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/shenandoahSharedVariables.hpp"
31 #include "runtime/task.hpp"
32 #include "utilities/ostream.hpp"
33
34 class ShenandoahControlThread;
35
36 // Periodic task is useful for doing asynchronous things that do not require (heap) locks,
37 // or synchronization with other parts of collector. These could run even when ShenandoahConcurrentThread
38 // is busy driving the GC cycle.
39 class ShenandoahPeriodicTask : public PeriodicTask {
40 private:
41 ShenandoahControlThread* _thread;
42 public:
43 ShenandoahPeriodicTask(ShenandoahControlThread* thread) :
44 PeriodicTask(100), _thread(thread) {}
45 virtual void task();
46 };
47
48 // Periodic task to flush SATB buffers periodically.
49 class ShenandoahPeriodicSATBFlushTask : public PeriodicTask {
50 public:
51 ShenandoahPeriodicSATBFlushTask() : PeriodicTask(ShenandoahSATBBufferFlushInterval) {}
52 virtual void task();
53 };
54
55 class ShenandoahControlThread: public ConcurrentGCThread {
56 friend class VMStructs;
57
58 private:
59 typedef enum {
60 none,
61 concurrent_normal,
62 stw_degenerated,
63 stw_full,
64 } GCMode;
65
66 // While we could have a single lock for these, it may risk unblocking
67 // GC waiters when alloc failure GC cycle finishes. We want instead
68 // to make complete explicit cycle for for demanding customers.
69 Monitor _alloc_failure_waiters_lock;
70 Monitor _gc_waiters_lock;
71 ShenandoahPeriodicTask _periodic_task;
72 ShenandoahPeriodicSATBFlushTask _periodic_satb_flush_task;
73
74 private:
75 static SurrogateLockerThread* _slt;
76
77 public:
78 void run();
79 void stop();
80
81 private:
82 ShenandoahSharedFlag _gc_requested;
83 ShenandoahSharedFlag _alloc_failure_gc;
84 ShenandoahSharedFlag _graceful_shutdown;
85 ShenandoahSharedFlag _heap_changed;
86 ShenandoahSharedFlag _do_counters_update;
87 ShenandoahSharedFlag _force_counters_update;
88 GCCause::Cause _requested_gc_cause;
89 ShenandoahHeap::ShenandoahDegenPoint _degen_point;
90
91 char _pad0[DEFAULT_CACHE_LINE_SIZE];
92 volatile intptr_t _allocs_seen;
93 char _pad1[DEFAULT_CACHE_LINE_SIZE];
94
95 bool check_cancellation_or_degen(ShenandoahHeap::ShenandoahDegenPoint point);
96 void service_concurrent_normal_cycle(GCCause::Cause cause);
97 void service_stw_full_cycle(GCCause::Cause cause);
98 void service_stw_degenerated_cycle(GCCause::Cause cause, ShenandoahHeap::ShenandoahDegenPoint point);
99 void service_uncommit(double shrink_before);
100
101 bool try_set_alloc_failure_gc();
102 void notify_alloc_failure_waiters();
103 bool is_alloc_failure_gc();
104
105 void notify_gc_waiters();
106
107 // Handle GC request.
108 // Blocks until GC is over.
109 void handle_requested_gc(GCCause::Cause cause);
110
111 bool is_explicit_gc(GCCause::Cause cause) const;
112 public:
113 // Constructor
114 ShenandoahControlThread();
115 ~ShenandoahControlThread();
116
117 static void makeSurrogateLockerThread(TRAPS);
118 static SurrogateLockerThread* slt() { return _slt; }
119
120 // Handle allocation failure from normal allocation.
121 // Blocks until memory is available.
122 void handle_alloc_failure(size_t words);
123
124 // Handle allocation failure from evacuation path.
125 // Optionally blocks while collector is handling the failure.
126 void handle_alloc_failure_evac(size_t words);
127
128 void request_gc(GCCause::Cause cause);
129
130 void handle_counters_update();
131 void handle_force_counters_update();
132 void set_forced_counters_update(bool value);
133
134 void notify_heap_changed();
135
136 void pacing_notify_alloc(size_t words);
137
138 void start();
139 void prepare_for_graceful_shutdown();
140 bool in_graceful_shutdown();
141
142 char* name() const { return (char*)"ShenandoahConcurrentThread";}
143
144 // Printing
145 void print_on(outputStream* st) const;
146 void print() const;
147
148 };
149
150 #endif // SHARE_VM_GC_SHENANDOAH_SHENANDOAHCONCURRENTTHREAD_HPP