duke@435: /*
mikael@4153:  * Copyright (c) 1997, 2012, Oracle and/or its affiliates. All rights reserved.
duke@435:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
duke@435:  *
duke@435:  * This code is free software; you can redistribute it and/or modify it
duke@435:  * under the terms of the GNU General Public License version 2 only, as
duke@435:  * published by the Free Software Foundation.
duke@435:  *
duke@435:  * This code is distributed in the hope that it will be useful, but WITHOUT
duke@435:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
duke@435:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
duke@435:  * version 2 for more details (a copy is included in the LICENSE file that
duke@435:  * accompanied this code).
duke@435:  *
duke@435:  * You should have received a copy of the GNU General Public License version
duke@435:  * 2 along with this work; if not, write to the Free Software Foundation,
duke@435:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
duke@435:  *
trims@1907:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
trims@1907:  * or visit www.oracle.com if you need additional information or have any
trims@1907:  * questions.
duke@435:  *
duke@435:  */
duke@435: 
stefank@2314: #ifndef SHARE_VM_RUNTIME_TASK_HPP
stefank@2314: #define SHARE_VM_RUNTIME_TASK_HPP
stefank@2314: 
stefank@2314: #include "utilities/top.hpp"
stefank@2314: 
duke@435: // A PeriodicTask has the sole purpose of executing its task
duke@435: // function with regular intervals.
duke@435: // Usage:
duke@435: //   PeriodicTask pf(10);
duke@435: //   pf.enroll();
duke@435: //   ...
duke@435: //   pf.disenroll();
duke@435: 
zgu@3900: class PeriodicTask: public CHeapObj<mtInternal> {
duke@435:  public:
duke@435:   // Useful constants.
duke@435:   // The interval constants are used to ensure the declared interval
duke@435:   // is appropriate;  it must be between min_interval and max_interval,
duke@435:   // and have a granularity of interval_gran (all in millis).
duke@435:   enum { max_tasks     = 10,       // Max number of periodic tasks in system
duke@435:          interval_gran = 10,
duke@435:          min_interval  = 10,
duke@435:          max_interval  = 10000 };
duke@435: 
duke@435:   static int num_tasks()   { return _num_tasks; }
duke@435: 
duke@435:  private:
rbackman@4250:   int _counter;
rbackman@4250:   const int _interval;
duke@435: 
duke@435:   static int _num_tasks;
duke@435:   static PeriodicTask* _tasks[PeriodicTask::max_tasks];
rbackman@4250:   static void real_time_tick(int delay_time);
duke@435: 
duke@435: #ifndef PRODUCT
duke@435:   static elapsedTimer _timer;                      // measures time between ticks
duke@435:   static int _ticks;                               // total number of ticks
duke@435:   static int _intervalHistogram[max_interval];     // to check spacing of timer interrupts
duke@435:  public:
duke@435:   static void print_intervals();
duke@435: #endif
duke@435:   // Only the WatcherThread can cause us to execute PeriodicTasks
duke@435:   friend class WatcherThread;
duke@435:  public:
duke@435:   PeriodicTask(size_t interval_time); // interval is in milliseconds of elapsed time
duke@435:   ~PeriodicTask();
duke@435: 
duke@435:   // Make the task active
rbackman@4250:   // For dynamic enrollment at the time T, the task will execute somewhere
rbackman@4250:   // between T and T + interval_time.
duke@435:   void enroll();
duke@435: 
duke@435:   // Make the task deactive
duke@435:   void disenroll();
duke@435: 
rbackman@4250:   void execute_if_pending(int delay_time) {
rbackman@4250:     // make sure we don't overflow
rbackman@4250:     jlong tmp = (jlong) _counter + (jlong) delay_time;
rbackman@4250: 
rbackman@4250:     if (tmp >= (jlong) _interval) {
duke@435:       _counter = 0;
duke@435:       task();
rbackman@4250:     } else {
rbackman@4250:       _counter += delay_time;
duke@435:     }
duke@435:   }
duke@435: 
duke@435:   // Returns how long (time in milliseconds) before the next time we should
duke@435:   // execute this task.
rbackman@4250:   int time_to_next_interval() const {
duke@435:     assert(_interval > _counter,  "task counter greater than interval?");
duke@435:     return _interval - _counter;
duke@435:   }
duke@435: 
duke@435:   // Calculate when the next periodic task will fire.
duke@435:   // Called by the WatcherThread's run method.
rbackman@4250:   static int time_to_wait();
duke@435: 
duke@435:   // The task to perform at each period
duke@435:   virtual void task() = 0;
duke@435: };
stefank@2314: 
stefank@2314: #endif // SHARE_VM_RUNTIME_TASK_HPP