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104 lines
4.0 KiB
104 lines
4.0 KiB
//serverSemaphore.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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//
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//this file is contributed by Martin Thelian
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//last major change: 24.04.2005
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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.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() {
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this(0,Long.MAX_VALUE);
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}
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public serverSemaphore(long initialValue) {
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this(initialValue,Long.MAX_VALUE);
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}
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protected serverSemaphore(long initialValue, 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(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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} |