[ONOS-2809] Support a TransactionalSet data structure
Change-Id: Ia99bc2285b3fea39ee3845f5f6613a45a6a61626
diff --git a/core/api/src/main/java/org/onosproject/store/service/TransactionalSet.java b/core/api/src/main/java/org/onosproject/store/service/TransactionalSet.java
new file mode 100644
index 0000000..97d9fe7
--- /dev/null
+++ b/core/api/src/main/java/org/onosproject/store/service/TransactionalSet.java
@@ -0,0 +1,75 @@
+/*
+ * Copyright 2015 Open Networking Laboratory
+ *
+ * Licensed 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.onosproject.store.service;
+
+/**
+ * Transactional Set data structure.
+ * <p>
+ * A TransactionalSet is implemented with the help of TransactionalMap data structure.
+ * All operations performed on this set within a transaction boundary are invisible externally
+ * until the point when the transaction commits. A commit usually succeeds in the absence of conflicts.
+ *
+ * @param <E> type of element.
+ */
+public interface TransactionalSet<E> {
+
+ /**
+ * Adds the specified element to this set if it is not already present
+ * (optional operation). More formally, adds the specified element
+ * <tt>e</tt> to this set if the set contains no element <tt>e2</tt>
+ * such that
+ * <tt>(e==null ? e2==null : e.equals(e2))</tt>.
+ * If this set already contains the element, the call leaves the set
+ * unchanged and returns <tt>false</tt>. In combination with the
+ * restriction on constructors, this ensures that sets never contain
+ * duplicate elements.
+ *
+ * @param e element to be added to this set
+ * @return <tt>true</tt> if this set did not already contain the specified
+ * element
+ */
+ boolean add(E e);
+
+ /**
+ * Removes the specified element from this set if it is present
+ * (optional operation). More formally, removes an element <tt>e</tt>
+ * such that
+ * <tt>(o==null ? e==null : o.equals(e))</tt>, if
+ * this set contains such an element. Returns <tt>true</tt> if this set
+ * contained the element (or equivalently, if this set changed as a
+ * result of the call). (This set will not contain the element once the
+ * call returns.)
+ *
+ * @param e element to be removed to this set
+ * @return <tt>true</tt> if this set contained the specified element
+ */
+ boolean remove(E e);
+
+ /**
+ * Returns <tt>true</tt> if this set contains the specified element.
+ * More formally, returns <tt>true</tt> if and only if this set
+ * contains an element <tt>e</tt> such that
+ * <tt>(o==null ? e==null : o.equals(e))</tt>.
+ *
+ * @param e element whose presence in this set is to be tested
+ * @return <tt>true</tt> if this set contains the specified element
+ * @throws ClassCastException if the type of the specified element
+ * is incompatible with this set
+ * @throws NullPointerException if the specified element is null and this
+ * set does not permit null elements
+ */
+ boolean contains(E e);
+}
diff --git a/core/store/dist/src/main/java/org/onosproject/store/consistent/impl/DefaultTransactionalSet.java b/core/store/dist/src/main/java/org/onosproject/store/consistent/impl/DefaultTransactionalSet.java
new file mode 100644
index 0000000..11fcb80
--- /dev/null
+++ b/core/store/dist/src/main/java/org/onosproject/store/consistent/impl/DefaultTransactionalSet.java
@@ -0,0 +1,58 @@
+/*
+ * Copyright 2015 Open Networking Laboratory
+ *
+ * Licensed 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.onosproject.store.consistent.impl;
+
+
+import org.onosproject.store.service.Serializer;
+import org.onosproject.store.service.TransactionContext;
+import org.onosproject.store.service.TransactionalMap;
+import org.onosproject.store.service.TransactionalSet;
+
+/**
+ * Default TransactionalSet implementation that provides a repeatable reads
+ * transaction isolation level.
+ *
+ * @param <E> element type.
+ */
+public class DefaultTransactionalSet<E> implements TransactionalSet<E> {
+
+ private TransactionalMap<E, Boolean> map;
+
+ // dummy value to associate with an Object in the backing map
+ private static final Boolean PRESENT = new Boolean(true);
+
+ public DefaultTransactionalSet(
+ String name,
+ TransactionContext txContext,
+ Serializer serializer) {
+ map = txContext.getTransactionalMap(name, serializer);
+ }
+
+ @Override
+ public boolean add(E e) {
+ return map.put(e, PRESENT) == null;
+ }
+
+ @Override
+ public boolean remove(E e) {
+ return map.remove(e) != null;
+ }
+
+ @Override
+ public boolean contains(E e) {
+ return map.get(e) != null;
+ }
+}