush_task;
81 ShenandoahPeriodicPacerNotify _periodic_pacer_notify_task;
82
83 private:
84 static SurrogateLockerThread* _slt;
85
86 public:
87 void run();
88 void stop();
89
90 private:
91 ShenandoahSharedFlag _gc_requested;
92 ShenandoahSharedFlag _alloc_failure_gc;
93 ShenandoahSharedFlag _graceful_shutdown;
94 ShenandoahSharedFlag _heap_changed;
95 ShenandoahSharedFlag _do_counters_update;
96 ShenandoahSharedFlag _force_counters_update;
97 GCCause::Cause _requested_gc_cause;
98 ShenandoahHeap::ShenandoahDegenPoint _degen_point;
99
100 shenandoah_padding(0);
101 volatile intptr_t _allocs_seen;
102 shenandoah_padding(1);
103 volatile intptr_t _gc_id;
104 shenandoah_padding(2);
105
106 bool check_cancellation_or_degen(ShenandoahHeap::ShenandoahDegenPoint point);
107 void service_concurrent_normal_cycle(GCCause::Cause cause);
108 void service_stw_full_cycle(GCCause::Cause cause);
109 void service_stw_degenerated_cycle(GCCause::Cause cause, ShenandoahHeap::ShenandoahDegenPoint point);
110 void service_uncommit(double shrink_before, size_t shrink_until);
111
112 bool try_set_alloc_failure_gc();
113 void notify_alloc_failure_waiters();
114 bool is_alloc_failure_gc();
115
116 void reset_gc_id();
117 void update_gc_id();
118 size_t get_gc_id();
119
120 void notify_gc_waiters();
121
122 // Handle GC request.
123 // Blocks until GC is over.
124 void handle_requested_gc(GCCause::Cause cause);
125
126 bool is_explicit_gc(GCCause::Cause cause) const;
127
128 bool check_soft_max_changed() const;
129
130 public:
131 // Constructor
132 ShenandoahControlThread();
133 ~ShenandoahControlThread();
134
135 static void makeSurrogateLockerThread(TRAPS);
136 static SurrogateLockerThread* slt() { return _slt; }
137
138 // Handle allocation failure from normal allocation.
139 // Blocks until memory is available.
140 void handle_alloc_failure(ShenandoahAllocRequest& req);
141
142 // Handle allocation failure from evacuation path.
143 // Optionally blocks while collector is handling the failure.
144 void handle_alloc_failure_evac(size_t words);
145
146 void request_gc(GCCause::Cause cause);
147
148 void handle_counters_update();
149 void handle_force_counters_update();
150 void set_forced_counters_update(bool value);
151
152 void notify_heap_changed();
153
154 void pacing_notify_alloc(size_t words);
155
156 void start();
157 void prepare_for_graceful_shutdown();
158 bool in_graceful_shutdown();
159
160 char* name() const { return (char*)"ShenandoahConcurrentThread";}
161
162 // Printing
163 void print_on(outputStream* st) const;
164 void print() const;
165
166 };
167
168 #endif // SHARE_VM_GC_SHENANDOAH_SHENANDOAHCONCURRENTTHREAD_HPP