0N/A/*
2362N/A * Copyright (c) 2004, Oracle and/or its affiliates. All rights reserved.
0N/A * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
0N/A *
0N/A * This code is free software; you can redistribute it and/or modify it
0N/A * under the terms of the GNU General Public License version 2 only, as
2362N/A * published by the Free Software Foundation. Oracle designates this
0N/A * particular file as subject to the "Classpath" exception as provided
2362N/A * by Oracle in the LICENSE file that accompanied this code.
0N/A *
0N/A * This code is distributed in the hope that it will be useful, but WITHOUT
0N/A * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
0N/A * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
0N/A * version 2 for more details (a copy is included in the LICENSE file that
0N/A * accompanied this code).
0N/A *
0N/A * You should have received a copy of the GNU General Public License version
0N/A * 2 along with this work; if not, write to the Free Software Foundation,
0N/A * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
0N/A *
2362N/A * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
2362N/A * or visit www.oracle.com if you need additional information or have any
2362N/A * questions.
0N/A */
0N/A
0N/Apackage sun.jvmstat.perfdata.monitor;
0N/A
0N/Aimport java.util.*;
0N/A
0N/A/**
0N/A * Utility methods for use with {@link CountedTimerTask} instances.
0N/A *
0N/A * @author Brian Doherty
0N/A * @since 1.5
0N/A */
0N/Apublic class CountedTimerTaskUtils {
0N/A
0N/A private static final boolean DEBUG = false;
0N/A
0N/A /**
0N/A * Reschedule a CountedTimeTask at a different interval. Probably not
0N/A * named correctly. This method cancels the old task and computes the
0N/A * delay for starting the new task based on the new interval and the
0N/A * time at which the old task was last executed.
0N/A *
0N/A * @param timer the Timer for the task
0N/A * @param oldTask the old Task
0N/A * @param newTask the new Task
0N/A * @param oldInterval the old interval; use for debugging output
0N/A * purposes only.
0N/A * @param newInterval scheduling interval in milliseconds
0N/A */
0N/A public static void reschedule(Timer timer, CountedTimerTask oldTask,
0N/A CountedTimerTask newTask, int oldInterval,
0N/A int newInterval) {
0N/A
0N/A long now = System.currentTimeMillis();
0N/A long lastRun = oldTask.scheduledExecutionTime();
0N/A long expired = now - lastRun;
0N/A
0N/A if (DEBUG) {
0N/A System.err.println("computing timer delay: "
0N/A + " oldInterval = " + oldInterval
0N/A + " newInterval = " + newInterval
0N/A + " samples = " + oldTask.executionCount()
0N/A + " expired = " + expired);
0N/A }
0N/A
0N/A /*
0N/A * check if original task ever ran - if not, then lastRun is
0N/A * undefined and we simply set the delay to 0.
0N/A */
0N/A long delay = 0;
0N/A if (oldTask.executionCount() > 0) {
0N/A long remainder = newInterval - expired;
0N/A delay = remainder >= 0 ? remainder : 0;
0N/A }
0N/A
0N/A if (DEBUG) {
0N/A System.err.println("rescheduling sampler task: interval = "
0N/A + newInterval
0N/A + " delay = " + delay);
0N/A }
0N/A
0N/A timer.schedule(newTask, delay, newInterval);
0N/A }
0N/A}