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/*
* Copyright (c) 1997, 2021, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*
*/
#include "precompiled.hpp"
#include "memory/allocation.hpp"
#include "runtime/init.hpp"
#include "runtime/javaThread.hpp"
#include "runtime/mutexLocker.hpp"
#include "runtime/nonJavaThread.hpp"
#include "runtime/task.hpp"
#include "runtime/timer.hpp"
int PeriodicTask::_num_tasks = 0;
PeriodicTask* PeriodicTask::_tasks[PeriodicTask::max_tasks];
void PeriodicTask::real_time_tick(int delay_time) {
assert(Thread::current()->is_Watcher_thread(), "must be WatcherThread");
// The WatcherThread does not participate in the safepoint protocol
// for the PeriodicTask_lock because it is not a JavaThread.
MutexLocker ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
int orig_num_tasks = _num_tasks;
for(int index = 0; index < _num_tasks; index++) {
_tasks[index]->execute_if_pending(delay_time);
if (_num_tasks < orig_num_tasks) { // task dis-enrolled itself
index--; // re-do current slot as it has changed
orig_num_tasks = _num_tasks;
}
}
}
int PeriodicTask::time_to_wait() {
assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
if (_num_tasks == 0) {
return 0; // sleep until shutdown or a task is enrolled
}
int delay = _tasks[0]->time_to_next_interval();
for (int index = 1; index < _num_tasks; index++) {
delay = MIN2(delay, _tasks[index]->time_to_next_interval());
}
return delay;
}
PeriodicTask::PeriodicTask(size_t interval_time) :
_counter(0), _interval((int) interval_time) {
// Sanity check the interval time
assert(_interval >= PeriodicTask::min_interval &&
_interval % PeriodicTask::interval_gran == 0,
"improper PeriodicTask interval time");
}
PeriodicTask::~PeriodicTask() {
// This PeriodicTask may have already been disenrolled by a call
// to disenroll() before the PeriodicTask was deleted.
disenroll();
}
// enroll the current PeriodicTask
void PeriodicTask::enroll() {
// Follow normal safepoint aware lock enter protocol if the caller does
// not already own the PeriodicTask_lock. Otherwise, we don't try to
// enter it again because VM internal Mutexes do not support recursion.
//
MutexLocker ml(PeriodicTask_lock->owned_by_self() ? NULL : PeriodicTask_lock);
if (_num_tasks == PeriodicTask::max_tasks) {
fatal("Overflow in PeriodicTask table");
} else {
_tasks[_num_tasks++] = this;
}
WatcherThread* thread = WatcherThread::watcher_thread();
if (thread != NULL) {
thread->unpark();
} else {
WatcherThread::start();
}
}
// disenroll the current PeriodicTask
void PeriodicTask::disenroll() {
// Follow normal safepoint aware lock enter protocol if the caller does
// not already own the PeriodicTask_lock. Otherwise, we don't try to
// enter it again because VM internal Mutexes do not support recursion.
//
MutexLocker ml(PeriodicTask_lock->owned_by_self() ? NULL : PeriodicTask_lock);
int index;
for(index = 0; index < _num_tasks && _tasks[index] != this; index++)
;
if (index == _num_tasks) {
return;
}
_num_tasks--;
for (; index < _num_tasks; index++) {
_tasks[index] = _tasks[index+1];
}
}
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