1 /*
   2  * Copyright (c) 1997, 2013, 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/thread.inline.hpp"
  30 #include "runtime/timer.hpp"
  31 #ifdef TARGET_OS_FAMILY_linux
  32 # include "os_linux.inline.hpp"
  33 #endif
  34 #ifdef TARGET_OS_FAMILY_solaris
  35 # include "os_solaris.inline.hpp"
  36 #endif
  37 #ifdef TARGET_OS_FAMILY_windows
  38 # include "os_windows.inline.hpp"
  39 #endif
  40 #ifdef TARGET_OS_FAMILY_bsd
  41 # include "os_bsd.inline.hpp"
  42 #endif
  43 
  44 int PeriodicTask::_num_tasks = 0;
  45 PeriodicTask* PeriodicTask::_tasks[PeriodicTask::max_tasks];
  46 #ifndef PRODUCT
  47 elapsedTimer PeriodicTask::_timer;
  48 int PeriodicTask::_intervalHistogram[PeriodicTask::max_interval];
  49 int PeriodicTask::_ticks;
  50 
  51 void PeriodicTask::print_intervals() {
  52   if (ProfilerCheckIntervals) {
  53     for (int i = 0; i < PeriodicTask::max_interval; i++) {
  54       int n = _intervalHistogram[i];
  55       if (n > 0) tty->print_cr("%3d: %5d (%4.1f%%)", i, n, 100.0 * n / _ticks);
  56     }
  57   }
  58 }
  59 #endif
  60 
  61 void PeriodicTask::real_time_tick(int delay_time) {
  62 #ifndef PRODUCT
  63   if (ProfilerCheckIntervals) {
  64     _ticks++;
  65     _timer.stop();
  66     int ms = (int)(_timer.seconds() * 1000.0);
  67     _timer.reset();
  68     _timer.start();
  69     if (ms >= PeriodicTask::max_interval) ms = PeriodicTask::max_interval - 1;
  70     _intervalHistogram[ms]++;
  71   }
  72 #endif
  73 
  74   {
  75     MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
  76     int orig_num_tasks = _num_tasks;
  77 
  78     for(int index = 0; index < _num_tasks; index++) {
  79       _tasks[index]->execute_if_pending(delay_time);
  80       if (_num_tasks < orig_num_tasks) { // task dis-enrolled itself
  81         index--;  // re-do current slot as it has changed
  82         orig_num_tasks = _num_tasks;
  83       }
  84     }
  85   }
  86 }
  87 
  88 int PeriodicTask::time_to_wait() {
  89   MutexLockerEx ml(PeriodicTask_lock->owned_by_self() ?
  90                      NULL : PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
  91 
  92   if (_num_tasks == 0) {
  93     return 0; // sleep until shutdown or a task is enrolled
  94   }
  95 
  96   int delay = _tasks[0]->time_to_next_interval();
  97   for (int index = 1; index < _num_tasks; index++) {
  98     delay = MIN2(delay, _tasks[index]->time_to_next_interval());
  99   }
 100   return delay;
 101 }
 102 
 103 
 104 PeriodicTask::PeriodicTask(size_t interval_time) :
 105   _counter(0), _interval((int) interval_time) {
 106   // Sanity check the interval time
 107   assert(_interval >= PeriodicTask::min_interval &&
 108          _interval <= PeriodicTask::max_interval &&
 109          _interval %  PeriodicTask::interval_gran == 0,
 110               "improper PeriodicTask interval time");
 111 }
 112 
 113 PeriodicTask::~PeriodicTask() {
 114   disenroll();
 115 }
 116 
 117 /* enroll could be called from a JavaThread, so we have to check for
 118  * safepoint when taking the lock to avoid deadlocking */
 119 void PeriodicTask::enroll() {
 120   MutexLockerEx ml(PeriodicTask_lock->owned_by_self() ?
 121                      NULL : PeriodicTask_lock);
 122 
 123   if (_num_tasks == PeriodicTask::max_tasks) {
 124     fatal("Overflow in PeriodicTask table");
 125   }
 126   _tasks[_num_tasks++] = this;
 127 
 128   WatcherThread* thread = WatcherThread::watcher_thread();
 129   if (thread) {
 130     thread->unpark();
 131   } else {
 132     WatcherThread::start();
 133   }
 134 }
 135 
 136 /* disenroll could be called from a JavaThread, so we have to check for
 137  * safepoint when taking the lock to avoid deadlocking */
 138 void PeriodicTask::disenroll() {
 139   MutexLockerEx ml(PeriodicTask_lock->owned_by_self() ?
 140                      NULL : PeriodicTask_lock);
 141 
 142   int index;
 143   for(index = 0; index < _num_tasks && _tasks[index] != this; index++)
 144     ;
 145 
 146   if (index == _num_tasks) {
 147     return;
 148   }
 149 
 150   _num_tasks--;
 151 
 152   for (; index < _num_tasks; index++) {
 153     _tasks[index] = _tasks[index+1];
 154   }
 155 }