ARTEMIS-3373 Using consistent template terminology under the collections package

artemis-commons/src/main/java/org/apache/activemq/artemis/utils/collections/ArrayResettableIterator.java

@@ -22,9 +22,9 @@ import java.util.Collection;
  * Provides an Array Iterator that is able to reset, allowing you to iterate over the full array.
  * It achieves this though by moving end position mark to the the current cursors position,
  * so it round robins, even with reset.
- * @param <T>
+ * @param <E>
  */
-public class ArrayResettableIterator<T> implements ResettableIterator<T> {
+public class ArrayResettableIterator<E> implements ResettableIterator<E> {
 
    private final Object[] array;
    private int cursor = 0;
@@ -36,7 +36,7 @@ public class ArrayResettableIterator<T> implements ResettableIterator<T> {
       reset();
    }
 
-   public static <T> ResettableIterator<T> iterator(Collection<T> collection) {
+   public static <E> ResettableIterator<E> iterator(Collection<E> collection) {
       return new ArrayResettableIterator<>(collection.toArray());
    }
 
@@ -52,11 +52,12 @@ public class ArrayResettableIterator<T> implements ResettableIterator<T> {
    }
 
    @Override
-   public T next() {
+   public E next() {
       if (!hasNext) {
          throw new IllegalStateException();
       }
-      @SuppressWarnings("unchecked") T result = (T) array[cursor];
+      @SuppressWarnings("unchecked")
+      E result = (E) array[cursor];
       cursor++;
       if (cursor == array.length) {
          cursor = 0;

artemis-commons/src/main/java/org/apache/activemq/artemis/utils/collections/ConcurrentAppendOnlyChunkedList.java

@@ -25,15 +25,15 @@ import java.util.function.IntFunction;
  * This collection is a concurrent append-only list that grows in chunks.<br>
  * It's safe to be used by many threads concurrently and has a max capacity of {@link Integer#MAX_VALUE}.
  */
-public final class ConcurrentAppendOnlyChunkedList<T> {
+public final class ConcurrentAppendOnlyChunkedList<E> {
 
-   private static final class AtomicChunk<T> extends AtomicReferenceArray<T> {
+   private static final class AtomicChunk<E> extends AtomicReferenceArray<E> {
 
-      AtomicChunk<T> next = null;
+      AtomicChunk<E> next = null;
-      final AtomicChunk<T> prev;
+      final AtomicChunk<E> prev;
       final int index;
 
-      AtomicChunk(int index, AtomicChunk<T> prev, int length) {
+      AtomicChunk(int index, AtomicChunk<E> prev, int length) {
          super(length);
          this.index = index;
          this.prev = prev;
@@ -48,9 +48,9 @@ public final class ConcurrentAppendOnlyChunkedList<T> {
 
    private final int chunkSizeLog2;
 
-   private AtomicChunk<T> firstBuffer = null;
+   private AtomicChunk<E> firstBuffer = null;
 
-   private AtomicChunk<T> lastBuffer = null;
+   private AtomicChunk<E> lastBuffer = null;
 
    //it is both the current index of the next element to be claimed and the current size of the collection
    //it's using a parity bit to mark the rotation state ie size === lastIndex >> 1
@@ -86,8 +86,8 @@ public final class ConcurrentAppendOnlyChunkedList<T> {
    /**
     * It appends {@code elements} to the collection.
     */
-   public void addAll(T[] elements) {
+   public void addAll(E[] elements) {
-      for (T e : elements) {
+      for (E e : elements) {
          add(e);
       }
    }
@@ -95,7 +95,7 @@ public final class ConcurrentAppendOnlyChunkedList<T> {
    /**
     * Returns the element at the specified position in this collection or {@code null} if not found.
     */
-   public T get(int index) {
+   public E get(int index) {
       if (index < 0) {
          return null;
       }
@@ -104,7 +104,7 @@ public final class ConcurrentAppendOnlyChunkedList<T> {
       if (index >= lastIndex) {
          return null;
       }
-      final AtomicChunk<T> buffer;
+      final AtomicChunk<E> buffer;
       final int offset;
       if (index >= chunkSize) {
          offset = index & chunkMask;
@@ -121,20 +121,20 @@ public final class ConcurrentAppendOnlyChunkedList<T> {
     * Implements a lock-free version of the optimization used on {@link java.util.LinkedList#get(int)} to speed up queries
     * ie backward search of a node if needed.
     */
-   private AtomicChunk<T> getChunkOf(final int index, final long lastIndex) {
+   private AtomicChunk<E> getChunkOf(final int index, final long lastIndex) {
       final int chunkSizeLog2 = this.chunkSizeLog2;
       //fast division by a power of 2
       final int chunkIndex = index >> chunkSizeLog2;
       //size is never allowed to be > Integer.MAX_VALUE
       final int lastChunkIndex = (int) lastIndex >> chunkSizeLog2;
       int distance = chunkIndex;
-      AtomicChunk<T> buffer = null;
+      AtomicChunk<E> buffer = null;
       boolean forward = true;
       int distanceFromLast = lastChunkIndex - chunkIndex;
       //it's worth to go backward from lastChunkIndex?
       //trying first to check against the value we already have: if it won't worth, won't make sense to load the lastBuffer
       if (distanceFromLast < distance) {
-         final AtomicChunk<T> lastBuffer = this.lastBuffer;
+         final AtomicChunk<E> lastBuffer = this.lastBuffer;
          //lastBuffer is a potential moving, always increasing, target ie better to re-check the distance
          distanceFromLast = lastBuffer.index - chunkIndex;
          if (distanceFromLast < distance) {
@@ -161,7 +161,7 @@ public final class ConcurrentAppendOnlyChunkedList<T> {
     *
     * @throws NullPointerException if {@code e} is {@code null}
     **/
-   public void add(T e) {
+   public void add(E e) {
       Objects.requireNonNull(e);
       while (true) {
          final long lastIndex = this.lastIndex;
@@ -174,7 +174,7 @@ public final class ConcurrentAppendOnlyChunkedList<T> {
             throw new IllegalStateException("can't add more then " + Integer.MAX_VALUE + " elements");
          }
          //load acquire the current lastBuffer
-         final AtomicChunk<T> lastBuffer = this.lastBuffer;
+         final AtomicChunk<E> lastBuffer = this.lastBuffer;
          final int offset = (int) (validLastIndex & chunkMask);
          //only the first attempt to add an element to a chunk can attempt to resize
          if (offset == 0) {
@@ -190,12 +190,12 @@ public final class ConcurrentAppendOnlyChunkedList<T> {
       }
    }
 
-   private boolean addChunkAndElement(AtomicChunk<T> lastBuffer, long lastIndex, long validLastIndex, T element) {
+   private boolean addChunkAndElement(AtomicChunk<E> lastBuffer, long lastIndex, long validLastIndex, E element) {
       // adding 1 will set the lower bit
       if (!LAST_INDEX_UPDATER.compareAndSet(this, lastIndex, lastIndex + 1)) {
          return false;
       }
-      final AtomicChunk<T> newChunk;
+      final AtomicChunk<E> newChunk;
       try {
          final int index = (int) (validLastIndex >> chunkSizeLog2);
          newChunk = new AtomicChunk<>(index, lastBuffer, chunkSize);
@@ -222,7 +222,7 @@ public final class ConcurrentAppendOnlyChunkedList<T> {
       return true;
    }
 
-   public T[] toArray(IntFunction<T[]> arrayAllocator) {
+   public E[] toArray(IntFunction<E[]> arrayAllocator) {
       return toArray(arrayAllocator, 0);
    }
 
@@ -231,21 +231,21 @@ public final class ConcurrentAppendOnlyChunkedList<T> {
     * sequence (from first to last element).<br>
     * {@code arrayAllocator} will be used to instantiate the array of the correct size with the right runtime type.
     */
-   public T[] toArray(IntFunction<T[]> arrayAllocator, int startIndex) {
+   public E[] toArray(IntFunction<E[]> arrayAllocator, int startIndex) {
       if (startIndex < 0) {
          throw new ArrayIndexOutOfBoundsException("startIndex must be >= 0");
       }
       final long lastIndex = getValidLastIndex();
       assert lastIndex <= Integer.MAX_VALUE;
       final int size = (int) lastIndex;
-      final T[] elements = arrayAllocator.apply(size);
+      final E[] elements = arrayAllocator.apply(size);
       if (startIndex + size > elements.length) {
          throw new ArrayIndexOutOfBoundsException();
       }
       //fast division by a power of 2
       final int chunkSize = this.chunkSize;
       final int chunks = size > chunkSize ? size >> chunkSizeLog2 : 0;
-      AtomicChunk<T> buffer = firstBuffer;
+      AtomicChunk<E> buffer = firstBuffer;
       int elementIndex = startIndex;
       for (int i = 0; i < chunks; i++) {
          drain(buffer, elements, elementIndex, chunkSize);
@@ -259,16 +259,16 @@ public final class ConcurrentAppendOnlyChunkedList<T> {
    }
 
    //NOTE: lastIndex is being updated BEFORE setting a new value ie on reader side need to spin until a not null value is set
-   private static <T> T pollElement(AtomicChunk<T> buffer, int i) {
+   private static <E> E pollElement(AtomicChunk<E> buffer, int i) {
-      T e;
+      E e;
       while ((e = buffer.get(i)) == null) {
       }
       return e;
    }
 
-   private static <T> void drain(AtomicChunk<T> buffer, T[] elements, int elementNumber, int length) {
+   private static <E> void drain(AtomicChunk<E> buffer, E[] elements, int elementNumber, int length) {
       for (int j = 0; j < length; j++) {
-         final T e = pollElement(buffer, j);
+         final E e = pollElement(buffer, j);
          assert e != null;
          elements[elementNumber] = e;
          elementNumber++;

artemis-commons/src/main/java/org/apache/activemq/artemis/utils/collections/IterableStream.java

@@ -24,7 +24,7 @@ public final class IterableStream {
 
    }
 
-   public static <T> Iterable<T> iterableOf(Stream<T> stream) {
+   public static <E> Iterable<E> iterableOf(Stream<E> stream) {
       return stream::iterator;
    }
 

artemis-commons/src/main/java/org/apache/activemq/artemis/utils/collections/LinkedListImpl.java

@@ -372,30 +372,30 @@ public class LinkedListImpl<E> implements LinkedList<E> {
       throw new IllegalStateException("Cannot find iter to remove");
    }
 
-   private static final class NodeHolder<T> extends Node<T> {
+   private static final class NodeHolder<E> extends Node<E> {
 
-      private final T val;
+      private final E val;
 
       //only the head is allowed to hold a null
-      private NodeHolder(T e) {
+      private NodeHolder(E e) {
          val = e;
       }
 
       @Override
-      protected T val() {
+      protected E val() {
          return val;
       }
    }
 
-   public static class Node<T> {
+   public static class Node<E> {
 
-      private Node<T> next;
+      private Node<E> next;
 
-      private Node<T> prev;
+      private Node<E> prev;
 
       private int iterCount;
 
-      private static <T> Node<T> with(final T o) {
+      private static <E> Node<E> with(final E o) {
          Objects.requireNonNull(o, "Only HEAD nodes are allowed to hold null values");
          if (o instanceof Node) {
             final Node node = (Node) o;
@@ -410,15 +410,15 @@ public class LinkedListImpl<E> implements LinkedList<E> {
       }
 
       @SuppressWarnings("unchecked")
-      protected T val() {
+      protected E val() {
-         return (T) this;
+         return (E) this;
       }
 
-      protected final LinkedListImpl.Node<T> next() {
+      protected final LinkedListImpl.Node<E> next() {
          return next;
       }
 
-      protected final LinkedListImpl.Node<T> prev() {
+      protected final LinkedListImpl.Node<E> prev() {
          return prev;
       }
 

artemis-commons/src/main/java/org/apache/activemq/artemis/utils/collections/LongHashSet.java

@@ -405,14 +405,14 @@ public class LongHashSet extends AbstractSet<Long> implements Serializable {
     */
    @SuppressWarnings("unchecked")
    @Override
-   public <T> T[] toArray(final T[] a) {
+   public <E> E[] toArray(final E[] a) {
       final Class<?> componentType = a.getClass().getComponentType();
       if (!componentType.isAssignableFrom(Long.class)) {
          throw new ArrayStoreException("cannot store Longs in array of type " + componentType);
       }
 
       final int size = size();
-      final T[] arrayCopy = a.length >= size ? a : (T[]) Array.newInstance(componentType, size);
+      final E[] arrayCopy = a.length >= size ? a : (E[]) Array.newInstance(componentType, size);
       copyValues(arrayCopy);
 
       return arrayCopy;

artemis-commons/src/main/java/org/apache/activemq/artemis/utils/collections/MultiIterator.java

@@ -21,11 +21,11 @@ import java.util.Iterator;
 /**
  * Provides an Iterator that works over multiple underlying iterators.
  *
- * @param <T> type of the class of the iterator.
+ * @param <E> type of the class of the iterator.
  */
-public class MultiIterator<T> extends MultiIteratorBase<T, Iterator<T>> {
+public class MultiIterator<E> extends MultiIteratorBase<E, Iterator<E>> {
 
-   public MultiIterator(Iterator<T>[] iterators) {
+   public MultiIterator(Iterator<E>[] iterators) {
       super(iterators);
    }
 }

artemis-commons/src/main/java/org/apache/activemq/artemis/utils/collections/MultiIteratorBase.java

@@ -21,10 +21,10 @@ import java.util.Iterator;
 /**
  * Provides an Abstract Iterator that works over multiple underlying iterators.
  *
- * @param <T> type of the class of the iterator.
+ * @param <E> type of the class of the iterator.
  * @param <I> type of the iterator
  */
-abstract class MultiIteratorBase<T, I extends Iterator<T>> implements Iterator<T> {
+abstract class MultiIteratorBase<E, I extends Iterator<E>> implements Iterator<E> {
 
    private final I[] iterators;
    private int index = -1;
@@ -52,7 +52,7 @@ abstract class MultiIteratorBase<T, I extends Iterator<T>> implements Iterator<T
    }
 
    @Override
-   public T next() {
+   public E next() {
       while (true) {
          if (index != -1) {
             I currentIterator = get(index);

artemis-commons/src/main/java/org/apache/activemq/artemis/utils/collections/MultiResettableIterator.java

@@ -20,11 +20,11 @@ package org.apache.activemq.artemis.utils.collections;
  * Extends MultiIterator, adding the ability if the underlying iterators are resettable, then its self can reset.
  * It achieves this by going back to the first iterator, and as moves to another iterator it resets it.
  *
- * @param <T> type of the class of the iterator.
+ * @param <E> type of the class of the iterator.
  */
-public class MultiResettableIterator<T> extends MultiIteratorBase<T, ResettableIterator<T>> implements ResettableIterator<T> {
+public class MultiResettableIterator<E> extends MultiIteratorBase<E, ResettableIterator<E>> implements ResettableIterator<E> {
 
-   public MultiResettableIterator(ResettableIterator<T>[] iterators) {
+   public MultiResettableIterator(ResettableIterator<E>[] iterators) {
       super(iterators);
    }
 

artemis-commons/src/main/java/org/apache/activemq/artemis/utils/collections/PriorityCollection.java

@@ -38,30 +38,30 @@ import java.util.stream.Collectors;
  *
  * Methods getArray, setArray MUST never be exposed, and all array modifications must go through these.
  *
- * @param <T> The type this class may hold, this is generic as can be anything that extends PriorityAware.
+ * @param <E> The type this class may hold, this is generic as can be anything that extends PriorityAware.
  */
-public class PriorityCollection<T extends PriorityAware> extends AbstractCollection<T> {
+public class PriorityCollection<E extends PriorityAware> extends AbstractCollection<E> {
 
-   private final Supplier<Collection<T>> supplier;
+   private final Supplier<Collection<E>> supplier;
-   private volatile PriorityHolder<T>[] priorityHolders = newPrioritySetArrayInstance(0);
+   private volatile PriorityHolder<E>[] priorityHolders = newPrioritySetArrayInstance(0);
    private volatile int size;
 
-   private void setArray(PriorityHolder<T>[] priorityHolders) {
+   private void setArray(PriorityHolder<E>[] priorityHolders) {
       this.priorityHolders = priorityHolders;
    }
 
-   private PriorityHolder<T>[] getArray() {
+   private PriorityHolder<E>[] getArray() {
       return priorityHolders;
    }
 
 
-   public PriorityCollection(Supplier<Collection<T>> supplier) {
+   public PriorityCollection(Supplier<Collection<E>> supplier) {
       this.supplier = supplier;
    }
 
    @SuppressWarnings("unchecked")
-   private static <T> PriorityHolder<T>[] newPrioritySetArrayInstance(int length) {
+   private static <E> PriorityHolder<E>[] newPrioritySetArrayInstance(int length) {
-      return (PriorityHolder<T>[]) Array.newInstance(PriorityHolder.class, length);
+      return (PriorityHolder<E>[]) Array.newInstance(PriorityHolder.class, length);
    }
 
    @Override
@@ -75,20 +75,20 @@ public class PriorityCollection<T extends PriorityAware> extends AbstractCollect
    }
 
    public Set<Integer> getPriorites() {
-      PriorityHolder<T>[] snapshot = getArray();
+      PriorityHolder<E>[] snapshot = getArray();
       return Arrays.stream(snapshot).map(PriorityAware::getPriority).collect(Collectors.toSet());
    }
 
    @Override
-   public Iterator<T> iterator() {
+   public Iterator<E> iterator() {
-      Iterator<T>[] iterators = getIterators();
+      Iterator<E>[] iterators = getIterators();
       return new MultiIterator<>(iterators);
    }
 
-   private Iterator<T>[] getIterators() {
+   private Iterator<E>[] getIterators() {
-      PriorityHolder<T>[] snapshot = this.getArray();
+      PriorityHolder<E>[] snapshot = this.getArray();
       int size = snapshot.length;
-      Iterator<T>[] iterators = newIteratorArrayInstance(size);
+      Iterator<E>[] iterators = newIteratorArrayInstance(size);
       for (int i = 0; i < size; i++) {
          iterators[i] = snapshot[i].getValues().iterator();
       }
@@ -96,18 +96,18 @@ public class PriorityCollection<T extends PriorityAware> extends AbstractCollect
    }
 
    @SuppressWarnings("unchecked")
-   private static <T> Iterator<T>[] newIteratorArrayInstance(int length) {
+   private static <E> Iterator<E>[] newIteratorArrayInstance(int length) {
-      return (Iterator<T>[]) Array.newInstance(Iterator.class, length);
+      return (Iterator<E>[]) Array.newInstance(Iterator.class, length);
    }
 
-   public ResettableIterator<T> resettableIterator() {
+   public ResettableIterator<E> resettableIterator() {
-      return new MultiResettableIterator<T>(getResettableIterators());
+      return new MultiResettableIterator<E>(getResettableIterators());
    }
 
-   private ResettableIterator<T>[] getResettableIterators() {
+   private ResettableIterator<E>[] getResettableIterators() {
-      PriorityHolder<T>[] snapshot = this.getArray();
+      PriorityHolder<E>[] snapshot = this.getArray();
       int size = snapshot.length;
-      ResettableIterator<T>[] iterators = newResettableIteratorArrayInstance(size);
+      ResettableIterator<E>[] iterators = newResettableIteratorArrayInstance(size);
       for (int i = 0; i < size; i++) {
          iterators[i] = ArrayResettableIterator.iterator(snapshot[i].getValues());
       }
@@ -115,28 +115,28 @@ public class PriorityCollection<T extends PriorityAware> extends AbstractCollect
    }
 
    @SuppressWarnings("unchecked")
-   private static <T> ResettableIterator<T>[] newResettableIteratorArrayInstance(int length) {
+   private static <E> ResettableIterator<E>[] newResettableIteratorArrayInstance(int length) {
-      return (ResettableIterator<T>[]) Array.newInstance(ResettableIterator.class, length);
+      return (ResettableIterator<E>[]) Array.newInstance(ResettableIterator.class, length);
    }
 
    @Override
-   public void forEach(Consumer<? super T> action) {
+   public void forEach(Consumer<? super E> action) {
       Objects.requireNonNull(action);
-      PriorityHolder<T>[] current = getArray();
+      PriorityHolder<E>[] current = getArray();
       int len = current.length;
       for (int i = 0; i < len; ++i) {
          current[i].getValues().forEach(action);
       }
    }
 
-   private Collection<T> getCollection(int priority, boolean createIfMissing) {
+   private Collection<E> getCollection(int priority, boolean createIfMissing) {
-      PriorityHolder<T>[] current = getArray();
+      PriorityHolder<E>[] current = getArray();
       int low = 0;
       int high = current.length - 1;
 
       while (low <= high) {
          int mid = (low + high) >>> 1;
-         PriorityHolder<T> midVal = current[mid];
+         PriorityHolder<E> midVal = current[mid];
 
          if (midVal.getPriority() > priority)
             low = mid + 1;
@@ -147,14 +147,14 @@ public class PriorityCollection<T extends PriorityAware> extends AbstractCollect
       }
 
       if (createIfMissing) {
-         PriorityHolder<T>[] newArray = newPrioritySetArrayInstance(current.length + 1);
+         PriorityHolder<E>[] newArray = newPrioritySetArrayInstance(current.length + 1);
          if (low > 0) {
             System.arraycopy(current, 0, newArray, 0, low);
          }
          if (current.length - low > 0) {
             System.arraycopy(current, low, newArray, low + 1, current.length - low);
          }
-         newArray[low] = new PriorityHolder<T>(priority, supplier);
+         newArray[low] = new PriorityHolder<E>(priority, supplier);
          setArray(newArray);
          return newArray[low].getValues();
       }
@@ -162,17 +162,17 @@ public class PriorityCollection<T extends PriorityAware> extends AbstractCollect
    }
 
    @Override
-   public synchronized boolean add(T t) {
+   public synchronized boolean add(E e) {
       if (size() == Integer.MAX_VALUE) return false;
-      boolean result = addInternal(t);
+      boolean result = addInternal(e);
       calcSize();
       return result;
    }
 
-   private boolean addInternal(T t) {
+   private boolean addInternal(E e) {
-      if (t == null) return false;
+      if (e == null) return false;
-      Collection<T> priority = getCollection(t.getPriority(), true);
+      Collection<E> priority = getCollection(e.getPriority(), true);
-      return priority.add(t);
+      return priority.add(e);
    }
 
    @Override
@@ -185,7 +185,7 @@ public class PriorityCollection<T extends PriorityAware> extends AbstractCollect
    private boolean removeInternal(Object o) {
       if (o instanceof PriorityAware) {
          PriorityAware priorityAware = (PriorityAware) o;
-         Collection<T> priority = getCollection(priorityAware.getPriority(), false);
+         Collection<E> priority = getCollection(priorityAware.getPriority(), false);
          boolean result = priority != null && priority.remove(priorityAware);
          if (priority != null && priority.isEmpty()) {
             removeCollection(priorityAware.getPriority());
@@ -196,22 +196,22 @@ public class PriorityCollection<T extends PriorityAware> extends AbstractCollect
       }
    }
 
-   private Collection<T> removeCollection(int priority) {
+   private Collection<E> removeCollection(int priority) {
-      PriorityHolder<T>[] current = getArray();
+      PriorityHolder<E>[] current = getArray();
       int len = current.length;
       int low = 0;
       int high = len - 1;
 
       while (low <= high) {
          int mid = (low + high) >>> 1;
-         PriorityHolder<T> midVal = current[mid];
+         PriorityHolder<E> midVal = current[mid];
 
          if (midVal.getPriority() > priority)
             low = mid + 1;
          else if (midVal.getPriority() < priority)
             high = mid - 1;
          else {
-            PriorityHolder<T>[] newArray = newPrioritySetArrayInstance(len - 1);
+            PriorityHolder<E>[] newArray = newPrioritySetArrayInstance(len - 1);
             System.arraycopy(current, 0, newArray, 0, mid);
             System.arraycopy(current, mid + 1, newArray, mid, len - mid - 1);
             setArray(newArray);
@@ -231,11 +231,11 @@ public class PriorityCollection<T extends PriorityAware> extends AbstractCollect
    }
 
    @Override
-   public synchronized boolean addAll(Collection<? extends T> c) {
+   public synchronized boolean addAll(Collection<? extends E> c) {
       Objects.requireNonNull(c);
       if (size() >= Integer.MAX_VALUE - c.size()) return false;
       boolean modified = false;
-      for (T e : c)
+      for (E e : c)
          if (addInternal(e))
             modified = true;
       calcSize();
@@ -259,8 +259,8 @@ public class PriorityCollection<T extends PriorityAware> extends AbstractCollect
    public synchronized boolean retainAll(Collection<?> c) {
       Objects.requireNonNull(c);
       boolean modified = false;
-      PriorityHolder<T>[] snapshot = getArray();
+      PriorityHolder<E>[] snapshot = getArray();
-      for (PriorityHolder<T> priorityHolder : snapshot) {
+      for (PriorityHolder<E> priorityHolder : snapshot) {
          if (priorityHolder.getValues().retainAll(c)) {
             modified = true;
             if (priorityHolder.getValues().isEmpty()) {
@@ -274,8 +274,8 @@ public class PriorityCollection<T extends PriorityAware> extends AbstractCollect
 
    @Override
    public synchronized void clear() {
-      PriorityHolder<T>[] snapshot = getArray();
+      PriorityHolder<E>[] snapshot = getArray();
-      for (PriorityHolder<T> priorityHolder : snapshot) {
+      for (PriorityHolder<E> priorityHolder : snapshot) {
          priorityHolder.getValues().clear();
       }
       calcSize();
@@ -288,14 +288,14 @@ public class PriorityCollection<T extends PriorityAware> extends AbstractCollect
 
    public boolean contains(PriorityAware priorityAware) {
       if (priorityAware == null) return false;
-      Collection<T> prioritySet = getCollection(priorityAware.getPriority(), false);
+      Collection<E> prioritySet = getCollection(priorityAware.getPriority(), false);
       return prioritySet != null && prioritySet.contains(priorityAware);
    }
 
    private void calcSize() {
-      PriorityHolder<T>[] current = getArray();
+      PriorityHolder<E>[] current = getArray();
       int size = 0;
-      for (PriorityHolder<T> priorityHolder : current) {
+      for (PriorityHolder<E> priorityHolder : current) {
          size += priorityHolder.getValues().size();
       }
       this.size = size;

artemis-commons/src/main/java/org/apache/activemq/artemis/utils/collections/PriorityLinkedList.java

@@ -23,15 +23,15 @@ import java.util.function.ToLongFunction;
  * and allows adding and removing of elements at both ends, and peeking.<br>
  * Only {@link #size()} and {@link #isEmpty()} are safe to be called concurrently.
  */
-public interface PriorityLinkedList<T> {
+public interface PriorityLinkedList<E> {
 
-   void addHead(T t, int priority);
+   void addHead(E e, int priority);
 
-   void addTail(T t, int priority);
+   void addTail(E e, int priority);
 
-   void addSorted(T t, int priority);
+   void addSorted(E e, int priority);
 
-   T poll();
+   E poll();
 
    void clear();
 
@@ -39,9 +39,9 @@ public interface PriorityLinkedList<T> {
     * @see LinkedList#setIDSupplier(ToLongFunction)
     * @param supplier
     */
-   void setIDSupplier(ToLongFunction<T> supplier);
+   void setIDSupplier(ToLongFunction<E> supplier);
 
-   T removeWithID(long id);
+   E removeWithID(long id);
 
    /**
     * Returns the size of this list.<br>
@@ -49,7 +49,7 @@ public interface PriorityLinkedList<T> {
     */
    int size();
 
-   LinkedListIterator<T> iterator();
+   LinkedListIterator<E> iterator();
 
    /**
     * Returns {@code true} if empty, {@code false} otherwise.<br>

artemis-commons/src/main/java/org/apache/activemq/artemis/utils/collections/PriorityLinkedListImpl.java

@@ -27,11 +27,11 @@ import java.util.function.ToLongFunction;
  * <p>
  * It implements this by maintaining an individual LinkedBlockingDeque for each priority level.
  */
-public class PriorityLinkedListImpl<T> implements PriorityLinkedList<T> {
+public class PriorityLinkedListImpl<E> implements PriorityLinkedList<E> {
 
    private static final AtomicIntegerFieldUpdater<PriorityLinkedListImpl> SIZE_UPDATER = AtomicIntegerFieldUpdater.newUpdater(PriorityLinkedListImpl.class, "size");
 
-   protected LinkedListImpl<T>[] levels;
+   protected LinkedListImpl<E>[] levels;
 
    private volatile int size;
 
@@ -46,8 +46,8 @@ public class PriorityLinkedListImpl<T> implements PriorityLinkedList<T> {
    }
 
 
-   public PriorityLinkedListImpl(final int priorities, Comparator<T> comparator) {
+   public PriorityLinkedListImpl(final int priorities, Comparator<E> comparator) {
-      levels = (LinkedListImpl<T>[]) Array.newInstance(LinkedListImpl.class, priorities);
+      levels = (LinkedListImpl<E>[]) Array.newInstance(LinkedListImpl.class, priorities);
 
       for (int i = 0; i < priorities; i++) {
          levels[i] = new LinkedListImpl<>(comparator);
@@ -70,45 +70,45 @@ public class PriorityLinkedListImpl<T> implements PriorityLinkedList<T> {
    }
 
    @Override
-   public void addHead(final T t, final int priority) {
+   public void addHead(final E e, final int priority) {
       checkHighest(priority);
 
-      levels[priority].addHead(t);
+      levels[priority].addHead(e);
 
       exclusiveIncrementSize(1);
    }
 
    @Override
-   public void addTail(final T t, final int priority) {
+   public void addTail(final E e, final int priority) {
       checkHighest(priority);
 
-      levels[priority].addTail(t);
+      levels[priority].addTail(e);
 
       exclusiveIncrementSize(1);
    }
 
    @Override
-   public void addSorted(T t, int priority) {
+   public void addSorted(E e, int priority) {
       checkHighest(priority);
 
-      levels[priority].addSorted(t);
+      levels[priority].addSorted(e);
 
       exclusiveIncrementSize(1);
    }
 
    @Override
-   public void setIDSupplier(ToLongFunction<T> supplier) {
+   public void setIDSupplier(ToLongFunction<E> supplier) {
-      for (LinkedList<T> list : levels) {
+      for (LinkedList<E> list : levels) {
          list.setIDSupplier(supplier);
       }
    }
 
    @Override
-   public T removeWithID(long id) {
+   public E removeWithID(long id) {
       // we start at 4 just as an optimization, since most times we only use level 4 as the level on messages
       if (levels.length > 4) {
          for (int l = 4; l < levels.length; l++) {
-            T removed = levels[l].removeWithID(id);
+            E removed = levels[l].removeWithID(id);
             if (removed != null) {
                exclusiveIncrementSize(-1);
                return removed;
@@ -117,7 +117,7 @@ public class PriorityLinkedListImpl<T> implements PriorityLinkedList<T> {
       }
 
       for (int l = Math.min(3, levels.length); l >= 0; l--) {
-         T removed = levels[l].removeWithID(id);
+         E removed = levels[l].removeWithID(id);
          if (removed != null) {
             exclusiveIncrementSize(-1);
             return removed;
@@ -129,8 +129,8 @@ public class PriorityLinkedListImpl<T> implements PriorityLinkedList<T> {
 
 
    @Override
-   public T poll() {
+   public E poll() {
-      T t = null;
+      E e = null;
 
       // We are just using a simple prioritization algorithm:
       // Highest priority refs always get returned first.
@@ -139,12 +139,12 @@ public class PriorityLinkedListImpl<T> implements PriorityLinkedList<T> {
       // TODO - A better prioritization algorithm
 
       for (int i = highestPriority; i >= 0; i--) {
-         LinkedListImpl<T> ll = levels[i];
+         LinkedListImpl<E> ll = levels[i];
 
          if (ll.size() != 0) {
-            t = ll.poll();
+            e = ll.poll();
 
-            if (t != null) {
+            if (e != null) {
                exclusiveIncrementSize(-1);
 
                if (ll.size() == 0) {
@@ -158,12 +158,12 @@ public class PriorityLinkedListImpl<T> implements PriorityLinkedList<T> {
          }
       }
 
-      return t;
+      return e;
    }
 
    @Override
    public void clear() {
-      for (LinkedListImpl<T> list : levels) {
+      for (LinkedListImpl<E> list : levels) {
          list.clear();
       }
 
@@ -189,17 +189,17 @@ public class PriorityLinkedListImpl<T> implements PriorityLinkedList<T> {
    }
 
    @Override
-   public LinkedListIterator<T> iterator() {
+   public LinkedListIterator<E> iterator() {
       return new PriorityLinkedListIterator();
    }
 
-   private class PriorityLinkedListIterator implements LinkedListIterator<T> {
+   private class PriorityLinkedListIterator implements LinkedListIterator<E> {
 
       private int index;
 
-      private final LinkedListIterator<T>[] cachedIters = new LinkedListIterator[levels.length];
+      private final LinkedListIterator<E>[] cachedIters = new LinkedListIterator[levels.length];
 
-      private LinkedListIterator<T> lastIter;
+      private LinkedListIterator<E> lastIter;
 
       private int resetCount = lastReset;
 
@@ -229,7 +229,7 @@ public class PriorityLinkedListImpl<T> implements PriorityLinkedList<T> {
             closed = true;
             lastIter = null;
 
-            for (LinkedListIterator<T> iter : cachedIters) {
+            for (LinkedListIterator<E> iter : cachedIters) {
                if (iter != null) {
                   iter.close();
                }
@@ -274,7 +274,7 @@ public class PriorityLinkedListImpl<T> implements PriorityLinkedList<T> {
       }
 
       @Override
-      public T next() {
+      public E next() {
          if (lastIter == null) {
             throw new NoSuchElementException();
          }

artemis-commons/src/main/java/org/apache/activemq/artemis/utils/collections/SparseArrayLinkedList.java

@@ -34,12 +34,12 @@ import java.util.function.Predicate;
  * From the memory footprint's point of view, this list won't remove the last remaining array although empty to optimize
  * the case where its capacity would be enough to hold incoming elements, hence saving a new array allocation.
  */
-public final class SparseArrayLinkedList<T> {
+public final class SparseArrayLinkedList<E> {
 
    // the whole chunk fit into 1 or 2 cache lines depending if JVM COOPS are used
    private static final int SPARSE_ARRAY_DEFAULT_CAPACITY = 16;
 
-   private static final class SparseArray<T> {
+   private static final class SparseArray<E> {
 
       private final Object[] elements;
       private int size;
@@ -52,18 +52,18 @@ public final class SparseArrayLinkedList<T> {
          tail = 0;
       }
 
-      private boolean add(T e) {
+      private boolean add(E e) {
          final int capacity = elements.length;
          if (tail == capacity) {
             return false;
          }
-         elements[tail] = (T) e;
+         elements[tail] = (E) e;
          tail++;
          size++;
          return true;
       }
 
-      private int remove(Predicate<? super T> filter) {
+      private int remove(Predicate<? super E> filter) {
          if (size == 0) {
             // this shouldn't happen: the chunk should be removed if empty
             return 0;
@@ -75,7 +75,7 @@ public final class SparseArrayLinkedList<T> {
          int visited = 0;
          final int originalSize = size;
          for (int i = 0, capacity = elements.length; i < capacity; i++) {
-            final T e = (T) elements[i];
+            final E e = (E) elements[i];
             if (e != null) {
                if (filter.test(e)) {
                   elements[i] = null;
@@ -100,7 +100,7 @@ public final class SparseArrayLinkedList<T> {
          return removed;
       }
 
-      public int clear(Consumer<? super T> consumer) {
+      public int clear(Consumer<? super E> consumer) {
          final int originalSize = size;
          if (originalSize == 0) {
             return 0;
@@ -108,7 +108,7 @@ public final class SparseArrayLinkedList<T> {
          int visited = 0;
          final Object[] elements = this.elements;
          for (int i = 0, capacity = elements.length; i < capacity; i++) {
-            final T e = (T) elements[i];
+            final E e = (E) elements[i];
             if (e != null) {
                if (consumer != null) {
                   consumer.accept(e);
@@ -131,14 +131,14 @@ public final class SparseArrayLinkedList<T> {
       }
    }
 
-   public static <T> long removeFromSparseArrayList(List<SparseArray<T>> sparseArrayList, Predicate<? super T> filter) {
+   public static <E> long removeFromSparseArrayList(List<SparseArray<E>> sparseArrayList, Predicate<? super E> filter) {
       if (filter == null) {
          return 0;
       }
       long removed = 0;
-      Iterator<SparseArray<T>> iter = sparseArrayList.iterator();
+      Iterator<SparseArray<E>> iter = sparseArrayList.iterator();
       while (iter.hasNext()) {
-         final SparseArray<T> sparseArray = iter.next();
+         final SparseArray<E> sparseArray = iter.next();
          final int justRemoved = sparseArray.remove(filter);
          removed += justRemoved;
          if (justRemoved > 0) {
@@ -153,23 +153,23 @@ public final class SparseArrayLinkedList<T> {
       return removed;
    }
 
-   public static <T> void addToSparseArrayList(List<SparseArray<T>> sparseArrayList, T e, int sparseArrayCapacity) {
+   public static <E> void addToSparseArrayList(List<SparseArray<E>> sparseArrayList, E e, int sparseArrayCapacity) {
       final int size = sparseArrayList.size();
       // LinkedList::get(size-1) is fast as LinkedList::getLast
       if (size == 0 || !sparseArrayList.get(size - 1).add(e)) {
-         final SparseArray<T> sparseArray = new SparseArray<>(sparseArrayCapacity);
+         final SparseArray<E> sparseArray = new SparseArray<>(sparseArrayCapacity);
          sparseArray.add(e);
          sparseArrayList.add(sparseArray);
       }
    }
 
-   public static <T> long clearSparseArrayList(List<SparseArray<T>> sparseArrayList, Consumer<? super T> consumer) {
+   public static <E> long clearSparseArrayList(List<SparseArray<E>> sparseArrayList, Consumer<? super E> consumer) {
       final int size = sparseArrayList.size();
       long count = 0;
       if (size > 0) {
          for (int i = 0; i < size - 1; i++) {
             // LinkedList::remove(0) is fast as LinkedList::getFirst
-            final SparseArray<T> removed = sparseArrayList.remove(0);
+            final SparseArray<E> removed = sparseArrayList.remove(0);
             count += removed.clear(consumer);
          }
          // LinkedList::get(0) is fast as LinkedList::getFirst
@@ -178,7 +178,7 @@ public final class SparseArrayLinkedList<T> {
       return count;
    }
 
-   private final LinkedList<SparseArray<T>> list;
+   private final LinkedList<SparseArray<E>> list;
    private final int sparseArrayCapacity;
    private long size;
 
@@ -198,7 +198,7 @@ public final class SparseArrayLinkedList<T> {
    /**
     * Appends {@code e} to the end of this list.
     */
-   public void add(T e) {
+   public void add(E e) {
       Objects.requireNonNull(e, "e cannot be null");
       addToSparseArrayList(list, e, sparseArrayCapacity);
       size++;
@@ -207,7 +207,7 @@ public final class SparseArrayLinkedList<T> {
    /**
     * Removes any element of the list matching the given predicate.
     */
-   public long remove(Predicate<? super T> filter) {
+   public long remove(Predicate<? super E> filter) {
       if (size == 0) {
          return 0;
       }
@@ -220,7 +220,7 @@ public final class SparseArrayLinkedList<T> {
    /**
     * Clear while consuming (using the given {@code consumer} all the elements of this list.
     */
-   public long clear(Consumer<? super T> consumer) {
+   public long clear(Consumer<? super E> consumer) {
       if (size == 0) {
          return 0;
       }