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82 lines
2.9 KiB
82 lines
2.9 KiB
//serverSemaphore.java
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//------------------------
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//part of YaCy
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//(C) by Michael Peter Christen; mc@yacy.net
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//first published on http://www.anomic.de
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//Frankfurt, Germany, 2005
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//
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//this file is contributed by Martin Thelian
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//last major change: $LastChangedDate$ by $LastChangedBy$
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//Revision: $LastChangedRevision$
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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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package de.anomic.server;
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public final class serverSemaphore {
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private long currentValue = 0;
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private long maximumValue = Long.MAX_VALUE;
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public serverSemaphore(final long initialValue) {
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this(initialValue,Long.MAX_VALUE);
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}
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protected serverSemaphore(final long initialValue, final long maxValue) {
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/* some errorhandling */
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if (maxValue < initialValue) {
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throw new IllegalArgumentException("The semaphore maximum value must not be " +
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"greater than the semaphore init value.");
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}
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if (maxValue < 1) {
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throw new IllegalArgumentException("The semaphore maximum value must be greater or equal 1.");
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}
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if (initialValue < 0) {
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throw new IllegalArgumentException("The semaphore initial value must be greater or equal 0.");
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}
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// setting the initial Sempahore Values
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this.currentValue = initialValue;
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this.maximumValue = maxValue;
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}
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public synchronized void P() throws InterruptedException
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{
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this.currentValue-- ;
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if (this.currentValue < 0) {
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try {
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wait();
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} catch(final InterruptedException e) {
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this.currentValue++;
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throw e;
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}
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}
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}
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public synchronized void V() {
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if (this.currentValue+1 == this.maximumValue) {
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throw new IndexOutOfBoundsException("The maximum value of the semaphore was reached");
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}
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this.currentValue++;
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if (this.currentValue <= 0) {
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notify();
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}
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}
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} |