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annotate src/share/vm/runtime/task.hpp @ 3757:f8c9417e3571
7052219: JSR 292: Crash in ~BufferBlob::MethodHandles adapters
Reviewed-by: twisti, kvn, jrose
author | never |
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date | Tue, 14 Jun 2011 14:41:33 -0700 |
parents | f95d63e2154a |
children | d2a62e0f25eb |
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0 | 1 /* |
1972 | 2 * Copyright (c) 1997, 2010, Oracle and/or its affiliates. All rights reserved. |
0 | 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 * | |
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
0 | 22 * |
23 */ | |
24 | |
1972 | 25 #ifndef SHARE_VM_RUNTIME_TASK_HPP |
26 #define SHARE_VM_RUNTIME_TASK_HPP | |
27 | |
28 #include "utilities/top.hpp" | |
29 | |
0 | 30 // A PeriodicTask has the sole purpose of executing its task |
31 // function with regular intervals. | |
32 // Usage: | |
33 // PeriodicTask pf(10); | |
34 // pf.enroll(); | |
35 // ... | |
36 // pf.disenroll(); | |
37 | |
38 class PeriodicTask: public CHeapObj { | |
39 public: | |
40 // Useful constants. | |
41 // The interval constants are used to ensure the declared interval | |
42 // is appropriate; it must be between min_interval and max_interval, | |
43 // and have a granularity of interval_gran (all in millis). | |
44 enum { max_tasks = 10, // Max number of periodic tasks in system | |
45 interval_gran = 10, | |
46 min_interval = 10, | |
47 max_interval = 10000 }; | |
48 | |
49 static int num_tasks() { return _num_tasks; } | |
50 | |
51 private: | |
52 size_t _counter; | |
53 const size_t _interval; | |
54 | |
55 static int _num_tasks; | |
56 static PeriodicTask* _tasks[PeriodicTask::max_tasks]; | |
57 static void real_time_tick(size_t delay_time); | |
58 | |
59 #ifndef PRODUCT | |
60 static elapsedTimer _timer; // measures time between ticks | |
61 static int _ticks; // total number of ticks | |
62 static int _intervalHistogram[max_interval]; // to check spacing of timer interrupts | |
63 public: | |
64 static void print_intervals(); | |
65 #endif | |
66 // Only the WatcherThread can cause us to execute PeriodicTasks | |
67 friend class WatcherThread; | |
68 public: | |
69 PeriodicTask(size_t interval_time); // interval is in milliseconds of elapsed time | |
70 ~PeriodicTask(); | |
71 | |
72 // Tells whether is enrolled | |
73 bool is_enrolled() const; | |
74 | |
75 // Make the task active | |
76 // NOTE: this may only be called before the WatcherThread has been started | |
77 void enroll(); | |
78 | |
79 // Make the task deactive | |
80 // NOTE: this may only be called either while the WatcherThread is | |
81 // inactive or by a task from within its task() method. One-shot or | |
82 // several-shot tasks may be implemented this way. | |
83 void disenroll(); | |
84 | |
85 void execute_if_pending(size_t delay_time) { | |
86 _counter += delay_time; | |
87 if (_counter >= _interval) { | |
88 _counter = 0; | |
89 task(); | |
90 } | |
91 } | |
92 | |
93 // Returns how long (time in milliseconds) before the next time we should | |
94 // execute this task. | |
95 size_t time_to_next_interval() const { | |
96 assert(_interval > _counter, "task counter greater than interval?"); | |
97 return _interval - _counter; | |
98 } | |
99 | |
100 // Calculate when the next periodic task will fire. | |
101 // Called by the WatcherThread's run method. | |
102 // This assumes that periodic tasks aren't entering the system | |
103 // dynamically, except for during startup. | |
104 static size_t time_to_wait() { | |
105 if (_num_tasks == 0) { | |
106 // Don't wait any more; shut down the thread since we don't | |
107 // currently support dynamic enrollment. | |
108 return 0; | |
109 } | |
110 | |
111 size_t delay = _tasks[0]->time_to_next_interval(); | |
112 for (int index = 1; index < _num_tasks; index++) { | |
113 delay = MIN2(delay, _tasks[index]->time_to_next_interval()); | |
114 } | |
115 return delay; | |
116 } | |
117 | |
118 // The task to perform at each period | |
119 virtual void task() = 0; | |
120 }; | |
1972 | 121 |
122 #endif // SHARE_VM_RUNTIME_TASK_HPP |