Support for a distributed queue primitive.
Change-Id: I13abb93ec1703105ff0137e137738483a5b6a143
diff --git a/core/api/src/main/java/org/onosproject/store/service/DistributedQueue.java b/core/api/src/main/java/org/onosproject/store/service/DistributedQueue.java
new file mode 100644
index 0000000..cc0b00d
--- /dev/null
+++ b/core/api/src/main/java/org/onosproject/store/service/DistributedQueue.java
@@ -0,0 +1,62 @@
+/*
+ * 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;
+
+import java.util.concurrent.CompletableFuture;
+
+/**
+ * A distributed collection designed for holding elements prior to processing.
+ * A queue provides insertion, extraction and inspection operations. The extraction operation
+ * is designed to be non-blocking.
+ *
+ * @param <E> queue entry type
+ */
+public interface DistributedQueue<E> {
+
+ /**
+ * Returns total number of entries in the queue.
+ * @return queue size
+ */
+ long size();
+
+ /**
+ * Returns true if queue has elements in it.
+ * @return true is queue has elements, false otherwise
+ */
+ default boolean isEmpty() {
+ return size() == 0;
+ }
+
+ /**
+ * Inserts an entry into the queue.
+ * @param entry entry to insert
+ */
+ void push(E entry);
+
+ /**
+ * If the queue is non-empty, an entry will be removed from the queue and the returned future
+ * will be immediately completed with it. If queue is empty when this call is made, the returned
+ * future will be eventually completed when an entry is added to the queue.
+ * @return queue entry
+ */
+ CompletableFuture<E> pop();
+
+ /**
+ * Returns an entry from the queue without removing it. If the queue is empty returns null.
+ * @return queue entry or null if queue is empty
+ */
+ E peek();
+}
\ No newline at end of file
diff --git a/core/api/src/main/java/org/onosproject/store/service/DistributedQueueBuilder.java b/core/api/src/main/java/org/onosproject/store/service/DistributedQueueBuilder.java
new file mode 100644
index 0000000..f938b64
--- /dev/null
+++ b/core/api/src/main/java/org/onosproject/store/service/DistributedQueueBuilder.java
@@ -0,0 +1,71 @@
+/*
+ * 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;
+
+/**
+ * Builder for distributed queue.
+ *
+ * @param <E> type queue elements.
+ */
+public interface DistributedQueueBuilder<E> {
+
+ /**
+ * Sets the name of the queue.
+ * <p>
+ * Each queue is identified by a unique name.
+ * </p>
+ * <p>
+ * Note: This is a mandatory parameter.
+ * </p>
+ *
+ * @param name name of the queue
+ * @return this DistributedQueueBuilder for method chaining
+ */
+ DistributedQueueBuilder<E> withName(String name);
+
+ /**
+ * Sets a serializer that can be used to serialize
+ * the elements pushed into the queue. The serializer
+ * builder should be pre-populated with any classes that will be
+ * put into the queue.
+ * <p>
+ * Note: This is a mandatory parameter.
+ * </p>
+ *
+ * @param serializer serializer
+ * @return this DistributedQueueBuilder for method chaining
+ */
+ DistributedQueueBuilder<E> withSerializer(Serializer serializer);
+
+ /**
+ * Disables persistence of queues entries.
+ * <p>
+ * When persistence is disabled, a full cluster restart will wipe out all
+ * queue entries.
+ * </p>
+ * @return this DistributedQueueBuilder for method chaining
+ */
+ DistributedQueueBuilder<E> withPersistenceDisabled();
+
+ /**
+ * Builds a queue based on the configuration options
+ * supplied to this builder.
+ *
+ * @return new distributed queue
+ * @throws java.lang.RuntimeException if a mandatory parameter is missing
+ */
+ DistributedQueue<E> build();
+}
diff --git a/core/api/src/main/java/org/onosproject/store/service/DistributedSet.java b/core/api/src/main/java/org/onosproject/store/service/DistributedSet.java
index 4c9116a..460206e 100644
--- a/core/api/src/main/java/org/onosproject/store/service/DistributedSet.java
+++ b/core/api/src/main/java/org/onosproject/store/service/DistributedSet.java
@@ -1,3 +1,18 @@
+/*
+ * 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;
import java.util.Set;
diff --git a/core/api/src/main/java/org/onosproject/store/service/StorageService.java b/core/api/src/main/java/org/onosproject/store/service/StorageService.java
index 55a07ed..58ac390 100644
--- a/core/api/src/main/java/org/onosproject/store/service/StorageService.java
+++ b/core/api/src/main/java/org/onosproject/store/service/StorageService.java
@@ -56,6 +56,14 @@
<E> DistributedSetBuilder<E> setBuilder();
/**
+ * Creates a new distributed queue builder.
+ *
+ * @param <E> queue entry type
+ * @return builder for an distributed queue
+ */
+ <E> DistributedQueueBuilder<E> queueBuilder();
+
+ /**
* Creates a new AtomicCounterBuilder.
*
* @return atomic counter builder