1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/src/share/vm/runtime/task.hpp Wed Apr 27 01:25:04 2016 +0800
1.3 @@ -0,0 +1,107 @@
1.4 +/*
1.5 + * Copyright (c) 1997, 2012, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
1.23 + * or visit www.oracle.com if you need additional information or have any
1.24 + * questions.
1.25 + *
1.26 + */
1.27 +
1.28 +#ifndef SHARE_VM_RUNTIME_TASK_HPP
1.29 +#define SHARE_VM_RUNTIME_TASK_HPP
1.30 +
1.31 +#include "utilities/top.hpp"
1.32 +
1.33 +// A PeriodicTask has the sole purpose of executing its task
1.34 +// function with regular intervals.
1.35 +// Usage:
1.36 +// PeriodicTask pf(10);
1.37 +// pf.enroll();
1.38 +// ...
1.39 +// pf.disenroll();
1.40 +
1.41 +class PeriodicTask: public CHeapObj<mtInternal> {
1.42 + public:
1.43 + // Useful constants.
1.44 + // The interval constants are used to ensure the declared interval
1.45 + // is appropriate; it must be between min_interval and max_interval,
1.46 + // and have a granularity of interval_gran (all in millis).
1.47 + enum { max_tasks = 10, // Max number of periodic tasks in system
1.48 + interval_gran = 10,
1.49 + min_interval = 10,
1.50 + max_interval = 10000 };
1.51 +
1.52 + static int num_tasks() { return _num_tasks; }
1.53 +
1.54 + private:
1.55 + int _counter;
1.56 + const int _interval;
1.57 +
1.58 + static int _num_tasks;
1.59 + static PeriodicTask* _tasks[PeriodicTask::max_tasks];
1.60 + static void real_time_tick(int delay_time);
1.61 +
1.62 +#ifndef PRODUCT
1.63 + static elapsedTimer _timer; // measures time between ticks
1.64 + static int _ticks; // total number of ticks
1.65 + static int _intervalHistogram[max_interval]; // to check spacing of timer interrupts
1.66 + public:
1.67 + static void print_intervals();
1.68 +#endif
1.69 + // Only the WatcherThread can cause us to execute PeriodicTasks
1.70 + friend class WatcherThread;
1.71 + public:
1.72 + PeriodicTask(size_t interval_time); // interval is in milliseconds of elapsed time
1.73 + ~PeriodicTask();
1.74 +
1.75 + // Make the task active
1.76 + // For dynamic enrollment at the time T, the task will execute somewhere
1.77 + // between T and T + interval_time.
1.78 + void enroll();
1.79 +
1.80 + // Make the task deactive
1.81 + void disenroll();
1.82 +
1.83 + void execute_if_pending(int delay_time) {
1.84 + // make sure we don't overflow
1.85 + jlong tmp = (jlong) _counter + (jlong) delay_time;
1.86 +
1.87 + if (tmp >= (jlong) _interval) {
1.88 + _counter = 0;
1.89 + task();
1.90 + } else {
1.91 + _counter += delay_time;
1.92 + }
1.93 + }
1.94 +
1.95 + // Returns how long (time in milliseconds) before the next time we should
1.96 + // execute this task.
1.97 + int time_to_next_interval() const {
1.98 + assert(_interval > _counter, "task counter greater than interval?");
1.99 + return _interval - _counter;
1.100 + }
1.101 +
1.102 + // Calculate when the next periodic task will fire.
1.103 + // Called by the WatcherThread's run method.
1.104 + static int time_to_wait();
1.105 +
1.106 + // The task to perform at each period
1.107 + virtual void task() = 0;
1.108 +};
1.109 +
1.110 +#endif // SHARE_VM_RUNTIME_TASK_HPP
