66 lines
1.7 KiB
Java
66 lines
1.7 KiB
Java
// Time-stamp: <08 Apr 2008 11:35 queinnec@enseeiht.fr>
|
|
|
|
import java.util.concurrent.locks.Condition;
|
|
import java.util.concurrent.locks.Lock;
|
|
import java.util.concurrent.locks.ReentrantLock;
|
|
|
|
/**
|
|
* Lecteurs/rédacteurs stratégie d'ordonnancement: priorité aux lecteurs,
|
|
* implantation: avec un moniteur.
|
|
*/
|
|
public class LectRed_PrioLecteur implements LectRed {
|
|
|
|
Lock lock;
|
|
Condition requestRead;
|
|
Condition requestWrite;
|
|
boolean activeWriter;
|
|
int activeReaders;
|
|
|
|
public LectRed_PrioLecteur() {
|
|
lock = new ReentrantLock();
|
|
requestRead = lock.newCondition();
|
|
requestWrite = lock.newCondition();
|
|
activeWriter = false;
|
|
activeReaders = 0;
|
|
}
|
|
|
|
public void demanderLecture() throws InterruptedException {
|
|
lock.lock();
|
|
if (activeWriter) {
|
|
requestRead.await();
|
|
}
|
|
activeReaders++;
|
|
lock.unlock();
|
|
}
|
|
|
|
public void terminerLecture() throws InterruptedException {
|
|
lock.lock();
|
|
activeReaders--;
|
|
if (activeReaders == 0) {
|
|
requestWrite.signal();
|
|
}
|
|
lock.unlock();
|
|
}
|
|
|
|
public void demanderEcriture() throws InterruptedException {
|
|
lock.lock();
|
|
while (activeWriter || activeReaders > 0) {
|
|
requestWrite.await();
|
|
}
|
|
activeWriter = true;
|
|
lock.unlock();
|
|
}
|
|
|
|
public void terminerEcriture() throws InterruptedException {
|
|
lock.lock();
|
|
activeWriter = false;
|
|
requestRead.signalAll();
|
|
requestWrite.signalAll();
|
|
lock.unlock();
|
|
}
|
|
|
|
public String nomStrategie() {
|
|
return "Stratégie: Moniteur, prio lecteur.";
|
|
}
|
|
}
|