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