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2010-06-01T06:58:58Z

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в 18:01, 31 мая 2010

2010-05-31T18:01:46Z

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== An implementation of a producer and consumer that use semaphores to control synchronization. ==



<source lang="java">

import java.util.concurrent.Semaphore;
class Queue {
int value;
static Semaphore semCon = new Semaphore(0);
static Semaphore semProd = new Semaphore(1);
void get() {
try {
semCon.acquire();
} catch (InterruptedException e) {
System.out.println("InterruptedException caught");
}
System.out.println("Got: " + value);
semProd.release();
}
void put(int n) {
try {
semProd.acquire();
} catch (InterruptedException e) {
System.out.println("InterruptedException caught");
}
this.value = n;
System.out.println("Put: " + n);
semCon.release();
}
}
class Producer implements Runnable {
Queue q;
Producer(Queue q) {
this.q = q;
new Thread(this, "Producer").start();
}
public void run() {
for (int i = 0; i < 20; i++)
q.put(i);
}
}
class Consumer implements Runnable {
Queue q;
Consumer(Queue q) {
this.q = q;
new Thread(this, "Consumer").start();
}
public void run() {
for (int i = 0; i < 20; i++)
q.get();
}
}
public class ProdCon {
public static void main(String args[]) {
Queue q = new Queue();
new Consumer(q);
new Producer(q);
}
}

</source>



== A semaphore ==



<source lang="java">

import java.util.concurrent.Semaphore;
public class Main {
public static void main(String args[]) throws Exception {
Semaphore sem = new Semaphore(1, true);
Thread thrdA = new Thread(new SyncOutput(sem, "Message 1"));
Thread thrdB = new Thread(new SyncOutput(sem, "Message 2!"));
thrdA.start();
thrdB.start();
thrdA.join();
thrdB.join();
}
}
class SyncOutput implements Runnable {
Semaphore sem;
String msg;
SyncOutput(Semaphore s, String m) {
sem = s;
msg = m;
}
public void run() {
try {
sem.acquire();
System.out.println(msg);
Thread.sleep(10);
} catch (Exception exc) {
System.out.println("Error Writing File");
}
sem.release();
}
}

</source>



== Semaphore that can allow a specified number of threads to enter, blocking the others. ==



<source lang="java">

/*
* JBoss, Home of Professional Open Source
* Copyright 2005, JBoss Inc., and individual contributors as indicated
* by the @authors tag. See the copyright.txt in the distribution for a
* full listing of individual contributors.
*
* This is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* This software 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this software; if not, write to the Free
* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA, or see the FSF site: http://www.fsf.org.
*/
import java.io.PrintWriter;
import java.io.StringWriter;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.Map;
/**
* Semaphore that can allow a specified number of threads to enter, blocking the
* others. If the specified number of threads is 1, it acts as an exclusive
* semaphore and can be used instead of synchronized blocks
*
* @author
* @version $Revision: 2787 $
*/
interface Sync {
/**
* Acquires this sync
*
* @see #release
* @throws InterruptedException
*/
void acquire() throws InterruptedException;
/**
* Releases this sync
*
* @see #acquire
*/
void release();
}

</source>



== Wait exclusive semaphore with wait - notify primitives ==



<source lang="java">

/*
* JBoss, Home of Professional Open Source
* Copyright 2005, JBoss Inc., and individual contributors as indicated
* by the @authors tag. See the copyright.txt in the distribution for a
* full listing of individual contributors.
*
* This is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* This software 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this software; if not, write to the Free
* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA, or see the FSF site: http://www.fsf.org.
*/
import java.io.PrintWriter;
import java.io.StringWriter;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.Map;
/*
* JBoss, Home of Professional Open Source Copyright 2005, JBoss Inc., and
* individual contributors as indicated by the @authors tag. See the
* copyright.txt in the distribution for a full listing of individual
* contributors.
*
* This is free software; you can redistribute it and/or modify it under the
* terms of the GNU Lesser General Public License as published by the Free
* Software Foundation; either version 2.1 of the License, or (at your option)
* any later version.
*
* This software 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 Lesser General Public License for more
* details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this software; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA, or see the FSF
* site: http://www.fsf.org.
*/
/**
* Wait exclusive semaphore with wait - notify primitives
*
* @author
* @version $Revision: 2787 $
*/
interface WaitSync extends Sync {
/**
* Pone in wait status this sync, until {@link #doNotify} is called to wake it
* up.
*
* @see #doNotify
* @throws InterruptedException
*/
void doWait() throws InterruptedException;
/**
* Wakes up this sync that has been posed in wait status by a {@link #doWait}
* call. If this sync is not waiting, invoking this method should have no
* effect.
*
* @see #doWait
* @throws InterruptedException
*/
void doNotify() throws InterruptedException;
}

</source>

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Admin: 1 версия

в 18:01, 31 мая 2010