OpenFlow Meter Provider - still need to parse meter stats

Change-Id: I4b313ea003b3801f81ec7d4823bf69de37fd8643
diff --git a/core/api/src/main/java/org/onosproject/net/meter/Band.java b/core/api/src/main/java/org/onosproject/net/meter/Band.java
index e434073..db42ba7 100644
--- a/core/api/src/main/java/org/onosproject/net/meter/Band.java
+++ b/core/api/src/main/java/org/onosproject/net/meter/Band.java
@@ -32,7 +32,7 @@
 
         /**
          * defines a simple DiffServ policer that remark
-         * the drop precedence of the DSCP eld in the
+         * the drop precedence of the DSCP field in the
          * IP header of the packets that exceed the band
          * rate value.
          */
@@ -42,16 +42,32 @@
     /**
      * The rate at which this meter applies.
      *
-     * @return the integer value of the rate
+     * @return the long value of the rate
      */
-    int rate();
+    long rate();
 
     /**
      * The burst size at which the meter applies.
      *
-     * @return the integer value of the size
+     * @return the long value of the size
      */
-    int burst();
+    long burst();
+
+    /**
+     * Only meaningful in the case of a REMARK band type.
+     * indicates by which amount the drop precedence of
+     * the packet should be increase if the band is exceeded.
+     *
+     * @return a short value
+     */
+    short dropPrecedence();
+
+    /**
+     * Signals the type of band to create.
+     *
+     * @return a band type
+     */
+    Type type();
 
 
 }
diff --git a/core/api/src/main/java/org/onosproject/net/meter/MeterFailReason.java b/core/api/src/main/java/org/onosproject/net/meter/MeterFailReason.java
index 70f65ef..8683e2a 100644
--- a/core/api/src/main/java/org/onosproject/net/meter/MeterFailReason.java
+++ b/core/api/src/main/java/org/onosproject/net/meter/MeterFailReason.java
@@ -38,5 +38,52 @@
     /**
      * The meter that was attempted to be modified is unknown.
      */
-    UNKNOWN
+    UNKNOWN,
+
+    /**
+     * The operation for this meter installation timed out.
+     */
+    TIMEOUT,
+
+    /**
+     * Invalid meter definition.
+     */
+    INVALID_METER,
+
+    /**
+     * The target device is unknown.
+     */
+    UNKNOWN_DEVICE,
+
+    /**
+     * Unknown command.
+     */
+    UNKNOWN_COMMAND,
+
+    /**
+     * Unknown flags.
+     */
+    UNKNOWN_FLAGS,
+
+    /**
+     * Bad rate value.
+     */
+    BAD_RATE,
+
+    /**
+     * Bad burst size value.
+     */
+    BAD_BURST,
+
+    /**
+     * Bad band.
+     */
+    BAD_BAND,
+
+    /**
+     * Bad value value.
+     */
+    BAD_BAND_VALUE
+
+
 }
diff --git a/core/api/src/main/java/org/onosproject/net/meter/MeterId.java b/core/api/src/main/java/org/onosproject/net/meter/MeterId.java
index b62db10..6a85a99 100644
--- a/core/api/src/main/java/org/onosproject/net/meter/MeterId.java
+++ b/core/api/src/main/java/org/onosproject/net/meter/MeterId.java
@@ -41,7 +41,7 @@
      *
      * @return an integer
      */
-    int id() {
+    public int id() {
         return id;
     }
 
diff --git a/core/api/src/main/java/org/onosproject/net/meter/MeterProviderService.java b/core/api/src/main/java/org/onosproject/net/meter/MeterProviderService.java
index 831c88a..85c0c43 100644
--- a/core/api/src/main/java/org/onosproject/net/meter/MeterProviderService.java
+++ b/core/api/src/main/java/org/onosproject/net/meter/MeterProviderService.java
@@ -29,10 +29,10 @@
     /**
      * Notifies the core that a meter operaton failed for a
      * specific reason.
-     * @param deviceId
-     * @param operation
+     * @param operation the failed operation
+     * @param reason the failure reason
      */
-    void meterOperationFailed(DeviceId deviceId, MeterOperation operation,
+    void meterOperationFailed(MeterOperation operation,
                               MeterFailReason reason);
 
     /**
diff --git a/providers/openflow/app/app.xml b/providers/openflow/app/app.xml
index 2604cd6..e54d1a8 100644
--- a/providers/openflow/app/app.xml
+++ b/providers/openflow/app/app.xml
@@ -29,4 +29,5 @@
     <artifact>mvn:${project.groupId}/onos-of-provider-packet/${project.version}</artifact>
     <artifact>mvn:${project.groupId}/onos-of-provider-flow/${project.version}</artifact>
     <artifact>mvn:${project.groupId}/onos-of-provider-group/${project.version}</artifact>
+    <artifact>mvn:${project.groupId}/onos-of-provider-meter/${project.version}</artifact>
 </app>
diff --git a/providers/openflow/app/features.xml b/providers/openflow/app/features.xml
index 39e5eed..7c41017 100644
--- a/providers/openflow/app/features.xml
+++ b/providers/openflow/app/features.xml
@@ -29,5 +29,6 @@
         <bundle>mvn:${project.groupId}/onos-of-provider-packet/${project.version}</bundle>
         <bundle>mvn:${project.groupId}/onos-of-provider-flow/${project.version}</bundle>
         <bundle>mvn:${project.groupId}/onos-of-provider-group/${project.version}</bundle>
+        <bundle>mvn:${project.groupId}/onos-of-provider-meter/${project.version}</bundle>
     </feature>
 </features>
diff --git a/providers/openflow/meter/src/main/java/org/onosproject/provider/of/meter/impl/MeterModBuilder.java b/providers/openflow/meter/src/main/java/org/onosproject/provider/of/meter/impl/MeterModBuilder.java
new file mode 100644
index 0000000..a9a3889
--- /dev/null
+++ b/providers/openflow/meter/src/main/java/org/onosproject/provider/of/meter/impl/MeterModBuilder.java
@@ -0,0 +1,158 @@
+/*
+ * 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.provider.of.meter.impl;
+
+import org.onosproject.net.meter.Band;
+import org.onosproject.net.meter.Meter;
+import org.onosproject.net.meter.MeterId;
+import org.projectfloodlight.openflow.protocol.OFFactory;
+import org.projectfloodlight.openflow.protocol.OFMeterFlags;
+import org.projectfloodlight.openflow.protocol.OFMeterMod;
+import org.projectfloodlight.openflow.protocol.OFMeterModCommand;
+import org.projectfloodlight.openflow.protocol.meterband.OFMeterBand;
+import org.projectfloodlight.openflow.protocol.meterband.OFMeterBandDrop;
+import org.projectfloodlight.openflow.protocol.meterband.OFMeterBandDscpRemark;
+import org.slf4j.Logger;
+
+import java.util.Collection;
+import java.util.List;
+import java.util.stream.Collectors;
+
+import static com.google.common.base.Preconditions.checkArgument;
+import static com.google.common.base.Preconditions.checkNotNull;
+import static org.slf4j.LoggerFactory.getLogger;
+
+/**
+ * Builder for a meter modification.
+ */
+public final class MeterModBuilder {
+
+    private final Logger log = getLogger(getClass());
+
+    private final long xid;
+    private final OFFactory factory;
+    private Meter.Unit unit = Meter.Unit.KB_PER_SEC;
+    private boolean burst = false;
+    private Integer id;
+    private Collection<Band> bands;
+
+    public MeterModBuilder(long xid, OFFactory factory) {
+        this.xid = xid;
+        this.factory = factory;
+    }
+
+    public static MeterModBuilder builder(long xid, OFFactory factory) {
+        return new MeterModBuilder(xid, factory);
+    }
+
+    public MeterModBuilder withRateUnit(Meter.Unit unit) {
+        this.unit = unit;
+        return this;
+    }
+
+    public MeterModBuilder burst() {
+        this.burst = true;
+        return this;
+    }
+
+    public MeterModBuilder withId(MeterId meterId) {
+        this.id = meterId.id();
+        return this;
+    }
+
+    public MeterModBuilder withBands(Collection<Band> bands) {
+        this.bands = bands;
+        return this;
+    }
+
+    public OFMeterMod add() {
+        validate();
+        OFMeterMod.Builder builder = builderMeterMod();
+        builder.setCommand(OFMeterModCommand.ADD.ordinal());
+        return builder.build();
+    }
+
+    public OFMeterMod remove() {
+        validate();
+        OFMeterMod.Builder builder = builderMeterMod();
+        builder.setCommand(OFMeterModCommand.DELETE.ordinal());
+        return builder.build();
+    }
+
+    public OFMeterMod modify() {
+        validate();
+        OFMeterMod.Builder builder = builderMeterMod();
+        builder.setCommand(OFMeterModCommand.MODIFY.ordinal());
+        return builder.build();
+    }
+
+    private OFMeterMod.Builder builderMeterMod() {
+        OFMeterMod.Builder builder = factory.buildMeterMod();
+        int flags = 0;
+        if (burst) {
+            // covering loxi short comings.
+            flags |= 1 << OFMeterFlags.BURST.ordinal();
+        }
+        switch (unit) {
+            case PKTS_PER_SEC:
+                flags |= 1 << OFMeterFlags.PKTPS.ordinal();
+                break;
+            case KB_PER_SEC:
+                flags |= 1 << OFMeterFlags.KBPS.ordinal();
+                break;
+            default:
+                log.warn("Unknown unit type {}", unit);
+        }
+        builder.setBands(buildBands());
+        builder.setFlags(flags)
+                .setMeterId(id)
+                .setXid(xid);
+        return builder;
+    }
+
+    private List<OFMeterBand> buildBands() {
+        return bands.stream().map(b -> {
+            switch (b.type()) {
+                case DROP:
+                    OFMeterBandDrop.Builder dropBuilder =
+                            factory.meterBands().buildDrop();
+                    if (burst) {
+                        dropBuilder.setBurstSize(b.burst());
+                    }
+                    dropBuilder.setRate(b.rate());
+                    return dropBuilder.build();
+                case REMARK:
+                    OFMeterBandDscpRemark.Builder remarkBand =
+                            factory.meterBands().buildDscpRemark();
+                    if (burst) {
+                        remarkBand.setBurstSize(b.burst());
+                    }
+                    remarkBand.setRate(b.rate());
+                    remarkBand.setPrecLevel(b.dropPrecedence());
+                    return remarkBand.build();
+                default:
+                    log.warn("Unknown band type {}", b.type());
+                    return null;
+            }
+        }).filter(value -> value != null).collect(Collectors.toList());
+    }
+
+    private void validate() {
+        checkNotNull(id, "id cannot be null");
+        checkNotNull(bands, "Must have bands");
+        checkArgument(bands.size() > 0, "Must have at lease one band");
+    }
+}
diff --git a/providers/openflow/meter/src/main/java/org/onosproject/provider/of/meter/impl/MeterStatsCollector.java b/providers/openflow/meter/src/main/java/org/onosproject/provider/of/meter/impl/MeterStatsCollector.java
new file mode 100644
index 0000000..83dc645
--- /dev/null
+++ b/providers/openflow/meter/src/main/java/org/onosproject/provider/of/meter/impl/MeterStatsCollector.java
@@ -0,0 +1,103 @@
+/*
+ * 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.provider.of.meter.impl;
+
+import org.jboss.netty.util.HashedWheelTimer;
+import org.jboss.netty.util.Timeout;
+import org.jboss.netty.util.TimerTask;
+import org.onlab.util.Timer;
+import org.onosproject.openflow.controller.OpenFlowSwitch;
+import org.onosproject.openflow.controller.RoleState;
+import org.projectfloodlight.openflow.protocol.OFMeterStatsRequest;
+import org.slf4j.Logger;
+
+import java.util.concurrent.TimeUnit;
+
+import static org.slf4j.LoggerFactory.getLogger;
+
+/*
+ * Sends Meter Stats Request and collect the Meter statistics with a time interval.
+ */
+public class MeterStatsCollector implements TimerTask {
+
+    private final HashedWheelTimer timer = Timer.getTimer();
+    private final OpenFlowSwitch sw;
+    private final Logger log = getLogger(getClass());
+    private final int refreshInterval;
+
+    private Timeout timeout;
+
+    private boolean stopTimer = false;
+
+    /**
+     * Creates a GroupStatsCollector object.
+     *
+     * @param sw Open Flow switch
+     * @param interval time interval for collecting group statistic
+     */
+    public MeterStatsCollector(OpenFlowSwitch sw, int interval) {
+        this.sw = sw;
+        this.refreshInterval = interval;
+    }
+
+    @Override
+    public void run(Timeout timeout) throws Exception {
+        log.trace("Collecting stats for {}", sw.getStringId());
+
+        sendMeterStatistic();
+
+        if (!this.stopTimer) {
+            log.trace("Scheduling stats collection in {} seconds for {}",
+                    this.refreshInterval, this.sw.getStringId());
+            timeout.getTimer().newTimeout(this, refreshInterval,
+                    TimeUnit.SECONDS);
+        }
+    }
+
+    private void sendMeterStatistic() {
+        if (log.isTraceEnabled()) {
+            log.trace("sendMeterStatistics {}:{}", sw.getStringId(), sw.getRole());
+        }
+        if (sw.getRole() != RoleState.MASTER) {
+            return;
+        }
+
+        OFMeterStatsRequest.Builder builder =
+                sw.factory().buildMeterStatsRequest();
+        builder.setXid(0).setMeterId(0xFFFFFFFF);
+
+        sw.sendMsg(builder.build());
+
+    }
+
+    /**
+     * Starts the collector.
+     */
+    public void start() {
+        log.info("Starting Meter Stats collection thread for {}", sw.getStringId());
+        timeout = timer.newTimeout(this, 1, TimeUnit.SECONDS);
+    }
+
+    /**
+     * Stops the collector.
+     */
+    public void stop() {
+        log.info("Stopping Meter Stats collection thread for {}", sw.getStringId());
+        this.stopTimer = true;
+        timeout.cancel();
+    }
+}
diff --git a/providers/openflow/meter/src/main/java/org/onosproject/provider/of/meter/impl/OpenFlowMeterProvider.java b/providers/openflow/meter/src/main/java/org/onosproject/provider/of/meter/impl/OpenFlowMeterProvider.java
index 5c9940c..4b459c5 100644
--- a/providers/openflow/meter/src/main/java/org/onosproject/provider/of/meter/impl/OpenFlowMeterProvider.java
+++ b/providers/openflow/meter/src/main/java/org/onosproject/provider/of/meter/impl/OpenFlowMeterProvider.java
@@ -16,18 +16,45 @@
 
 package org.onosproject.provider.of.meter.impl;
 
+import com.google.common.cache.Cache;
+import com.google.common.cache.CacheBuilder;
+import com.google.common.cache.RemovalCause;
+import com.google.common.cache.RemovalNotification;
+import com.google.common.collect.Maps;
+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.net.DeviceId;
+import org.onosproject.net.meter.Meter;
+import org.onosproject.net.meter.MeterFailReason;
 import org.onosproject.net.meter.MeterOperation;
 import org.onosproject.net.meter.MeterOperations;
 import org.onosproject.net.meter.MeterProvider;
+import org.onosproject.net.meter.MeterProviderRegistry;
+import org.onosproject.net.meter.MeterProviderService;
 import org.onosproject.net.provider.AbstractProvider;
 import org.onosproject.net.provider.ProviderId;
+import org.onosproject.openflow.controller.Dpid;
 import org.onosproject.openflow.controller.OpenFlowController;
+import org.onosproject.openflow.controller.OpenFlowEventListener;
+import org.onosproject.openflow.controller.OpenFlowSwitch;
+import org.onosproject.openflow.controller.OpenFlowSwitchListener;
+import org.onosproject.openflow.controller.RoleState;
+import org.projectfloodlight.openflow.protocol.OFErrorMsg;
+import org.projectfloodlight.openflow.protocol.OFErrorType;
+import org.projectfloodlight.openflow.protocol.OFMessage;
+import org.projectfloodlight.openflow.protocol.OFPortStatus;
+import org.projectfloodlight.openflow.protocol.OFStatsReply;
+import org.projectfloodlight.openflow.protocol.OFVersion;
+import org.projectfloodlight.openflow.protocol.errormsg.OFMeterModFailedErrorMsg;
 import org.slf4j.Logger;
 
+import java.util.Map;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicLong;
+
 import static org.slf4j.LoggerFactory.getLogger;
 
 /**
@@ -36,11 +63,28 @@
 @Component(immediate = true)
 public class OpenFlowMeterProvider extends AbstractProvider implements MeterProvider {
 
+
     private final Logger log = getLogger(getClass());
 
     @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
     protected OpenFlowController controller;
 
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected MeterProviderRegistry providerRegistry;
+
+    private MeterProviderService providerService;
+
+    private static final AtomicLong XID_COUNTER = new AtomicLong(1);
+
+    static final int POLL_INTERVAL = 10;
+    static final long TIMEOUT = 30;
+
+    private Cache<Integer, MeterOperation> pendingOperations;
+    private Cache<Long, MeterOperation> pendingXid;
+
+
+    private InternalMeterListener listener = new InternalMeterListener();
+    private Map<Dpid, MeterStatsCollector> collectors = Maps.newHashMap();
 
     /**
      * Creates a OpenFlow meter provider.
@@ -49,13 +93,232 @@
         super(new ProviderId("of", "org.onosproject.provider.meter"));
     }
 
+    @Activate
+    public void activate() {
+        providerService = providerRegistry.register(this);
+
+        pendingOperations = CacheBuilder.newBuilder()
+                .expireAfterWrite(TIMEOUT, TimeUnit.SECONDS)
+                .removalListener((RemovalNotification<Integer, MeterOperation> notification) -> {
+                    if (notification.getCause() == RemovalCause.EXPIRED) {
+                        providerService.meterOperationFailed(notification.getValue(),
+                                                             MeterFailReason.TIMEOUT);
+                    }
+                }).build();
+
+        controller.addEventListener(listener);
+        controller.addListener(listener);
+
+        controller.getSwitches().forEach((sw -> createStatsCollection(sw)));
+    }
+
+    @Deactivate
+    public void deactivate() {
+        providerRegistry.unregister(this);
+        controller.removeEventListener(listener);
+        controller.removeListener(listener);
+        providerService = null;
+    }
+
     @Override
     public void performMeterOperation(DeviceId deviceId, MeterOperations meterOps) {
+        Dpid dpid = Dpid.dpid(deviceId.uri());
+        OpenFlowSwitch sw = controller.getSwitch(dpid);
+        if (sw == null) {
+            log.error("Unknown device {}", deviceId);
+            meterOps.operations().forEach(op ->
+                                                  providerService.meterOperationFailed(op,
+                                                                                       MeterFailReason.UNKNOWN_DEVICE)
+            );
+            return;
+        }
 
+        meterOps.operations().forEach(op -> performOperation(sw, op));
     }
 
     @Override
     public void performMeterOperation(DeviceId deviceId, MeterOperation meterOp) {
+        Dpid dpid = Dpid.dpid(deviceId.uri());
+        OpenFlowSwitch sw = controller.getSwitch(dpid);
+        if (sw == null) {
+            log.error("Unknown device {}", deviceId);
+            providerService.meterOperationFailed(meterOp,
+                                                 MeterFailReason.UNKNOWN_DEVICE);
+            return;
+        }
 
     }
+
+    private void performOperation(OpenFlowSwitch sw, MeterOperation op) {
+
+        pendingOperations.put(op.meter().id().id(), op);
+
+
+        Meter meter = op.meter();
+        MeterModBuilder builder = MeterModBuilder.builder(meter.id().id(), sw.factory());
+        if (meter.isBurst()) {
+            builder.burst();
+        }
+        builder.withBands(meter.bands())
+                .withId(meter.id())
+                .withRateUnit(meter.unit());
+
+        switch (op.type()) {
+            case ADD:
+                sw.sendMsg(builder.add());
+                break;
+            case REMOVE:
+                sw.sendMsg(builder.remove());
+                break;
+            case MODIFY:
+                sw.sendMsg(builder.modify());
+                break;
+            default:
+                log.warn("Unknown Meter command {}; not sending anything",
+                         op.type());
+                providerService.meterOperationFailed(op,
+                                                     MeterFailReason.UNKNOWN_COMMAND);
+        }
+
+    }
+
+    private void createStatsCollection(OpenFlowSwitch sw) {
+        if (isMeterSupported(sw)) {
+            MeterStatsCollector msc = new MeterStatsCollector(sw, POLL_INTERVAL);
+            msc.start();
+            collectors.put(new Dpid(sw.getId()), msc);
+        }
+    }
+
+    private boolean isMeterSupported(OpenFlowSwitch sw) {
+        if (sw.factory().getVersion() == OFVersion.OF_10 ||
+                sw.factory().getVersion() == OFVersion.OF_11 ||
+                sw.factory().getVersion() == OFVersion.OF_12) {
+            return false;
+        }
+
+        return true;
+    }
+
+    private void pushMeterStats(Dpid dpid, OFStatsReply msg) {
+
+    }
+
+    private void signalMeterError(OFMeterModFailedErrorMsg meterError,
+                                  MeterOperation op) {
+        switch (meterError.getCode()) {
+            case UNKNOWN:
+                providerService.meterOperationFailed(op,
+                                                     MeterFailReason.UNKNOWN_DEVICE);
+                break;
+            case METER_EXISTS:
+                providerService.meterOperationFailed(op,
+                                                     MeterFailReason.EXISTING_METER);
+                break;
+            case INVALID_METER:
+                providerService.meterOperationFailed(op,
+                                                     MeterFailReason.INVALID_METER);
+                break;
+            case UNKNOWN_METER:
+                providerService.meterOperationFailed(op,
+                                                     MeterFailReason.UNKNOWN);
+                break;
+            case BAD_COMMAND:
+                providerService.meterOperationFailed(op,
+                                                     MeterFailReason.UNKNOWN_COMMAND);
+                break;
+            case BAD_FLAGS:
+                providerService.meterOperationFailed(op,
+                                                     MeterFailReason.UNKNOWN_FLAGS);
+                break;
+            case BAD_RATE:
+                providerService.meterOperationFailed(op,
+                                                     MeterFailReason.BAD_RATE);
+                break;
+            case BAD_BURST:
+                providerService.meterOperationFailed(op,
+                                                     MeterFailReason.BAD_BURST);
+                break;
+            case BAD_BAND:
+                providerService.meterOperationFailed(op,
+                                                     MeterFailReason.BAD_BAND);
+                break;
+            case BAD_BAND_VALUE:
+                providerService.meterOperationFailed(op,
+                                                     MeterFailReason.BAD_BAND_VALUE);
+                break;
+            case OUT_OF_METERS:
+                providerService.meterOperationFailed(op,
+                                                     MeterFailReason.OUT_OF_METERS);
+                break;
+            case OUT_OF_BANDS:
+                providerService.meterOperationFailed(op,
+                                                     MeterFailReason.OUT_OF_BANDS);
+                break;
+            default:
+                providerService.meterOperationFailed(op,
+                                                     MeterFailReason.UNKNOWN);
+        }
+    }
+
+    private class InternalMeterListener
+            implements OpenFlowSwitchListener, OpenFlowEventListener {
+        @Override
+        public void handleMessage(Dpid dpid, OFMessage msg) {
+            switch (msg.getType()) {
+                case STATS_REPLY:
+                    pushMeterStats(dpid, (OFStatsReply) msg);
+                    break;
+                case ERROR:
+                    OFErrorMsg error = (OFErrorMsg) msg;
+                    if (error.getErrType() == OFErrorType.METER_MOD_FAILED) {
+                        MeterOperation op =
+                                pendingOperations.getIfPresent(error.getXid());
+                        pendingOperations.invalidate(error.getXid());
+                        if (op == null) {
+                            log.warn("Unknown Meter operation failed {}", error);
+                        } else {
+                            OFMeterModFailedErrorMsg meterError =
+                                    (OFMeterModFailedErrorMsg) error;
+                            signalMeterError(meterError, op);
+                        }
+                    }
+                    break;
+                default:
+                    break;
+            }
+
+        }
+
+        @Override
+        public void switchAdded(Dpid dpid) {
+            createStatsCollection(controller.getSwitch(dpid));
+        }
+
+        @Override
+        public void switchRemoved(Dpid dpid) {
+            MeterStatsCollector msc = collectors.remove(dpid);
+            if (msc != null) {
+                msc.stop();
+            }
+        }
+
+        @Override
+        public void switchChanged(Dpid dpid) {
+
+        }
+
+        @Override
+        public void portChanged(Dpid dpid, OFPortStatus status) {
+
+        }
+
+        @Override
+        public void receivedRoleReply(Dpid dpid, RoleState requested, RoleState response) {
+
+        }
+    }
+
+
+
 }