GOSSIP-53 CRDT types

src/main/java/org/apache/gossip/crdt/GrowOnlySet.java

@@ -0,0 +1,168 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.gossip.crdt;
+
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.Iterator;
+import java.util.LinkedHashSet;
+import java.util.Set;
+
+public class GrowOnlySet<ElementType> implements CrdtSet<ElementType, Set<ElementType>, GrowOnlySet<ElementType>>{
+
+  private final Set<ElementType> hidden = new LinkedHashSet<>();
+  
+  @SuppressWarnings("unused")
+  /*
+   * Used by SerDe
+   */
+  private GrowOnlySet(){
+    
+  }
+  
+  public GrowOnlySet(Set<ElementType> c){
+    hidden.addAll(c);
+  }
+  
+  public GrowOnlySet(Collection<ElementType> c){
+    hidden.addAll(c);
+  }
+  
+  public GrowOnlySet(GrowOnlySet<ElementType> first, GrowOnlySet<ElementType> second){
+    hidden.addAll(first.value());
+    hidden.addAll(second.value());
+  }
+  
+  @Override
+  public GrowOnlySet<ElementType> merge(GrowOnlySet<ElementType> other) {
+    return new GrowOnlySet<>(this, other);
+  }
+
+  @Override
+  public Set<ElementType> value() {
+    Set<ElementType> copy = new LinkedHashSet<>();
+    copy.addAll(hidden);
+    return Collections.unmodifiableSet(copy);
+  }
+  
+  @Override
+  public GrowOnlySet<ElementType> optimize() {
+    return new GrowOnlySet<>(hidden);
+  }
+
+  @Override
+  public int size() {
+    return hidden.size();
+  }
+
+  @Override
+  public boolean isEmpty() {
+    return hidden.isEmpty();
+  }
+
+  @Override
+  public boolean contains(Object o) {
+    return hidden.contains(o);
+  }
+
+  @Override
+  public Iterator<ElementType> iterator() {
+    Set<ElementType> copy = new HashSet<>();
+    copy.addAll(hidden);
+    return copy.iterator();
+  }
+
+  @Override
+  public Object[] toArray() {
+    return hidden.toArray();
+  }
+
+  @Override
+  public <T> T[] toArray(T[] a) {
+    return hidden.toArray(a);
+  }
+
+  @Override
+  public boolean add(ElementType e) {
+    throw new UnsupportedOperationException();
+  }
+
+  @Override
+  public boolean remove(Object o) {
+    throw new UnsupportedOperationException();
+  }
+
+  @Override
+  public boolean containsAll(Collection<?> c) {
+    return hidden.containsAll(c);
+  }
+
+  @Override
+  public boolean addAll(Collection<? extends ElementType> c) {
+    throw new UnsupportedOperationException();
+  }
+
+  @Override
+  public boolean retainAll(Collection<?> c) {
+    throw new UnsupportedOperationException();
+  }
+
+  @Override
+  public boolean removeAll(Collection<?> c) {
+    throw new UnsupportedOperationException();
+  }
+
+  @Override
+  public void clear() {
+    throw new UnsupportedOperationException();
+    
+  }
+
+  @Override
+  public String toString() {
+    return "GrowOnlySet [hidden=" + hidden + "]";
+  }
+
+  @Override
+  public int hashCode() {
+    final int prime = 31;
+    int result = 1;
+    result = prime * result + ((hidden == null) ? 0 : hidden.hashCode());
+    return result;
+  }
+
+  @Override
+  public boolean equals(Object obj) {
+    if (this == obj)
+      return true;
+    if (obj == null)
+      return false;
+    if (getClass() != obj.getClass())
+      return false;
+    @SuppressWarnings("rawtypes")
+    GrowOnlySet other = (GrowOnlySet) obj;
+    if (hidden == null) {
+      if (other.hidden != null)
+        return false;
+    } else if (!hidden.equals(other.hidden))
+      return false;
+    return true;
+  }
+
+}