Show candidate hosts for the given query (#2282)

* Show candidate hosts for the given query

* Added test cases & minor changes to address comments

* Changed path-param to query-pram for intervals/numCandidates

docs/content/design/broker.md

@@ -59,7 +59,17 @@ Returns the dimensions of the datasource.
 
 Returns the metrics of the datasource.
 
+* `/druid/v2/datasources/{dataSourceName}/candidates?intervals={comma-separated-intervals-in-ISO8601-format}&numCandidates={numCandidates}`
+
+Returns segment information lists including server locations for the given datasource and intervals. If "numCandidates" is not specified, it will return all servers for each interval.
+
 * `/druid/broker/v1/loadstatus`
 
 Returns a flag indicating if the broker knows about all segments in Zookeeper. This can be used to know when a broker node is ready to be queried after a restart.
 
+
+### POST
+
+* `/druid/v2/candidates/`
+
+Returns segment information lists including server locations for the given query.

processing/src/main/java/io/druid/query/QueryInterruptedException.java

@@ -145,4 +145,9 @@ public class QueryInterruptedException extends RuntimeException
       return null;
     }
   }
+
+  public static QueryInterruptedException wrapIfNeeded(Throwable e)
+  {
+    return e instanceof QueryInterruptedException ? (QueryInterruptedException) e : new QueryInterruptedException(e);
+  }
 }

server/src/main/java/io/druid/client/ServerViewUtil.java

@@ -0,0 +1,78 @@
+/*
+ * Licensed to Metamarkets Group Inc. (Metamarkets) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. Metamarkets 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 io.druid.client;
+
+import com.google.common.collect.Lists;
+import io.druid.client.selector.ServerSelector;
+import io.druid.query.DataSource;
+import io.druid.query.LocatedSegmentDescriptor;
+import io.druid.query.SegmentDescriptor;
+import io.druid.query.TableDataSource;
+import io.druid.server.coordination.DruidServerMetadata;
+import io.druid.timeline.TimelineLookup;
+import io.druid.timeline.TimelineObjectHolder;
+import io.druid.timeline.partition.PartitionChunk;
+import org.joda.time.Interval;
+
+import java.util.Collections;
+import java.util.List;
+
+/**
+ */
+public class ServerViewUtil
+{
+  public static List<LocatedSegmentDescriptor> getTargetLocations(
+      TimelineServerView serverView,
+      String datasource,
+      List<Interval> intervals,
+      int numCandidates
+  )
+  {
+    return getTargetLocations(serverView, new TableDataSource(datasource), intervals, numCandidates);
+  }
+
+  public static List<LocatedSegmentDescriptor> getTargetLocations(
+      TimelineServerView serverView,
+      DataSource datasource,
+      List<Interval> intervals,
+      int numCandidates
+  )
+  {
+    TimelineLookup<String, ServerSelector> timeline = serverView.getTimeline(datasource);
+    if (timeline == null) {
+      return Collections.emptyList();
+    }
+    List<LocatedSegmentDescriptor> located = Lists.newArrayList();
+    for (Interval interval : intervals) {
+      for (TimelineObjectHolder<String, ServerSelector> holder : timeline.lookup(interval)) {
+        for (PartitionChunk<ServerSelector> chunk : holder.getObject()) {
+          ServerSelector selector = chunk.getObject();
+          final SegmentDescriptor descriptor = new SegmentDescriptor(
+              holder.getInterval(), holder.getVersion(), chunk.getChunkNumber()
+          );
+          long size = selector.getSegment().getSize();
+          List<DruidServerMetadata> candidates = selector.getCandidates(numCandidates);
+          located.add(new LocatedSegmentDescriptor(descriptor, size, candidates));
+        }
+      }
+    }
+    return located;
+  }
+}

server/src/main/java/io/druid/client/selector/QueryableDruidServer.java

@@ -44,4 +44,13 @@ public class QueryableDruidServer
   {
     return client;
   }
+
+  @Override
+  public String toString()
+  {
+    return "QueryableDruidServer{" +
+           "server=" + server +
+           ", client=" + client +
+           '}';
+  }
 }

server/src/main/java/io/druid/client/selector/ServerSelector.java

@@ -19,10 +19,15 @@
 
 package io.druid.client.selector;
 
+import com.google.common.collect.Lists;
+import com.google.common.collect.Maps;
 import com.google.common.collect.Sets;
 import com.metamx.emitter.EmittingLogger;
+import io.druid.server.coordination.DruidServerMetadata;
 import io.druid.timeline.DataSegment;
 
+import java.util.List;
+import java.util.Map;
 import java.util.Set;
 import java.util.TreeMap;
 import java.util.concurrent.atomic.AtomicReference;
@@ -78,20 +83,49 @@ public class ServerSelector implements DiscoverySelector<QueryableDruidServer>
     }
   }
 
+  public List<DruidServerMetadata> getCandidates(final int numCandidates) {
+    List<DruidServerMetadata> result = Lists.newArrayList();
+    synchronized (this) {
+      final DataSegment target = segment.get();
+      for (Map.Entry<Integer, Set<QueryableDruidServer>> entry : toPrioritizedServers().entrySet()) {
+        Set<QueryableDruidServer> servers = entry.getValue();
+        TreeMap<Integer, Set<QueryableDruidServer>> tieredMap = Maps.newTreeMap();
+        while (!servers.isEmpty()) {
+          tieredMap.put(entry.getKey(), servers);   // strategy.pick() removes entry
+          QueryableDruidServer server = strategy.pick(tieredMap, target);
+          if (server == null) {
+            // regard this as any server in tieredMap is not appropriate
+            break;
+          }
+          result.add(server.getServer().getMetadata());
+          if (numCandidates > 0 && result.size() >= numCandidates) {
+            return result;
+          }
+          servers.remove(server);
+        }
+      }
+    }
+    return result;
+  }
+
   public QueryableDruidServer pick()
   {
     synchronized (this) {
-      final TreeMap<Integer, Set<QueryableDruidServer>> prioritizedServers = new TreeMap<>(strategy.getComparator());
-      for (QueryableDruidServer server : servers) {
-        Set<QueryableDruidServer> theServers = prioritizedServers.get(server.getServer().getPriority());
-        if (theServers == null) {
-          theServers = Sets.newHashSet();
-          prioritizedServers.put(server.getServer().getPriority(), theServers);
-        }
-        theServers.add(server);
-      }
-
-      return strategy.pick(prioritizedServers, segment.get());
+      return strategy.pick(toPrioritizedServers(), segment.get());
     }
   }
+
+  private TreeMap<Integer, Set<QueryableDruidServer>> toPrioritizedServers()
+  {
+    final TreeMap<Integer, Set<QueryableDruidServer>> prioritizedServers = new TreeMap<>(strategy.getComparator());
+    for (QueryableDruidServer server : servers) {
+      Set<QueryableDruidServer> theServers = prioritizedServers.get(server.getServer().getPriority());
+      if (theServers == null) {
+        theServers = Sets.newHashSet();
+        prioritizedServers.put(server.getServer().getPriority(), theServers);
+      }
+      theServers.add(server);
+    }
+    return prioritizedServers;
+  }
 }

server/src/main/java/io/druid/query/LocatedSegmentDescriptor.java

@@ -0,0 +1,134 @@
+/*
+* Licensed to Metamarkets Group Inc. (Metamarkets) under one
+* or more contributor license agreements. See the NOTICE file
+* distributed with this work for additional information
+* regarding copyright ownership. Metamarkets 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 io.druid.query;
+
+import com.fasterxml.jackson.annotation.JsonCreator;
+import com.fasterxml.jackson.annotation.JsonProperty;
+import com.google.common.collect.ImmutableList;
+import io.druid.server.coordination.DruidServerMetadata;
+import org.joda.time.Interval;
+
+import java.util.List;
+import java.util.Objects;
+
+/**
+ * public, evolving
+ * <p/>
+ * extended version of SegmentDescriptor, which is internal class, with location and size information attached
+ */
+public class LocatedSegmentDescriptor
+{
+  private final Interval interval;
+  private final String version;
+  private final int partitionNumber;
+  private final long size;
+  private final List<DruidServerMetadata> locations;
+
+  @JsonCreator
+  public LocatedSegmentDescriptor(
+      @JsonProperty("interval") Interval interval,
+      @JsonProperty("version") String version,
+      @JsonProperty("partitionNumber") int partitionNumber,
+      @JsonProperty("size") long size,
+      @JsonProperty("locations") List<DruidServerMetadata> locations
+  )
+  {
+    this.interval = interval;
+    this.version = version;
+    this.partitionNumber = partitionNumber;
+    this.size = size;
+    this.locations = locations == null ? ImmutableList.<DruidServerMetadata>of() : locations;
+  }
+
+  public LocatedSegmentDescriptor(SegmentDescriptor descriptor, long size, List<DruidServerMetadata> candidates)
+  {
+    this(descriptor.getInterval(), descriptor.getVersion(), descriptor.getPartitionNumber(), size, candidates);
+  }
+
+  @JsonProperty("interval")
+  public Interval getInterval()
+  {
+    return interval;
+  }
+
+  @JsonProperty("version")
+  public String getVersion()
+  {
+    return version;
+  }
+
+  @JsonProperty("partitionNumber")
+  public int getPartitionNumber()
+  {
+    return partitionNumber;
+  }
+
+  @JsonProperty("size")
+  public long getSize()
+  {
+    return size;
+  }
+
+  @JsonProperty("locations")
+  public List<DruidServerMetadata> getLocations()
+  {
+    return locations;
+  }
+
+  @Override
+  public boolean equals(Object o)
+  {
+    if (!(o instanceof LocatedSegmentDescriptor)) {
+      return false;
+    }
+
+    LocatedSegmentDescriptor other = (LocatedSegmentDescriptor) o;
+
+    if (partitionNumber != other.partitionNumber) {
+      return false;
+    }
+    if (!Objects.equals(interval, other.interval)) {
+      return false;
+    }
+    if (!Objects.equals(version, other.version)) {
+      return false;
+    }
+
+    return true;
+  }
+
+  @Override
+  public int hashCode()
+  {
+    return Objects.hash(partitionNumber, interval, version);
+  }
+
+  @Override
+  public String toString()
+  {
+    return "LocatedSegmentDescriptor{" +
+           "interval=" + interval +
+           ", version='" + version + '\'' +
+           ", partitionNumber=" + partitionNumber +
+           ", size=" + size +
+           ", locations=" + locations +
+           '}';
+  }
+}

server/src/main/java/io/druid/server/BrokerQueryResource.java

@@ -0,0 +1,102 @@
+/*
+* Licensed to Metamarkets Group Inc. (Metamarkets) under one
+* or more contributor license agreements. See the NOTICE file
+* distributed with this work for additional information
+* regarding copyright ownership. Metamarkets 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 io.druid.server;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.jaxrs.smile.SmileMediaTypes;
+import com.google.inject.Inject;
+import com.metamx.emitter.service.ServiceEmitter;
+import io.druid.client.ServerViewUtil;
+import io.druid.client.TimelineServerView;
+import io.druid.guice.annotations.Json;
+import io.druid.guice.annotations.Smile;
+import io.druid.query.Query;
+import io.druid.query.QuerySegmentWalker;
+import io.druid.query.QueryToolChestWarehouse;
+import io.druid.server.initialization.ServerConfig;
+import io.druid.server.log.RequestLogger;
+import io.druid.server.security.AuthConfig;
+
+import javax.servlet.http.HttpServletRequest;
+import javax.ws.rs.Consumes;
+import javax.ws.rs.DefaultValue;
+import javax.ws.rs.POST;
+import javax.ws.rs.Path;
+import javax.ws.rs.Produces;
+import javax.ws.rs.QueryParam;
+import javax.ws.rs.core.Context;
+import javax.ws.rs.core.MediaType;
+import javax.ws.rs.core.Response;
+import java.io.IOException;
+import java.io.InputStream;
+
+/**
+ */
+@Path("/druid/v2/")
+public class BrokerQueryResource extends QueryResource
+{
+  private final TimelineServerView brokerServerView;
+
+  @Inject
+  public BrokerQueryResource(
+      QueryToolChestWarehouse warehouse,
+      ServerConfig config,
+      @Json ObjectMapper jsonMapper,
+      @Smile ObjectMapper smileMapper,
+      QuerySegmentWalker texasRanger,
+      ServiceEmitter emitter,
+      RequestLogger requestLogger,
+      QueryManager queryManager,
+      AuthConfig authConfig,
+      TimelineServerView brokerServerView
+  )
+  {
+    super(warehouse, config, jsonMapper, smileMapper, texasRanger, emitter, requestLogger, queryManager, authConfig);
+    this.brokerServerView = brokerServerView;
+  }
+
+  @POST
+  @Path("/candidates")
+  @Produces({MediaType.APPLICATION_JSON, SmileMediaTypes.APPLICATION_JACKSON_SMILE})
+  @Consumes({MediaType.APPLICATION_JSON, SmileMediaTypes.APPLICATION_JACKSON_SMILE, APPLICATION_SMILE})
+  public Response getQueryTargets(
+      InputStream in,
+      @QueryParam("pretty") String pretty,
+      @QueryParam("numCandidates") @DefaultValue("-1") int numCandidates,
+      @Context final HttpServletRequest req
+  ) throws IOException
+  {
+    final ResponseContext context = createContext(req.getContentType(), pretty != null);
+    try {
+      Query<?> query = context.getObjectMapper().readValue(in, Query.class);
+      return context.ok(
+          ServerViewUtil.getTargetLocations(
+              brokerServerView,
+              query.getDataSource(),
+              query.getIntervals(),
+              numCandidates
+          )
+      );
+    }
+    catch (Exception e) {
+      return context.gotError(e);
+    }
+  }
+}

server/src/main/java/io/druid/server/ClientInfoResource.java

@@ -33,9 +33,11 @@ import com.sun.jersey.spi.container.ResourceFilters;
 import io.druid.client.DruidDataSource;
 import io.druid.client.DruidServer;
 import io.druid.client.FilteredServerInventoryView;
-import io.druid.client.InventoryView;
+import io.druid.client.ServerViewUtil;
 import io.druid.client.TimelineServerView;
 import io.druid.client.selector.ServerSelector;
+import io.druid.common.utils.JodaUtils;
+import io.druid.query.LocatedSegmentDescriptor;
 import io.druid.query.TableDataSource;
 import io.druid.query.metadata.SegmentMetadataQueryConfig;
 import io.druid.server.http.security.DatasourceResourceFilter;
@@ -53,6 +55,7 @@ import org.joda.time.DateTime;
 import org.joda.time.Interval;
 
 import javax.servlet.http.HttpServletRequest;
+import javax.ws.rs.DefaultValue;
 import javax.ws.rs.GET;
 import javax.ws.rs.Path;
 import javax.ws.rs.PathParam;
@@ -60,6 +63,7 @@ import javax.ws.rs.Produces;
 import javax.ws.rs.QueryParam;
 import javax.ws.rs.core.Context;
 import javax.ws.rs.core.MediaType;
+import java.io.IOException;
 import java.util.Collections;
 import java.util.Comparator;
 import java.util.HashMap;
@@ -300,6 +304,25 @@ public class ClientInfoResource
     return metrics;
   }
 
+  @GET
+  @Path("/{dataSourceName}/candidates")
+  @Produces(MediaType.APPLICATION_JSON)
+  @ResourceFilters(DatasourceResourceFilter.class)
+  public Iterable<LocatedSegmentDescriptor> getQueryTargets(
+      @PathParam("dataSourceName") String datasource,
+      @QueryParam("intervals") String intervals,
+      @QueryParam("numCandidates") @DefaultValue("-1") int numCandidates,
+      @Context final HttpServletRequest req
+  ) throws IOException
+  {
+    List<Interval> intervalList = Lists.newArrayList();
+    for (String interval : intervals.split(",")) {
+      intervalList.add(Interval.parse(interval.trim()));
+    }
+    List<Interval> condensed = JodaUtils.condenseIntervals(intervalList);
+    return ServerViewUtil.getTargetLocations(timelineServerView, datasource, condensed, numCandidates);
+  }
+
   protected DateTime getCurrentTime()
   {
     return new DateTime();

server/src/main/java/io/druid/server/QueryResource.java

@@ -79,21 +79,21 @@ import java.util.UUID;
 @Path("/druid/v2/")
 public class QueryResource
 {
-  private static final EmittingLogger log = new EmittingLogger(QueryResource.class);
+  protected static final EmittingLogger log = new EmittingLogger(QueryResource.class);
   @Deprecated // use SmileMediaTypes.APPLICATION_JACKSON_SMILE
-  private static final String APPLICATION_SMILE = "application/smile";
+  protected static final String APPLICATION_SMILE = "application/smile";
 
-  private static final int RESPONSE_CTX_HEADER_LEN_LIMIT = 7 * 1024;
+  protected static final int RESPONSE_CTX_HEADER_LEN_LIMIT = 7 * 1024;
 
-  private final QueryToolChestWarehouse warehouse;
-  private final ServerConfig config;
-  private final ObjectMapper jsonMapper;
-  private final ObjectMapper smileMapper;
-  private final QuerySegmentWalker texasRanger;
-  private final ServiceEmitter emitter;
-  private final RequestLogger requestLogger;
-  private final QueryManager queryManager;
-  private final AuthConfig authConfig;
+  protected final QueryToolChestWarehouse warehouse;
+  protected final ServerConfig config;
+  protected final ObjectMapper jsonMapper;
+  protected final ObjectMapper smileMapper;
+  protected final QuerySegmentWalker texasRanger;
+  protected final ServiceEmitter emitter;
+  protected final RequestLogger requestLogger;
+  protected final QueryManager queryManager;
+  protected final AuthConfig authConfig;
 
   @Inject
   public QueryResource(
@@ -167,19 +167,11 @@ public class QueryResource
     QueryToolChest toolChest = null;
     String queryId = null;
 
-    final String reqContentType = req.getContentType();
-    final boolean isSmile = SmileMediaTypes.APPLICATION_JACKSON_SMILE.equals(reqContentType)
-                            || APPLICATION_SMILE.equals(reqContentType);
-    final String contentType = isSmile ? SmileMediaTypes.APPLICATION_JACKSON_SMILE : MediaType.APPLICATION_JSON;
-
-    ObjectMapper objectMapper = isSmile ? smileMapper : jsonMapper;
-    final ObjectWriter jsonWriter = pretty != null
-                                    ? objectMapper.writerWithDefaultPrettyPrinter()
-                                    : objectMapper.writer();
+    final ResponseContext context = createContext(req.getContentType(), pretty != null);
 
     final String currThreadName = Thread.currentThread().getName();
     try {
-      query = objectMapper.readValue(in, Query.class);
+      query = context.getObjectMapper().readValue(in, Query.class);
       queryId = query.getId();
       if (queryId == null) {
         queryId = UUID.randomUUID().toString();
@@ -244,6 +236,7 @@ public class QueryResource
       try {
         final Query theQuery = query;
         final QueryToolChest theToolChest = toolChest;
+        final ObjectWriter jsonWriter = context.newOutputWriter();
         Response.ResponseBuilder builder = Response
             .ok(
                 new StreamingOutput()
@@ -285,7 +278,7 @@ public class QueryResource
                     );
                   }
                 },
-                contentType
+                context.getContentType()
             )
             .header("X-Druid-Query-Id", queryId);
 
@@ -344,9 +337,7 @@ public class QueryResource
       catch (Exception e2) {
         log.error(e2, "Unable to log query [%s]!", query);
       }
-      return Response.serverError().type(contentType).entity(
-          jsonWriter.writeValueAsBytes(new QueryInterruptedException(e))
-      ).build();
+      return context.gotError(e);
     }
     catch (Exception e) {
       // Input stream has already been consumed by the json object mapper if query == null
@@ -390,12 +381,60 @@ public class QueryResource
          .addData("peer", req.getRemoteAddr())
          .emit();
 
-      return Response.serverError().type(contentType).entity(
-          jsonWriter.writeValueAsBytes(new QueryInterruptedException(e))
-      ).build();
+      return context.gotError(e);
     }
     finally {
       Thread.currentThread().setName(currThreadName);
     }
   }
+
+  protected ResponseContext createContext(String requestType, boolean pretty)
+  {
+    boolean isSmile = SmileMediaTypes.APPLICATION_JACKSON_SMILE.equals(requestType) ||
+                      APPLICATION_SMILE.equals(requestType);
+    String contentType = isSmile ? SmileMediaTypes.APPLICATION_JACKSON_SMILE : MediaType.APPLICATION_JSON;
+    return new ResponseContext(contentType, isSmile ? smileMapper : jsonMapper, pretty);
+  }
+
+  protected static class ResponseContext
+  {
+    private final String contentType;
+    private final ObjectMapper inputMapper;
+    private final boolean isPretty;
+
+    ResponseContext(String contentType, ObjectMapper inputMapper, boolean isPretty)
+    {
+      this.contentType = contentType;
+      this.inputMapper = inputMapper;
+      this.isPretty = isPretty;
+    }
+
+    String getContentType()
+    {
+      return contentType;
+    }
+
+    public ObjectMapper getObjectMapper()
+    {
+      return inputMapper;
+    }
+
+    ObjectWriter newOutputWriter()
+    {
+      return isPretty ? inputMapper.writerWithDefaultPrettyPrinter() : inputMapper.writer();
+    }
+
+    Response ok(Object object) throws IOException
+    {
+      return Response.ok(newOutputWriter().writeValueAsString(object), contentType).build();
+    }
+
+    Response gotError(Exception e) throws IOException
+    {
+      return Response.serverError()
+                     .type(contentType)
+                     .entity(newOutputWriter().writeValueAsBytes(QueryInterruptedException.wrapIfNeeded(e)))
+                     .build();
+    }
+  }
 }

server/src/test/java/io/druid/client/selector/TierSelectorStrategyTest.java

@@ -22,6 +22,7 @@ package io.druid.client.selector;
 import com.google.common.collect.Lists;
 import io.druid.client.DirectDruidClient;
 import io.druid.client.DruidServer;
+import io.druid.server.coordination.DruidServerMetadata;
 import io.druid.timeline.DataSegment;
 import io.druid.timeline.partition.NoneShardSpec;
 import org.easymock.EasyMock;
@@ -31,6 +32,7 @@ import org.junit.Assert;
 import org.junit.Test;
 
 import java.util.Arrays;
+import java.util.Collections;
 import java.util.List;
 
 public class TierSelectorStrategyTest
@@ -51,8 +53,7 @@ public class TierSelectorStrategyTest
 
     testTierSelectorStrategy(
         new HighestPriorityTierSelectorStrategy(new ConnectionCountServerSelectorStrategy()),
-        Arrays.asList(lowPriority, highPriority),
-        highPriority
+        highPriority, lowPriority
     );
   }
 
@@ -71,8 +72,7 @@ public class TierSelectorStrategyTest
 
     testTierSelectorStrategy(
         new LowestPriorityTierSelectorStrategy(new ConnectionCountServerSelectorStrategy()),
-        Arrays.asList(lowPriority, highPriority),
-        lowPriority
+        lowPriority, highPriority
     );
   }
 
@@ -104,15 +104,13 @@ public class TierSelectorStrategyTest
           }
         }
         ),
-        Arrays.asList(lowPriority, mediumPriority, highPriority),
-        mediumPriority
+        mediumPriority, lowPriority, highPriority
     );
   }
 
   private void testTierSelectorStrategy(
       TierSelectorStrategy tierSelectorStrategy,
-      List<QueryableDruidServer> servers,
-      QueryableDruidServer expectedSelection
+      QueryableDruidServer... expectedSelection
   )
   {
     final ServerSelector serverSelector = new ServerSelector(
@@ -129,10 +127,21 @@ public class TierSelectorStrategyTest
         ),
         tierSelectorStrategy
     );
+
+    List<QueryableDruidServer> servers = Lists.newArrayList(expectedSelection);
+
+    List<DruidServerMetadata> expectedCandidates = Lists.newArrayList();
+    for (QueryableDruidServer server : servers) {
+      expectedCandidates.add(server.getServer().getMetadata());
+    }
+    Collections.shuffle(servers);
     for (QueryableDruidServer server : servers) {
       serverSelector.addServerAndUpdateSegment(server, serverSelector.getSegment());
     }
-    Assert.assertEquals(expectedSelection, serverSelector.pick());
+
+    Assert.assertEquals(expectedSelection[0], serverSelector.pick());
+    Assert.assertEquals(expectedCandidates, serverSelector.getCandidates(-1));
+    Assert.assertEquals(expectedCandidates.subList(0, 2), serverSelector.getCandidates(2));
   }
 
 }

server/src/test/java/io/druid/query/LocatedSegmentDescriptorSerdeTest.java

@@ -0,0 +1,57 @@
+/*
+ * Licensed to Metamarkets Group Inc. (Metamarkets) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. Metamarkets 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 io.druid.query;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import io.druid.jackson.DefaultObjectMapper;
+import io.druid.server.coordination.DruidServerMetadata;
+import org.joda.time.Interval;
+import org.junit.Assert;
+import org.junit.Test;
+
+import java.util.Arrays;
+
+/**
+ */
+public class LocatedSegmentDescriptorSerdeTest
+{
+  private final ObjectMapper mapper = new DefaultObjectMapper();
+
+  @Test
+  public void testDimensionsSpecSerde() throws Exception
+  {
+    LocatedSegmentDescriptor expected = new LocatedSegmentDescriptor(
+        new SegmentDescriptor(new Interval(100, 200), "version", 100),
+        65535,
+        Arrays.asList(
+            new DruidServerMetadata("server1", "host1", 30000L, "historical", "tier1", 0),
+            new DruidServerMetadata("server2", "host2", 40000L, "historical", "tier1", 1),
+            new DruidServerMetadata("server3", "host3", 50000L, "realtime", "tier2", 2)
+        )
+    );
+
+    LocatedSegmentDescriptor actual = mapper.readValue(
+        mapper.writeValueAsString(expected),
+        LocatedSegmentDescriptor.class
+    );
+
+    Assert.assertEquals(expected, actual);
+  }
+}

services/src/main/java/io/druid/cli/CliBroker.java

@@ -44,9 +44,9 @@ import io.druid.query.QuerySegmentWalker;
 import io.druid.query.QueryToolChestWarehouse;
 import io.druid.query.RetryQueryRunnerConfig;
 import io.druid.query.lookup.LookupModule;
+import io.druid.server.BrokerQueryResource;
 import io.druid.server.ClientInfoResource;
 import io.druid.server.ClientQuerySegmentWalker;
-import io.druid.server.QueryResource;
 import io.druid.server.coordination.broker.DruidBroker;
 import io.druid.server.http.BrokerResource;
 import io.druid.server.initialization.jetty.JettyServerInitializer;
@@ -101,10 +101,10 @@ public class CliBroker extends ServerRunnable
             binder.bind(QuerySegmentWalker.class).to(ClientQuerySegmentWalker.class).in(LazySingleton.class);
 
             binder.bind(JettyServerInitializer.class).to(QueryJettyServerInitializer.class).in(LazySingleton.class);
-            Jerseys.addResource(binder, QueryResource.class);
+            Jerseys.addResource(binder, BrokerQueryResource.class);
             Jerseys.addResource(binder, BrokerResource.class);
             Jerseys.addResource(binder, ClientInfoResource.class);
-            LifecycleModule.register(binder, QueryResource.class);
+            LifecycleModule.register(binder, BrokerQueryResource.class);
             LifecycleModule.register(binder, DruidBroker.class);
 
             MetricsModule.register(binder, CacheMonitor.class);