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Posted to commits@cassandra.apache.org by sl...@apache.org on 2013/06/25 18:59:24 UTC

[2/3] Redesign repair messages

http://git-wip-us.apache.org/repos/asf/cassandra/blob/eb4fa4a6/src/java/org/apache/cassandra/repair/messages/ValidationRequest.java
----------------------------------------------------------------------
diff --git a/src/java/org/apache/cassandra/repair/messages/ValidationRequest.java b/src/java/org/apache/cassandra/repair/messages/ValidationRequest.java
new file mode 100644
index 0000000..3b9f6dd
--- /dev/null
+++ b/src/java/org/apache/cassandra/repair/messages/ValidationRequest.java
@@ -0,0 +1,82 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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.apache.cassandra.repair.messages;
+
+import java.io.DataInput;
+import java.io.DataOutput;
+import java.io.IOException;
+
+import org.apache.cassandra.db.TypeSizes;
+import org.apache.cassandra.io.IVersionedSerializer;
+import org.apache.cassandra.repair.RepairJobDesc;
+
+/**
+ * ValidationRequest
+ *
+ * @since 2.0
+ */
+public class ValidationRequest extends RepairMessage
+{
+    public static MessageSerializer serializer = new ValidationRequestSerializer();
+
+    public final int gcBefore;
+
+    public ValidationRequest(RepairJobDesc desc, int gcBefore)
+    {
+        super(Type.VALIDATION_REQUEST, desc);
+        this.gcBefore = gcBefore;
+    }
+
+    @Override
+    public boolean equals(Object o)
+    {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+
+        ValidationRequest that = (ValidationRequest) o;
+        return gcBefore == that.gcBefore;
+    }
+
+    @Override
+    public int hashCode()
+    {
+        return gcBefore;
+    }
+
+    public static class ValidationRequestSerializer implements MessageSerializer<ValidationRequest>
+    {
+        public void serialize(ValidationRequest message, DataOutput out, int version) throws IOException
+        {
+            RepairJobDesc.serializer.serialize(message.desc, out, version);
+            out.writeInt(message.gcBefore);
+        }
+
+        public ValidationRequest deserialize(DataInput dis, int version) throws IOException
+        {
+            RepairJobDesc desc = RepairJobDesc.serializer.deserialize(dis, version);
+            return new ValidationRequest(desc, dis.readInt());
+        }
+
+        public long serializedSize(ValidationRequest message, int version)
+        {
+            long size = RepairJobDesc.serializer.serializedSize(message.desc, version);
+            size += TypeSizes.NATIVE.sizeof(message.gcBefore);
+            return size;
+        }
+    }
+}

http://git-wip-us.apache.org/repos/asf/cassandra/blob/eb4fa4a6/src/java/org/apache/cassandra/service/ActiveRepairService.java
----------------------------------------------------------------------
diff --git a/src/java/org/apache/cassandra/service/ActiveRepairService.java b/src/java/org/apache/cassandra/service/ActiveRepairService.java
index 82ecbe9..2bcf579 100644
--- a/src/java/org/apache/cassandra/service/ActiveRepairService.java
+++ b/src/java/org/apache/cassandra/service/ActiveRepairService.java
@@ -17,37 +17,25 @@
  */
 package org.apache.cassandra.service;
 
-import java.io.*;
 import java.net.InetAddress;
-import java.security.MessageDigest;
 import java.util.*;
 import java.util.concurrent.*;
-import java.util.concurrent.atomic.AtomicBoolean;
-import java.util.concurrent.locks.Condition;
 
-import com.google.common.base.Objects;
 import com.google.common.collect.Sets;
 
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
 import org.apache.cassandra.concurrent.JMXConfigurableThreadPoolExecutor;
 import org.apache.cassandra.concurrent.NamedThreadFactory;
-import org.apache.cassandra.concurrent.Stage;
-import org.apache.cassandra.concurrent.StageManager;
 import org.apache.cassandra.config.DatabaseDescriptor;
-import org.apache.cassandra.db.*;
-import org.apache.cassandra.db.compaction.AbstractCompactedRow;
-import org.apache.cassandra.db.compaction.CompactionManager;
-import org.apache.cassandra.dht.AbstractBounds;
 import org.apache.cassandra.dht.Range;
 import org.apache.cassandra.dht.Token;
-import org.apache.cassandra.gms.*;
-import org.apache.cassandra.io.IVersionedSerializer;
+import org.apache.cassandra.gms.FailureDetector;
+import org.apache.cassandra.gms.Gossiper;
 import org.apache.cassandra.locator.TokenMetadata;
-import org.apache.cassandra.net.*;
-import org.apache.cassandra.streaming.StreamingRepairTask;
-import org.apache.cassandra.utils.*;
+import org.apache.cassandra.repair.*;
+import org.apache.cassandra.repair.messages.RepairMessage;
+import org.apache.cassandra.repair.messages.SyncComplete;
+import org.apache.cassandra.repair.messages.ValidationComplete;
+import org.apache.cassandra.utils.FBUtilities;
 
 /**
  * ActiveRepairService encapsulates "validating" (hashing) individual column families,
@@ -79,8 +67,6 @@ import org.apache.cassandra.utils.*;
  */
 public class ActiveRepairService
 {
-    private static final Logger logger = LoggerFactory.getLogger(ActiveRepairService.class);
-
     // singleton enforcement
     public static final ActiveRepairService instance = new ActiveRepairService();
 
@@ -103,14 +89,14 @@ public class ActiveRepairService
     /**
      * A map of active session.
      */
-    private final ConcurrentMap<String, RepairSession> sessions;
+    private final ConcurrentMap<UUID, RepairSession> sessions;
 
     /**
      * Protected constructor. Use ActiveRepairService.instance.
      */
     protected ActiveRepairService()
     {
-        sessions = new ConcurrentHashMap<String, RepairSession>();
+        sessions = new ConcurrentHashMap<>();
     }
 
     /**
@@ -118,16 +104,30 @@ public class ActiveRepairService
      *
      * @return Future for asynchronous call or null if there is no need to repair
      */
-    public RepairFuture submitRepairSession(Range<Token> range, String tablename, boolean isSequential, boolean isLocal, String... cfnames)
+    public RepairFuture submitRepairSession(Range<Token> range, String keyspace, boolean isSequential, boolean isLocal, String... cfnames)
     {
-        RepairSession session = new RepairSession(range, tablename, isSequential, isLocal, cfnames);
+        RepairSession session = new RepairSession(range, keyspace, isSequential, isLocal, cfnames);
         if (session.endpoints.isEmpty())
             return null;
-        RepairFuture futureTask = session.getFuture();
+        RepairFuture futureTask = new RepairFuture(session);
         executor.execute(futureTask);
         return futureTask;
     }
 
+    public void addToActiveSessions(RepairSession session)
+    {
+        sessions.put(session.getId(), session);
+        Gossiper.instance.register(session);
+        FailureDetector.instance.registerFailureDetectionEventListener(session);
+    }
+
+    public void removeFromActiveSessions(RepairSession session)
+    {
+        FailureDetector.instance.unregisterFailureDetectionEventListener(session);
+        Gossiper.instance.unregister(session);
+        sessions.remove(session.getId());
+    }
+
     public void terminateSessions()
     {
         for (RepairSession session : sessions.values())
@@ -138,9 +138,11 @@ public class ActiveRepairService
 
     // for testing only. Create a session corresponding to a fake request and
     // add it to the sessions (avoid NPE in tests)
-    RepairFuture submitArtificialRepairSession(TreeRequest req, String tablename, String... cfnames)
+    RepairFuture submitArtificialRepairSession(RepairJobDesc desc)
     {
-        RepairFuture futureTask = new RepairSession(req, tablename, cfnames).getFuture();
+        RepairSession session = new RepairSession(desc.sessionId, desc.range, desc.keyspace, false, false, new String[]{desc.columnFamily});
+        sessions.put(session.getId(), session);
+        RepairFuture futureTask = new RepairFuture(session);
         executor.execute(futureTask);
         return futureTask;
     }
@@ -154,7 +156,7 @@ public class ActiveRepairService
      *
      * @return neighbors with whom we share the provided range
      */
-    static Set<InetAddress> getNeighbors(String table, Range<Token> toRepair, boolean isLocal)
+    public static Set<InetAddress> getNeighbors(String table, Range<Token> toRepair, boolean isLocal)
     {
         StorageService ss = StorageService.instance;
         Map<Range<Token>, List<InetAddress>> replicaSets = ss.getRangeToAddressMap(table);
@@ -174,7 +176,7 @@ public class ActiveRepairService
         if (rangeSuperSet == null || !replicaSets.containsKey(rangeSuperSet))
             return Collections.emptySet();
 
-        Set<InetAddress> neighbors = new HashSet<InetAddress>(replicaSets.get(rangeSuperSet));
+        Set<InetAddress> neighbors = new HashSet<>(replicaSets.get(rangeSuperSet));
         neighbors.remove(FBUtilities.getBroadcastAddress());
 
         if (isLocal)
@@ -187,949 +189,25 @@ public class ActiveRepairService
         return neighbors;
     }
 
-    /**
-     * Register a tree for the given request to be compared to the appropriate trees in Stage.ANTIENTROPY when they become available.
-     */
-    private void rendezvous(TreeRequest request, MerkleTree tree)
+    public void handleMessage(InetAddress endpoint, RepairMessage message)
     {
-        RepairSession session = sessions.get(request.sessionid);
+        RepairJobDesc desc = message.desc;
+        RepairSession session = sessions.get(desc.sessionId);
         if (session == null)
-        {
-            logger.warn("Got a merkle tree response for unknown repair session {}: either this node has been restarted since the session was started, or the session has been interrupted for an unknown reason. ", request.sessionid);
             return;
-        }
-
-        RepairSession.RepairJob job = session.jobs.peek();
-        if (job == null)
-        {
-            assert session.terminated();
-            return;
-        }
-
-        logger.info(String.format("[repair #%s] Received merkle tree for %s from %s", session.getName(), request.cf.right, request.endpoint));
-
-        if (job.addTree(request, tree) == 0)
-        {
-            logger.debug("All trees received for " + session.getName() + "/" + request.cf.right);
-            job.submitDifferencers();
-
-            // This job is complete, switching to next in line (note that only
-            // one thread will can ever do this)
-            session.jobs.poll();
-            RepairSession.RepairJob nextJob = session.jobs.peek();
-            if (nextJob == null)
-                // We are done with this repair session as far as differencing
-                // is considern. Just inform the session
-                session.differencingDone.signalAll();
-            else
-                nextJob.sendTreeRequests();
-        }
-    }
-
-    /**
-     * Responds to the node that requested the given valid tree.
-     * @param validator A locally generated validator
-     * @param local localhost (parameterized for testing)
-     */
-    void respond(Validator validator, InetAddress local)
-    {
-        MessagingService ms = MessagingService.instance();
-
-        try
-        {
-            if (!validator.request.endpoint.equals(FBUtilities.getBroadcastAddress()))
-                logger.info(String.format("[repair #%s] Sending completed merkle tree to %s for %s", validator.request.sessionid, validator.request.endpoint, validator.request.cf));
-            ms.sendOneWay(validator.createMessage(), validator.request.endpoint);
-        }
-        catch (Exception e)
-        {
-            logger.error(String.format("[repair #%s] Error sending completed merkle tree to %s for %s ", validator.request.sessionid, validator.request.endpoint, validator.request.cf), e);
-        }
-    }
-
-    /**
-     * A Strategy to handle building a merkle tree for a column family.
-     *
-     * Lifecycle:
-     * 1. prepare() - Initialize tree with samples.
-     * 2. add() - 0 or more times, to add hashes to the tree.
-     * 3. complete() - complete building tree and send it back to the initiator
-     */
-    public static class Validator implements Runnable
-    {
-        public final TreeRequest request;
-        public final MerkleTree tree;
-
-        // null when all rows with the min token have been consumed
-        private transient long validated;
-        private transient MerkleTree.TreeRange range;
-        private transient MerkleTree.TreeRangeIterator ranges;
-        private transient DecoratedKey lastKey;
-
-        public final static MerkleTree.RowHash EMPTY_ROW = new MerkleTree.RowHash(null, new byte[0]);
-        public static ValidatorSerializer serializer = new ValidatorSerializer();
-
-        public Validator(TreeRequest request)
-        {
-            this(request,
-                 // TODO: memory usage (maxsize) should either be tunable per
-                 // CF, globally, or as shared for all CFs in a cluster
-                 new MerkleTree(DatabaseDescriptor.getPartitioner(), request.range, MerkleTree.RECOMMENDED_DEPTH, (int)Math.pow(2, 15)));
-        }
-
-        Validator(TreeRequest request, MerkleTree tree)
-        {
-            this.request = request;
-            this.tree = tree;
-            // Reestablishing the range because we don't serialize it (for bad
-            // reason - see MerkleTree for details)
-            this.tree.fullRange = this.request.range;
-            validated = 0;
-            range = null;
-            ranges = null;
-        }
-
-        public void prepare(ColumnFamilyStore cfs)
-        {
-            if (!tree.partitioner().preservesOrder())
-            {
-                // You can't beat an even tree distribution for md5
-                tree.init();
-            }
-            else
-            {
-                List<DecoratedKey> keys = new ArrayList<DecoratedKey>();
-                for (DecoratedKey sample : cfs.keySamples(request.range))
-                {
-                    assert request.range.contains(sample.token): "Token " + sample.token + " is not within range " + request.range;
-                    keys.add(sample);
-                }
-
-                if (keys.isEmpty())
-                {
-                    // use an even tree distribution
-                    tree.init();
-                }
-                else
-                {
-                    int numkeys = keys.size();
-                    Random random = new Random();
-                    // sample the column family using random keys from the index
-                    while (true)
-                    {
-                        DecoratedKey dk = keys.get(random.nextInt(numkeys));
-                        if (!tree.split(dk.token))
-                            break;
-                    }
-                }
-            }
-            logger.debug("Prepared AEService tree of size " + tree.size() + " for " + request);
-            ranges = tree.invalids();
-        }
-
-        /**
-         * Called (in order) for rows in given range present in the CF.
-         * Hashes the row, and adds it to the tree being built.
-         *
-         * @param row The row.
-         */
-        public void add(AbstractCompactedRow row)
-        {
-            assert request.range.contains(row.key.token) : row.key.token + " is not contained in " + request.range;
-            assert lastKey == null || lastKey.compareTo(row.key) < 0
-                   : "row " + row.key + " received out of order wrt " + lastKey;
-            lastKey = row.key;
-
-            if (range == null)
-                range = ranges.next();
-
-            // generate new ranges as long as case 1 is true
-            while (!range.contains(row.key.token))
-            {
-                // add the empty hash, and move to the next range
-                range.addHash(EMPTY_ROW);
-                range = ranges.next();
-            }
-
-            // case 3 must be true: mix in the hashed row
-            range.addHash(rowHash(row));
-        }
-
-        private MerkleTree.RowHash rowHash(AbstractCompactedRow row)
-        {
-            validated++;
-            // MerkleTree uses XOR internally, so we want lots of output bits here
-            MessageDigest digest = FBUtilities.newMessageDigest("SHA-256");
-            row.update(digest);
-            return new MerkleTree.RowHash(row.key.token, digest.digest());
-        }
-
-        /**
-         * Registers the newly created tree for rendezvous in Stage.ANTI_ENTROPY.
-         */
-        public void complete()
-        {
-            completeTree();
-
-            StageManager.getStage(Stage.ANTI_ENTROPY).execute(this);
-            logger.debug("Validated " + validated + " rows into AEService tree for " + request);
-        }
-
-        void completeTree()
-        {
-            assert ranges != null : "Validator was not prepared()";
-
-            if (range != null)
-                range.addHash(EMPTY_ROW);
-            while (ranges.hasNext())
-            {
-                range = ranges.next();
-                range.addHash(EMPTY_ROW);
-            }
-        }
-
-        /**
-         * Called after the validation lifecycle to respond with the now valid tree. Runs in Stage.ANTI_ENTROPY.
-         */
-        public void run()
-        {
-            // respond to the request that triggered this validation
-            ActiveRepairService.instance.respond(this, FBUtilities.getBroadcastAddress());
-        }
-
-        public MessageOut<Validator> createMessage()
-        {
-            return new MessageOut<Validator>(MessagingService.Verb.TREE_RESPONSE, this, Validator.serializer);
-        }
-
-        public static class ValidatorSerializer implements IVersionedSerializer<Validator>
-        {
-            public void serialize(Validator validator, DataOutput out, int version) throws IOException
-            {
-                TreeRequest.serializer.serialize(validator.request, out, version);
-                MerkleTree.serializer.serialize(validator.tree, out, version);
-            }
-
-            public Validator deserialize(DataInput in, int version) throws IOException
-            {
-                final TreeRequest request = TreeRequest.serializer.deserialize(in, version);
-                try
-                {
-                    return new Validator(request, MerkleTree.serializer.deserialize(in, version));
-                }
-                catch(Exception e)
-                {
-                    throw new RuntimeException(e);
-                }
-            }
-
-            public long serializedSize(Validator validator, int version)
-            {
-                return TreeRequest.serializer.serializedSize(validator.request, version)
-                       + MerkleTree.serializer.serializedSize(validator.tree, version);
-            }
-        }
-    }
-
-    /**
-     * Handler for requests from remote nodes to generate a valid tree.
-     */
-    public static class TreeRequestVerbHandler implements IVerbHandler<TreeRequest>
-    {
-        /**
-         * Trigger a validation compaction which will return the tree upon completion.
-         */
-        public void doVerb(MessageIn<TreeRequest> message, int id)
-        {
-            TreeRequest remotereq = message.payload;
-            TreeRequest request = new TreeRequest(remotereq.sessionid, message.from, remotereq.range, remotereq.gcBefore, remotereq.cf);
-
-            // trigger read-only compaction
-            ColumnFamilyStore store = Table.open(request.cf.left).getColumnFamilyStore(request.cf.right);
-            Validator validator = new Validator(request);
-            logger.debug("Queueing validation compaction for " + request);
-            CompactionManager.instance.submitValidation(store, validator);
-        }
-    }
-
-    /**
-     * Handler for responses from remote nodes which contain a valid tree.
-     * The payload is a completed Validator object from the remote endpoint.
-     */
-    public static class TreeResponseVerbHandler implements IVerbHandler<Validator>
-    {
-        public void doVerb(MessageIn<Validator> message, int id)
-        {
-            // deserialize the remote tree, and register it
-            Validator response = message.payload;
-            TreeRequest request = new TreeRequest(response.request.sessionid, message.from, response.request.range, response.request.gcBefore, response.request.cf);
-            ActiveRepairService.instance.rendezvous(request, response.tree);
-        }
-    }
-
-    /**
-     * A tuple of table and cf.
-     */
-    public static class CFPair extends Pair<String,String>
-    {
-        public CFPair(String table, String cf)
-        {
-            super(table, cf);
-            assert table != null && cf != null;
-        }
-    }
-
-    /**
-     * A tuple of table, cf, address and range that represents a location we have an outstanding TreeRequest for.
-     */
-    public static class TreeRequest
-    {
-        public static final TreeRequestSerializer serializer = new TreeRequestSerializer();
-
-        public final String sessionid;
-        public final InetAddress endpoint;
-        public final Range<Token> range;
-        public final int gcBefore;
-        public final CFPair cf;
-
-        public TreeRequest(String sessionid, InetAddress endpoint, Range<Token> range, int gcBefore, CFPair cf)
-        {
-            this.sessionid = sessionid;
-            this.endpoint = endpoint;
-            this.cf = cf;
-            this.gcBefore = gcBefore;
-            this.range = range;
-        }
-
-        @Override
-        public final int hashCode()
-        {
-            return Objects.hashCode(sessionid, endpoint, gcBefore, cf, range);
-        }
-
-        @Override
-        public final boolean equals(Object o)
-        {
-            if(!(o instanceof TreeRequest))
-                return false;
-            TreeRequest that = (TreeRequest)o;
-            // handles nulls properly
-            return Objects.equal(sessionid, that.sessionid) && Objects.equal(endpoint, that.endpoint) && gcBefore == that.gcBefore && Objects.equal(cf, that.cf) && Objects.equal(range, that.range);
-        }
-
-        @Override
-        public String toString()
-        {
-            return "#<TreeRequest " + sessionid + ", " + endpoint + ", " + gcBefore + ", " + cf  + ", " + range + ">";
-        }
-
-        public MessageOut<TreeRequest> createMessage()
-        {
-            return new MessageOut<TreeRequest>(MessagingService.Verb.TREE_REQUEST, this, TreeRequest.serializer);
-        }
-
-        public static class TreeRequestSerializer implements IVersionedSerializer<TreeRequest>
-        {
-            public void serialize(TreeRequest request, DataOutput out, int version) throws IOException
-            {
-                out.writeUTF(request.sessionid);
-                CompactEndpointSerializationHelper.serialize(request.endpoint, out);
-
-                if (version >= MessagingService.VERSION_20)
-                    out.writeInt(request.gcBefore);
-                out.writeUTF(request.cf.left);
-                out.writeUTF(request.cf.right);
-                AbstractBounds.serializer.serialize(request.range, out, version);
-            }
-
-            public TreeRequest deserialize(DataInput in, int version) throws IOException
-            {
-                String sessId = in.readUTF();
-                InetAddress endpoint = CompactEndpointSerializationHelper.deserialize(in);
-                int gcBefore = -1;
-                if (version >= MessagingService.VERSION_20)
-                    gcBefore = in.readInt();
-                CFPair cfpair = new CFPair(in.readUTF(), in.readUTF());
-                Range<Token> range;
-                range = (Range<Token>) AbstractBounds.serializer.deserialize(in, version);
-
-                return new TreeRequest(sessId, endpoint, range, gcBefore, cfpair);
-            }
-
-            public long serializedSize(TreeRequest request, int version)
-            {
-                return TypeSizes.NATIVE.sizeof(request.sessionid)
-                     + CompactEndpointSerializationHelper.serializedSize(request.endpoint)
-                     + TypeSizes.NATIVE.sizeof(request.gcBefore)
-                     + TypeSizes.NATIVE.sizeof(request.cf.left)
-                     + TypeSizes.NATIVE.sizeof(request.cf.right)
-                     + AbstractBounds.serializer.serializedSize(request.range, version);
-            }
-        }
-    }
-
-    /**
-     * Triggers repairs with all neighbors for the given table, cfs and range.
-     */
-    static class RepairSession extends WrappedRunnable implements IEndpointStateChangeSubscriber, IFailureDetectionEventListener
-    {
-        private final String sessionName;
-        private final boolean isSequential;
-        private final String tablename;
-        private final String[] cfnames;
-        private final Range<Token> range;
-        private volatile Exception exception;
-        private final AtomicBoolean isFailed = new AtomicBoolean(false);
-
-        private final Set<InetAddress> endpoints;
-        final Queue<RepairJob> jobs = new ConcurrentLinkedQueue<RepairJob>();
-        final Map<String, RepairJob> activeJobs = new ConcurrentHashMap<String, RepairJob>();
-
-        private final SimpleCondition completed = new SimpleCondition();
-        public final Condition differencingDone = new SimpleCondition();
-
-        private volatile boolean terminated = false;
-
-        public RepairSession(TreeRequest req, String tablename, String... cfnames)
-        {
-            this(req.sessionid, req.range, tablename, false, false, cfnames);
-            ActiveRepairService.instance.sessions.put(getName(), this);
-        }
-
-        public RepairSession(Range<Token> range, String tablename, boolean isSequential, boolean isLocal, String... cfnames)
-        {
-            this(UUIDGen.getTimeUUID().toString(), range, tablename, isSequential, isLocal, cfnames);
-        }
-
-        private RepairSession(String id, Range<Token> range, String tablename, boolean isSequential, boolean isLocal, String[] cfnames)
-        {
-            this.sessionName = id;
-            this.isSequential = isSequential;
-            this.tablename = tablename;
-            this.cfnames = cfnames;
-            assert cfnames.length > 0 : "Repairing no column families seems pointless, doesn't it";
-            this.range = range;
-            this.endpoints = ActiveRepairService.getNeighbors(tablename, range, isLocal);
-        }
-
-        public String getName()
-        {
-            return sessionName;
-        }
-
-        public Range<Token> getRange()
-        {
-            return range;
-        }
-
-        RepairFuture getFuture()
-        {
-            return new RepairFuture(this);
-        }
-
-        private String repairedNodes()
-        {
-            StringBuilder sb = new StringBuilder();
-            sb.append(FBUtilities.getBroadcastAddress());
-            for (InetAddress ep : endpoints)
-                sb.append(", ").append(ep);
-            return sb.toString();
-        }
-
-        // we don't care about the return value but care about it throwing exception
-        public void runMayThrow() throws Exception
-        {
-            logger.info(String.format("[repair #%s] new session: will sync %s on range %s for %s.%s", getName(), repairedNodes(), range, tablename, Arrays.toString(cfnames)));
-
-            if (endpoints.isEmpty())
-            {
-                differencingDone.signalAll();
-                logger.info(String.format("[repair #%s] No neighbors to repair with on range %s: session completed", getName(), range));
-                return;
-            }
-
-            // Checking all nodes are live
-            for (InetAddress endpoint : endpoints)
-            {
-                if (!FailureDetector.instance.isAlive(endpoint))
-                {
-                    String message = String.format("Cannot proceed on repair because a neighbor (%s) is dead: session failed", endpoint);
-                    differencingDone.signalAll();
-                    logger.error(String.format("[repair #%s] ", getName()) + message);
-                    throw new IOException(message);
-                }
-            }
-
-            ActiveRepairService.instance.sessions.put(getName(), this);
-            Gossiper.instance.register(this);
-            FailureDetector.instance.registerFailureDetectionEventListener(this);
-            try
-            {
-                // Create and queue a RepairJob for each column family
-                for (String cfname : cfnames)
-                {
-                    RepairJob job = new RepairJob(cfname);
-                    jobs.offer(job);
-                    activeJobs.put(cfname, job);
-                }
-
-                jobs.peek().sendTreeRequests();
-
-                // block whatever thread started this session until all requests have been returned:
-                // if this thread dies, the session will still complete in the background
-                completed.await();
-                if (exception == null)
-                {
-                    logger.info(String.format("[repair #%s] session completed successfully", getName()));
-                }
-                else
-                {
-                    logger.error(String.format("[repair #%s] session completed with the following error", getName()), exception);
-                    throw exception;
-                }
-            }
-            catch (InterruptedException e)
-            {
-                throw new RuntimeException("Interrupted while waiting for repair.");
-            }
-            finally
-            {
-                // mark this session as terminated
-                terminate();
-                FailureDetector.instance.unregisterFailureDetectionEventListener(this);
-                Gossiper.instance.unregister(this);
-                ActiveRepairService.instance.sessions.remove(getName());
-            }
-        }
-
-        /**
-         * @return whether this session is terminated
-         */
-        public boolean terminated()
-        {
-            return terminated;
-        }
-
-        public void terminate()
-        {
-            terminated = true;
-            for (RepairJob job : jobs)
-                job.terminate();
-            jobs.clear();
-            activeJobs.clear();
-        }
-
-        /**
-         * terminate this session.
-         */
-        public void forceShutdown()
-        {
-            differencingDone.signalAll();
-            completed.signalAll();
-        }
-
-        void completed(Differencer differencer)
-        {
-            logger.debug(String.format("[repair #%s] Repair completed between %s and %s on %s",
-                                       getName(),
-                                       differencer.r1.endpoint,
-                                       differencer.r2.endpoint,
-                                       differencer.cfname));
-            RepairJob job = activeJobs.get(differencer.cfname);
-            if (job == null)
-            {
-                assert terminated;
-                return;
-            }
-
-            if (job.completedSynchronization(differencer))
-            {
-                activeJobs.remove(differencer.cfname);
-                String remaining = activeJobs.size() == 0 ? "" : String.format(" (%d remaining column family to sync for this session)", activeJobs.size());
-                logger.info(String.format("[repair #%s] %s is fully synced%s", getName(), differencer.cfname, remaining));
-                if (activeJobs.isEmpty())
-                    completed.signalAll();
-            }
-        }
-
-        void failedNode(InetAddress remote)
-        {
-            String errorMsg = String.format("Endpoint %s died", remote);
-            exception = new IOException(errorMsg);
-            // If a node failed, we stop everything (though there could still be some activity in the background)
-            forceShutdown();
-        }
-
-        public void onJoin(InetAddress endpoint, EndpointState epState) {}
-        public void onChange(InetAddress endpoint, ApplicationState state, VersionedValue value) {}
-        public void onAlive(InetAddress endpoint, EndpointState state) {}
-        public void onDead(InetAddress endpoint, EndpointState state) {}
-
-        public void onRemove(InetAddress endpoint)
-        {
-            convict(endpoint, Double.MAX_VALUE);
-        }
-
-        public void onRestart(InetAddress endpoint, EndpointState epState)
-        {
-            convict(endpoint, Double.MAX_VALUE);
-        }
-
-        public void convict(InetAddress endpoint, double phi)
-        {
-            if (!endpoints.contains(endpoint))
-                return;
-
-            // We want a higher confidence in the failure detection than usual because failing a repair wrongly has a high cost.
-            if (phi < 2 * DatabaseDescriptor.getPhiConvictThreshold())
-                return;
-
-            // Though unlikely, it is possible to arrive here multiple time and we
-            // want to avoid print an error message twice
-            if (!isFailed.compareAndSet(false, true))
-                return;
-
-            failedNode(endpoint);
-        }
-
-        class RepairJob
-        {
-            private final String cfname;
-            // first we send tree requests.  this tracks the endpoints remaining to hear from
-            private final RequestCoordinator<TreeRequest> treeRequests;
-            // tree responses are then tracked here
-            private final List<TreeResponse> trees = new ArrayList<TreeResponse>(endpoints.size() + 1);
-            // once all responses are received, each tree is compared with each other, and differencer tasks
-            // are submitted.  the job is done when all differencers are complete.
-            private final RequestCoordinator<Differencer> differencers;
-            private final Condition requestsSent = new SimpleCondition();
-            private CountDownLatch snapshotLatch = null;
-
-            public RepairJob(String cfname)
-            {
-                this.cfname = cfname;
-                this.treeRequests = new RequestCoordinator<TreeRequest>(isSequential)
-                {
-                    public void send(TreeRequest r)
-                    {
-                        MessagingService.instance().sendOneWay(r.createMessage(), r.endpoint);
-                    }
-                };
-                this.differencers = new RequestCoordinator<Differencer>(isSequential)
-                {
-                    public void send(Differencer d)
-                    {
-                        StageManager.getStage(Stage.ANTI_ENTROPY).execute(d);
-                    }
-                };
-            }
-
-            /**
-             * Send merkle tree request to every involved neighbor.
-             */
-            public void sendTreeRequests()
-            {
-                // send requests to all nodes
-                List<InetAddress> allEndpoints = new ArrayList<InetAddress>(endpoints);
-                allEndpoints.add(FBUtilities.getBroadcastAddress());
-
-                if (isSequential)
-                    makeSnapshots(endpoints);
-
-                int gcBefore = Table.open(tablename).getColumnFamilyStore(cfname).gcBefore(System.currentTimeMillis());
-
-                for (InetAddress endpoint : allEndpoints)
-                    treeRequests.add(new TreeRequest(getName(), endpoint, range, gcBefore, new CFPair(tablename, cfname)));
-
-                logger.info(String.format("[repair #%s] requesting merkle trees for %s (to %s)", getName(), cfname, allEndpoints));
-                treeRequests.start();
-                requestsSent.signalAll();
-            }
-
-            public void makeSnapshots(Collection<InetAddress> endpoints)
-            {
-                try
-                {
-                    snapshotLatch = new CountDownLatch(endpoints.size());
-                    IAsyncCallback callback = new IAsyncCallback()
-                    {
-                        public boolean isLatencyForSnitch()
-                        {
-                            return false;
-                        }
-
-                        public void response(MessageIn msg)
-                        {
-                            RepairJob.this.snapshotLatch.countDown();
-                        }
-                    };
-                    for (InetAddress endpoint : endpoints)
-                        MessagingService.instance().sendRR(new SnapshotCommand(tablename, cfname, sessionName, false).createMessage(), endpoint, callback);
-                    snapshotLatch.await();
-                    snapshotLatch = null;
-                }
-                catch (InterruptedException e)
-                {
-                    throw new RuntimeException(e);
-                }
-            }
-
-            /**
-             * Add a new received tree and return the number of remaining tree to
-             * be received for the job to be complete.
-             *
-             * Callers may assume exactly one addTree call will result in zero remaining endpoints.
-             */
-            public synchronized int addTree(TreeRequest request, MerkleTree tree)
-            {
-                // Wait for all request to have been performed (see #3400)
-                try
-                {
-                    requestsSent.await();
-                }
-                catch (InterruptedException e)
-                {
-                    throw new AssertionError("Interrupted while waiting for requests to be sent");
-                }
-
-                assert request.cf.right.equals(cfname);
-                trees.add(new TreeResponse(request.endpoint, tree));
-                return treeRequests.completed(request);
-            }
-
-            /**
-             * Submit differencers for running.
-             * All tree *must* have been received before this is called.
-             */
-            public void submitDifferencers()
-            {
-                // We need to difference all trees one against another
-                for (int i = 0; i < trees.size() - 1; ++i)
-                {
-                    TreeResponse r1 = trees.get(i);
-                    for (int j = i + 1; j < trees.size(); ++j)
-                    {
-                        TreeResponse r2 = trees.get(j);
-                        Differencer differencer = new Differencer(cfname, r1, r2);
-                        logger.debug("Queueing comparison {}", differencer);
-                        differencers.add(differencer);
-                    }
-                }
-                differencers.start();
-                trees.clear(); // allows gc to do its thing
-            }
-
-            /**
-             * @return true if the differencer was the last remaining
-             */
-            synchronized boolean completedSynchronization(Differencer differencer)
-            {
-                return differencers.completed(differencer) == 0;
-            }
-
-            public void terminate()
-            {
-                if (snapshotLatch != null)
-                {
-                    while (snapshotLatch.getCount() > 0)
-                        snapshotLatch.countDown();
-                }
-            }
-        }
-
-        /**
-         * Runs on the node that initiated a request to compare two trees, and launch repairs for disagreeing ranges.
-         */
-        class Differencer implements Runnable
+        switch (message.messageType)
         {
-            public final String cfname;
-            public final TreeResponse r1;
-            public final TreeResponse r2;
-            public final List<Range<Token>> differences = new ArrayList<Range<Token>>();
-
-            Differencer(String cfname, TreeResponse r1, TreeResponse r2)
-            {
-                this.cfname = cfname;
-                this.r1 = r1;
-                this.r2 = r2;
-            }
-
-            /**
-             * Compares our trees, and triggers repairs for any ranges that mismatch.
-             */
-            public void run()
-            {
-                // restore partitioners (in case we were serialized)
-                if (r1.tree.partitioner() == null)
-                    r1.tree.partitioner(StorageService.getPartitioner());
-                if (r2.tree.partitioner() == null)
-                    r2.tree.partitioner(StorageService.getPartitioner());
-
-                // compare trees, and collect differences
-                differences.addAll(MerkleTree.difference(r1.tree, r2.tree));
-
-                // choose a repair method based on the significance of the difference
-                String format = String.format("[repair #%s] Endpoints %s and %s %%s for %s", getName(), r1.endpoint, r2.endpoint, cfname);
-                if (differences.isEmpty())
-                {
-                    logger.info(String.format(format, "are consistent"));
-                    completed(this);
-                    return;
-                }
-
-                // non-0 difference: perform streaming repair
-                logger.info(String.format(format, "have " + differences.size() + " range(s) out of sync"));
-                performStreamingRepair();
-            }
-
-            /**
-             * Starts sending/receiving our list of differences to/from the remote endpoint: creates a callback
-             * that will be called out of band once the streams complete.
-             */
-            void performStreamingRepair()
-            {
-                Runnable callback = new Runnable()
-                {
-                    public void run()
-                    {
-                        completed(Differencer.this);
-                    }
-                };
-                StreamingRepairTask task = StreamingRepairTask.create(r1.endpoint, r2.endpoint, tablename, cfname, differences, callback);
-
-                task.run();
-            }
-
-            public String toString()
-            {
-                return "#<Differencer " + r1.endpoint + "<->" + r2.endpoint + "/" + range + ">";
-            }
-        }
-    }
-
-    static class TreeResponse
-    {
-        public final InetAddress endpoint;
-        public final MerkleTree tree;
-
-        TreeResponse(InetAddress endpoint, MerkleTree tree)
-        {
-            this.endpoint = endpoint;
-            this.tree = tree;
-        }
-    }
-
-    public static class RepairFuture extends FutureTask
-    {
-        public final RepairSession session;
-
-        RepairFuture(RepairSession session)
-        {
-            super(session, null);
-            this.session = session;
-        }
-    }
-
-    public static abstract class RequestCoordinator<R>
-    {
-        private final Order<R> orderer;
-
-        protected RequestCoordinator(boolean isSequential)
-        {
-            this.orderer = isSequential ? new SequentialOrder(this) : new ParallelOrder(this);
-        }
-
-        public abstract void send(R request);
-
-        public void add(R request)
-        {
-            orderer.add(request);
-        }
-
-        public void start()
-        {
-            orderer.start();
-        }
-
-        // Returns how many request remains
-        public int completed(R request)
-        {
-            return orderer.completed(request);
-        }
-
-        private static abstract class Order<R>
-        {
-            protected final RequestCoordinator<R> coordinator;
-
-            Order(RequestCoordinator<R> coordinator)
-            {
-                this.coordinator = coordinator;
-            }
-
-            public abstract void add(R request);
-            public abstract void start();
-            public abstract int completed(R request);
-        }
-
-        private static class SequentialOrder<R> extends Order<R>
-        {
-            private final Queue<R> requests = new LinkedList<R>();
-
-            SequentialOrder(RequestCoordinator<R> coordinator)
-            {
-                super(coordinator);
-            }
-
-            public void add(R request)
-            {
-                requests.add(request);
-            }
-
-            public void start()
-            {
-                if (requests.isEmpty())
-                    return;
-
-                coordinator.send(requests.peek());
-            }
-
-            public int completed(R request)
-            {
-                assert request.equals(requests.peek());
-                requests.poll();
-                int remaining = requests.size();
-                if (remaining != 0)
-                    coordinator.send(requests.peek());
-                return remaining;
-            }
-        }
-
-        private static class ParallelOrder<R> extends Order<R>
-        {
-            private final Set<R> requests = new HashSet<R>();
-
-            ParallelOrder(RequestCoordinator<R> coordinator)
-            {
-                super(coordinator);
-            }
-
-            public void add(R request)
-            {
-                requests.add(request);
-            }
-
-            public void start()
-            {
-                for (R request : requests)
-                    coordinator.send(request);
-            }
-
-            public int completed(R request)
-            {
-                requests.remove(request);
-                return requests.size();
-            }
+            case VALIDATION_COMPLETE:
+                ValidationComplete validation = (ValidationComplete) message;
+                session.validationComplete(desc, endpoint, validation.tree);
+                break;
+            case SYNC_COMPLETE:
+                // one of replica is synced.
+                SyncComplete sync = (SyncComplete) message;
+                session.syncComplete(desc, sync.nodes, sync.success);
+                break;
+            default:
+                break;
         }
-
     }
 }

http://git-wip-us.apache.org/repos/asf/cassandra/blob/eb4fa4a6/src/java/org/apache/cassandra/service/StorageService.java
----------------------------------------------------------------------
diff --git a/src/java/org/apache/cassandra/service/StorageService.java b/src/java/org/apache/cassandra/service/StorageService.java
index accc2c5..a67889a 100644
--- a/src/java/org/apache/cassandra/service/StorageService.java
+++ b/src/java/org/apache/cassandra/service/StorageService.java
@@ -41,8 +41,8 @@ import com.google.common.util.concurrent.FutureCallback;
 import com.google.common.util.concurrent.Futures;
 import com.google.common.util.concurrent.Uninterruptibles;
 
-import org.apache.log4j.Level;
 import org.apache.commons.lang.StringUtils;
+import org.apache.log4j.Level;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -72,7 +72,8 @@ import org.apache.cassandra.net.AsyncOneResponse;
 import org.apache.cassandra.net.MessageOut;
 import org.apache.cassandra.net.MessagingService;
 import org.apache.cassandra.net.ResponseVerbHandler;
-import org.apache.cassandra.service.ActiveRepairService.TreeRequestVerbHandler;
+import org.apache.cassandra.repair.RepairFuture;
+import org.apache.cassandra.repair.RepairMessageVerbHandler;
 import org.apache.cassandra.service.paxos.CommitVerbHandler;
 import org.apache.cassandra.service.paxos.PrepareVerbHandler;
 import org.apache.cassandra.service.paxos.ProposeVerbHandler;
@@ -238,10 +239,7 @@ public class StorageService extends NotificationBroadcasterSupport implements IE
         MessagingService.instance().registerVerbHandlers(MessagingService.Verb.REPLICATION_FINISHED, new ReplicationFinishedVerbHandler());
         MessagingService.instance().registerVerbHandlers(MessagingService.Verb.REQUEST_RESPONSE, new ResponseVerbHandler());
         MessagingService.instance().registerVerbHandlers(MessagingService.Verb.INTERNAL_RESPONSE, new ResponseVerbHandler());
-        MessagingService.instance().registerVerbHandlers(MessagingService.Verb.TREE_REQUEST, new TreeRequestVerbHandler());
-        MessagingService.instance().registerVerbHandlers(MessagingService.Verb.TREE_RESPONSE, new ActiveRepairService.TreeResponseVerbHandler());
-        MessagingService.instance().registerVerbHandlers(MessagingService.Verb.STREAMING_REPAIR_REQUEST, new StreamingRepairTask.StreamingRepairRequest());
-        MessagingService.instance().registerVerbHandlers(MessagingService.Verb.STREAMING_REPAIR_RESPONSE, new StreamingRepairTask.StreamingRepairResponse());
+        MessagingService.instance().registerVerbHandlers(MessagingService.Verb.REPAIR_MESSAGE, new RepairMessageVerbHandler());
         MessagingService.instance().registerVerbHandlers(MessagingService.Verb.GOSSIP_SHUTDOWN, new GossipShutdownVerbHandler());
 
         MessagingService.instance().registerVerbHandlers(MessagingService.Verb.GOSSIP_DIGEST_SYN, new GossipDigestSynVerbHandler());
@@ -2348,10 +2346,10 @@ public class StorageService extends NotificationBroadcasterSupport implements IE
                 logger.info(message);
                 sendNotification("repair", message, new int[]{cmd, ActiveRepairService.Status.STARTED.ordinal()});
 
-                List<ActiveRepairService.RepairFuture> futures = new ArrayList<ActiveRepairService.RepairFuture>(ranges.size());
+                List<RepairFuture> futures = new ArrayList<RepairFuture>(ranges.size());
                 for (Range<Token> range : ranges)
                 {
-                    ActiveRepairService.RepairFuture future;
+                    RepairFuture future;
                     try
                     {
                         future = forceTableRepair(range, keyspace, isSequential, isLocal, columnFamilies);
@@ -2377,23 +2375,24 @@ public class StorageService extends NotificationBroadcasterSupport implements IE
                         sendNotification("repair", message, new int[]{cmd, ActiveRepairService.Status.SESSION_FAILED.ordinal()});
                     }
                 }
-                for (ActiveRepairService.RepairFuture future : futures)
+                for (RepairFuture future : futures)
                 {
                     try
                     {
                         future.get();
-                        message = String.format("Repair session %s for range %s finished", future.session.getName(), future.session.getRange().toString());
+                        message = String.format("Repair session %s for range %s finished", future.session.getId(), future.session.getRange().toString());
+                        logger.info(message);
                         sendNotification("repair", message, new int[]{cmd, ActiveRepairService.Status.SESSION_SUCCESS.ordinal()});
                     }
                     catch (ExecutionException e)
                     {
-                        message = String.format("Repair session %s for range %s failed with error %s", future.session.getName(), future.session.getRange().toString(), e.getCause().getMessage());
+                        message = String.format("Repair session %s for range %s failed with error %s", future.session.getId(), future.session.getRange().toString(), e.getCause().getMessage());
                         logger.error(message, e);
                         sendNotification("repair", message, new int[]{cmd, ActiveRepairService.Status.SESSION_FAILED.ordinal()});
                     }
                     catch (Exception e)
                     {
-                        message = String.format("Repair session %s for range %s failed with error %s", future.session.getName(), future.session.getRange().toString(), e.getMessage());
+                        message = String.format("Repair session %s for range %s failed with error %s", future.session.getId(), future.session.getRange().toString(), e.getMessage());
                         logger.error(message, e);
                         sendNotification("repair", message, new int[]{cmd, ActiveRepairService.Status.SESSION_FAILED.ordinal()});
                     }
@@ -2403,7 +2402,7 @@ public class StorageService extends NotificationBroadcasterSupport implements IE
         }, null);
     }
 
-    public ActiveRepairService.RepairFuture forceTableRepair(final Range<Token> range, final String tableName, boolean isSequential, boolean  isLocal, final String... columnFamilies) throws IOException
+    public RepairFuture forceTableRepair(final Range<Token> range, final String tableName, boolean isSequential, boolean  isLocal, final String... columnFamilies) throws IOException
     {
         ArrayList<String> names = new ArrayList<String>();
         for (ColumnFamilyStore cfStore : getValidColumnFamilies(false, false, tableName, columnFamilies))

http://git-wip-us.apache.org/repos/asf/cassandra/blob/eb4fa4a6/src/java/org/apache/cassandra/streaming/StreamingRepairTask.java
----------------------------------------------------------------------
diff --git a/src/java/org/apache/cassandra/streaming/StreamingRepairTask.java b/src/java/org/apache/cassandra/streaming/StreamingRepairTask.java
deleted file mode 100644
index 3730b0e..0000000
--- a/src/java/org/apache/cassandra/streaming/StreamingRepairTask.java
+++ /dev/null
@@ -1,254 +0,0 @@
-/*
- * Licensed to the Apache Software Foundation (ASF) under one
- * or more contributor license agreements.  See the NOTICE file
- * distributed with this work for additional information
- * regarding copyright ownership.  The ASF licenses this file
- * to you 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.apache.cassandra.streaming;
-
-import java.io.DataInput;
-import java.io.DataOutput;
-import java.io.IOException;
-import java.net.InetAddress;
-import java.util.ArrayList;
-import java.util.Collection;
-import java.util.List;
-import java.util.UUID;
-import java.util.concurrent.ConcurrentHashMap;
-import java.util.concurrent.ConcurrentMap;
-
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
-import org.apache.cassandra.db.TypeSizes;
-import org.apache.cassandra.dht.AbstractBounds;
-import org.apache.cassandra.dht.Range;
-import org.apache.cassandra.dht.Token;
-import org.apache.cassandra.io.IVersionedSerializer;
-import org.apache.cassandra.net.*;
-import org.apache.cassandra.utils.FBUtilities;
-import org.apache.cassandra.utils.UUIDGen;
-import org.apache.cassandra.utils.UUIDSerializer;
-
-/**
- * Task that make two nodes exchange (stream) some ranges (for a given table/cf).
- * This handle the case where the local node is neither of the two nodes that
- * must stream their range, and allow to register a callback to be called on
- * completion.
- */
-public class StreamingRepairTask implements Runnable
-{
-    private static final Logger logger = LoggerFactory.getLogger(StreamingRepairTask.class);
-
-    // maps of tasks created on this node
-    private static final ConcurrentMap<UUID, StreamingRepairTask> tasks = new ConcurrentHashMap<UUID, StreamingRepairTask>();
-    public static final StreamingRepairTaskSerializer serializer = new StreamingRepairTaskSerializer();
-
-    public final UUID id;
-    private final InetAddress owner; // the node where the task is created; can be == src but don't need to
-    public final InetAddress src;
-    public final InetAddress dst;
-
-    private final String tableName;
-    private final String cfName;
-    private final Collection<Range<Token>> ranges;
-    private final StreamEventHandler callback;
-
-    private StreamingRepairTask(UUID id, InetAddress owner, InetAddress src, InetAddress dst, String tableName, String cfName, Collection<Range<Token>> ranges, StreamEventHandler callback)
-    {
-        this.id = id;
-        this.owner = owner;
-        this.src = src;
-        this.dst = dst;
-        this.tableName = tableName;
-        this.cfName = cfName;
-        this.ranges = ranges;
-        this.callback = callback;
-    }
-
-    public static StreamingRepairTask create(InetAddress ep1, InetAddress ep2, String tableName, String cfName, Collection<Range<Token>> ranges, Runnable callback)
-    {
-        InetAddress local = FBUtilities.getBroadcastAddress();
-        UUID id = UUIDGen.getTimeUUID();
-        // We can take anyone of the node as source or destination, however if one is localhost, we put at source to avoid a forwarding
-        InetAddress src = ep2.equals(local) ? ep2 : ep1;
-        InetAddress dst = ep2.equals(local) ? ep1 : ep2;
-        StreamingRepairTask task = new StreamingRepairTask(id, local, src, dst, tableName, cfName, ranges, wrapCallback(callback, id, local.equals(src)));
-        tasks.put(id, task);
-        return task;
-    }
-
-    /**
-     * Returns true if the task if the task can be executed locally, false if
-     * it has to be forwarded.
-     */
-    public boolean isLocalTask()
-    {
-        return owner.equals(src);
-    }
-
-    public void run()
-    {
-        if (src.equals(FBUtilities.getBroadcastAddress()))
-        {
-            initiateStreaming();
-        }
-        else
-        {
-            forwardToSource();
-        }
-    }
-
-    private void initiateStreaming()
-    {
-        logger.info(String.format("[streaming task #%s] Performing streaming repair of %d ranges with %s", id, ranges.size(), dst));
-        StreamResultFuture op = new StreamPlan("Repair")
-                                    .flushBeforeTransfer(true)
-                                    // request ranges from the remote node
-                                    .requestRanges(dst, tableName, ranges, cfName)
-                                    // send ranges to the remote node
-                                    .transferRanges(dst, tableName, ranges, cfName)
-                                    .execute();
-        op.addEventListener(callback);
-    }
-
-    private void forwardToSource()
-    {
-        logger.info(String.format("[streaming task #%s] Forwarding streaming repair of %d ranges to %s (to be streamed with %s)", id, ranges.size(), src, dst));
-        MessageOut<StreamingRepairTask> msg = new MessageOut<StreamingRepairTask>(MessagingService.Verb.STREAMING_REPAIR_REQUEST,
-                                                                                  this,
-                                                                                  StreamingRepairTask.serializer);
-        MessagingService.instance().sendOneWay(msg, src);
-    }
-
-    private static StreamEventHandler makeReplyingCallback(final InetAddress taskOwner, final UUID taskId)
-    {
-        return new StreamEventHandler()
-        {
-            public void onSuccess(StreamState finalState)
-            {
-                StreamingRepairResponse.reply(taskOwner, taskId);
-            }
-
-            public void onFailure(Throwable t) {}
-            public void handleStreamEvent(StreamEvent event) {}
-        };
-    }
-
-    // wrap a given callback so as to unregister the streaming repair task on completion
-    private static StreamEventHandler wrapCallback(final Runnable callback, final UUID taskid, final boolean isLocalTask)
-    {
-        return new StreamEventHandler()
-        {
-            public void onSuccess(StreamState finalState)
-            {
-                tasks.remove(taskid);
-                if (callback != null)
-                    callback.run();
-            }
-
-            public void onFailure(Throwable t) {}
-            public void handleStreamEvent(StreamEvent event) {}
-        };
-    }
-
-    public static class StreamingRepairRequest implements IVerbHandler<StreamingRepairTask>
-    {
-        public void doVerb(MessageIn<StreamingRepairTask> message, int id)
-        {
-            StreamingRepairTask task = message.payload;
-            assert task.src.equals(FBUtilities.getBroadcastAddress());
-            assert task.owner.equals(message.from);
-
-            logger.info(String.format("[streaming task #%s] Received task from %s to stream %d ranges to %s", task.id, message.from, task.ranges.size(), task.dst));
-
-            task.run();
-        }
-
-    }
-
-    public static class StreamingRepairResponse implements IVerbHandler<UUID>
-    {
-        public void doVerb(MessageIn<UUID> message, int id)
-        {
-            UUID taskid = message.payload;
-            StreamingRepairTask task = tasks.get(taskid);
-            if (task == null)
-            {
-                logger.error(String.format("Received a stream repair response from %s for unknow taks %s (have this node been restarted recently?)", message.from, taskid));
-                return;
-            }
-
-            assert task.owner.equals(FBUtilities.getBroadcastAddress());
-
-            logger.info(String.format("[streaming task #%s] task succeeded", task.id));
-            if (task.callback != null)
-            {
-                // TODO null
-                task.callback.onSuccess(null);
-            }
-        }
-
-        private static void reply(InetAddress remote, UUID taskid)
-        {
-            logger.info(String.format("[streaming task #%s] task suceed, forwarding response to %s", taskid, remote));
-            MessageOut<UUID> message = new MessageOut<UUID>(MessagingService.Verb.STREAMING_REPAIR_RESPONSE, taskid, UUIDSerializer.serializer);
-            MessagingService.instance().sendOneWay(message, remote);
-        }
-    }
-
-    private static class StreamingRepairTaskSerializer implements IVersionedSerializer<StreamingRepairTask>
-    {
-        public void serialize(StreamingRepairTask task, DataOutput out, int version) throws IOException
-        {
-            UUIDSerializer.serializer.serialize(task.id, out, version);
-            CompactEndpointSerializationHelper.serialize(task.owner, out);
-            CompactEndpointSerializationHelper.serialize(task.src, out);
-            CompactEndpointSerializationHelper.serialize(task.dst, out);
-            out.writeUTF(task.tableName);
-            out.writeUTF(task.cfName);
-            out.writeInt(task.ranges.size());
-            for (Range<Token> range : task.ranges)
-                AbstractBounds.serializer.serialize(range, out, version);
-            // We don't serialize the callback on purpose
-        }
-
-        public StreamingRepairTask deserialize(DataInput in, int version) throws IOException
-        {
-            UUID id = UUIDSerializer.serializer.deserialize(in, version);
-            InetAddress owner = CompactEndpointSerializationHelper.deserialize(in);
-            InetAddress src = CompactEndpointSerializationHelper.deserialize(in);
-            InetAddress dst = CompactEndpointSerializationHelper.deserialize(in);
-            String tableName = in.readUTF();
-            String cfName = in.readUTF();
-            int rangesCount = in.readInt();
-            List<Range<Token>> ranges = new ArrayList<Range<Token>>(rangesCount);
-            for (int i = 0; i < rangesCount; ++i)
-                ranges.add((Range<Token>) AbstractBounds.serializer.deserialize(in, version).toTokenBounds());
-            return new StreamingRepairTask(id, owner, src, dst, tableName, cfName, ranges, makeReplyingCallback(owner, id));
-        }
-
-        public long serializedSize(StreamingRepairTask task, int version)
-        {
-            long size = UUIDSerializer.serializer.serializedSize(task.id, version);
-            size += 3 * CompactEndpointSerializationHelper.serializedSize(task.owner);
-            size += TypeSizes.NATIVE.sizeof(task.tableName);
-            size += TypeSizes.NATIVE.sizeof(task.cfName);
-            size += TypeSizes.NATIVE.sizeof(task.ranges.size());
-            for (Range<Token> range : task.ranges)
-                size += AbstractBounds.serializer.serializedSize(range, version);
-            return size;
-        }
-    }
-}

http://git-wip-us.apache.org/repos/asf/cassandra/blob/eb4fa4a6/src/java/org/apache/cassandra/utils/FBUtilities.java
----------------------------------------------------------------------
diff --git a/src/java/org/apache/cassandra/utils/FBUtilities.java b/src/java/org/apache/cassandra/utils/FBUtilities.java
index 8a5572e..9288759 100644
--- a/src/java/org/apache/cassandra/utils/FBUtilities.java
+++ b/src/java/org/apache/cassandra/utils/FBUtilities.java
@@ -213,6 +213,11 @@ public class FBUtilities
         return FastByteComparisons.compareTo(bytes1, offset1, len1, bytes2, offset2, len2);
     }
 
+    public static int compareUnsigned(byte[] bytes1, byte[] bytes2)
+    {
+        return compareUnsigned(bytes1, bytes2, 0, 0, bytes1.length, bytes2.length);
+    }
+
     /**
      * @return The bitwise XOR of the inputs. The output will be the same length as the
      * longer input, but if either input is null, the output will be null.

http://git-wip-us.apache.org/repos/asf/cassandra/blob/eb4fa4a6/src/java/org/apache/cassandra/utils/MerkleTree.java
----------------------------------------------------------------------
diff --git a/src/java/org/apache/cassandra/utils/MerkleTree.java b/src/java/org/apache/cassandra/utils/MerkleTree.java
index 5284a57..a16c2b9 100644
--- a/src/java/org/apache/cassandra/utils/MerkleTree.java
+++ b/src/java/org/apache/cassandra/utils/MerkleTree.java
@@ -23,6 +23,7 @@ import java.io.IOException;
 import java.io.Serializable;
 import java.util.*;
 
+import com.google.common.base.Preconditions;
 import com.google.common.collect.AbstractIterator;
 import com.google.common.collect.PeekingIterator;
 
@@ -30,6 +31,7 @@ import org.apache.cassandra.db.TypeSizes;
 import org.apache.cassandra.dht.IPartitioner;
 import org.apache.cassandra.dht.Range;
 import org.apache.cassandra.dht.Token;
+import org.apache.cassandra.exceptions.ConfigurationException;
 import org.apache.cassandra.io.IVersionedSerializer;
 
 /**
@@ -65,18 +67,9 @@ public class MerkleTree implements Serializable
 
     public final byte hashdepth;
 
-    /**
-     * The top level range that this MerkleTree covers.
-     * In a perfect world, this should be final and *not* transient. However
-     * this would break serialization with version &gte; 0.7 because it uses
-     * java serialization. We are moreover always shipping the fullRange will
-     * the request so we can add it back post-deserialization (as for the
-     * partitioner).
-     */
-    public transient Range<Token> fullRange;
-
-    // TODO This is broken; Token serialization assumes system partitioner, so if this doesn't match all hell breaks loose
-    private transient IPartitioner partitioner;
+    /** The top level range that this MerkleTree covers. */
+    public final Range<Token> fullRange;
+    private final IPartitioner partitioner;
 
     private long maxsize;
     private long size;
@@ -89,6 +82,10 @@ public class MerkleTree implements Serializable
             out.writeByte(mt.hashdepth);
             out.writeLong(mt.maxsize);
             out.writeLong(mt.size);
+            out.writeUTF(mt.partitioner.getClass().getCanonicalName());
+            // full range
+            Token.serializer.serialize(mt.fullRange.left, out);
+            Token.serializer.serialize(mt.fullRange.right, out);
             Hashable.serializer.serialize(mt.root, out, version);
         }
 
@@ -97,7 +94,22 @@ public class MerkleTree implements Serializable
             byte hashdepth = in.readByte();
             long maxsize = in.readLong();
             long size = in.readLong();
-            MerkleTree mt = new MerkleTree(null, null, hashdepth, maxsize);
+            IPartitioner partitioner;
+            try
+            {
+                partitioner = FBUtilities.newPartitioner(in.readUTF());
+            }
+            catch (ConfigurationException e)
+            {
+                throw new IOException(e);
+            }
+
+            // full range
+            Token left = Token.serializer.deserialize(in);
+            Token right = Token.serializer.deserialize(in);
+            Range<Token> fullRange = new Range<>(left, right, partitioner);
+
+            MerkleTree mt = new MerkleTree(partitioner, fullRange, hashdepth, maxsize);
             mt.size = size;
             mt.root = Hashable.serializer.deserialize(in, version);
             return mt;
@@ -105,10 +117,17 @@ public class MerkleTree implements Serializable
 
         public long serializedSize(MerkleTree mt, int version)
         {
-            return 1 // mt.hashdepth
+            long size = 1 // mt.hashdepth
                  + TypeSizes.NATIVE.sizeof(mt.maxsize)
                  + TypeSizes.NATIVE.sizeof(mt.size)
-                 + Hashable.serializer.serializedSize(mt.root, version);
+                 + TypeSizes.NATIVE.sizeof(mt.partitioner.getClass().getCanonicalName());
+
+            // full range
+            size += Token.serializer.serializedSize(mt.fullRange.left, TypeSizes.NATIVE);
+            size += Token.serializer.serializedSize(mt.fullRange.right, TypeSizes.NATIVE);
+
+            size += Hashable.serializer.serializedSize(mt.root, version);
+            return size;
         }
     }
 
@@ -122,8 +141,8 @@ public class MerkleTree implements Serializable
     public MerkleTree(IPartitioner partitioner, Range<Token> range, byte hashdepth, long maxsize)
     {
         assert hashdepth < Byte.MAX_VALUE;
-        this.fullRange = range;
-        this.partitioner = partitioner;
+        this.fullRange = Preconditions.checkNotNull(range);
+        this.partitioner = Preconditions.checkNotNull(partitioner);
         this.hashdepth = hashdepth;
         this.maxsize = maxsize;
 
@@ -199,14 +218,6 @@ public class MerkleTree implements Serializable
     }
 
     /**
-     * TODO: Find another way to use the local partitioner after serialization.
-     */
-    public void partitioner(IPartitioner partitioner)
-    {
-        this.partitioner = partitioner;
-    }
-
-    /**
      * @param ltree First tree.
      * @param rtree Second tree.
      * @return A list of the largest contiguous ranges where the given trees disagree.

http://git-wip-us.apache.org/repos/asf/cassandra/blob/eb4fa4a6/test/data/serialization/2.0/service.SyncComplete.bin
----------------------------------------------------------------------
diff --git a/test/data/serialization/2.0/service.SyncComplete.bin b/test/data/serialization/2.0/service.SyncComplete.bin
new file mode 100644
index 0000000..66c72e1
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http://git-wip-us.apache.org/repos/asf/cassandra/blob/eb4fa4a6/test/data/serialization/2.0/service.SyncRequest.bin
----------------------------------------------------------------------
diff --git a/test/data/serialization/2.0/service.SyncRequest.bin b/test/data/serialization/2.0/service.SyncRequest.bin
new file mode 100644
index 0000000..8918405
Binary files /dev/null and b/test/data/serialization/2.0/service.SyncRequest.bin differ

http://git-wip-us.apache.org/repos/asf/cassandra/blob/eb4fa4a6/test/data/serialization/2.0/service.TreeRequest.bin
----------------------------------------------------------------------
diff --git a/test/data/serialization/2.0/service.TreeRequest.bin b/test/data/serialization/2.0/service.TreeRequest.bin
deleted file mode 100644
index b336e50..0000000
Binary files a/test/data/serialization/2.0/service.TreeRequest.bin and /dev/null differ

http://git-wip-us.apache.org/repos/asf/cassandra/blob/eb4fa4a6/test/data/serialization/2.0/service.TreeResponse.bin
----------------------------------------------------------------------
diff --git a/test/data/serialization/2.0/service.TreeResponse.bin b/test/data/serialization/2.0/service.TreeResponse.bin
deleted file mode 100644
index b63d8a2..0000000
Binary files a/test/data/serialization/2.0/service.TreeResponse.bin and /dev/null differ

http://git-wip-us.apache.org/repos/asf/cassandra/blob/eb4fa4a6/test/data/serialization/2.0/service.ValidationComplete.bin
----------------------------------------------------------------------
diff --git a/test/data/serialization/2.0/service.ValidationComplete.bin b/test/data/serialization/2.0/service.ValidationComplete.bin
new file mode 100644
index 0000000..bc633bc
Binary files /dev/null and b/test/data/serialization/2.0/service.ValidationComplete.bin differ

http://git-wip-us.apache.org/repos/asf/cassandra/blob/eb4fa4a6/test/data/serialization/2.0/service.ValidationRequest.bin
----------------------------------------------------------------------
diff --git a/test/data/serialization/2.0/service.ValidationRequest.bin b/test/data/serialization/2.0/service.ValidationRequest.bin
new file mode 100644
index 0000000..4ec4c47
Binary files /dev/null and b/test/data/serialization/2.0/service.ValidationRequest.bin differ

http://git-wip-us.apache.org/repos/asf/cassandra/blob/eb4fa4a6/test/unit/org/apache/cassandra/db/compaction/LeveledCompactionStrategyTest.java
----------------------------------------------------------------------
diff --git a/test/unit/org/apache/cassandra/db/compaction/LeveledCompactionStrategyTest.java b/test/unit/org/apache/cassandra/db/compaction/LeveledCompactionStrategyTest.java
index 3fb828b..9218dc9 100644
--- a/test/unit/org/apache/cassandra/db/compaction/LeveledCompactionStrategyTest.java
+++ b/test/unit/org/apache/cassandra/db/compaction/LeveledCompactionStrategyTest.java
@@ -24,6 +24,7 @@ import java.util.HashSet;
 import java.util.List;
 import java.util.Set;
 import java.util.concurrent.ExecutionException;
+import java.util.UUID;
 
 import org.junit.Test;
 import org.junit.runner.RunWith;
@@ -40,12 +41,12 @@ import org.apache.cassandra.dht.Token;
 import org.apache.cassandra.io.sstable.Component;
 import org.apache.cassandra.io.sstable.SSTable;
 import org.apache.cassandra.io.sstable.SSTableReader;
-import org.apache.cassandra.service.ActiveRepairService;
+import org.apache.cassandra.repair.RepairJobDesc;
+import org.apache.cassandra.repair.Validator;
 import org.apache.cassandra.utils.ByteBufferUtil;
 import org.apache.cassandra.utils.FBUtilities;
 
 import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
 
 @RunWith(OrderedJUnit4ClassRunner.class)
@@ -87,11 +88,10 @@ public class LeveledCompactionStrategyTest extends SchemaLoader
         assert strategy.getLevelSize(1) > 0;
         assert strategy.getLevelSize(2) > 0;
 
-        ActiveRepairService.CFPair p = new ActiveRepairService.CFPair(ksname, cfname);
         Range<Token> range = new Range<Token>(Util.token(""), Util.token(""));
         int gcBefore = table.getColumnFamilyStore(cfname).gcBefore(System.currentTimeMillis());
-        ActiveRepairService.TreeRequest req = new ActiveRepairService.TreeRequest("1", FBUtilities.getLocalAddress(), range, gcBefore, p);
-        ActiveRepairService.Validator validator = new ActiveRepairService.Validator(req);
+        RepairJobDesc desc = new RepairJobDesc(UUID.randomUUID(), ksname, cfname, range);
+        Validator validator = new Validator(desc, FBUtilities.getBroadcastAddress(), gcBefore);
         CompactionManager.instance.submitValidation(cfs, validator).get();
     }
 

http://git-wip-us.apache.org/repos/asf/cassandra/blob/eb4fa4a6/test/unit/org/apache/cassandra/repair/DifferencerTest.java
----------------------------------------------------------------------
diff --git a/test/unit/org/apache/cassandra/repair/DifferencerTest.java b/test/unit/org/apache/cassandra/repair/DifferencerTest.java
new file mode 100644
index 0000000..2502620
--- /dev/null
+++ b/test/unit/org/apache/cassandra/repair/DifferencerTest.java
@@ -0,0 +1,139 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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.apache.cassandra.repair;
+
+import java.net.InetAddress;
+import java.util.HashSet;
+import java.util.Set;
+import java.util.UUID;
+
+import org.junit.After;
+import org.junit.Test;
+
+import org.apache.cassandra.SchemaLoader;
+import org.apache.cassandra.dht.IPartitioner;
+import org.apache.cassandra.dht.Murmur3Partitioner;
+import org.apache.cassandra.dht.Range;
+import org.apache.cassandra.dht.Token;
+import org.apache.cassandra.net.MessageIn;
+import org.apache.cassandra.net.MessageOut;
+import org.apache.cassandra.net.MessagingService;
+import org.apache.cassandra.net.sink.IMessageSink;
+import org.apache.cassandra.net.sink.SinkManager;
+import org.apache.cassandra.repair.messages.RepairMessage;
+import org.apache.cassandra.repair.messages.SyncComplete;
+import org.apache.cassandra.utils.MerkleTree;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+
+public class DifferencerTest extends SchemaLoader
+{
+    private static final IPartitioner partirioner = new Murmur3Partitioner();
+
+    @After
+    public void tearDown()
+    {
+        SinkManager.clear();
+    }
+
+    /**
+     * When there is no difference between two, Differencer should respond SYNC_COMPLETE
+     */
+    @Test
+    public void testNoDifference() throws Throwable
+    {
+        final InetAddress ep1 = InetAddress.getByName("127.0.0.1");
+        final InetAddress ep2 = InetAddress.getByName("127.0.0.1");
+
+        SinkManager.add(new IMessageSink()
+        {
+            @SuppressWarnings("unchecked")
+            public MessageOut handleMessage(MessageOut message, int id, InetAddress to)
+            {
+                if (message.verb == MessagingService.Verb.REPAIR_MESSAGE)
+                {
+                    RepairMessage m = (RepairMessage) message.payload;
+                    assertEquals(RepairMessage.Type.SYNC_COMPLETE, m.messageType);
+                    // we should see SYNC_COMPLETE
+                    assertEquals(new NodePair(ep1, ep2), ((SyncComplete)m).nodes);
+                }
+                return null;
+            }
+
+            public MessageIn handleMessage(MessageIn message, int id, InetAddress to)
+            {
+                return null;
+            }
+        });
+        Range<Token> range = new Range<>(partirioner.getMinimumToken(), partirioner.getRandomToken());
+        RepairJobDesc desc = new RepairJobDesc(UUID.randomUUID(), "Keyspace1", "Standard1", range);
+
+        MerkleTree tree1 = createInitialTree(desc);
+        MerkleTree tree2 = createInitialTree(desc);
+
+        // difference the trees
+        // note: we reuse the same endpoint which is bogus in theory but fine here
+        TreeResponse r1 = new TreeResponse(ep1, tree1);
+        TreeResponse r2 = new TreeResponse(ep2, tree2);
+        Differencer diff = new Differencer(desc, r1, r2);
+        diff.run();
+
+        assertTrue(diff.differences.isEmpty());
+    }
+
+    @Test
+    public void testDifference() throws Throwable
+    {
+        Range<Token> range = new Range<>(partirioner.getMinimumToken(), partirioner.getRandomToken());
+        RepairJobDesc desc = new RepairJobDesc(UUID.randomUUID(), "Keyspace1", "Standard1", range);
+
+        MerkleTree tree1 = createInitialTree(desc);
+        MerkleTree tree2 = createInitialTree(desc);
+
+        // change a range in one of the trees
+        Token token = partirioner.midpoint(range.left, range.right);
+        tree1.invalidate(token);
+        MerkleTree.TreeRange changed = tree1.get(token);
+        changed.hash("non-empty hash!".getBytes());
+
+        Set<Range<Token>> interesting = new HashSet<>();
+        interesting.add(changed);
+
+        // difference the trees
+        // note: we reuse the same endpoint which is bogus in theory but fine here
+        TreeResponse r1 = new TreeResponse(InetAddress.getByName("127.0.0.1"), tree1);
+        TreeResponse r2 = new TreeResponse(InetAddress.getByName("127.0.0.2"), tree2);
+        Differencer diff = new Differencer(desc, r1, r2);
+        diff.run();
+
+        // ensure that the changed range was recorded
+        assertEquals("Wrong differing ranges", interesting, new HashSet<>(diff.differences));
+    }
+
+    private MerkleTree createInitialTree(RepairJobDesc desc)
+    {
+        MerkleTree tree = new MerkleTree(partirioner, desc.range, MerkleTree.RECOMMENDED_DEPTH, (int)Math.pow(2, 15));
+        tree.init();
+        for (MerkleTree.TreeRange r : tree.invalids())
+        {
+            r.addHash(Validator.EMPTY_ROW);
+        }
+        return tree;
+    }
+}

http://git-wip-us.apache.org/repos/asf/cassandra/blob/eb4fa4a6/test/unit/org/apache/cassandra/repair/ValidatorTest.java
----------------------------------------------------------------------
diff --git a/test/unit/org/apache/cassandra/repair/ValidatorTest.java b/test/unit/org/apache/cassandra/repair/ValidatorTest.java
new file mode 100644
index 0000000..12abd24
--- /dev/null
+++ b/test/unit/org/apache/cassandra/repair/ValidatorTest.java
@@ -0,0 +1,169 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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.apache.cassandra.repair;
+
+import java.net.InetAddress;
+import java.util.UUID;
+
+import org.junit.After;
+import org.junit.Test;
+
+import org.apache.cassandra.SchemaLoader;
+import org.apache.cassandra.db.ColumnFamilyStore;
+import org.apache.cassandra.db.DecoratedKey;
+import org.apache.cassandra.db.Table;
+import org.apache.cassandra.db.TreeMapBackedSortedColumns;
+import org.apache.cassandra.db.compaction.PrecompactedRow;
+import org.apache.cassandra.dht.IPartitioner;
+import org.apache.cassandra.dht.Range;
+import org.apache.cassandra.dht.Token;
+import org.apache.cassandra.net.MessageIn;
+import org.apache.cassandra.net.MessageOut;
+import org.apache.cassandra.net.MessagingService;
+import org.apache.cassandra.net.sink.IMessageSink;
+import org.apache.cassandra.net.sink.SinkManager;
+import org.apache.cassandra.repair.messages.RepairMessage;
+import org.apache.cassandra.repair.messages.ValidationComplete;
+import org.apache.cassandra.service.StorageService;
+import org.apache.cassandra.utils.ByteBufferUtil;
+import org.apache.cassandra.utils.MerkleTree;
+import org.apache.cassandra.utils.SimpleCondition;
+
+import static junit.framework.Assert.assertFalse;
+import static junit.framework.Assert.assertNull;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertTrue;
+
+public class ValidatorTest extends SchemaLoader
+{
+    private final String keyspace = "Keyspace1";
+    private final String columnFamily = "Standard1";
+    private final IPartitioner partitioner = StorageService.getPartitioner();
+
+    @After
+    public void tearDown()
+    {
+        SinkManager.clear();
+    }
+
+    @Test
+    public void testValidatorComplete() throws Throwable
+    {
+        Range<Token> range = new Range<>(partitioner.getMinimumToken(), partitioner.getRandomToken());
+        final RepairJobDesc desc = new RepairJobDesc(UUID.randomUUID(), keyspace, columnFamily, range);
+
+        final SimpleCondition lock = new SimpleCondition();
+        SinkManager.add(new IMessageSink()
+        {
+            @SuppressWarnings("unchecked")
+            public MessageOut handleMessage(MessageOut message, int id, InetAddress to)
+            {
+                try
+                {
+                    if (message.verb == MessagingService.Verb.REPAIR_MESSAGE)
+                    {
+                        RepairMessage m = (RepairMessage) message.payload;
+                        assertEquals(RepairMessage.Type.VALIDATION_COMPLETE, m.messageType);
+                        assertEquals(desc, m.desc);
+                        assertTrue(((ValidationComplete)m).success);
+                        assertNotNull(((ValidationComplete)m).tree);
+                    }
+                }
+                finally
+                {
+                    lock.signalAll();
+                }
+                return null;
+            }
+
+            public MessageIn handleMessage(MessageIn message, int id, InetAddress to)
+            {
+                return null;
+            }
+        });
+
+        InetAddress remote = InetAddress.getByName("127.0.0.2");
+
+        ColumnFamilyStore cfs = Table.open(keyspace).getColumnFamilyStore(columnFamily);
+
+        Validator validator = new Validator(desc, remote, 0);
+        validator.prepare(cfs);
+
+        // and confirm that the tree was split
+        assertTrue(validator.tree.size() > 1);
+
+        // add a row
+        Token mid = partitioner.midpoint(range.left, range.right);
+        validator.add(new PrecompactedRow(new DecoratedKey(mid, ByteBufferUtil.bytes("inconceivable!")),
+                                                 TreeMapBackedSortedColumns.factory.create(cfs.metadata)));
+        validator.complete();
+
+        // confirm that the tree was validated
+        Token min = validator.tree.partitioner().getMinimumToken();
+        assertNotNull(validator.tree.hash(new Range<>(min, min)));
+
+        if (!lock.isSignaled())
+            lock.await();
+    }
+
+    @Test
+    public void testValidatorFailed() throws Throwable
+    {
+        Range<Token> range = new Range<>(partitioner.getMinimumToken(), partitioner.getRandomToken());
+        final RepairJobDesc desc = new RepairJobDesc(UUID.randomUUID(), keyspace, columnFamily, range);
+
+        final SimpleCondition lock = new SimpleCondition();
+        SinkManager.add(new IMessageSink()
+        {
+            @SuppressWarnings("unchecked")
+            public MessageOut handleMessage(MessageOut message, int id, InetAddress to)
+            {
+                try
+                {
+                    if (message.verb == MessagingService.Verb.REPAIR_MESSAGE)
+                    {
+                        RepairMessage m = (RepairMessage) message.payload;
+                        assertEquals(RepairMessage.Type.VALIDATION_COMPLETE, m.messageType);
+                        assertEquals(desc, m.desc);
+                        assertFalse(((ValidationComplete) m).success);
+                        assertNull(((ValidationComplete)m).tree);
+                    }
+                }
+                finally
+                {
+                    lock.signalAll();
+                }
+                return null;
+            }
+
+            public MessageIn handleMessage(MessageIn message, int id, InetAddress to)
+            {
+                return null;
+            }
+        });
+
+        InetAddress remote = InetAddress.getByName("127.0.0.2");
+
+        Validator validator = new Validator(desc, remote, 0);
+        validator.fail();
+
+        if (!lock.isSignaled())
+            lock.await();
+    }
+}