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/*
* Copyright (c) 2013, 2015, 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. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* 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.
*/
/**
* Interfaces and classes for using system watchdog timers (WDT).
*
* A watchdog timer is used to reset/reboot the system in case of hang or critical failure. This is used to reset the
* system from a unresponsive state to a normal state. A watchdog timer can be set with a time interval for the
* reset/reboot. Continuously refreshing the watchdog timer within the specified time interval prevents the
* reset/reboot. If the watchdog timer has not been refreshed within the specified time interval a critical failure is
* assumed and a system reset/reboot is carried out.
* A windowed watchdog timer must be refreshed within an open time window. If the watchdog is refreshed too soon -
* during the closed window - or if it is refreshed too late - after the watchdog timeout has expired - the device will
* be rebooted.
*
* In order to use with a specific watchdog timer, an application should first open and obtain an
* {@link jdk.dio.watchdog.WatchdogTimer} instance for the watchdog timer the application wants to use,
* using its numeric ID, name, type (interface) and/or properties:
*
*
* - Using its ID
* -
*
*
* WatchdogTimer wdt = DeviceManager.open(8);
*
*
* - Using its name and interface
* -
*
*
* WatchdogTimer wdt = DeviceManager.open("WDT", WatchdogTimer.class, null);
*
*
Or for a windowed watchdog timer,
*
* WindowedWatchdogTimer wdt = DeviceManager.open("WWDT", WindowedWatchdogTimer.class, null);
*
*
*
*
*
* Once the device opened, the application can start using it and can especially start the timer using the
* {@link jdk.dio.watchdog.WatchdogTimer#start(long) WatchdogTimer.start} method and subsequently
* refresh the timer periodically using the {@link jdk.dio.watchdog.WatchdogTimer#refresh
* WatchdogTimer.refresh} method:
*
*
* wdt.start(1000);
* ...
* wdt.refresh();
*
*
*
* When done, the application should call the
* {@link jdk.dio.watchdog.WatchdogTimer#close WatchdogTimer.close} method to close the watchdog
* timer.
*
*
*
* wdt.close();
*
*
*
* The following sample codes give examples of using the watchdog timer API:
*
* public class WatchdogSample {
* public boolean checkSomeStatus() {
* // check some status....
* // if status is ok then return true to kick watch dog timer.
* return true;
* }
*
* public void test_loop() {
* WatchdogTimer watchdogTimer = (WatchdogTimer) DeviceManager.open(WDT_ID);
*
* watchdogTimer.start(180000); // Start watch dog timer with 3 min duration.
*
* while (true) {
* if (checkSomeStatus() == true) {
* // Everything goes fine, timer will be kick.
* watchdogTimer.refresh();
* // do something more...
* } else {
* // Something goes wrong. Timer will not be kick.
* // If status not recovered within 2-3 turns then system will be reboot.
* }
* sleep(60000); // sleep for 1 min.
* }
* }
* }
*
*
*
* Unless otherwise noted, permission and security checks that may cause
* a {@link java.lang.SecurityException SecurityException} to be thrown must be performed
* in priority to any other checks or operations once performed the checking of the input parameters
* from which the permission target names and action lists are retrieved and assembled.
*
* Unless otherwise noted, passing a {@code null} argument to a constructor or method in any class
* or interface in this package will cause a {@link java.lang.NullPointerException NullPointerException} to be thrown.
*
*
* @since 1.0
*/
package jdk.dio.watchdog;