Added automatic mastership load balancing. Added comments in patch set.
Change-Id: Ia29dfbdd9d2afcc79b1f25c7690d073e6ad94f61
diff --git a/apps/mlb/pom.xml b/apps/mlb/pom.xml
new file mode 100644
index 0000000..2169237
--- /dev/null
+++ b/apps/mlb/pom.xml
@@ -0,0 +1,45 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+ ~ 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.
+ -->
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+ xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+ xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
+ <modelVersion>4.0.0</modelVersion>
+
+ <parent>
+ <groupId>org.onosproject</groupId>
+ <artifactId>onos-apps</artifactId>
+ <version>1.4.0-SNAPSHOT</version>
+ <relativePath>../pom.xml</relativePath>
+ </parent>
+
+ <artifactId>onos-app-mlb</artifactId>
+ <packaging>bundle</packaging>
+
+ <description>Balances mastership among nodes</description>
+
+ <properties>
+ <onos.app.name>org.onosproject.mlb</onos.app.name>
+ </properties>
+
+ <dependencies>
+ <dependency>
+ <groupId>org.osgi</groupId>
+ <artifactId>org.osgi.compendium</artifactId>
+ </dependency>
+ </dependencies>
+
+</project>
diff --git a/apps/mlb/src/main/java/org/onosproject/mlb/MastershipLoadBalancer.java b/apps/mlb/src/main/java/org/onosproject/mlb/MastershipLoadBalancer.java
new file mode 100644
index 0000000..bcf4e2e
--- /dev/null
+++ b/apps/mlb/src/main/java/org/onosproject/mlb/MastershipLoadBalancer.java
@@ -0,0 +1,165 @@
+/*
+ * 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.mlb;
+
+import com.google.common.util.concurrent.ListenableScheduledFuture;
+import com.google.common.util.concurrent.ListeningScheduledExecutorService;
+import com.google.common.util.concurrent.MoreExecutors;
+import org.apache.felix.scr.annotations.Activate;
+import org.apache.felix.scr.annotations.Component;
+import org.apache.felix.scr.annotations.Deactivate;
+import org.apache.felix.scr.annotations.Reference;
+import org.apache.felix.scr.annotations.ReferenceCardinality;
+import org.onosproject.cluster.ClusterService;
+import org.onosproject.cluster.LeadershipEvent;
+import org.onosproject.cluster.LeadershipEventListener;
+import org.onosproject.cluster.LeadershipService;
+import org.onosproject.cluster.NodeId;
+import org.onosproject.mastership.MastershipAdminService;
+import org.onosproject.mastership.MastershipEvent;
+import org.onosproject.mastership.MastershipListener;
+import org.onosproject.mastership.MastershipService;
+import org.slf4j.Logger;
+
+import java.util.concurrent.Executors;
+import java.util.concurrent.Future;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.concurrent.atomic.AtomicReference;
+
+import static org.slf4j.LoggerFactory.getLogger;
+
+/**
+ * An app to perform automatic load balancing in response to events. Load balancing events are triggered by any
+ * change in mastership and are limited to a frequency of one every 30 seconds, all load balancing is run on an outside
+ * thread executor that must only have one thread due to issues that can occur is multiple balancing events occur in
+ * parallel.
+ */
+@Component(immediate = true)
+public class MastershipLoadBalancer {
+
+ private final Logger log = getLogger(getClass());
+
+ private static final String REBALANCE_MASTERSHIP = "rebalance/mastership";
+
+ private NodeId localId;
+
+ private AtomicBoolean isLeader = new AtomicBoolean(false);
+
+ private AtomicReference<Future> nextTask = new AtomicReference<>();
+
+ @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+ protected MastershipService mastershipService;
+
+ @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+ protected MastershipAdminService mastershipAdminService;
+
+ @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+ protected LeadershipService leadershipService;
+
+ @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+ protected ClusterService clusterService;
+
+ private InnerLeadershipListener leadershipListener = new InnerLeadershipListener();
+
+ /* This listener is used to trigger balancing for any mastership event which will include switches changing state
+ between active and inactive states as well as the same variety of event occurring with ONOS nodes. Must
+ use a listenable executor to ensure events are triggered with no frequency greater than once every 30 seconds.
+ */
+ private InnerMastershipListener mastershipListener = new InnerMastershipListener();
+
+ //Ensures that all executions do not interfere with one another (single thread)
+ private ListeningScheduledExecutorService executorService = MoreExecutors.
+ listeningDecorator(Executors.newSingleThreadScheduledExecutor());
+
+ @Activate
+ public void activate() {
+ mastershipService.addListener(mastershipListener);
+ localId = clusterService.getLocalNode().id();
+ leadershipService.addListener(leadershipListener);
+ leadershipService.runForLeadership(REBALANCE_MASTERSHIP);
+ log.info("Started");
+ }
+
+ @Deactivate
+ public void deactivate() {
+ mastershipService.removeListener(mastershipListener);
+ leadershipService.withdraw(REBALANCE_MASTERSHIP);
+ leadershipService.removeListener(leadershipListener);
+ cancelBalance();
+ executorService.shutdown();
+ log.info("Stopped");
+ }
+
+ private synchronized void processLeadershipChange(NodeId newLeader) {
+ if (newLeader == null) {
+ return;
+ }
+ boolean currLeader = newLeader.equals(localId);
+ if (isLeader.getAndSet(currLeader) != currLeader) {
+ if (currLeader) {
+ scheduleBalance();
+ } else {
+ cancelBalance();
+ }
+ }
+ }
+
+ private void scheduleBalance() {
+ if (isLeader.get() && nextTask.get() == null) {
+
+ ListenableScheduledFuture task = executorService.schedule(mastershipAdminService::balanceRoles, 30,
+ TimeUnit.SECONDS);
+ task.addListener(() -> {
+ log.info("Completed balance roles");
+ nextTask.set(null);
+ }, MoreExecutors.directExecutor()
+ );
+ if (!nextTask.compareAndSet(null, task)) {
+ task.cancel(false);
+ }
+ }
+ }
+
+ private void cancelBalance() {
+ Future task = nextTask.getAndSet(null);
+ if (task != null) {
+ task.cancel(false);
+ }
+ }
+
+ private class InnerMastershipListener implements MastershipListener {
+
+ @Override
+ public void event(MastershipEvent event) {
+ //Sets flag at execution to indicate there is currently a scheduled rebalancing, reverts upon completion
+ scheduleBalance();
+ }
+ }
+
+ private class InnerLeadershipListener implements LeadershipEventListener {
+ @Override
+ public boolean isRelevant(LeadershipEvent event) {
+ return REBALANCE_MASTERSHIP.equals(event.subject().topic());
+ }
+
+ @Override
+ public void event(LeadershipEvent event) {
+ processLeadershipChange(event.subject().leader());
+ }
+ }
+}
\ No newline at end of file
diff --git a/apps/pom.xml b/apps/pom.xml
index b955130..9821073 100644
--- a/apps/pom.xml
+++ b/apps/pom.xml
@@ -59,6 +59,7 @@
<module>mfwd</module>
<module>igmp</module>
<module>pim</module>
+ <module>mlb</module>
</modules>
<properties>