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.seconds() * 1000.0);
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 // The WatcherThread is not a JavaThread so we do not honor the
66 // safepoint protocol for the PeriodicTask_lock.
67 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
68 int orig_num_tasks = _num_tasks;
69
70 for(int index = 0; index < _num_tasks; index++) {
71 _tasks[index]->execute_if_pending(delay_time);
72 if (_num_tasks < orig_num_tasks) { // task dis-enrolled itself
73 index--; // re-do current slot as it has changed
74 orig_num_tasks = _num_tasks;
75 }
76 }
77 }
78 }
79
80 int PeriodicTask::time_to_wait() {
81 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
82
83 if (_num_tasks == 0) {
84 return 0; // sleep until shutdown or a task is enrolled
85 }
86
87 int delay = _tasks[0]->time_to_next_interval();
88 for (int index = 1; index < _num_tasks; index++) {
89 delay = MIN2(delay, _tasks[index]->time_to_next_interval());
90 }
91 return delay;
92 }
93
94
95 PeriodicTask::PeriodicTask(size_t interval_time) :
96 _counter(0), _interval((int) interval_time) {
97 // Sanity check the interval time
98 assert(_interval >= PeriodicTask::min_interval &&
99 _interval % PeriodicTask::interval_gran == 0,
100 "improper PeriodicTask interval time");
101 }
102
103 PeriodicTask::~PeriodicTask() {
104 // This PeriodicTask may have already been disenrolled by a call
105 // to disenroll() before the PeriodicTask was deleted.
106 disenroll();
107 }
108
109 // enroll the current PeriodicTask
110 void PeriodicTask::enroll() {
111 // Follow normal safepoint aware lock enter protocol if the caller does
112 // not already own the PeriodicTask_lock. Otherwise, we don't try to
113 // enter it again because VM internal Mutexes do not support recursion.
114 //
115 MutexLockerEx ml(PeriodicTask_lock->owned_by_self() ? NULL
116 : PeriodicTask_lock);
117
118 if (_num_tasks == PeriodicTask::max_tasks) {
119 fatal("Overflow in PeriodicTask table");
120 }
121 _tasks[_num_tasks++] = this;
122
123 WatcherThread* thread = WatcherThread::watcher_thread();
124 if (thread != NULL) {
125 thread->unpark();
126 } else {
127 WatcherThread::start();
128 }
129 }
130
131 // disenroll the current PeriodicTask
132 void PeriodicTask::disenroll() {
133 // Follow normal safepoint aware lock enter protocol if the caller does
134 // not already own the PeriodicTask_lock. Otherwise, we don't try to
135 // enter it again because VM internal Mutexes do not support recursion.
136 //
137 MutexLockerEx ml(PeriodicTask_lock->owned_by_self() ? NULL
138 : PeriodicTask_lock);
139
140 int index;
141 for(index = 0; index < _num_tasks && _tasks[index] != this; index++)
142 ;
143
144 if (index == _num_tasks) {
145 return;
146 }
147
148 _num_tasks--;
149
150 for (; index < _num_tasks; index++) {
151 _tasks[index] = _tasks[index+1];
152 }
153 }