1 /* 2 * Copyright (c) 1997, 2015, 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 32 int PeriodicTask::_num_tasks = 0; 33 PeriodicTask* PeriodicTask::_tasks[PeriodicTask::max_tasks]; 34 #ifndef PRODUCT 35 elapsedTimer PeriodicTask::_timer; 36 int PeriodicTask::_intervalHistogram[PeriodicTask::max_interval]; 37 int PeriodicTask::_ticks; 38 39 void PeriodicTask::print_intervals() { 40 if (ProfilerCheckIntervals) { 41 for (int i = 0; i < PeriodicTask::max_interval; i++) { 42 int n = _intervalHistogram[i]; 43 if (n > 0) tty->print_cr("%3d: %5d (%4.1f%%)", i, n, 100.0 * n / _ticks); 44 } 45 } 46 } 47 #endif 48 49 void PeriodicTask::real_time_tick(int delay_time) { 50 assert(Thread::current()->is_Watcher_thread(), "must be WatcherThread"); 51 52 #ifndef PRODUCT 53 if (ProfilerCheckIntervals) { 54 _ticks++; 55 _timer.stop(); 56 int ms = (int)_timer.milliseconds(); 57 _timer.reset(); 58 _timer.start(); 59 if (ms >= PeriodicTask::max_interval) ms = PeriodicTask::max_interval - 1; 60 _intervalHistogram[ms]++; 61 } 62 #endif 63 64 { 65 MutexLocker ml(PeriodicTask_lock); 66 int orig_num_tasks = _num_tasks; 67 68 for(int index = 0; index < _num_tasks; index++) { 69 _tasks[index]->execute_if_pending(delay_time); 70 if (_num_tasks < orig_num_tasks) { // task dis-enrolled itself 71 index--; // re-do current slot as it has changed 72 orig_num_tasks = _num_tasks; 73 } 74 } 75 } 76 } 77 78 int PeriodicTask::time_to_wait() { 79 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 80 81 if (_num_tasks == 0) { 82 return 0; // sleep until shutdown or a task is enrolled 83 } 84 85 int delay = _tasks[0]->time_to_next_interval(); 86 for (int index = 1; index < _num_tasks; index++) { 87 delay = MIN2(delay, _tasks[index]->time_to_next_interval()); 88 } 89 return delay; 90 } 91 92 93 PeriodicTask::PeriodicTask(size_t interval_time) : 94 _counter(0), _interval((int) interval_time) { 95 // Sanity check the interval time 96 assert(_interval >= PeriodicTask::min_interval && 97 _interval % PeriodicTask::interval_gran == 0, 98 "improper PeriodicTask interval time"); 99 } 100 101 PeriodicTask::~PeriodicTask() { 102 // This PeriodicTask may have already been disenrolled by a call 103 // to disenroll() before the PeriodicTask was deleted. 104 disenroll(); 105 } 106 107 // enroll the current PeriodicTask 108 void PeriodicTask::enroll() { 109 // Follow normal safepoint aware lock enter protocol if the caller does 110 // not already own the PeriodicTask_lock. Otherwise, we don't try to 111 // enter it again because VM internal Mutexes do not support recursion. 112 // 113 MutexLockerEx ml(PeriodicTask_lock->owned_by_self() ? NULL 114 : PeriodicTask_lock); 115 116 if (_num_tasks == PeriodicTask::max_tasks) { 117 fatal("Overflow in PeriodicTask table"); 118 } else { 119 _tasks[_num_tasks++] = this; 120 } 121 122 WatcherThread* thread = WatcherThread::watcher_thread(); 123 if (thread != NULL) { 124 thread->unpark(); 125 } else { 126 WatcherThread::start(); 127 } 128 } 129 130 // disenroll the current PeriodicTask 131 void PeriodicTask::disenroll() { 132 // Follow normal safepoint aware lock enter protocol if the caller does 133 // not already own the PeriodicTask_lock. Otherwise, we don't try to 134 // enter it again because VM internal Mutexes do not support recursion. 135 // 136 MutexLockerEx ml(PeriodicTask_lock->owned_by_self() ? NULL 137 : PeriodicTask_lock); 138 139 int index; 140 for(index = 0; index < _num_tasks && _tasks[index] != this; index++) 141 ; 142 143 if (index == _num_tasks) { 144 return; 145 } 146 147 _num_tasks--; 148 149 for (; index < _num_tasks; index++) { 150 _tasks[index] = _tasks[index+1]; 151 } 152 }