Thu, 02 Apr 2009 18:17:03 -0400
Merge
duke@435 | 1 | /* |
xdono@631 | 2 | * Copyright 1997-2008 Sun Microsystems, Inc. All Rights Reserved. |
duke@435 | 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
duke@435 | 4 | * |
duke@435 | 5 | * This code is free software; you can redistribute it and/or modify it |
duke@435 | 6 | * under the terms of the GNU General Public License version 2 only, as |
duke@435 | 7 | * published by the Free Software Foundation. |
duke@435 | 8 | * |
duke@435 | 9 | * This code is distributed in the hope that it will be useful, but WITHOUT |
duke@435 | 10 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
duke@435 | 11 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
duke@435 | 12 | * version 2 for more details (a copy is included in the LICENSE file that |
duke@435 | 13 | * accompanied this code). |
duke@435 | 14 | * |
duke@435 | 15 | * You should have received a copy of the GNU General Public License version |
duke@435 | 16 | * 2 along with this work; if not, write to the Free Software Foundation, |
duke@435 | 17 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
duke@435 | 18 | * |
duke@435 | 19 | * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
duke@435 | 20 | * CA 95054 USA or visit www.sun.com if you need additional information or |
duke@435 | 21 | * have any questions. |
duke@435 | 22 | * |
duke@435 | 23 | */ |
duke@435 | 24 | |
duke@435 | 25 | // A PeriodicTask has the sole purpose of executing its task |
duke@435 | 26 | // function with regular intervals. |
duke@435 | 27 | // Usage: |
duke@435 | 28 | // PeriodicTask pf(10); |
duke@435 | 29 | // pf.enroll(); |
duke@435 | 30 | // ... |
duke@435 | 31 | // pf.disenroll(); |
duke@435 | 32 | |
duke@435 | 33 | class PeriodicTask: public CHeapObj { |
duke@435 | 34 | public: |
duke@435 | 35 | // Useful constants. |
duke@435 | 36 | // The interval constants are used to ensure the declared interval |
duke@435 | 37 | // is appropriate; it must be between min_interval and max_interval, |
duke@435 | 38 | // and have a granularity of interval_gran (all in millis). |
duke@435 | 39 | enum { max_tasks = 10, // Max number of periodic tasks in system |
duke@435 | 40 | interval_gran = 10, |
duke@435 | 41 | min_interval = 10, |
duke@435 | 42 | max_interval = 10000 }; |
duke@435 | 43 | |
duke@435 | 44 | static int num_tasks() { return _num_tasks; } |
duke@435 | 45 | |
duke@435 | 46 | private: |
duke@435 | 47 | size_t _counter; |
duke@435 | 48 | const size_t _interval; |
duke@435 | 49 | |
duke@435 | 50 | static int _num_tasks; |
duke@435 | 51 | static PeriodicTask* _tasks[PeriodicTask::max_tasks]; |
duke@435 | 52 | static void real_time_tick(size_t delay_time); |
duke@435 | 53 | |
duke@435 | 54 | #ifndef PRODUCT |
duke@435 | 55 | static elapsedTimer _timer; // measures time between ticks |
duke@435 | 56 | static int _ticks; // total number of ticks |
duke@435 | 57 | static int _intervalHistogram[max_interval]; // to check spacing of timer interrupts |
duke@435 | 58 | public: |
duke@435 | 59 | static void print_intervals(); |
duke@435 | 60 | #endif |
duke@435 | 61 | // Only the WatcherThread can cause us to execute PeriodicTasks |
duke@435 | 62 | friend class WatcherThread; |
duke@435 | 63 | public: |
duke@435 | 64 | PeriodicTask(size_t interval_time); // interval is in milliseconds of elapsed time |
duke@435 | 65 | ~PeriodicTask(); |
duke@435 | 66 | |
duke@435 | 67 | // Tells whether is enrolled |
duke@435 | 68 | bool is_enrolled() const; |
duke@435 | 69 | |
duke@435 | 70 | // Make the task active |
duke@435 | 71 | // NOTE: this may only be called before the WatcherThread has been started |
duke@435 | 72 | void enroll(); |
duke@435 | 73 | |
duke@435 | 74 | // Make the task deactive |
duke@435 | 75 | // NOTE: this may only be called either while the WatcherThread is |
duke@435 | 76 | // inactive or by a task from within its task() method. One-shot or |
duke@435 | 77 | // several-shot tasks may be implemented this way. |
duke@435 | 78 | void disenroll(); |
duke@435 | 79 | |
duke@435 | 80 | void execute_if_pending(size_t delay_time) { |
duke@435 | 81 | _counter += delay_time; |
duke@435 | 82 | if (_counter >= _interval) { |
duke@435 | 83 | _counter = 0; |
duke@435 | 84 | task(); |
duke@435 | 85 | } |
duke@435 | 86 | } |
duke@435 | 87 | |
duke@435 | 88 | // Returns how long (time in milliseconds) before the next time we should |
duke@435 | 89 | // execute this task. |
duke@435 | 90 | size_t time_to_next_interval() const { |
duke@435 | 91 | assert(_interval > _counter, "task counter greater than interval?"); |
duke@435 | 92 | return _interval - _counter; |
duke@435 | 93 | } |
duke@435 | 94 | |
duke@435 | 95 | // Calculate when the next periodic task will fire. |
duke@435 | 96 | // Called by the WatcherThread's run method. |
duke@435 | 97 | // This assumes that periodic tasks aren't entering the system |
duke@435 | 98 | // dynamically, except for during startup. |
duke@435 | 99 | static size_t time_to_wait() { |
duke@435 | 100 | if (_num_tasks == 0) { |
duke@435 | 101 | // Don't wait any more; shut down the thread since we don't |
duke@435 | 102 | // currently support dynamic enrollment. |
duke@435 | 103 | return 0; |
duke@435 | 104 | } |
duke@435 | 105 | |
duke@435 | 106 | size_t delay = _tasks[0]->time_to_next_interval(); |
duke@435 | 107 | for (int index = 1; index < _num_tasks; index++) { |
duke@435 | 108 | delay = MIN2(delay, _tasks[index]->time_to_next_interval()); |
duke@435 | 109 | } |
duke@435 | 110 | return delay; |
duke@435 | 111 | } |
duke@435 | 112 | |
duke@435 | 113 | // The task to perform at each period |
duke@435 | 114 | virtual void task() = 0; |
duke@435 | 115 | }; |