Mercurial > jdk8-mips64-public > hotspot / file comparison
comparison: src/share/vm/runtime/task.hpp
src/share/vm/runtime/task.hpp
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| 1 /* | |
| 2 * Copyright 1997-2007 Sun Microsystems, 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, | |
| 20 * CA 95054 USA or visit www.sun.com if you need additional information or | |
| 21 * have any questions. | |
| 22 * | |
| 23 */ | |
| 24 | |
| 25 // A PeriodicTask has the sole purpose of executing its task | |
| 26 // function with regular intervals. | |
| 27 // Usage: | |
| 28 // PeriodicTask pf(10); | |
| 29 // pf.enroll(); | |
| 30 // ... | |
| 31 // pf.disenroll(); | |
| 32 | |
| 33 class PeriodicTask: public CHeapObj { | |
| 34 public: | |
| 35 // Useful constants. | |
| 36 // The interval constants are used to ensure the declared interval | |
| 37 // is appropriate; it must be between min_interval and max_interval, | |
| 38 // and have a granularity of interval_gran (all in millis). | |
| 39 enum { max_tasks = 10, // Max number of periodic tasks in system | |
| 40 interval_gran = 10, | |
| 41 min_interval = 10, | |
| 42 max_interval = 10000 }; | |
| 43 | |
| 44 static int num_tasks() { return _num_tasks; } | |
| 45 | |
| 46 private: | |
| 47 size_t _counter; | |
| 48 const size_t _interval; | |
| 49 | |
| 50 static int _num_tasks; | |
| 51 static PeriodicTask* _tasks[PeriodicTask::max_tasks]; | |
| 52 static void real_time_tick(size_t delay_time); | |
| 53 | |
| 54 #ifndef PRODUCT | |
| 55 static elapsedTimer _timer; // measures time between ticks | |
| 56 static int _ticks; // total number of ticks | |
| 57 static int _intervalHistogram[max_interval]; // to check spacing of timer interrupts | |
| 58 public: | |
| 59 static void print_intervals(); | |
| 60 #endif | |
| 61 // Only the WatcherThread can cause us to execute PeriodicTasks | |
| 62 friend class WatcherThread; | |
| 63 public: | |
| 64 PeriodicTask(size_t interval_time); // interval is in milliseconds of elapsed time | |
| 65 ~PeriodicTask(); | |
| 66 | |
| 67 // Tells whether is enrolled | |
| 68 bool is_enrolled() const; | |
| 69 | |
| 70 // Make the task active | |
| 71 // NOTE: this may only be called before the WatcherThread has been started | |
| 72 void enroll(); | |
| 73 | |
| 74 // Make the task deactive | |
| 75 // NOTE: this may only be called either while the WatcherThread is | |
| 76 // inactive or by a task from within its task() method. One-shot or | |
| 77 // several-shot tasks may be implemented this way. | |
| 78 void disenroll(); | |
| 79 | |
| 80 void execute_if_pending(size_t delay_time) { | |
| 81 _counter += delay_time; | |
| 82 if (_counter >= _interval) { | |
| 83 _counter = 0; | |
| 84 task(); | |
| 85 } | |
| 86 } | |
| 87 | |
| 88 // Returns how long (time in milliseconds) before the next time we should | |
| 89 // execute this task. | |
| 90 size_t time_to_next_interval() const { | |
| 91 assert(_interval > _counter, "task counter greater than interval?"); | |
| 92 return _interval - _counter; | |
| 93 } | |
| 94 | |
| 95 // Calculate when the next periodic task will fire. | |
| 96 // Called by the WatcherThread's run method. | |
| 97 // This assumes that periodic tasks aren't entering the system | |
| 98 // dynamically, except for during startup. | |
| 99 static size_t time_to_wait() { | |
| 100 if (_num_tasks == 0) { | |
| 101 // Don't wait any more; shut down the thread since we don't | |
| 102 // currently support dynamic enrollment. | |
| 103 return 0; | |
| 104 } | |
| 105 | |
| 106 size_t delay = _tasks[0]->time_to_next_interval(); | |
| 107 for (int index = 1; index < _num_tasks; index++) { | |
| 108 delay = MIN2(delay, _tasks[index]->time_to_next_interval()); | |
| 109 } | |
| 110 return delay; | |
| 111 } | |
| 112 | |
| 113 // The task to perform at each period | |
| 114 virtual void task() = 0; | |
| 115 }; | |
| 116 | |
| 117 class TimeMillisUpdateTask : public PeriodicTask { | |
| 118 private: | |
| 119 static TimeMillisUpdateTask* _task; | |
| 120 public: | |
| 121 TimeMillisUpdateTask(int interval) : PeriodicTask(interval) {} | |
| 122 void task(); | |
| 123 static void engage(); | |
| 124 static void disengage(); | |
| 125 }; |
