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final Version

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Obai Albek 2025-05-23 15:57:07 +02:00
parent 9982245715
commit 0d8f596ea1
1 changed files with 110 additions and 126 deletions
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234
pp.A4-HandOverHandLocking/src/main/java/pp/ThreadsafeSimplifiedList.java
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@ -3,137 +3,121 @@ package pp;
import java.util.concurrent.locks.Lock; import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock; import java.util.concurrent.locks.ReentrantLock;
import net.jcip.annotations.ThreadSafe; public class ThreadsafeSimplifiedList<T>
implements SimplifiedList<T> {
@ThreadSafe private Node<T> head;
public class ThreadsafeSimplifiedList<T> implements SimplifiedList<T> { private final Lock listLock = new ReentrantLock();
private Node<T> first;
private final Lock listLock = new ReentrantLock();
private class Node<U> { private class Node<U> {
private U element; private U element;
private Node<U> prev; private Node<U> next;
private Node<U> next; private final Lock nodeLock;
private final Lock lock = new ReentrantLock();
private Node(U element, Node<U> prev, Node<U> next) { private Node(U element, Node<U> prev, Node<U> next) {
super(); super();
this.element = element; this.element = element;
this.prev = prev; this.next = next;
this.next = next; this.nodeLock = new ReentrantLock();
} }
} }
public ThreadsafeSimplifiedList() { /**
super(); * Returns the element at the specified position in this list.
this.first = null; *
} * @param index index of the element to return
* @return the element at the specified position in this list
*/
@Override
public T get(int index) {
this.listLock.lock();
var ptr = this.head;
ptr.nodeLock.lock();
this.listLock.unlock();
for (var i = 0; i < index; i++) {
if (ptr.next != null) {
ptr.next.nodeLock.lock();
var savePtr = ptr;
ptr = ptr.next;
savePtr.nodeLock.unlock();
} else {
throw new IndexOutOfBoundsException(index + " out of bounds");
}
}
/** try {return delay(ptr.element);}
* Returns the element at the specified position in this list. finally { ptr.nodeLock.unlock();}
* }
* @param index index of the element to return
* @return the element at the specified position in this list
*/
@Override
public T get(int index) {
this.listLock.lock();
var ptr = this.first;
ptr.lock.lock();
this.listLock.unlock();
for (var j = 0; j < index; j++) {
if (ptr.next != null) {
ptr.next.lock.lock();
var savePtr = ptr;
ptr = ptr.next;
savePtr.lock.unlock();
} else {
throw new IndexOutOfBoundsException(index + " out of bounds");
}
}
try {
return delay(ptr.element);
} finally {
ptr.lock.unlock();
}
}
/** /**
* Appends the specified element to the end of this list. There are no * Appends the specified element to the end of this list. There are no
* limitations on what elements may be added to this list. * limitations on what elements may be added to this list.
* *
* @param element element to be appended to this list * @param element element to be appended to this list
* @return true * @return true
* @see java.util.Collection#add(Object) * @see java.util.Collection#add(Object)
* *
*/ */
@Override @Override
public boolean add(T element) { public boolean add(T element) {
this.listLock.lock(); this.listLock.lock();
if (this.first != null) { if (this.head != null) {
var ptr = this.first; var ptr = this.head;
ptr.lock.lock(); ptr.nodeLock.lock();
this.listLock.unlock(); this.listLock.unlock();
while (ptr.next != null) { while (ptr.next != null) {
ptr.next.lock.lock(); ptr.next.nodeLock.lock();
var saveNode = ptr; var savePtr = ptr;
ptr = ptr.next; ptr = ptr.next;
saveNode.lock.unlock(); savePtr.nodeLock.unlock();
} }
ptr.next = new Node<>(element, ptr, null); ptr.next = new Node<>(element, ptr, null);
} else { ptr.nodeLock.unlock();
this.first = new Node<>(element, null, null); } else {
this.listLock.unlock(); this.head = new Node<>(element, null, null);
} this.listLock.unlock();
return true; }
} return true;
}
/** /**
* Replaces the element at the specified position in this list with the * Replaces the element at the specified position in this list with the
* specified element. * specified element.
* *
* @param index index of the element to replace * @param index index of the element to replace
* @param element element to be stored at the specified position * @param element element to be stored at the specified position
* @return the element previously at the specified position * @return the element previously at the specified position
*/ */
@Override @Override
public T set(int index, T element) { public T set(int index, T element) {
this.listLock.lock(); this.listLock.lock();
var ptr = this.first; var ptr = this.head;
ptr.lock.lock(); ptr.nodeLock.lock();
this.listLock.unlock(); this.listLock.unlock();
for (var j = 0; j < index; j++) { for (var i = 0; i < index; i++) {
if (ptr.next != null) { if (ptr.next != null) {
ptr.next.lock.lock(); ptr.next.nodeLock.lock();
var saveNode = ptr; var savePtr = ptr;
ptr = ptr.next; ptr = ptr.next;
saveNode.lock.unlock(); savePtr.nodeLock.unlock();
} else { } else
throw new IndexOutOfBoundsException(index + " out of bounds"); throw new IndexOutOfBoundsException(index + " out of bounds");
}
}
try {
var prevElement = ptr.element;
ptr.element = element;
return prevElement;
} finally {
ptr.lock.unlock();
}
}
/** }
* Returns true if this list contains no elements. ptr.element = element;
* ptr.nodeLock.unlock();
* @return true if this list contains no elements return element;
*/ }
@Override
public boolean isEmpty() { /**
this.listLock.lock(); * Returns true if this list contains no elements.
try { *
return this.first == null; * @return true if this list contains no elements
} finally { */
this.listLock.unlock(); @Override
} public boolean isEmpty() {
} this.listLock.lock();
try { return this.head == null; }
finally { this.listLock.unlock();}
}
} }