[ONOS-7025] Restore old flow rule store for testing

Moved to ECFlowRuleStore and deactivated by default

Change-Id: I45e5f26df049b04dcd23d355f477c938961d8720
diff --git a/core/store/dist/src/main/java/org/onosproject/store/flow/impl/ECFlowRuleStore.java b/core/store/dist/src/main/java/org/onosproject/store/flow/impl/ECFlowRuleStore.java
new file mode 100644
index 0000000..af87754
--- /dev/null
+++ b/core/store/dist/src/main/java/org/onosproject/store/flow/impl/ECFlowRuleStore.java
@@ -0,0 +1,954 @@
+ /*
+ * Copyright 2014-present Open Networking Foundation
+ *
+ * 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.flow.impl;
+
+import java.util.Collections;
+import java.util.Dictionary;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Set;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.ScheduledFuture;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicReference;
+import java.util.stream.Collectors;
+
+import com.google.common.collect.Streams;
+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.Modified;
+import org.apache.felix.scr.annotations.Property;
+import org.apache.felix.scr.annotations.Reference;
+import org.apache.felix.scr.annotations.ReferenceCardinality;
+import org.apache.felix.scr.annotations.Service;
+import org.onlab.util.KryoNamespace;
+import org.onlab.util.Tools;
+import org.onosproject.cfg.ComponentConfigService;
+import org.onosproject.cluster.ClusterService;
+import org.onosproject.cluster.NodeId;
+import org.onosproject.core.CoreService;
+import org.onosproject.core.IdGenerator;
+import org.onosproject.mastership.MastershipService;
+import org.onosproject.net.DeviceId;
+import org.onosproject.net.device.DeviceService;
+import org.onosproject.net.flow.CompletedBatchOperation;
+import org.onosproject.net.flow.DefaultFlowEntry;
+import org.onosproject.net.flow.FlowEntry;
+import org.onosproject.net.flow.FlowEntry.FlowEntryState;
+import org.onosproject.net.flow.FlowId;
+import org.onosproject.net.flow.FlowRule;
+import org.onosproject.net.flow.oldbatch.FlowRuleBatchEntry;
+import org.onosproject.net.flow.oldbatch.FlowRuleBatchEntry.FlowRuleOperation;
+import org.onosproject.net.flow.oldbatch.FlowRuleBatchEvent;
+import org.onosproject.net.flow.oldbatch.FlowRuleBatchOperation;
+import org.onosproject.net.flow.oldbatch.FlowRuleBatchRequest;
+import org.onosproject.net.flow.FlowRuleEvent;
+import org.onosproject.net.flow.FlowRuleEvent.Type;
+import org.onosproject.net.flow.FlowRuleService;
+import org.onosproject.net.flow.FlowRuleStore;
+import org.onosproject.net.flow.FlowRuleStoreDelegate;
+import org.onosproject.net.flow.StoredFlowEntry;
+import org.onosproject.net.flow.TableStatisticsEntry;
+import org.onosproject.persistence.PersistenceService;
+import org.onosproject.store.AbstractStore;
+import org.onosproject.store.cluster.messaging.ClusterCommunicationService;
+import org.onosproject.store.cluster.messaging.ClusterMessage;
+import org.onosproject.store.cluster.messaging.ClusterMessageHandler;
+import org.onosproject.store.flow.ReplicaInfoEvent;
+import org.onosproject.store.flow.ReplicaInfoEventListener;
+import org.onosproject.store.flow.ReplicaInfoService;
+import org.onosproject.store.impl.MastershipBasedTimestamp;
+import org.onosproject.store.serializers.KryoNamespaces;
+import org.onosproject.store.service.EventuallyConsistentMap;
+import org.onosproject.store.service.EventuallyConsistentMapEvent;
+import org.onosproject.store.service.EventuallyConsistentMapListener;
+import org.onosproject.store.service.Serializer;
+import org.onosproject.store.service.StorageService;
+import org.onosproject.store.service.WallClockTimestamp;
+import org.osgi.service.component.ComponentContext;
+import org.slf4j.Logger;
+
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.Iterables;
+import com.google.common.collect.Maps;
+import com.google.common.collect.Sets;
+import com.google.common.util.concurrent.Futures;
+
+import static com.google.common.base.Strings.isNullOrEmpty;
+import static org.onlab.util.Tools.get;
+import static org.onlab.util.Tools.groupedThreads;
+import static org.onosproject.net.flow.FlowRuleEvent.Type.RULE_REMOVED;
+import static org.onosproject.store.flow.ReplicaInfoEvent.Type.MASTER_CHANGED;
+import static org.onosproject.store.flow.impl.ECFlowRuleStoreMessageSubjects.APPLY_BATCH_FLOWS;
+import static org.onosproject.store.flow.impl.ECFlowRuleStoreMessageSubjects.FLOW_TABLE_BACKUP;
+import static org.onosproject.store.flow.impl.ECFlowRuleStoreMessageSubjects.GET_DEVICE_FLOW_ENTRIES;
+import static org.onosproject.store.flow.impl.ECFlowRuleStoreMessageSubjects.GET_FLOW_ENTRY;
+import static org.onosproject.store.flow.impl.ECFlowRuleStoreMessageSubjects.REMOTE_APPLY_COMPLETED;
+import static org.onosproject.store.flow.impl.ECFlowRuleStoreMessageSubjects.REMOVE_FLOW_ENTRY;
+import static org.slf4j.LoggerFactory.getLogger;
+
+/**
+ * Manages inventory of flow rules using a distributed state management protocol.
+ */
+@Component(enabled = false)
+@Service
+public class ECFlowRuleStore
+        extends AbstractStore<FlowRuleBatchEvent, FlowRuleStoreDelegate>
+        implements FlowRuleStore {
+
+    private final Logger log = getLogger(getClass());
+
+    private static final int MESSAGE_HANDLER_THREAD_POOL_SIZE = 8;
+    private static final int DEFAULT_MAX_BACKUP_COUNT = 2;
+    private static final boolean DEFAULT_PERSISTENCE_ENABLED = false;
+    private static final int DEFAULT_BACKUP_PERIOD_MILLIS = 2000;
+    private static final long FLOW_RULE_STORE_TIMEOUT_MILLIS = 5000;
+    // number of devices whose flow entries will be backed up in one communication round
+    private static final int FLOW_TABLE_BACKUP_BATCH_SIZE = 1;
+
+    @Property(name = "msgHandlerPoolSize", intValue = MESSAGE_HANDLER_THREAD_POOL_SIZE,
+            label = "Number of threads in the message handler pool")
+    private int msgHandlerPoolSize = MESSAGE_HANDLER_THREAD_POOL_SIZE;
+
+    @Property(name = "backupPeriod", intValue = DEFAULT_BACKUP_PERIOD_MILLIS,
+            label = "Delay in ms between successive backup runs")
+    private int backupPeriod = DEFAULT_BACKUP_PERIOD_MILLIS;
+    @Property(name = "persistenceEnabled", boolValue = false,
+            label = "Indicates whether or not changes in the flow table should be persisted to disk.")
+    private boolean persistenceEnabled = DEFAULT_PERSISTENCE_ENABLED;
+
+    @Property(name = "backupCount", intValue = DEFAULT_MAX_BACKUP_COUNT,
+            label = "Max number of backup copies for each device")
+    private volatile int backupCount = DEFAULT_MAX_BACKUP_COUNT;
+
+    private InternalFlowTable flowTable = new InternalFlowTable();
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected ReplicaInfoService replicaInfoManager;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected ClusterCommunicationService clusterCommunicator;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected ClusterService clusterService;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected DeviceService deviceService;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected CoreService coreService;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected ComponentConfigService configService;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected MastershipService mastershipService;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected PersistenceService persistenceService;
+
+    private Map<Long, NodeId> pendingResponses = Maps.newConcurrentMap();
+    private ExecutorService messageHandlingExecutor;
+    private ExecutorService eventHandler;
+
+    private ScheduledFuture<?> backupTask;
+    private final ScheduledExecutorService backupSenderExecutor =
+            Executors.newSingleThreadScheduledExecutor(groupedThreads("onos/flow", "backup-sender", log));
+
+    private EventuallyConsistentMap<DeviceId, List<TableStatisticsEntry>> deviceTableStats;
+    private final EventuallyConsistentMapListener<DeviceId, List<TableStatisticsEntry>> tableStatsListener =
+            new InternalTableStatsListener();
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected StorageService storageService;
+
+    protected final Serializer serializer = Serializer.using(KryoNamespaces.API);
+
+    protected final KryoNamespace.Builder serializerBuilder = KryoNamespace.newBuilder()
+            .register(KryoNamespaces.API)
+            .register(MastershipBasedTimestamp.class);
+
+
+    private IdGenerator idGenerator;
+    private NodeId local;
+
+    @Activate
+    public void activate(ComponentContext context) {
+        configService.registerProperties(getClass());
+
+        idGenerator = coreService.getIdGenerator(FlowRuleService.FLOW_OP_TOPIC);
+
+        local = clusterService.getLocalNode().id();
+
+        eventHandler = Executors.newSingleThreadExecutor(
+                groupedThreads("onos/flow", "event-handler", log));
+        messageHandlingExecutor = Executors.newFixedThreadPool(
+                msgHandlerPoolSize, groupedThreads("onos/store/flow", "message-handlers", log));
+
+        registerMessageHandlers(messageHandlingExecutor);
+
+        replicaInfoManager.addListener(flowTable);
+        backupTask = backupSenderExecutor.scheduleWithFixedDelay(
+                flowTable::backup,
+                0,
+                backupPeriod,
+                TimeUnit.MILLISECONDS);
+
+        deviceTableStats = storageService.<DeviceId, List<TableStatisticsEntry>>eventuallyConsistentMapBuilder()
+                .withName("onos-flow-table-stats")
+                .withSerializer(serializerBuilder)
+                .withAntiEntropyPeriod(5, TimeUnit.SECONDS)
+                .withTimestampProvider((k, v) -> new WallClockTimestamp())
+                .withTombstonesDisabled()
+                .build();
+        deviceTableStats.addListener(tableStatsListener);
+
+        logConfig("Started");
+    }
+
+    @Deactivate
+    public void deactivate(ComponentContext context) {
+        replicaInfoManager.removeListener(flowTable);
+        backupTask.cancel(true);
+        configService.unregisterProperties(getClass(), false);
+        unregisterMessageHandlers();
+        deviceTableStats.removeListener(tableStatsListener);
+        deviceTableStats.destroy();
+        eventHandler.shutdownNow();
+        messageHandlingExecutor.shutdownNow();
+        backupSenderExecutor.shutdownNow();
+        log.info("Stopped");
+    }
+
+    @SuppressWarnings("rawtypes")
+    @Modified
+    public void modified(ComponentContext context) {
+        if (context == null) {
+            logConfig("Default config");
+            return;
+        }
+
+        Dictionary properties = context.getProperties();
+        int newPoolSize;
+        int newBackupPeriod;
+        int newBackupCount;
+        try {
+            String s = get(properties, "msgHandlerPoolSize");
+            newPoolSize = isNullOrEmpty(s) ? msgHandlerPoolSize : Integer.parseInt(s.trim());
+
+            s = get(properties, "backupPeriod");
+            newBackupPeriod = isNullOrEmpty(s) ? backupPeriod : Integer.parseInt(s.trim());
+
+            s = get(properties, "backupCount");
+            newBackupCount = isNullOrEmpty(s) ? backupCount : Integer.parseInt(s.trim());
+        } catch (NumberFormatException | ClassCastException e) {
+            newPoolSize = MESSAGE_HANDLER_THREAD_POOL_SIZE;
+            newBackupPeriod = DEFAULT_BACKUP_PERIOD_MILLIS;
+            newBackupCount = DEFAULT_MAX_BACKUP_COUNT;
+        }
+
+        boolean restartBackupTask = false;
+
+        if (newBackupPeriod != backupPeriod) {
+            backupPeriod = newBackupPeriod;
+            restartBackupTask = true;
+        }
+        if (restartBackupTask) {
+            if (backupTask != null) {
+                // cancel previously running task
+                backupTask.cancel(false);
+            }
+            backupTask = backupSenderExecutor.scheduleWithFixedDelay(
+                    flowTable::backup,
+                    0,
+                    backupPeriod,
+                    TimeUnit.MILLISECONDS);
+        }
+        if (newPoolSize != msgHandlerPoolSize) {
+            msgHandlerPoolSize = newPoolSize;
+            ExecutorService oldMsgHandler = messageHandlingExecutor;
+            messageHandlingExecutor = Executors.newFixedThreadPool(
+                    msgHandlerPoolSize, groupedThreads("onos/store/flow", "message-handlers", log));
+
+            // replace previously registered handlers.
+            registerMessageHandlers(messageHandlingExecutor);
+            oldMsgHandler.shutdown();
+        }
+        if (backupCount != newBackupCount) {
+            backupCount = newBackupCount;
+        }
+        logConfig("Reconfigured");
+    }
+
+    private void registerMessageHandlers(ExecutorService executor) {
+
+        clusterCommunicator.addSubscriber(APPLY_BATCH_FLOWS, new OnStoreBatch(), executor);
+        clusterCommunicator.<FlowRuleBatchEvent>addSubscriber(
+                REMOTE_APPLY_COMPLETED, serializer::decode, this::notifyDelegate, executor);
+        clusterCommunicator.addSubscriber(
+                GET_FLOW_ENTRY, serializer::decode, flowTable::getFlowEntry, serializer::encode, executor);
+        clusterCommunicator.addSubscriber(
+                GET_DEVICE_FLOW_ENTRIES, serializer::decode, flowTable::getFlowEntries, serializer::encode, executor);
+        clusterCommunicator.addSubscriber(
+                REMOVE_FLOW_ENTRY, serializer::decode, this::removeFlowRuleInternal, serializer::encode, executor);
+        clusterCommunicator.addSubscriber(
+                FLOW_TABLE_BACKUP, serializer::decode, flowTable::onBackupReceipt, serializer::encode, executor);
+    }
+
+    private void unregisterMessageHandlers() {
+        clusterCommunicator.removeSubscriber(REMOVE_FLOW_ENTRY);
+        clusterCommunicator.removeSubscriber(GET_DEVICE_FLOW_ENTRIES);
+        clusterCommunicator.removeSubscriber(GET_FLOW_ENTRY);
+        clusterCommunicator.removeSubscriber(APPLY_BATCH_FLOWS);
+        clusterCommunicator.removeSubscriber(REMOTE_APPLY_COMPLETED);
+        clusterCommunicator.removeSubscriber(FLOW_TABLE_BACKUP);
+    }
+
+    private void logConfig(String prefix) {
+        log.info("{} with msgHandlerPoolSize = {}; backupPeriod = {}, backupCount = {}",
+                 prefix, msgHandlerPoolSize, backupPeriod, backupCount);
+    }
+
+    // This is not a efficient operation on a distributed sharded
+    // flow store. We need to revisit the need for this operation or at least
+    // make it device specific.
+    @Override
+    public int getFlowRuleCount() {
+        return Streams.stream(deviceService.getDevices()).parallel()
+                        .mapToInt(device -> Iterables.size(getFlowEntries(device.id())))
+                        .sum();
+    }
+
+    @Override
+    public FlowEntry getFlowEntry(FlowRule rule) {
+        NodeId master = mastershipService.getMasterFor(rule.deviceId());
+
+        if (master == null) {
+            log.debug("Failed to getFlowEntry: No master for {}", rule.deviceId());
+            return null;
+        }
+
+        if (Objects.equals(local, master)) {
+            return flowTable.getFlowEntry(rule);
+        }
+
+        log.trace("Forwarding getFlowEntry to {}, which is the primary (master) for device {}",
+                  master, rule.deviceId());
+
+        return Tools.futureGetOrElse(clusterCommunicator.sendAndReceive(rule,
+                                    ECFlowRuleStoreMessageSubjects.GET_FLOW_ENTRY,
+                                    serializer::encode,
+                                    serializer::decode,
+                                    master),
+                               FLOW_RULE_STORE_TIMEOUT_MILLIS,
+                               TimeUnit.MILLISECONDS,
+                               null);
+    }
+
+    @Override
+    public Iterable<FlowEntry> getFlowEntries(DeviceId deviceId) {
+        NodeId master = mastershipService.getMasterFor(deviceId);
+
+        if (master == null) {
+            log.debug("Failed to getFlowEntries: No master for {}", deviceId);
+            return Collections.emptyList();
+        }
+
+        if (Objects.equals(local, master)) {
+            return flowTable.getFlowEntries(deviceId);
+        }
+
+        log.trace("Forwarding getFlowEntries to {}, which is the primary (master) for device {}",
+                  master, deviceId);
+
+        return Tools.futureGetOrElse(clusterCommunicator.sendAndReceive(deviceId,
+                                    ECFlowRuleStoreMessageSubjects.GET_DEVICE_FLOW_ENTRIES,
+                                    serializer::encode,
+                                    serializer::decode,
+                                    master),
+                               FLOW_RULE_STORE_TIMEOUT_MILLIS,
+                               TimeUnit.MILLISECONDS,
+                               Collections.emptyList());
+    }
+
+    @Override
+    public void storeFlowRule(FlowRule rule) {
+        storeBatch(new FlowRuleBatchOperation(
+                Collections.singletonList(new FlowRuleBatchEntry(FlowRuleOperation.ADD, rule)),
+                rule.deviceId(), idGenerator.getNewId()));
+    }
+
+    @Override
+    public void storeBatch(FlowRuleBatchOperation operation) {
+        if (operation.getOperations().isEmpty()) {
+            notifyDelegate(FlowRuleBatchEvent.completed(
+                    new FlowRuleBatchRequest(operation.id(), Collections.emptySet()),
+                    new CompletedBatchOperation(true, Collections.emptySet(), operation.deviceId())));
+            return;
+        }
+
+        DeviceId deviceId = operation.deviceId();
+        NodeId master = mastershipService.getMasterFor(deviceId);
+
+        if (master == null) {
+            log.warn("No master for {} ", deviceId);
+
+            updateStoreInternal(operation);
+
+            notifyDelegate(FlowRuleBatchEvent.completed(
+                    new FlowRuleBatchRequest(operation.id(), Collections.emptySet()),
+                    new CompletedBatchOperation(true, Collections.emptySet(), operation.deviceId())));
+            return;
+        }
+
+        if (Objects.equals(local, master)) {
+            storeBatchInternal(operation);
+            return;
+        }
+
+        log.trace("Forwarding storeBatch to {}, which is the primary (master) for device {}",
+                  master, deviceId);
+
+        clusterCommunicator.unicast(operation,
+                                    APPLY_BATCH_FLOWS,
+                                    serializer::encode,
+                                    master)
+                           .whenComplete((result, error) -> {
+                               if (error != null) {
+                                   log.warn("Failed to storeBatch: {} to {}", operation, master, error);
+
+                                   Set<FlowRule> allFailures = operation.getOperations()
+                                           .stream()
+                                           .map(op -> op.target())
+                                           .collect(Collectors.toSet());
+
+                                   notifyDelegate(FlowRuleBatchEvent.completed(
+                                           new FlowRuleBatchRequest(operation.id(), Collections.emptySet()),
+                                           new CompletedBatchOperation(false, allFailures, deviceId)));
+                               }
+                           });
+    }
+
+    private void storeBatchInternal(FlowRuleBatchOperation operation) {
+
+        final DeviceId did = operation.deviceId();
+        //final Collection<FlowEntry> ft = flowTable.getFlowEntries(did);
+        Set<FlowRuleBatchEntry> currentOps = updateStoreInternal(operation);
+        if (currentOps.isEmpty()) {
+            batchOperationComplete(FlowRuleBatchEvent.completed(
+                    new FlowRuleBatchRequest(operation.id(), Collections.emptySet()),
+                    new CompletedBatchOperation(true, Collections.emptySet(), did)));
+            return;
+        }
+
+        notifyDelegate(FlowRuleBatchEvent.requested(new
+                           FlowRuleBatchRequest(operation.id(),
+                                                currentOps), operation.deviceId()));
+    }
+
+    private Set<FlowRuleBatchEntry> updateStoreInternal(FlowRuleBatchOperation operation) {
+        return operation.getOperations().stream().map(
+                op -> {
+                    StoredFlowEntry entry;
+                    switch (op.operator()) {
+                        case ADD:
+                            entry = new DefaultFlowEntry(op.target());
+                            // always add requested FlowRule
+                            // Note: 2 equal FlowEntry may have different treatment
+                            flowTable.remove(entry.deviceId(), entry);
+                            flowTable.add(entry);
+
+                            return op;
+                        case REMOVE:
+                            entry = flowTable.getFlowEntry(op.target());
+                            if (entry != null) {
+                                //FIXME modification of "stored" flow entry outside of flow table
+                                entry.setState(FlowEntryState.PENDING_REMOVE);
+                                log.debug("Setting state of rule to pending remove: {}", entry);
+                                return op;
+                            }
+                            break;
+                        case MODIFY:
+                            //TODO: figure this out at some point
+                            break;
+                        default:
+                            log.warn("Unknown flow operation operator: {}", op.operator());
+                    }
+                    return null;
+                }
+        ).filter(Objects::nonNull).collect(Collectors.toSet());
+    }
+
+    @Override
+    public void deleteFlowRule(FlowRule rule) {
+        storeBatch(
+                new FlowRuleBatchOperation(
+                        Collections.singletonList(
+                                new FlowRuleBatchEntry(
+                                        FlowRuleOperation.REMOVE,
+                                        rule)), rule.deviceId(), idGenerator.getNewId()));
+    }
+
+    @Override
+    public FlowRuleEvent pendingFlowRule(FlowEntry rule) {
+        if (mastershipService.isLocalMaster(rule.deviceId())) {
+            StoredFlowEntry stored = flowTable.getFlowEntry(rule);
+            if (stored != null &&
+                    stored.state() != FlowEntryState.PENDING_ADD) {
+                stored.setState(FlowEntryState.PENDING_ADD);
+                return new FlowRuleEvent(Type.RULE_UPDATED, rule);
+            }
+        }
+        return null;
+    }
+
+    @Override
+    public FlowRuleEvent addOrUpdateFlowRule(FlowEntry rule) {
+        NodeId master = mastershipService.getMasterFor(rule.deviceId());
+        if (Objects.equals(local, master)) {
+            return addOrUpdateFlowRuleInternal(rule);
+        }
+
+        log.warn("Tried to update FlowRule {} state,"
+                         + " while the Node was not the master.", rule);
+        return null;
+    }
+
+    private FlowRuleEvent addOrUpdateFlowRuleInternal(FlowEntry rule) {
+        // check if this new rule is an update to an existing entry
+        StoredFlowEntry stored = flowTable.getFlowEntry(rule);
+        if (stored != null) {
+            //FIXME modification of "stored" flow entry outside of flow table
+            stored.setBytes(rule.bytes());
+            stored.setLife(rule.life(TimeUnit.NANOSECONDS), TimeUnit.NANOSECONDS);
+            stored.setLiveType(rule.liveType());
+            stored.setPackets(rule.packets());
+            stored.setLastSeen();
+            if (stored.state() == FlowEntryState.PENDING_ADD) {
+                stored.setState(FlowEntryState.ADDED);
+                return new FlowRuleEvent(Type.RULE_ADDED, rule);
+            }
+            return new FlowRuleEvent(Type.RULE_UPDATED, rule);
+        }
+
+        // TODO: Confirm if this behavior is correct. See SimpleFlowRuleStore
+        // TODO: also update backup if the behavior is correct.
+        flowTable.add(rule);
+        return null;
+    }
+
+    @Override
+    public FlowRuleEvent removeFlowRule(FlowEntry rule) {
+        final DeviceId deviceId = rule.deviceId();
+        NodeId master = mastershipService.getMasterFor(deviceId);
+
+        if (Objects.equals(local, master)) {
+            // bypass and handle it locally
+            return removeFlowRuleInternal(rule);
+        }
+
+        if (master == null) {
+            log.warn("Failed to removeFlowRule: No master for {}", deviceId);
+            // TODO: revisit if this should be null (="no-op") or Exception
+            return null;
+        }
+
+        log.trace("Forwarding removeFlowRule to {}, which is the master for device {}",
+                  master, deviceId);
+
+        return Futures.getUnchecked(clusterCommunicator.sendAndReceive(
+                               rule,
+                               REMOVE_FLOW_ENTRY,
+                               serializer::encode,
+                               serializer::decode,
+                               master));
+    }
+
+    private FlowRuleEvent removeFlowRuleInternal(FlowEntry rule) {
+        final DeviceId deviceId = rule.deviceId();
+        // This is where one could mark a rule as removed and still keep it in the store.
+        final FlowEntry removed = flowTable.remove(deviceId, rule);
+        // rule may be partial rule that is missing treatment, we should use rule from store instead
+        return removed != null ? new FlowRuleEvent(RULE_REMOVED, removed) : null;
+    }
+
+    @Override
+    public void purgeFlowRule(DeviceId deviceId) {
+        flowTable.purgeFlowRule(deviceId);
+    }
+
+    @Override
+    public void purgeFlowRules() {
+        flowTable.purgeFlowRules();
+    }
+
+    @Override
+    public void batchOperationComplete(FlowRuleBatchEvent event) {
+        //FIXME: need a per device pending response
+        NodeId nodeId = pendingResponses.remove(event.subject().batchId());
+        if (nodeId == null) {
+            notifyDelegate(event);
+        } else {
+            // TODO check unicast return value
+            clusterCommunicator.unicast(event, REMOTE_APPLY_COMPLETED, serializer::encode, nodeId);
+            //error log: log.warn("Failed to respond to peer for batch operation result");
+        }
+    }
+
+    private final class OnStoreBatch implements ClusterMessageHandler {
+
+        @Override
+        public void handle(final ClusterMessage message) {
+            FlowRuleBatchOperation operation = serializer.decode(message.payload());
+            log.debug("received batch request {}", operation);
+
+            final DeviceId deviceId = operation.deviceId();
+            NodeId master = mastershipService.getMasterFor(deviceId);
+            if (!Objects.equals(local, master)) {
+                Set<FlowRule> failures = new HashSet<>(operation.size());
+                for (FlowRuleBatchEntry op : operation.getOperations()) {
+                    failures.add(op.target());
+                }
+                CompletedBatchOperation allFailed = new CompletedBatchOperation(false, failures, deviceId);
+                // This node is no longer the master, respond as all failed.
+                // TODO: we might want to wrap response in envelope
+                // to distinguish sw programming failure and hand over
+                // it make sense in the latter case to retry immediately.
+                message.respond(serializer.encode(allFailed));
+                return;
+            }
+
+            pendingResponses.put(operation.id(), message.sender());
+            storeBatchInternal(operation);
+        }
+    }
+
+    private class BackupOperation {
+        private final NodeId nodeId;
+        private final DeviceId deviceId;
+
+        public BackupOperation(NodeId nodeId, DeviceId deviceId) {
+            this.nodeId = nodeId;
+            this.deviceId = deviceId;
+        }
+
+        @Override
+        public int hashCode() {
+            return Objects.hash(nodeId, deviceId);
+        }
+
+        @Override
+        public boolean equals(Object other) {
+            if (other != null && other instanceof BackupOperation) {
+                BackupOperation that = (BackupOperation) other;
+                return this.nodeId.equals(that.nodeId) &&
+                        this.deviceId.equals(that.deviceId);
+            } else {
+                return false;
+            }
+        }
+    }
+
+    private class InternalFlowTable implements ReplicaInfoEventListener {
+
+        //TODO replace the Map<V,V> with ExtendedSet
+        private final Map<DeviceId, Map<FlowId, Map<StoredFlowEntry, StoredFlowEntry>>>
+                flowEntries = Maps.newConcurrentMap();
+
+        private final Map<BackupOperation, Long> lastBackupTimes = Maps.newConcurrentMap();
+        private final Map<DeviceId, Long> lastUpdateTimes = Maps.newConcurrentMap();
+
+        @Override
+        public void event(ReplicaInfoEvent event) {
+            eventHandler.execute(() -> handleEvent(event));
+        }
+
+        private void handleEvent(ReplicaInfoEvent event) {
+            DeviceId deviceId = event.subject();
+            if (!mastershipService.isLocalMaster(deviceId)) {
+                return;
+            }
+            if (event.type() == MASTER_CHANGED) {
+                lastUpdateTimes.put(deviceId, System.currentTimeMillis());
+            }
+            backupSenderExecutor.schedule(this::backup, 0, TimeUnit.SECONDS);
+        }
+
+        private void sendBackups(NodeId nodeId, Set<DeviceId> deviceIds) {
+            // split up the devices into smaller batches and send them separately.
+            Iterables.partition(deviceIds, FLOW_TABLE_BACKUP_BATCH_SIZE)
+                     .forEach(ids -> backupFlowEntries(nodeId, Sets.newHashSet(ids)));
+        }
+
+        private void backupFlowEntries(NodeId nodeId, Set<DeviceId> deviceIds) {
+            if (deviceIds.isEmpty()) {
+                return;
+            }
+            log.debug("Sending flowEntries for devices {} to {} for backup.", deviceIds, nodeId);
+            Map<DeviceId, Map<FlowId, Map<StoredFlowEntry, StoredFlowEntry>>>
+                    deviceFlowEntries = Maps.newConcurrentMap();
+            deviceIds.forEach(id -> deviceFlowEntries.put(id, getFlowTableCopy(id)));
+            clusterCommunicator.<Map<DeviceId,
+                                 Map<FlowId, Map<StoredFlowEntry, StoredFlowEntry>>>,
+                                 Set<DeviceId>>
+                    sendAndReceive(deviceFlowEntries,
+                                   FLOW_TABLE_BACKUP,
+                                   serializer::encode,
+                                   serializer::decode,
+                                   nodeId)
+                    .whenComplete((backedupDevices, error) -> {
+                        Set<DeviceId> devicesNotBackedup = error != null ?
+                            deviceFlowEntries.keySet() :
+                            Sets.difference(deviceFlowEntries.keySet(), backedupDevices);
+                        if (devicesNotBackedup.size() > 0) {
+                            log.warn("Failed to backup devices: {}. Reason: {}, Node: {}",
+                                     devicesNotBackedup, error != null ? error.getMessage() : "none",
+                                     nodeId);
+                        }
+                        if (backedupDevices != null) {
+                            backedupDevices.forEach(id -> {
+                                lastBackupTimes.put(new BackupOperation(nodeId, id), System.currentTimeMillis());
+                            });
+                        }
+                    });
+        }
+
+        /**
+         * Returns the flow table for specified device.
+         *
+         * @param deviceId identifier of the device
+         * @return Map representing Flow Table of given device.
+         */
+        private Map<FlowId, Map<StoredFlowEntry, StoredFlowEntry>> getFlowTable(DeviceId deviceId) {
+            if (persistenceEnabled) {
+                return flowEntries.computeIfAbsent(deviceId, id -> persistenceService
+                        .<FlowId, Map<StoredFlowEntry, StoredFlowEntry>>persistentMapBuilder()
+                        .withName("FlowTable:" + deviceId.toString())
+                        .withSerializer(new Serializer() {
+                            @Override
+                            public <T> byte[] encode(T object) {
+                                return serializer.encode(object);
+                            }
+
+                            @Override
+                            public <T> T decode(byte[] bytes) {
+                                return serializer.decode(bytes);
+                            }
+
+                            @Override
+                            public <T> T copy(T object) {
+                                return serializer.copy(object);
+                            }
+                        })
+                        .build());
+            } else {
+                return flowEntries.computeIfAbsent(deviceId, id -> Maps.newConcurrentMap());
+            }
+        }
+
+        private Map<FlowId, Map<StoredFlowEntry, StoredFlowEntry>> getFlowTableCopy(DeviceId deviceId) {
+            Map<FlowId, Map<StoredFlowEntry, StoredFlowEntry>> copy = Maps.newHashMap();
+            if (persistenceEnabled) {
+                return flowEntries.computeIfAbsent(deviceId, id -> persistenceService
+                        .<FlowId, Map<StoredFlowEntry, StoredFlowEntry>>persistentMapBuilder()
+                        .withName("FlowTable:" + deviceId.toString())
+                        .withSerializer(new Serializer() {
+                            @Override
+                            public <T> byte[] encode(T object) {
+                                return serializer.encode(object);
+                            }
+
+                            @Override
+                            public <T> T decode(byte[] bytes) {
+                                return serializer.decode(bytes);
+                            }
+
+                            @Override
+                            public <T> T copy(T object) {
+                                return serializer.copy(object);
+                            }
+                        })
+                        .build());
+            } else {
+                flowEntries.computeIfAbsent(deviceId, id -> Maps.newConcurrentMap()).forEach((k, v) -> {
+                    copy.put(k, Maps.newHashMap(v));
+                });
+                return copy;
+            }
+        }
+
+        private Map<StoredFlowEntry, StoredFlowEntry> getFlowEntriesInternal(DeviceId deviceId, FlowId flowId) {
+            return getFlowTable(deviceId).computeIfAbsent(flowId, id -> Maps.newConcurrentMap());
+        }
+
+        private StoredFlowEntry getFlowEntryInternal(FlowRule rule) {
+            return getFlowEntriesInternal(rule.deviceId(), rule.id()).get(rule);
+        }
+
+        private Set<FlowEntry> getFlowEntriesInternal(DeviceId deviceId) {
+            return getFlowTable(deviceId).values().stream()
+                        .flatMap(m -> m.values().stream())
+                        .collect(Collectors.toSet());
+        }
+
+        public StoredFlowEntry getFlowEntry(FlowRule rule) {
+            return getFlowEntryInternal(rule);
+        }
+
+        public Set<FlowEntry> getFlowEntries(DeviceId deviceId) {
+            return getFlowEntriesInternal(deviceId);
+        }
+
+        public void add(FlowEntry rule) {
+            getFlowEntriesInternal(rule.deviceId(), rule.id())
+                    .compute((StoredFlowEntry) rule, (k, stored) -> {
+                        //TODO compare stored and rule timestamps
+                        //TODO the key is not updated
+                        return (StoredFlowEntry) rule;
+                    });
+            lastUpdateTimes.put(rule.deviceId(), System.currentTimeMillis());
+        }
+
+        public FlowEntry remove(DeviceId deviceId, FlowEntry rule) {
+            final AtomicReference<FlowEntry> removedRule = new AtomicReference<>();
+            getFlowEntriesInternal(rule.deviceId(), rule.id())
+                .computeIfPresent((StoredFlowEntry) rule, (k, stored) -> {
+                    if (rule instanceof DefaultFlowEntry) {
+                        DefaultFlowEntry toRemove = (DefaultFlowEntry) rule;
+                        if (stored instanceof DefaultFlowEntry) {
+                            DefaultFlowEntry storedEntry = (DefaultFlowEntry) stored;
+                            if (toRemove.created() < storedEntry.created()) {
+                                log.debug("Trying to remove more recent flow entry {} (stored: {})",
+                                          toRemove, stored);
+                                // the key is not updated, removedRule remains null
+                                return stored;
+                            }
+                        }
+                    }
+                    removedRule.set(stored);
+                    return null;
+                });
+
+            if (removedRule.get() != null) {
+                lastUpdateTimes.put(deviceId, System.currentTimeMillis());
+                return removedRule.get();
+            } else {
+                return null;
+            }
+        }
+
+        public void purgeFlowRule(DeviceId deviceId) {
+            flowEntries.remove(deviceId);
+        }
+
+        public void purgeFlowRules() {
+            flowEntries.clear();
+        }
+
+        private List<NodeId> getBackupNodes(DeviceId deviceId) {
+            // The returned backup node list is in the order of preference i.e. next likely master first.
+            List<NodeId> allPossibleBackupNodes = replicaInfoManager.getReplicaInfoFor(deviceId).backups();
+            return ImmutableList.copyOf(allPossibleBackupNodes)
+                                .subList(0, Math.min(allPossibleBackupNodes.size(), backupCount));
+        }
+
+        private void backup() {
+            try {
+                // compute a mapping from node to the set of devices whose flow entries it should backup
+                Map<NodeId, Set<DeviceId>> devicesToBackupByNode = Maps.newHashMap();
+                flowEntries.keySet().forEach(deviceId -> {
+                    List<NodeId> backupNodes = getBackupNodes(deviceId);
+                    backupNodes.forEach(backupNode -> {
+                            if (lastBackupTimes.getOrDefault(new BackupOperation(backupNode, deviceId), 0L)
+                                    < lastUpdateTimes.getOrDefault(deviceId, 0L)) {
+                                devicesToBackupByNode.computeIfAbsent(backupNode,
+                                                                      nodeId -> Sets.newHashSet()).add(deviceId);
+                            }
+                    });
+                });
+                // send the device flow entries to their respective backup nodes
+                devicesToBackupByNode.forEach(this::sendBackups);
+            } catch (Exception e) {
+                log.error("Backup failed.", e);
+            }
+        }
+
+        private Set<DeviceId> onBackupReceipt(Map<DeviceId,
+                Map<FlowId, Map<StoredFlowEntry, StoredFlowEntry>>> flowTables) {
+            log.debug("Received flowEntries for {} to backup", flowTables.keySet());
+            Set<DeviceId> backedupDevices = Sets.newHashSet();
+            try {
+                flowTables.forEach((deviceId, deviceFlowTable) -> {
+                    // Only process those devices are that not managed by the local node.
+                    if (!Objects.equals(local, mastershipService.getMasterFor(deviceId))) {
+                        Map<FlowId, Map<StoredFlowEntry, StoredFlowEntry>> backupFlowTable =
+                                getFlowTable(deviceId);
+                        backupFlowTable.clear();
+                        backupFlowTable.putAll(deviceFlowTable);
+                        backedupDevices.add(deviceId);
+                    }
+                });
+            } catch (Exception e) {
+                log.warn("Failure processing backup request", e);
+            }
+            return backedupDevices;
+        }
+    }
+
+    @Override
+    public FlowRuleEvent updateTableStatistics(DeviceId deviceId,
+                                               List<TableStatisticsEntry> tableStats) {
+        deviceTableStats.put(deviceId, tableStats);
+        return null;
+    }
+
+    @Override
+    public Iterable<TableStatisticsEntry> getTableStatistics(DeviceId deviceId) {
+        NodeId master = mastershipService.getMasterFor(deviceId);
+
+        if (master == null) {
+            log.debug("Failed to getTableStats: No master for {}", deviceId);
+            return Collections.emptyList();
+        }
+
+        List<TableStatisticsEntry> tableStats = deviceTableStats.get(deviceId);
+        if (tableStats == null) {
+            return Collections.emptyList();
+        }
+        return ImmutableList.copyOf(tableStats);
+    }
+
+    @Override
+    public long getActiveFlowRuleCount(DeviceId deviceId) {
+        return Streams.stream(getTableStatistics(deviceId))
+                .mapToLong(TableStatisticsEntry::activeFlowEntries)
+                .sum();
+    }
+
+    private class InternalTableStatsListener
+        implements EventuallyConsistentMapListener<DeviceId, List<TableStatisticsEntry>> {
+        @Override
+        public void event(EventuallyConsistentMapEvent<DeviceId,
+                          List<TableStatisticsEntry>> event) {
+            //TODO: Generate an event to listeners (do we need?)
+        }
+    }
+}
diff --git a/core/store/dist/src/main/java/org/onosproject/store/flow/impl/ECFlowRuleStoreMessageSubjects.java b/core/store/dist/src/main/java/org/onosproject/store/flow/impl/ECFlowRuleStoreMessageSubjects.java
new file mode 100644
index 0000000..fd4f6d7
--- /dev/null
+++ b/core/store/dist/src/main/java/org/onosproject/store/flow/impl/ECFlowRuleStoreMessageSubjects.java
@@ -0,0 +1,43 @@
+/*
+ * Copyright 2014-present Open Networking Foundation
+ *
+ * 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.flow.impl;
+
+import org.onosproject.store.cluster.messaging.MessageSubject;
+
+/**
+ * MessageSubjects used by ECFlowRuleStore peer-peer communication.
+ */
+public final class ECFlowRuleStoreMessageSubjects {
+    private ECFlowRuleStoreMessageSubjects() {}
+
+    public static final  MessageSubject APPLY_BATCH_FLOWS
+        = new MessageSubject("peer-forward-apply-batch");
+
+    public static final MessageSubject GET_FLOW_ENTRY
+        = new MessageSubject("peer-forward-get-flow-entry");
+
+    public static final MessageSubject GET_DEVICE_FLOW_ENTRIES
+        = new MessageSubject("peer-forward-get-device-flow-entries");
+
+    public static final MessageSubject REMOVE_FLOW_ENTRY
+        = new MessageSubject("peer-forward-remove-flow-entry");
+
+    public static final MessageSubject REMOTE_APPLY_COMPLETED
+        = new MessageSubject("peer-apply-completed");
+
+    public static final MessageSubject FLOW_TABLE_BACKUP
+        = new MessageSubject("peer-flow-table-backup");
+}
diff --git a/core/store/dist/src/test/java/org/onosproject/store/flow/impl/ECFlowRuleStoreTest.java b/core/store/dist/src/test/java/org/onosproject/store/flow/impl/ECFlowRuleStoreTest.java
new file mode 100644
index 0000000..7fd0412
--- /dev/null
+++ b/core/store/dist/src/test/java/org/onosproject/store/flow/impl/ECFlowRuleStoreTest.java
@@ -0,0 +1,265 @@
+/*
+ * Copyright 2016-present Open Networking Foundation
+ *
+ * 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.flow.impl;
+
+import com.google.common.collect.ArrayListMultimap;
+import com.google.common.collect.Multimap;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+import org.onosproject.cfg.ComponentConfigAdapter;
+import org.onosproject.cluster.NodeId;
+import org.onosproject.cluster.ClusterService;
+import org.onosproject.cluster.ControllerNode;
+import org.onosproject.core.CoreServiceAdapter;
+import org.onosproject.mastership.MastershipServiceAdapter;
+import org.onosproject.net.device.DeviceServiceAdapter;
+import org.onosproject.net.DeviceId;
+import org.onosproject.net.MastershipRole;
+import org.onosproject.net.flow.FlowRuleOperation;
+import org.onosproject.net.flow.FlowRule;
+import org.onosproject.net.flow.oldbatch.FlowRuleBatchEntry;
+import org.onosproject.net.flow.DefaultFlowEntry;
+import org.onosproject.net.flow.FlowEntry;
+import org.onosproject.net.flow.DefaultFlowRule;
+import org.onosproject.net.flow.oldbatch.FlowRuleBatchOperation;
+import org.onosproject.net.intent.IntentTestsMocks;
+import org.onosproject.store.cluster.messaging.ClusterCommunicationServiceAdapter;
+import org.onosproject.store.persistence.PersistenceServiceAdapter;
+import org.onosproject.store.service.TestStorageService;
+
+import org.onlab.packet.Ip4Address;
+import java.util.Iterator;
+import org.osgi.service.component.ComponentContext;
+
+import static org.easymock.EasyMock.createMock;
+import static org.easymock.EasyMock.expect;
+import static org.easymock.EasyMock.replay;
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.emptyIterable;
+import static org.hamcrest.Matchers.is;
+import static org.hamcrest.Matchers.notNullValue;
+import static org.junit.Assert.assertEquals;
+import static org.onosproject.net.NetTestTools.APP_ID;
+import static org.onosproject.net.NetTestTools.did;
+
+/**
+ * Test class for ECFlowRuleStore.
+ */
+public class ECFlowRuleStoreTest {
+
+    ECFlowRuleStore flowStoreImpl;
+    ComponentContext context = null;
+    private ClusterService mockClusterService;
+    private ControllerNode mockControllerNode;
+
+    private NodeId nodeId;
+
+    private static final IntentTestsMocks.MockSelector SELECTOR =
+            new IntentTestsMocks.MockSelector();
+    private static final IntentTestsMocks.MockTreatment TREATMENT =
+            new IntentTestsMocks.MockTreatment();
+    DeviceId deviceId = did("device1");
+    FlowRule flowRule =
+            DefaultFlowRule.builder()
+                    .forDevice(deviceId)
+                    .withSelector(SELECTOR)
+                    .withTreatment(TREATMENT)
+                    .withPriority(22)
+                    .makeTemporary(44)
+                    .fromApp(APP_ID)
+                    .build();
+    FlowRule flowRule1 =
+            DefaultFlowRule.builder()
+                    .forDevice(deviceId)
+                    .withSelector(SELECTOR)
+                    .withTreatment(TREATMENT)
+                    .withPriority(33)
+                    .makeTemporary(44)
+                    .fromApp(APP_ID)
+                    .build();
+
+    static class MasterOfAll extends MastershipServiceAdapter {
+        @Override
+        public MastershipRole getLocalRole(DeviceId deviceId) {
+            return MastershipRole.MASTER;
+        }
+
+        @Override
+        public NodeId getMasterFor(DeviceId deviceId) {
+            return new NodeId("1");
+        }
+    }
+
+
+    private static class MockControllerNode implements ControllerNode {
+        final NodeId id;
+
+        public MockControllerNode(NodeId id) {
+            this.id = id;
+        }
+
+        @Override
+        public NodeId id() {
+            return this.id;
+        }
+
+        @Override
+        public Ip4Address ip() {
+            return Ip4Address.valueOf("127.0.0.1");
+        }
+
+        @Override
+        public int tcpPort() {
+            return 0;
+        }
+    }
+
+    @Before
+    public void setUp() throws Exception {
+        flowStoreImpl = new ECFlowRuleStore();
+        flowStoreImpl.storageService = new TestStorageService();
+        flowStoreImpl.replicaInfoManager = new ReplicaInfoManager();
+        mockClusterService = createMock(ClusterService.class);
+        flowStoreImpl.clusterService = mockClusterService;
+        nodeId = new NodeId("1");
+        mockControllerNode = new MockControllerNode(nodeId);
+
+        expect(mockClusterService.getLocalNode())
+                .andReturn(mockControllerNode).anyTimes();
+        replay(mockClusterService);
+
+        flowStoreImpl.clusterCommunicator = new ClusterCommunicationServiceAdapter();
+        flowStoreImpl.mastershipService = new MasterOfAll();
+        flowStoreImpl.deviceService = new DeviceServiceAdapter();
+        flowStoreImpl.coreService = new CoreServiceAdapter();
+        flowStoreImpl.configService = new ComponentConfigAdapter();
+        flowStoreImpl.persistenceService = new PersistenceServiceAdapter();
+        flowStoreImpl.activate(context);
+    }
+
+    @After
+    public void tearDown() throws Exception {
+        flowStoreImpl.deactivate(context);
+    }
+
+    /**
+     * Tests the initial state of the store.
+     */
+    @Test
+    public void testEmptyStore() {
+        assertThat(flowStoreImpl.getFlowRuleCount(), is(0));
+        assertThat(flowStoreImpl.getFlowEntries(deviceId), is(emptyIterable()));
+    }
+
+    /**
+     * Tests initial state of flowrule.
+     */
+    @Test
+    public void testStoreBatch() {
+        FlowRuleOperation op = new FlowRuleOperation(flowRule, FlowRuleOperation.Type.ADD);
+        Multimap<DeviceId, FlowRuleBatchEntry> perDeviceBatches = ArrayListMultimap.create();
+        perDeviceBatches.put(op.rule().deviceId(),
+                new FlowRuleBatchEntry(FlowRuleBatchEntry.FlowRuleOperation.ADD, op.rule()));
+        FlowRuleBatchOperation b = new FlowRuleBatchOperation(perDeviceBatches.get(deviceId),
+                deviceId, 1);
+        flowStoreImpl.storeBatch(b);
+        FlowEntry flowEntry1 = flowStoreImpl.getFlowEntry(flowRule);
+        assertEquals("PENDING_ADD", flowEntry1.state().toString());
+    }
+
+    /**
+     * Tests adding a flowrule.
+     */
+    @Test
+    public void testAddFlow() {
+        FlowEntry flowEntry = new DefaultFlowEntry(flowRule);
+        FlowRuleOperation op = new FlowRuleOperation(flowRule, FlowRuleOperation.Type.ADD);
+        Multimap<DeviceId, FlowRuleBatchEntry> perDeviceBatches = ArrayListMultimap.create();
+        perDeviceBatches.put(op.rule().deviceId(),
+                new FlowRuleBatchEntry(FlowRuleBatchEntry.FlowRuleOperation.ADD, op.rule()));
+        FlowRuleBatchOperation b = new FlowRuleBatchOperation(perDeviceBatches.get(deviceId),
+                deviceId, 1);
+        flowStoreImpl.storeBatch(b);
+        FlowEntry flowEntry1 = flowStoreImpl.getFlowEntry(flowRule);
+        assertEquals("PENDING_ADD", flowEntry1.state().toString());
+
+        flowStoreImpl.addOrUpdateFlowRule(flowEntry);
+        Iterable<FlowEntry> flows = flowStoreImpl.getFlowEntries(deviceId);
+        int sum = 0;
+        Iterator it = flows.iterator();
+        while (it.hasNext()) {
+            it.next();
+            sum++;
+        }
+        assertThat(sum, is(1));
+
+        FlowEntry flowEntry2 = flowStoreImpl.getFlowEntry(flowRule);
+        assertEquals("ADDED", flowEntry2.state().toString());
+        assertThat(flowStoreImpl.getTableStatistics(deviceId), notNullValue());
+    }
+
+    /**
+     * Tests flow removal.
+     */
+    @Test
+    public void testRemoveFlow() {
+        Iterable<FlowEntry> flows1 = flowStoreImpl.getFlowEntries(deviceId);
+        for (FlowEntry flow : flows1) {
+            flowStoreImpl.removeFlowRule(flow);
+        }
+
+        Iterable<FlowEntry> flows2 = flowStoreImpl.getFlowEntries(deviceId);
+        int sum = 0;
+        Iterator it = flows2.iterator();
+        while (it.hasNext()) {
+            it.next();
+            sum++;
+        }
+        assertThat(sum, is(0));
+    }
+
+    /**
+     * Tests purge flow for a device.
+     */
+    @Test
+    public void testPurgeFlow() {
+        FlowEntry flowEntry = new DefaultFlowEntry(flowRule);
+        flowStoreImpl.addOrUpdateFlowRule(flowEntry);
+
+        FlowEntry flowEntry1 = new DefaultFlowEntry(flowRule1);
+        flowStoreImpl.addOrUpdateFlowRule(flowEntry1);
+        Iterable<FlowEntry> flows1 = flowStoreImpl.getFlowEntries(deviceId);
+        int sum2 = 0;
+        Iterator it1 = flows1.iterator();
+        while (it1.hasNext()) {
+            it1.next();
+            sum2++;
+        }
+        assertThat(sum2, is(2));
+        flowStoreImpl.purgeFlowRule(deviceId);
+
+        Iterable<FlowEntry> flows3 = flowStoreImpl.getFlowEntries(deviceId);
+        int sum3 = 0;
+        Iterator it3 = flows3.iterator();
+        while (it3.hasNext()) {
+            it3.next();
+            sum3++;
+        }
+        assertThat(sum3, is(0));
+    }
+}