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106 lines
4.2 KiB
106 lines
4.2 KiB
19 years ago
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// kelondroLock.java
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// -----------------------
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// part of YaCy
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// (C) by Michael Peter Christen; mc@anomic.de
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// first published on http://www.anomic.de
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// Frankfurt, Germany, 2005
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// Created 08.12.2005
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//
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// This program is free software; you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation; either version 2 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program; if not, write to the Free Software
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// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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//
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// Using this software in any meaning (reading, learning, copying, compiling,
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// running) means that you agree that the Author(s) is (are) not responsible
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// for cost, loss of data or any harm that may be caused directly or indirectly
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// by usage of this softare or this documentation. The usage of this software
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// is on your own risk. The installation and usage (starting/running) of this
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// software may allow other people or application to access your computer and
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// any attached devices and is highly dependent on the configuration of the
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// software which must be done by the user of the software; the author(s) is
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// (are) also not responsible for proper configuration and usage of the
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// software, even if provoked by documentation provided together with
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// the software.
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//
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// Any changes to this file according to the GPL as documented in the file
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// gpl.txt aside this file in the shipment you received can be done to the
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// lines that follows this copyright notice here, but changes must not be
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// done inside the copyright notive above. A re-distribution must contain
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// the intact and unchanged copyright notice.
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// Contributions and changes to the program code must be marked as such.
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package de.anomic.kelondro;
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public class kelondroLock {
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private boolean lock;
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private long releaseTime;
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public kelondroLock() {
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lock = false;
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releaseTime = 0;
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}
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public synchronized void apply() {
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// this applies a lock to this objekt
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// if the lock is already applied
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// this object waits until it is released and applies it then again
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// before it returns
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apply(-1);
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}
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public synchronized void apply(long millis) {
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// sets a lock that is valid for a specific time
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// if the time is over, the lock is released automatically
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if (locked()) {
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do {
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try { wait(100); }
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catch (InterruptedException e) { }
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catch (Exception e) { e.printStackTrace(); }
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} while (locked());
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}
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lock = true;
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releaseTime = (millis < 0) ? Long.MAX_VALUE : System.currentTimeMillis() + millis;
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}
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public synchronized boolean stay(long waitMillis, long lockMillis) {
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// this tries to apply a lock, but does not block infinitely until
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// the lock is released. If after the given time the lock is not released
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// the method returns with false and no more lock is applied
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// if the lock was applied successfully, it returns with true
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if (locked()) {
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try { wait(waitMillis); }
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catch (InterruptedException e) { }
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catch (Exception e) { e.printStackTrace(); }
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if (locked()) return false;
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}
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lock = true;
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releaseTime = (lockMillis < 0) ? Long.MAX_VALUE : System.currentTimeMillis() + lockMillis;
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return true;
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}
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public synchronized void release() {
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// this must be called to releas the lock to the object
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// if it is not released, possibly all other tasks are blocked
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if (locked()) {
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lock = false;
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releaseTime = 0;
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notify();
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}
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}
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public synchronized boolean locked() {
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return lock && (System.currentTimeMillis() < releaseTime);
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}
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}
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