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