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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.ReentrantLock;
import net.jcip.annotations.ThreadSafe;
public class ThreadsafeSimplifiedList<T>
implements SimplifiedList<T> {
@ThreadSafe
public class ThreadsafeSimplifiedList<T> implements SimplifiedList<T> {
private Node<T> first;
private final Lock listLock = new ReentrantLock();
private Node<T> head;
private final Lock listLock = new ReentrantLock();
private class Node<U> {
private U element;
private Node<U> prev;
private Node<U> next;
private final Lock lock = new ReentrantLock();
private class Node<U> {
private U element;
private Node<U> next;
private final Lock nodeLock;
private Node(U element, Node<U> prev, Node<U> next) {
super();
this.element = element;
this.prev = prev;
this.next = next;
}
}
private Node(U element, Node<U> prev, Node<U> next) {
super();
this.element = element;
this.next = next;
this.nodeLock = new ReentrantLock();
}
}
public ThreadsafeSimplifiedList() {
super();
this.first = null;
}
/**
* Returns the element at the specified position in this list.
*
* @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");
}
}
/**
* Returns the element at the specified position in this list.
*
* @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();
}
}
try {return delay(ptr.element);}
finally { ptr.nodeLock.unlock();}
}
/**
* Appends the specified element to the end of this list. There are no
* limitations on what elements may be added to this list.
*
* @param element element to be appended to this list
* @return true
* @see java.util.Collection#add(Object)
*
*/
@Override
public boolean add(T element) {
this.listLock.lock();
if (this.first != null) {
var ptr = this.first;
ptr.lock.lock();
this.listLock.unlock();
while (ptr.next != null) {
ptr.next.lock.lock();
var saveNode = ptr;
ptr = ptr.next;
saveNode.lock.unlock();
}
ptr.next = new Node<>(element, ptr, null);
} else {
this.first = new Node<>(element, null, null);
this.listLock.unlock();
}
return true;
}
/**
* Appends the specified element to the end of this list. There are no
* limitations on what elements may be added to this list.
*
* @param element element to be appended to this list
* @return true
* @see java.util.Collection#add(Object)
*
*/
@Override
public boolean add(T element) {
this.listLock.lock();
if (this.head != null) {
var ptr = this.head;
ptr.nodeLock.lock();
this.listLock.unlock();
while (ptr.next != null) {
ptr.next.nodeLock.lock();
var savePtr = ptr;
ptr = ptr.next;
savePtr.nodeLock.unlock();
}
ptr.next = new Node<>(element, ptr, null);
ptr.nodeLock.unlock();
} else {
this.head = new Node<>(element, null, null);
this.listLock.unlock();
}
return true;
}
/**
* Replaces the element at the specified position in this list with the
* specified element.
*
* @param index index of the element to replace
* @param element element to be stored at the specified position
* @return the element previously at the specified position
*/
@Override
public T set(int index, T element) {
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 saveNode = ptr;
ptr = ptr.next;
saveNode.lock.unlock();
} else {
throw new IndexOutOfBoundsException(index + " out of bounds");
}
}
try {
var prevElement = ptr.element;
ptr.element = element;
return prevElement;
} finally {
ptr.lock.unlock();
}
}
/**
* Replaces the element at the specified position in this list with the
* specified element.
*
* @param index index of the element to replace
* @param element element to be stored at the specified position
* @return the element previously at the specified position
*/
@Override
public T set(int index, T element) {
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");
/**
* Returns true if this list contains no elements.
*
* @return true if this list contains no elements
*/
@Override
public boolean isEmpty() {
this.listLock.lock();
try {
return this.first == null;
} finally {
this.listLock.unlock();
}
}
}
ptr.element = element;
ptr.nodeLock.unlock();
return element;
}
/**
* Returns true if this list contains no elements.
*
* @return true if this list contains no elements
*/
@Override
public boolean isEmpty() {
this.listLock.lock();
try { return this.head == null; }
finally { this.listLock.unlock();}
}
}