1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/src/share/vm/runtime/task.hpp Sat Dec 01 00:00:00 2007 +0000
1.3 @@ -0,0 +1,125 @@
1.4 +/*
1.5 + * Copyright 1997-2007 Sun Microsystems, Inc. All Rights Reserved.
1.6 + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
1.7 + *
1.8 + * This code is free software; you can redistribute it and/or modify it
1.9 + * under the terms of the GNU General Public License version 2 only, as
1.10 + * published by the Free Software Foundation.
1.11 + *
1.12 + * This code is distributed in the hope that it will be useful, but WITHOUT
1.13 + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
1.14 + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
1.15 + * version 2 for more details (a copy is included in the LICENSE file that
1.16 + * accompanied this code).
1.17 + *
1.18 + * You should have received a copy of the GNU General Public License version
1.19 + * 2 along with this work; if not, write to the Free Software Foundation,
1.20 + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
1.21 + *
1.22 + * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
1.23 + * CA 95054 USA or visit www.sun.com if you need additional information or
1.24 + * have any questions.
1.25 + *
1.26 + */
1.27 +
1.28 +// A PeriodicTask has the sole purpose of executing its task
1.29 +// function with regular intervals.
1.30 +// Usage:
1.31 +// PeriodicTask pf(10);
1.32 +// pf.enroll();
1.33 +// ...
1.34 +// pf.disenroll();
1.35 +
1.36 +class PeriodicTask: public CHeapObj {
1.37 + public:
1.38 + // Useful constants.
1.39 + // The interval constants are used to ensure the declared interval
1.40 + // is appropriate; it must be between min_interval and max_interval,
1.41 + // and have a granularity of interval_gran (all in millis).
1.42 + enum { max_tasks = 10, // Max number of periodic tasks in system
1.43 + interval_gran = 10,
1.44 + min_interval = 10,
1.45 + max_interval = 10000 };
1.46 +
1.47 + static int num_tasks() { return _num_tasks; }
1.48 +
1.49 + private:
1.50 + size_t _counter;
1.51 + const size_t _interval;
1.52 +
1.53 + static int _num_tasks;
1.54 + static PeriodicTask* _tasks[PeriodicTask::max_tasks];
1.55 + static void real_time_tick(size_t delay_time);
1.56 +
1.57 +#ifndef PRODUCT
1.58 + static elapsedTimer _timer; // measures time between ticks
1.59 + static int _ticks; // total number of ticks
1.60 + static int _intervalHistogram[max_interval]; // to check spacing of timer interrupts
1.61 + public:
1.62 + static void print_intervals();
1.63 +#endif
1.64 + // Only the WatcherThread can cause us to execute PeriodicTasks
1.65 + friend class WatcherThread;
1.66 + public:
1.67 + PeriodicTask(size_t interval_time); // interval is in milliseconds of elapsed time
1.68 + ~PeriodicTask();
1.69 +
1.70 + // Tells whether is enrolled
1.71 + bool is_enrolled() const;
1.72 +
1.73 + // Make the task active
1.74 + // NOTE: this may only be called before the WatcherThread has been started
1.75 + void enroll();
1.76 +
1.77 + // Make the task deactive
1.78 + // NOTE: this may only be called either while the WatcherThread is
1.79 + // inactive or by a task from within its task() method. One-shot or
1.80 + // several-shot tasks may be implemented this way.
1.81 + void disenroll();
1.82 +
1.83 + void execute_if_pending(size_t delay_time) {
1.84 + _counter += delay_time;
1.85 + if (_counter >= _interval) {
1.86 + _counter = 0;
1.87 + task();
1.88 + }
1.89 + }
1.90 +
1.91 + // Returns how long (time in milliseconds) before the next time we should
1.92 + // execute this task.
1.93 + size_t time_to_next_interval() const {
1.94 + assert(_interval > _counter, "task counter greater than interval?");
1.95 + return _interval - _counter;
1.96 + }
1.97 +
1.98 + // Calculate when the next periodic task will fire.
1.99 + // Called by the WatcherThread's run method.
1.100 + // This assumes that periodic tasks aren't entering the system
1.101 + // dynamically, except for during startup.
1.102 + static size_t time_to_wait() {
1.103 + if (_num_tasks == 0) {
1.104 + // Don't wait any more; shut down the thread since we don't
1.105 + // currently support dynamic enrollment.
1.106 + return 0;
1.107 + }
1.108 +
1.109 + size_t delay = _tasks[0]->time_to_next_interval();
1.110 + for (int index = 1; index < _num_tasks; index++) {
1.111 + delay = MIN2(delay, _tasks[index]->time_to_next_interval());
1.112 + }
1.113 + return delay;
1.114 + }
1.115 +
1.116 + // The task to perform at each period
1.117 + virtual void task() = 0;
1.118 +};
1.119 +
1.120 +class TimeMillisUpdateTask : public PeriodicTask {
1.121 + private:
1.122 + static TimeMillisUpdateTask* _task;
1.123 + public:
1.124 + TimeMillisUpdateTask(int interval) : PeriodicTask(interval) {}
1.125 + void task();
1.126 + static void engage();
1.127 + static void disengage();
1.128 +};
