1 /*
   2  * Copyright (c) 1997, 2010, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "memory/allocation.hpp"
  27 #include "runtime/init.hpp"
  28 #include "runtime/task.hpp"
  29 #include "runtime/timer.hpp"
  30 #ifdef TARGET_OS_FAMILY_linux
  31 # include "os_linux.inline.hpp"
  32 # include "thread_linux.inline.hpp"
  33 #endif
  34 #ifdef TARGET_OS_FAMILY_solaris
  35 # include "os_solaris.inline.hpp"
  36 # include "thread_solaris.inline.hpp"
  37 #endif
  38 #ifdef TARGET_OS_FAMILY_windows
  39 # include "os_windows.inline.hpp"
  40 # include "thread_windows.inline.hpp"
  41 #endif
  42 
  43 int PeriodicTask::_num_tasks = 0;
  44 PeriodicTask* PeriodicTask::_tasks[PeriodicTask::max_tasks];
  45 #ifndef PRODUCT
  46 elapsedTimer PeriodicTask::_timer;
  47 int PeriodicTask::_intervalHistogram[PeriodicTask::max_interval];
  48 int PeriodicTask::_ticks;
  49 
  50 void PeriodicTask::print_intervals() {
  51   if (ProfilerCheckIntervals) {
  52     for (int i = 0; i < PeriodicTask::max_interval; i++) {
  53       int n = _intervalHistogram[i];
  54       if (n > 0) tty->print_cr("%3d: %5d (%4.1f%%)", i, n, 100.0 * n / _ticks);
  55     }
  56   }
  57 }
  58 #endif
  59 
  60 void PeriodicTask::real_time_tick(size_t delay_time) {
  61 #ifndef PRODUCT
  62   if (ProfilerCheckIntervals) {
  63     _ticks++;
  64     _timer.stop();
  65     int ms = (int)(_timer.seconds() * 1000.0);
  66     _timer.reset();
  67     _timer.start();
  68     if (ms >= PeriodicTask::max_interval) ms = PeriodicTask::max_interval - 1;
  69     _intervalHistogram[ms]++;
  70   }
  71 #endif
  72   int orig_num_tasks = _num_tasks;
  73   for(int index = 0; index < _num_tasks; index++) {
  74     _tasks[index]->execute_if_pending(delay_time);
  75     if (_num_tasks < orig_num_tasks) { // task dis-enrolled itself
  76       index--;  // re-do current slot as it has changed
  77       orig_num_tasks = _num_tasks;
  78     }
  79   }
  80 }
  81 
  82 
  83 PeriodicTask::PeriodicTask(size_t interval_time) :
  84   _counter(0), _interval(interval_time) {
  85   // Sanity check the interval time
  86   assert(_interval >= PeriodicTask::min_interval &&
  87          _interval <= PeriodicTask::max_interval &&
  88          _interval %  PeriodicTask::interval_gran == 0,
  89               "improper PeriodicTask interval time");
  90 }
  91 
  92 PeriodicTask::~PeriodicTask() {
  93   if (is_enrolled())
  94     disenroll();
  95 }
  96 
  97 bool PeriodicTask::is_enrolled() const {
  98   for(int index = 0; index < _num_tasks; index++)
  99     if (_tasks[index] == this) return true;
 100   return false;
 101 }
 102 
 103 void PeriodicTask::enroll() {
 104   assert(WatcherThread::watcher_thread() == NULL, "dynamic enrollment of tasks not yet supported");
 105 
 106   if (_num_tasks == PeriodicTask::max_tasks)
 107     fatal("Overflow in PeriodicTask table");
 108   _tasks[_num_tasks++] = this;
 109 }
 110 
 111 void PeriodicTask::disenroll() {
 112   assert(WatcherThread::watcher_thread() == NULL ||
 113          Thread::current() == WatcherThread::watcher_thread(),
 114          "dynamic disenrollment currently only handled from WatcherThread from within task() method");
 115 
 116   int index;
 117   for(index = 0; index < _num_tasks && _tasks[index] != this; index++);
 118   if (index == _num_tasks) return;
 119   _num_tasks--;
 120   for (; index < _num_tasks; index++) {
 121     _tasks[index] = _tasks[index+1];
 122   }
 123 }