bringing src to commit tag 65d551b50e782b0c1ea76c1a9ed1c5a801a5a7e4

Change-Id: Ib2da78962eaef856f418636c31b0f5c84286244f

3 files changed, 375 insertions, 279 deletions

diff --git a/framework/src/onos/providers/lldp/src/main/java/org/onosproject/provider/lldp/impl/DiscoveryContext.java b/framework/src/onos/providers/lldp/src/main/java/org/onosproject/provider/lldp/impl/DiscoveryContext.java
new file mode 100644
index 00000000..0cd19242
--- /dev/null
+++ b/framework/src/onos/providers/lldp/src/main/java/org/onosproject/provider/lldp/impl/DiscoveryContext.java
@@ -0,0 +1,69 @@
+/*
+ * 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.lldp.impl;
+
+import org.onosproject.mastership.MastershipService;
+import org.onosproject.net.LinkKey;
+import org.onosproject.net.link.LinkProviderService;
+import org.onosproject.net.packet.PacketService;
+
+/**
+ * Shared context for use by link discovery.
+ */
+interface DiscoveryContext {
+
+    /**
+     * Returns the shared mastership service reference.
+     *
+     * @return mastership service
+     */
+    MastershipService mastershipService();
+
+    /**
+     * Returns the shared link provider service reference.
+     *
+     * @return link provider service
+     */
+    LinkProviderService providerService();
+
+    /**
+     * Returns the shared packet service reference.
+     *
+     * @return packet service
+     */
+    PacketService packetService();
+
+    /**
+     * Returns the probe rate in millis.
+     *
+     * @return probe rate
+     */
+    long probeRate();
+
+    /**
+     * Indicates whether to emit BDDP.
+     *
+     * @return true to emit BDDP
+     */
+    boolean useBDDP();
+
+    /**
+     * Touches the link identified by the given key to indicate that it's active.
+     *
+     * @param key link key
+     */
+    void touchLink(LinkKey key);
+}
diff --git a/framework/src/onos/providers/lldp/src/main/java/org/onosproject/provider/lldp/impl/LLDPLinkProvider.java b/framework/src/onos/providers/lldp/src/main/java/org/onosproject/provider/lldp/impl/LLDPLinkProvider.java
index e9e2bfad..386d838f 100644
--- a/framework/src/onos/providers/lldp/src/main/java/org/onosproject/provider/lldp/impl/LLDPLinkProvider.java
+++ b/framework/src/onos/providers/lldp/src/main/java/org/onosproject/provider/lldp/impl/LLDPLinkProvider.java
@@ -15,9 +15,9 @@
  */
 package org.onosproject.provider.lldp.impl;
 
-import com.google.common.base.Strings;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
+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;
@@ -35,15 +35,18 @@ import org.onosproject.mastership.MastershipService;
 import org.onosproject.net.ConnectPoint;
 import org.onosproject.net.Device;
 import org.onosproject.net.DeviceId;
+import org.onosproject.net.LinkKey;
 import org.onosproject.net.Port;
 import org.onosproject.net.device.DeviceEvent;
 import org.onosproject.net.device.DeviceListener;
 import org.onosproject.net.device.DeviceService;
 import org.onosproject.net.flow.DefaultTrafficSelector;
 import org.onosproject.net.flow.TrafficSelector;
+import org.onosproject.net.link.DefaultLinkDescription;
 import org.onosproject.net.link.LinkProvider;
 import org.onosproject.net.link.LinkProviderRegistry;
 import org.onosproject.net.link.LinkProviderService;
+import org.onosproject.net.link.LinkService;
 import org.onosproject.net.packet.PacketContext;
 import org.onosproject.net.packet.PacketPriority;
 import org.onosproject.net.packet.PacketProcessor;
@@ -57,29 +60,29 @@ import java.io.IOException;
 import java.util.Dictionary;
 import java.util.EnumSet;
 import java.util.Map;
+import java.util.Properties;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ScheduledExecutorService;
 
+import static com.google.common.base.Strings.isNullOrEmpty;
 import static java.util.concurrent.Executors.newSingleThreadScheduledExecutor;
 import static java.util.concurrent.TimeUnit.SECONDS;
 import static org.onlab.util.Tools.get;
 import static org.onlab.util.Tools.groupedThreads;
+import static org.onosproject.net.Link.Type.DIRECT;
 import static org.slf4j.LoggerFactory.getLogger;
 
 /**
- * Provider which uses an OpenFlow controller to detect network
- * infrastructure links.
+ * Provider which uses LLDP and BDDP packets to detect network infrastructure links.
  */
 @Component(immediate = true)
 public class LLDPLinkProvider extends AbstractProvider implements LinkProvider {
 
     private static final String PROVIDER_NAME = "org.onosproject.provider.lldp";
 
-    private static final String PROP_USE_BDDP = "useBDDP";
-    private static final String PROP_DISABLE_LD = "disableLinkDiscovery";
-    private static final String PROP_LLDP_SUPPRESSION = "lldpSuppression";
-
-    private static final String DEFAULT_LLDP_SUPPRESSION_CONFIG = "../config/lldp_suppression.json";
+    private static final String FORMAT =
+            "Settings: enabled={}, useBDDP={}, probeRate={}, " +
+                    "staleLinkAge={}, lldpSuppression={}";
 
     private final Logger log = getLogger(getClass());
 
@@ -93,6 +96,9 @@ public class LLDPLinkProvider extends AbstractProvider implements LinkProvider {
     protected DeviceService deviceService;
 
     @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected LinkService linkService;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
     protected PacketService packetService;
 
     @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
@@ -105,28 +111,51 @@ public class LLDPLinkProvider extends AbstractProvider implements LinkProvider {
 
     private ScheduledExecutorService executor;
 
+    // TODO: Add sanity checking for the configurable params based on the delays
+    private static final long DEVICE_SYNC_DELAY = 5;
+    private static final long LINK_PRUNER_DELAY = 3;
+
+    private static final String PROP_ENABLED = "enabled";
+    @Property(name = PROP_ENABLED, boolValue = true,
+            label = "If false, link discovery is disabled")
+    private boolean enabled = false;
+
+    private static final String PROP_USE_BDDP = "useBDDP";
     @Property(name = PROP_USE_BDDP, boolValue = true,
             label = "Use BDDP for link discovery")
     private boolean useBDDP = true;
 
-    @Property(name = PROP_DISABLE_LD, boolValue = false,
-            label = "Permanently disable link discovery")
-    private boolean disableLinkDiscovery = false;
+    private static final String PROP_PROBE_RATE = "probeRate";
+    private static final int DEFAULT_PROBE_RATE = 3_000;
+    @Property(name = PROP_PROBE_RATE, intValue = DEFAULT_PROBE_RATE,
+            label = "LLDP and BDDP probe rate specified in millis")
+    private int probeRate = DEFAULT_PROBE_RATE;
 
-    private static final long INIT_DELAY = 5;
-    private static final long DELAY = 5;
+    private static final String PROP_STALE_LINK_AGE = "staleLinkAge";
+    private static final int DEFAULT_STALE_LINK_AGE = 10_000;
+    @Property(name = PROP_STALE_LINK_AGE, intValue = DEFAULT_STALE_LINK_AGE,
+            label = "Number of millis beyond which links will be considered stale")
+    private int staleLinkAge = DEFAULT_STALE_LINK_AGE;
 
+    // FIXME: convert to use network config subsystem instead
+    private static final String PROP_LLDP_SUPPRESSION = "lldpSuppression";
+    private static final String DEFAULT_LLDP_SUPPRESSION_CONFIG = "../config/lldp_suppression.json";
     @Property(name = PROP_LLDP_SUPPRESSION, value = DEFAULT_LLDP_SUPPRESSION_CONFIG,
             label = "Path to LLDP suppression configuration file")
     private String lldpSuppression = DEFAULT_LLDP_SUPPRESSION_CONFIG;
 
-
-    private final InternalLinkProvider listener = new InternalLinkProvider();
-
+    private final DiscoveryContext context = new InternalDiscoveryContext();
     private final InternalRoleListener roleListener = new InternalRoleListener();
+    private final InternalDeviceListener deviceListener = new InternalDeviceListener();
+    private final InternalPacketProcessor packetProcessor = new InternalPacketProcessor();
 
+    // Device link discovery helpers.
     protected final Map<DeviceId, LinkDiscovery> discoverers = new ConcurrentHashMap<>();
 
+    // Most recent time a tracked link was seen; links are tracked if their
+    // destination connection point is mastered by this controller instance.
+    private final Map<LinkKey, Long> linkTimes = Maps.newConcurrentMap();
+
     private SuppressionRules rules;
     private ApplicationId appId;
 
@@ -141,39 +170,125 @@ public class LLDPLinkProvider extends AbstractProvider implements LinkProvider {
     public void activate(ComponentContext context) {
         cfgService.registerProperties(getClass());
         appId = coreService.registerApplication(PROVIDER_NAME);
-
-        // to load configuration at startup
         modified(context);
-        if (disableLinkDiscovery) {
-            log.info("LinkDiscovery has been permanently disabled by configuration");
-            return;
+        log.info("Started");
+    }
+
+    @Deactivate
+    public void deactivate() {
+        cfgService.unregisterProperties(getClass(), false);
+        disable();
+        log.info("Stopped");
+    }
+
+    @Modified
+    public void modified(ComponentContext context) {
+        Dictionary<?, ?> properties = context != null ? context.getProperties() : new Properties();
+
+        boolean newEnabled, newUseBddp;
+        int newProbeRate, newStaleLinkAge;
+        String newLldpSuppression;
+        try {
+            String s = get(properties, PROP_ENABLED);
+            newEnabled = isNullOrEmpty(s) || Boolean.parseBoolean(s.trim());
+
+            s = get(properties, PROP_USE_BDDP);
+            newUseBddp = isNullOrEmpty(s) || Boolean.parseBoolean(s.trim());
+
+            s = get(properties, PROP_PROBE_RATE);
+            newProbeRate = isNullOrEmpty(s) ? probeRate : Integer.parseInt(s.trim());
+
+            s = get(properties, PROP_STALE_LINK_AGE);
+            newStaleLinkAge = isNullOrEmpty(s) ? staleLinkAge : Integer.parseInt(s.trim());
+
+            s = get(properties, PROP_LLDP_SUPPRESSION);
+            newLldpSuppression = isNullOrEmpty(s) ? DEFAULT_LLDP_SUPPRESSION_CONFIG : s;
+
+        } catch (NumberFormatException e) {
+            log.warn(e.getMessage());
+            newEnabled = enabled;
+            newUseBddp = useBDDP;
+            newProbeRate = probeRate;
+            newStaleLinkAge = staleLinkAge;
+            newLldpSuppression = lldpSuppression;
+        }
+
+        boolean wasEnabled = enabled;
+
+        enabled = newEnabled;
+        useBDDP = newUseBddp;
+        probeRate = newProbeRate;
+        staleLinkAge = newStaleLinkAge;
+        lldpSuppression = newLldpSuppression;
+
+        if (!wasEnabled && enabled) {
+            enable();
+        } else if (wasEnabled && !enabled) {
+            disable();
         }
 
+        log.info(FORMAT, enabled, useBDDP, probeRate, staleLinkAge, lldpSuppression);
+    }
+
+    /**
+     * Enables link discovery processing.
+     */
+    private void enable() {
         providerService = providerRegistry.register(this);
-        deviceService.addListener(listener);
-        packetService.addProcessor(listener, PacketProcessor.advisor(0));
         masterService.addListener(roleListener);
+        deviceService.addListener(deviceListener);
+        packetService.addProcessor(packetProcessor, PacketProcessor.advisor(0));
+
+        loadSuppressionRules();
+        loadDevices();
+
+        executor = newSingleThreadScheduledExecutor(groupedThreads("onos/link", "discovery-%d"));
+        executor.scheduleAtFixedRate(new SyncDeviceInfoTask(),
+                                     DEVICE_SYNC_DELAY, DEVICE_SYNC_DELAY, SECONDS);
+        executor.scheduleAtFixedRate(new LinkPrunerTask(),
+                                     LINK_PRUNER_DELAY, LINK_PRUNER_DELAY, SECONDS);
+
+        requestIntercepts();
+    }
+
+    /**
+     * Disables link discovery processing.
+     */
+    private void disable() {
+        withdrawIntercepts();
+
+        providerRegistry.unregister(this);
+        masterService.removeListener(roleListener);
+        deviceService.removeListener(deviceListener);
+        packetService.removeProcessor(packetProcessor);
+
+        if (executor != null) {
+            executor.shutdownNow();
+        }
+        discoverers.values().forEach(LinkDiscovery::stop);
+        discoverers.clear();
 
-        LinkDiscovery ld;
+        providerService = null;
+    }
+
+    /**
+     * Loads available devices and registers their ports to be probed.
+     */
+    private void loadDevices() {
         for (Device device : deviceService.getAvailableDevices()) {
             if (rules.isSuppressed(device)) {
                 log.debug("LinkDiscovery from {} disabled by configuration", device.id());
                 continue;
             }
-            ld = new LinkDiscovery(device, packetService, masterService,
-                                   providerService, useBDDP);
+            LinkDiscovery ld = new LinkDiscovery(device, context);
             discoverers.put(device.id(), ld);
             addPorts(ld, device.id());
         }
-
-        executor = newSingleThreadScheduledExecutor(groupedThreads("onos/device", "sync-%d"));
-        executor.scheduleAtFixedRate(new SyncDeviceInfoTask(), INIT_DELAY, DELAY, SECONDS);
-
-        requestIntercepts();
-
-        log.info("Started");
     }
 
+    /**
+     * Adds ports of the specified device to the specified discovery helper.
+     */
     private void addPorts(LinkDiscovery discoverer, DeviceId deviceId) {
         for (Port p : deviceService.getPorts(deviceId)) {
             if (rules.isSuppressed(p)) {
@@ -185,54 +300,12 @@ public class LLDPLinkProvider extends AbstractProvider implements LinkProvider {
         }
     }
 
-    @Deactivate
-    public void deactivate() {
-        cfgService.unregisterProperties(getClass(), false);
-        if (disableLinkDiscovery) {
-            return;
-        }
-
-        withdrawIntercepts();
-
-        providerRegistry.unregister(this);
-        deviceService.removeListener(listener);
-        packetService.removeProcessor(listener);
-        masterService.removeListener(roleListener);
-
-        executor.shutdownNow();
-        discoverers.values().forEach(LinkDiscovery::stop);
-        discoverers.clear();
-        providerService = null;
-
-        log.info("Stopped");
-    }
-
-    @Modified
-    public void modified(ComponentContext context) {
-        if (context == null) {
-            loadSuppressionRules();
-            return;
-        }
-        @SuppressWarnings("rawtypes")
-        Dictionary properties = context.getProperties();
-
-        String s = get(properties, PROP_DISABLE_LD);
-        if (!Strings.isNullOrEmpty(s)) {
-            disableLinkDiscovery = Boolean.valueOf(s);
-        }
-        s = get(properties, PROP_USE_BDDP);
-        if (!Strings.isNullOrEmpty(s)) {
-            useBDDP = Boolean.valueOf(s);
-        }
-        s = get(properties, PROP_LLDP_SUPPRESSION);
-        if (!Strings.isNullOrEmpty(s)) {
-            lldpSuppression = s;
-        }
-        requestIntercepts();
-        loadSuppressionRules();
-    }
 
+    /**
+     * Loads LLDP suppression rules.
+     */
     private void loadSuppressionRules() {
+        // FIXME: convert to use network configuration
         SuppressionRulesStore store = new SuppressionRulesStore(lldpSuppression);
         try {
             log.info("Reading suppression rules from {}", lldpSuppression);
@@ -249,7 +322,7 @@ public class LLDPLinkProvider extends AbstractProvider implements LinkProvider {
     }
 
     /**
-     * Request packet intercepts.
+     * Requests packet intercepts.
      */
     private void requestIntercepts() {
         TrafficSelector.Builder selector = DefaultTrafficSelector.builder();
@@ -265,7 +338,7 @@ public class LLDPLinkProvider extends AbstractProvider implements LinkProvider {
     }
 
     /**
-     * Withdraw packet intercepts.
+     * Withdraws packet intercepts.
      */
     private void withdrawIntercepts() {
         TrafficSelector.Builder selector = DefaultTrafficSelector.builder();
@@ -275,13 +348,10 @@ public class LLDPLinkProvider extends AbstractProvider implements LinkProvider {
         packetService.cancelPackets(selector.build(), PacketPriority.CONTROL, appId);
     }
 
-    private LinkDiscovery createLinkDiscovery(Device device) {
-        return new LinkDiscovery(device, packetService, masterService,
-                                 providerService, useBDDP);
-    }
-
+    /**
+     * Processes device mastership role changes.
+     */
     private class InternalRoleListener implements MastershipListener {
-
         @Override
         public void event(MastershipEvent event) {
             if (MastershipEvent.Type.BACKUPS_CHANGED.equals(event.type())) {
@@ -298,22 +368,18 @@ public class LLDPLinkProvider extends AbstractProvider implements LinkProvider {
             if (rules.isSuppressed(device)) {
                 return;
             }
-            synchronized (discoverers) {
-                if (!discoverers.containsKey(deviceId)) {
-                    // ideally, should never reach here
-                    log.debug("Device mastership changed ({}) {}", event.type(), deviceId);
-                    discoverers.put(deviceId, createLinkDiscovery(device));
-                }
-            }
+            discoverers.computeIfAbsent(deviceId, k -> new LinkDiscovery(device, context));
         }
 
     }
 
-    private class InternalLinkProvider implements PacketProcessor, DeviceListener {
-
+    /**
+     * Processes device events.
+     */
+    private class InternalDeviceListener implements DeviceListener {
         @Override
         public void event(DeviceEvent event) {
-            LinkDiscovery ld = null;
+            LinkDiscovery ld;
             Device device = event.subject();
             Port port = event.port();
             if (device == null) {
@@ -333,7 +399,7 @@ public class LLDPLinkProvider extends AbstractProvider implements LinkProvider {
                                 return;
                             }
                             log.debug("Device added ({}) {}", event.type(), deviceId);
-                            discoverers.put(deviceId, createLinkDiscovery(device));
+                            discoverers.put(deviceId, new LinkDiscovery(device, context));
                         } else {
                             if (ld.isStopped()) {
                                 log.debug("Device restarted ({}) {}", event.type(), deviceId);
@@ -400,7 +466,12 @@ public class LLDPLinkProvider extends AbstractProvider implements LinkProvider {
                     log.debug("Unknown event {}", event);
             }
         }
+    }
 
+    /**
+     * Processes incoming packets.
+     */
+    private class InternalPacketProcessor implements PacketProcessor {
         @Override
         public void process(PacketContext context) {
             if (context == null) {
@@ -417,8 +488,10 @@ public class LLDPLinkProvider extends AbstractProvider implements LinkProvider {
         }
     }
 
+    /**
+     * Auxiliary task to keep device ports up to date.
+     */
     private final class SyncDeviceInfoTask implements Runnable {
-
         @Override
         public void run() {
             if (Thread.currentThread().isInterrupted()) {
@@ -433,20 +506,90 @@ public class LLDPLinkProvider extends AbstractProvider implements LinkProvider {
                     }
                     DeviceId did = dev.id();
                     synchronized (discoverers) {
-                        LinkDiscovery discoverer = discoverers.get(did);
-                        if (discoverer == null) {
-                            discoverer = createLinkDiscovery(dev);
-                            discoverers.put(did, discoverer);
-                        }
-
-                        addPorts(discoverer, did);
+                        LinkDiscovery ld = discoverers
+                                .computeIfAbsent(did, k -> new LinkDiscovery(dev, context));
+                        addPorts(ld, did);
                     }
                 }
             } catch (Exception e) {
-                // catch all Exception to avoid Scheduled task being suppressed.
+                // Catch all exceptions to avoid task being suppressed
                 log.error("Exception thrown during synchronization process", e);
             }
         }
     }
 
+    /**
+     * Auxiliary task for pruning stale links.
+     */
+    private class LinkPrunerTask implements Runnable {
+        @Override
+        public void run() {
+            if (Thread.currentThread().isInterrupted()) {
+                log.info("Interrupted, quitting");
+                return;
+            }
+
+            try {
+                // TODO: There is still a slight possibility of mastership
+                // change occurring right with link going stale. This will
+                // result in the stale link not being pruned.
+                Maps.filterEntries(linkTimes, e -> {
+                    if (!masterService.isLocalMaster(e.getKey().dst().deviceId())) {
+                        return true;
+                    }
+                    if (isStale(e.getValue())) {
+                        providerService.linkVanished(new DefaultLinkDescription(e.getKey().src(),
+                                                                                e.getKey().dst(),
+                                                                                DIRECT));
+                        return true;
+                    }
+                    return false;
+                }).clear();
+
+            } catch (Exception e) {
+                // Catch all exceptions to avoid task being suppressed
+                log.error("Exception thrown during link pruning process", e);
+            }
+        }
+
+        private boolean isStale(long lastSeen) {
+            return lastSeen < System.currentTimeMillis() - staleLinkAge;
+        }
+    }
+
+    /**
+     * Provides processing context for the device link discovery helpers.
+     */
+    private class InternalDiscoveryContext implements DiscoveryContext {
+        @Override
+        public MastershipService mastershipService() {
+            return masterService;
+        }
+
+        @Override
+        public LinkProviderService providerService() {
+            return providerService;
+        }
+
+        @Override
+        public PacketService packetService() {
+            return packetService;
+        }
+
+        @Override
+        public long probeRate() {
+            return probeRate;
+        }
+
+        @Override
+        public boolean useBDDP() {
+            return useBDDP;
+        }
+
+        @Override
+        public void touchLink(LinkKey key) {
+            linkTimes.put(key, System.currentTimeMillis());
+        }
+    }
+
 }
diff --git a/framework/src/onos/providers/lldp/src/main/java/org/onosproject/provider/lldp/impl/LinkDiscovery.java b/framework/src/onos/providers/lldp/src/main/java/org/onosproject/provider/lldp/impl/LinkDiscovery.java
index a81eeb1d..8cdfd50f 100644
--- a/framework/src/onos/providers/lldp/src/main/java/org/onosproject/provider/lldp/impl/LinkDiscovery.java
+++ b/framework/src/onos/providers/lldp/src/main/java/org/onosproject/provider/lldp/impl/LinkDiscovery.java
@@ -15,44 +15,34 @@
  */
 package org.onosproject.provider.lldp.impl;
 
-import com.google.common.collect.Maps;
 import com.google.common.collect.Sets;
 import org.jboss.netty.util.Timeout;
 import org.jboss.netty.util.TimerTask;
 import org.onlab.packet.Ethernet;
 import org.onlab.packet.ONOSLLDP;
 import org.onlab.util.Timer;
-import org.onosproject.mastership.MastershipService;
 import org.onosproject.net.ConnectPoint;
 import org.onosproject.net.Device;
 import org.onosproject.net.DeviceId;
 import org.onosproject.net.Link.Type;
+import org.onosproject.net.LinkKey;
 import org.onosproject.net.Port;
 import org.onosproject.net.PortNumber;
 import org.onosproject.net.link.DefaultLinkDescription;
 import org.onosproject.net.link.LinkDescription;
-import org.onosproject.net.link.LinkProviderService;
 import org.onosproject.net.packet.DefaultOutboundPacket;
 import org.onosproject.net.packet.OutboundPacket;
 import org.onosproject.net.packet.PacketContext;
-import org.onosproject.net.packet.PacketService;
 import org.slf4j.Logger;
 
 import java.nio.ByteBuffer;
-import java.util.Iterator;
-import java.util.Map;
 import java.util.Set;
-import java.util.concurrent.atomic.AtomicInteger;
 
-import static com.google.common.base.Preconditions.checkNotNull;
 import static java.util.concurrent.TimeUnit.MILLISECONDS;
 import static org.onosproject.net.PortNumber.portNumber;
 import static org.onosproject.net.flow.DefaultTrafficTreatment.builder;
 import static org.slf4j.LoggerFactory.getLogger;
 
-// TODO: add 'fast discovery' mode: drop LLDPs in destination switch but listen for flow_removed messages
-// FIXME: add ability to track links using port pairs or the link inventory
-
 /**
  * Run discovery process from a physical switch. Ports are initially labeled as
  * slow ports. When an LLDP is successfully received, label the remote port as
@@ -60,57 +50,36 @@ import static org.slf4j.LoggerFactory.getLogger;
  * LLDP, send an LLDP for a single slow port. Based on FlowVisor topology
  * discovery implementation.
  */
-public class LinkDiscovery implements TimerTask {
+class LinkDiscovery implements TimerTask {
 
     private final Logger log = getLogger(getClass());
 
-    private static final short MAX_PROBE_COUNT = 3; // probes to send before link is removed
-    private static final short DEFAULT_PROBE_RATE = 3000; // millis
     private static final String SRC_MAC = "DE:AD:BE:EF:BA:11";
-    private static final String SERVICE_NULL = "Service cannot be null";
 
     private final Device device;
-
-    // send 1 probe every probeRate milliseconds
-    private final long probeRate = DEFAULT_PROBE_RATE;
-
-    private final Set<Long> slowPorts = Sets.newConcurrentHashSet();
-    // ports, known to have incoming links
-    private final Set<Long> fastPorts = Sets.newConcurrentHashSet();
-
-    // number of unacknowledged probes per port
-    private final Map<Long, AtomicInteger> portProbeCount = Maps.newHashMap();
+    private final DiscoveryContext context;
 
     private final ONOSLLDP lldpPacket;
     private final Ethernet ethPacket;
     private Ethernet bddpEth;
-    private final boolean useBDDP;
 
     private Timeout timeout;
     private volatile boolean isStopped;
 
-    private final LinkProviderService linkProvider;
-    private final PacketService pktService;
-    private final MastershipService mastershipService;
+    // Set of ports to be probed
+    private final Set<Long> ports = Sets.newConcurrentHashSet();
 
     /**
      * Instantiates discovery manager for the given physical switch. Creates a
      * generic LLDP packet that will be customized for the port it is sent out on.
      * Starts the the timer for the discovery process.
      *
-     * @param device          the physical switch
-     * @param pktService      packet service
-     * @param masterService   mastership service
-     * @param providerService link provider service
-     * @param useBDDP         flag to also use BDDP for discovery
+     * @param device  the physical switch
+     * @param context discovery context
      */
-    public LinkDiscovery(Device device, PacketService pktService,
-                         MastershipService masterService,
-                         LinkProviderService providerService, Boolean... useBDDP) {
+    LinkDiscovery(Device device, DiscoveryContext context) {
         this.device = device;
-        this.linkProvider = checkNotNull(providerService, SERVICE_NULL);
-        this.pktService = checkNotNull(pktService, SERVICE_NULL);
-        this.mastershipService = checkNotNull(masterService, SERVICE_NULL);
+        this.context = context;
 
         lldpPacket = new ONOSLLDP();
         lldpPacket.setChassisId(device.chassisId());
@@ -122,15 +91,11 @@ public class LinkDiscovery implements TimerTask {
         ethPacket.setPayload(this.lldpPacket);
         ethPacket.setPad(true);
 
-        this.useBDDP = useBDDP.length > 0 ? useBDDP[0] : false;
-        if (this.useBDDP) {
-            bddpEth = new Ethernet();
-            bddpEth.setPayload(lldpPacket);
-            bddpEth.setEtherType(Ethernet.TYPE_BSN);
-            bddpEth.setDestinationMACAddress(ONOSLLDP.BDDP_MULTICAST);
-            bddpEth.setPad(true);
-            log.info("Using BDDP to discover network");
-        }
+        bddpEth = new Ethernet();
+        bddpEth.setPayload(lldpPacket);
+        bddpEth.setEtherType(Ethernet.TYPE_BSN);
+        bddpEth.setDestinationMACAddress(ONOSLLDP.BDDP_MULTICAST);
+        bddpEth.setPad(true);
 
         isStopped = true;
         start();
@@ -138,82 +103,52 @@ public class LinkDiscovery implements TimerTask {
 
     }
 
-    /**
-     * Add physical port port to discovery process.
-     * Send out initial LLDP and label it as slow port.
-     *
-     * @param port the port
-     */
-    public void addPort(Port port) {
-        boolean newPort = false;
-        synchronized (this) {
-            if (!containsPort(port.number().toLong())) {
-                newPort = true;
-                slowPorts.add(port.number().toLong());
-            }
+    synchronized void stop() {
+        if (!isStopped) {
+            isStopped = true;
+            timeout.cancel();
+        } else {
+            log.warn("LinkDiscovery stopped multiple times?");
         }
+    }
 
-        boolean isMaster = mastershipService.isLocalMaster(device.id());
-        if (newPort && isMaster) {
-            log.debug("Sending init probe to port {}@{}", port.number().toLong(), device.id());
-            sendProbes(port.number().toLong());
+    synchronized void start() {
+        if (isStopped) {
+            isStopped = false;
+            timeout = Timer.getTimer().newTimeout(this, 0, MILLISECONDS);
+        } else {
+            log.warn("LinkDiscovery started multiple times?");
         }
     }
 
-    /**
-     * Removes physical port from discovery process.
-     *
-     * @param port the port
-     */
-    public void removePort(Port port) {
-        // Ignore ports that are not on this switch
-        long portnum = port.number().toLong();
-        synchronized (this) {
-            if (slowPorts.contains(portnum)) {
-                slowPorts.remove(portnum);
-
-            } else if (fastPorts.contains(portnum)) {
-                fastPorts.remove(portnum);
-                portProbeCount.remove(portnum);
-                // no iterator to update
-            } else {
-                log.warn("Tried to dynamically remove non-existing port {}", portnum);
-            }
-        }
+    synchronized boolean isStopped() {
+        return isStopped || timeout.isCancelled();
     }
 
     /**
-     * Method called by remote port to acknowledge receipt of LLDP sent by
-     * this port. If slow port, updates label to fast. If fast port, decrements
-     * number of unacknowledged probes.
+     * Add physical port port to discovery process.
+     * Send out initial LLDP and label it as slow port.
      *
-     * @param portNumber the port
+     * @param port the port
      */
-    public void ackProbe(Long portNumber) {
-        synchronized (this) {
-            if (slowPorts.contains(portNumber)) {
-                log.debug("Setting slow port to fast: {}:{}", device.id(), portNumber);
-                slowPorts.remove(portNumber);
-                fastPorts.add(portNumber);
-                portProbeCount.put(portNumber, new AtomicInteger(0));
-            } else if (fastPorts.contains(portNumber)) {
-                portProbeCount.get(portNumber).set(0);
-            } else {
-                log.debug("Got ackProbe for non-existing port: {}", portNumber);
-            }
+    void addPort(Port port) {
+        boolean newPort = ports.add(port.number().toLong());
+        boolean isMaster = context.mastershipService().isLocalMaster(device.id());
+        if (newPort && isMaster) {
+            log.debug("Sending initial probe to port {}@{}", port.number().toLong(), device.id());
+            sendProbes(port.number().toLong());
         }
     }
 
-
     /**
-     * Handles an incoming LLDP packet. Creates link in topology and sends ACK
-     * to port where LLDP originated.
+     * Handles an incoming LLDP packet. Creates link in topology and adds the
+     * link for staleness tracking.
      *
-     * @param context packet context
+     * @param packetContext packet context
      * @return true if handled
      */
-    public boolean handleLLDP(PacketContext context) {
-        Ethernet eth = context.inPacket().parsed();
+    boolean handleLLDP(PacketContext packetContext) {
+        Ethernet eth = packetContext.inPacket().parsed();
         if (eth == null) {
             return false;
         }
@@ -221,10 +156,9 @@ public class LinkDiscovery implements TimerTask {
         ONOSLLDP onoslldp = ONOSLLDP.parseONOSLLDP(eth);
         if (onoslldp != null) {
             PortNumber srcPort = portNumber(onoslldp.getPort());
-            PortNumber dstPort = context.inPacket().receivedFrom().port();
+            PortNumber dstPort = packetContext.inPacket().receivedFrom().port();
             DeviceId srcDeviceId = DeviceId.deviceId(onoslldp.getDeviceString());
-            DeviceId dstDeviceId = context.inPacket().receivedFrom().deviceId();
-            ackProbe(dstPort.toLong());
+            DeviceId dstDeviceId = packetContext.inPacket().receivedFrom().deviceId();
 
             ConnectPoint src = new ConnectPoint(srcDeviceId, srcPort);
             ConnectPoint dst = new ConnectPoint(dstDeviceId, dstPort);
@@ -234,7 +168,8 @@ public class LinkDiscovery implements TimerTask {
                     new DefaultLinkDescription(src, dst, Type.INDIRECT);
 
             try {
-                linkProvider.linkDetected(ld);
+                context.providerService().linkDetected(ld);
+                context.touchLink(LinkKey.linkKey(src, dst));
             } catch (IllegalStateException e) {
                 return true;
             }
@@ -256,61 +191,14 @@ public class LinkDiscovery implements TimerTask {
         if (isStopped()) {
             return;
         }
-        if (!mastershipService.isLocalMaster(device.id())) {
-            if (!isStopped()) {
-                // reschedule timer
-                timeout = Timer.getTimer().newTimeout(this, probeRate, MILLISECONDS);
-            }
-            return;
-        }
 
-        log.trace("Sending probes from {}", device.id());
-        synchronized (this) {
-            Iterator<Long> fastIterator = fastPorts.iterator();
-            while (fastIterator.hasNext()) {
-                long portNumber = fastIterator.next();
-                int probeCount = portProbeCount.get(portNumber).getAndIncrement();
-
-                if (probeCount < LinkDiscovery.MAX_PROBE_COUNT) {
-                    log.trace("Sending fast probe to port {}", portNumber);
-                    sendProbes(portNumber);
-
-                } else {
-                    // Link down, demote to slowPorts; update fast and slow ports
-                    fastIterator.remove();
-                    slowPorts.add(portNumber);
-                    portProbeCount.remove(portNumber);
-
-                    ConnectPoint cp = new ConnectPoint(device.id(), portNumber(portNumber));
-                    log.debug("Link down -> {}", cp);
-                    linkProvider.linksVanished(cp);
-                }
-            }
-
-            // send a probe for the next slow port
-            for (long portNumber : slowPorts) {
-                log.trace("Sending slow probe to port {}", portNumber);
-                sendProbes(portNumber);
-            }
+        if (context.mastershipService().isLocalMaster(device.id())) {
+            log.trace("Sending probes from {}", device.id());
+            ports.forEach(this::sendProbes);
         }
 
         if (!isStopped()) {
-            // reschedule timer
-            timeout = Timer.getTimer().newTimeout(this, probeRate, MILLISECONDS);
-        }
-    }
-
-    public synchronized void stop() {
-        isStopped = true;
-        timeout.cancel();
-    }
-
-    public synchronized void start() {
-        if (isStopped) {
-            isStopped = false;
-            timeout = Timer.getTimer().newTimeout(this, 0, MILLISECONDS);
-        } else {
-            log.warn("LinkDiscovery started multiple times?");
+            timeout = Timer.getTimer().newTimeout(this, context.probeRate(), MILLISECONDS);
         }
     }
 
@@ -351,19 +239,15 @@ public class LinkDiscovery implements TimerTask {
     private void sendProbes(Long portNumber) {
         log.trace("Sending probes out to {}@{}", portNumber, device.id());
         OutboundPacket pkt = createOutBoundLLDP(portNumber);
-        pktService.emit(pkt);
-        if (useBDDP) {
+        context.packetService().emit(pkt);
+        if (context.useBDDP()) {
             OutboundPacket bpkt = createOutBoundBDDP(portNumber);
-            pktService.emit(bpkt);
+            context.packetService().emit(bpkt);
         }
     }
 
-    public boolean containsPort(Long portNumber) {
-        return slowPorts.contains(portNumber) || fastPorts.contains(portNumber);
-    }
-
-    public synchronized boolean isStopped() {
-        return isStopped || timeout.isCancelled();
+    boolean containsPort(long portNumber) {
+        return ports.contains(portNumber);
     }
 
 }