1) Adjust the Announcer to cleanup parent nodes that it creates. This stops it from leaving little turdlings lying around on zookeeper as nodes exit

2) Rename *CuratorDataSegmentAnnouncer because neither of them depend directly on Curator.

client/src/main/java/com/metamx/druid/QueryableNode.java

@@ -40,11 +40,11 @@ import com.metamx.druid.client.ServerInventoryViewConfig;
 import com.metamx.druid.client.ServerView;
 import com.metamx.druid.concurrent.Execs;
 import com.metamx.druid.coordination.AbstractDataSegmentAnnouncer;
-import com.metamx.druid.coordination.BatchingCuratorDataSegmentAnnouncer;
-import com.metamx.druid.coordination.CuratorDataSegmentAnnouncer;
+import com.metamx.druid.coordination.BatchingDataSegmentAnnouncer;
 import com.metamx.druid.coordination.DataSegmentAnnouncer;
 import com.metamx.druid.coordination.DruidServerMetadata;
 import com.metamx.druid.coordination.MultipleDataSegmentAnnouncerDataSegmentAnnouncer;
+import com.metamx.druid.coordination.SingleDataSegmentAnnouncer;
 import com.metamx.druid.curator.announcement.Announcer;
 import com.metamx.druid.http.NoopRequestLogger;
 import com.metamx.druid.http.RequestLogger;
@@ -431,13 +431,13 @@ public abstract class QueryableNode<T extends QueryableNode> extends Registering
       setAnnouncer(
           new MultipleDataSegmentAnnouncerDataSegmentAnnouncer(
               Arrays.<AbstractDataSegmentAnnouncer>asList(
-                  new BatchingCuratorDataSegmentAnnouncer(
+                  new BatchingDataSegmentAnnouncer(
                       getDruidServerMetadata(),
                       getConfigFactory().build(ZkDataSegmentAnnouncerConfig.class),
                       announcer,
                       getJsonMapper()
                   ),
-                  new CuratorDataSegmentAnnouncer(getDruidServerMetadata(), getZkPaths(), announcer, getJsonMapper())
+                  new SingleDataSegmentAnnouncer(getDruidServerMetadata(), getZkPaths(), announcer, getJsonMapper())
               )
           )
       );

client/src/main/java/com/metamx/druid/coordination/AbstractDataSegmentAnnouncer.java

@@ -86,7 +86,7 @@ public abstract class AbstractDataSegmentAnnouncer implements DataSegmentAnnounc
         return;
       }
 
-      log.info("Stopping CuratorDataSegmentAnnouncer with config[%s]", config);
+      log.info("Stopping %s with config[%s]", getClass(), config);
       announcer.unannounce(makeAnnouncementPath());
 
       started = false;

client/src/main/java/com/metamx/druid/coordination/BatchingDataSegmentAnnouncer.java

@@ -22,33 +22,26 @@ package com.metamx.druid.coordination;
 import com.fasterxml.jackson.core.type.TypeReference;
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.google.common.base.Throwables;
-import com.google.common.collect.Iterables;
 import com.google.common.collect.Maps;
-import com.google.common.collect.MinMaxPriorityQueue;
 import com.google.common.collect.Sets;
-import com.google.common.primitives.Ints;
 import com.metamx.common.ISE;
 import com.metamx.common.logger.Logger;
 import com.metamx.druid.client.DataSegment;
 import com.metamx.druid.curator.announcement.Announcer;
 import com.metamx.druid.initialization.ZkDataSegmentAnnouncerConfig;
-import com.metamx.druid.initialization.ZkPathsConfig;
 import org.apache.curator.utils.ZKPaths;
 import org.joda.time.DateTime;
 
 import java.io.IOException;
-import java.util.Comparator;
 import java.util.Iterator;
-import java.util.List;
 import java.util.Map;
 import java.util.Set;
-import java.util.concurrent.ConcurrentHashMap;
 
 /**
  */
-public class BatchingCuratorDataSegmentAnnouncer extends AbstractDataSegmentAnnouncer
+public class BatchingDataSegmentAnnouncer extends AbstractDataSegmentAnnouncer
 {
-  private static final Logger log = new Logger(BatchingCuratorDataSegmentAnnouncer.class);
+  private static final Logger log = new Logger(BatchingDataSegmentAnnouncer.class);
 
   private final ZkDataSegmentAnnouncerConfig config;
   private final Announcer announcer;
@@ -58,7 +51,7 @@ public class BatchingCuratorDataSegmentAnnouncer extends AbstractDataSegmentAnno
   private final Set<SegmentZNode> availableZNodes = Sets.newHashSet();
   private final Map<DataSegment, SegmentZNode> segmentLookup = Maps.newHashMap();
 
-  public BatchingCuratorDataSegmentAnnouncer(
+  public BatchingDataSegmentAnnouncer(
       DruidServerMetadata server,
       ZkDataSegmentAnnouncerConfig config,
       Announcer announcer,

client/src/main/java/com/metamx/druid/coordination/SingleDataSegmentAnnouncer.java

@@ -28,15 +28,15 @@ import org.apache.curator.utils.ZKPaths;
 
 import java.io.IOException;
 
-public class CuratorDataSegmentAnnouncer extends AbstractDataSegmentAnnouncer
+public class SingleDataSegmentAnnouncer extends AbstractDataSegmentAnnouncer
 {
-  private static final Logger log = new Logger(CuratorDataSegmentAnnouncer.class);
+  private static final Logger log = new Logger(SingleDataSegmentAnnouncer.class);
 
   private final Announcer announcer;
   private final ObjectMapper jsonMapper;
   private final String servedSegmentsLocation;
 
-  public CuratorDataSegmentAnnouncer(
+  public SingleDataSegmentAnnouncer(
       DruidServerMetadata server,
       ZkPathsConfig config,
       Announcer announcer,

client/src/main/java/com/metamx/druid/curator/announcement/Announcer.java

@@ -48,6 +48,7 @@ import java.util.List;
 import java.util.Map;
 import java.util.Set;
 import java.util.concurrent.ConcurrentMap;
+import java.util.concurrent.CopyOnWriteArrayList;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.atomic.AtomicReference;
 
@@ -64,6 +65,7 @@ public class Announcer
   private final List<Pair<String, byte[]>> toAnnounce = Lists.newArrayList();
   private final ConcurrentMap<String, PathChildrenCache> listeners = new MapMaker().makeMap();
   private final ConcurrentMap<String, ConcurrentMap<String, byte[]>> announcements = new MapMaker().makeMap();
+  private final List<String> parentsIBuilt = new CopyOnWriteArrayList<String>();
 
   private boolean started = false;
 
@@ -114,6 +116,15 @@ public class Announcer
           unannounce(ZKPaths.makePath(basePath, announcementPath));
         }
       }
+
+      for (String parent : parentsIBuilt) {
+        try {
+          curator.delete().forPath(parent);
+        }
+        catch (Exception e) {
+          log.info(e, "Unable to delete parent[%s], boooo.", parent);
+        }
+      }
     }
   }
 
@@ -136,10 +147,19 @@ public class Announcer
     final ZKPaths.PathAndNode pathAndNode = ZKPaths.getPathAndNode(path);
 
     final String parentPath = pathAndNode.getPath();
+    boolean buildParentPath = false;
 
     ConcurrentMap<String, byte[]> subPaths = announcements.get(parentPath);
 
     if (subPaths == null) {
+      try {
+        if (curator.checkExists().forPath(parentPath) == null) {
+          buildParentPath = true;
+        }
+      }
+      catch (Exception e) {
+        log.debug(e, "Problem checking if the parent existed, ignoring.");
+      }
 
       // I don't have a watcher on this path yet, create a Map and start watching.
       announcements.putIfAbsent(parentPath, new MapMaker().<String, byte[]>makeMap());
@@ -208,17 +228,15 @@ public class Announcer
               }
           );
 
-          try {
-            synchronized (toAnnounce) {
-              if (started) {
-                cache.start();
-                listeners.put(parentPath, cache);
+          synchronized (toAnnounce) {
+            if (started) {
+              if (buildParentPath) {
+                createPath(parentPath);
               }
+              startCache(cache);
+              listeners.put(parentPath, cache);
             }
           }
-          catch (Exception e) {
-            throw Throwables.propagate(e);
-          }
         }
       }
 
@@ -261,7 +279,7 @@ public class Announcer
       throw new ISE("Cannot update a path[%s] that hasn't been announced!", path);
     }
 
-    synchronized (subPaths) {
+    synchronized (toAnnounce) {
       try {
         byte[] oldBytes = subPaths.get(nodePath);
 
@@ -320,4 +338,26 @@ public class Announcer
       throw Throwables.propagate(e);
     }
   }
+
+  private void startCache(PathChildrenCache cache)
+  {
+    try {
+      cache.start();
+    }
+    catch (Exception e) {
+      Closeables.closeQuietly(cache);
+      throw Throwables.propagate(e);
+    }
+  }
+
+  private void createPath(String parentPath)
+  {
+    try {
+      curator.create().creatingParentsIfNeeded().forPath(parentPath);
+      parentsIBuilt.add(parentPath);
+    }
+    catch (Exception e) {
+      log.info(e, "Problem creating parentPath[%s], someone else created it first?", parentPath);
+    }
+  }
 }

client/src/test/java/com/metamx/druid/coordination/BatchingDataSegmentAnnouncerTest.java

@@ -47,7 +47,7 @@ import java.util.Set;
 
 /**
  */
-public class BatchingCuratorDataSegmentAnnouncerTest
+public class BatchingDataSegmentAnnouncerTest
 {
   private static final String testBasePath = "/test";
   private static final String testSegmentsPath = "/test/segments/id";
@@ -58,7 +58,7 @@ public class BatchingCuratorDataSegmentAnnouncerTest
   private ObjectMapper jsonMapper;
   private Announcer announcer;
   private SegmentReader segmentReader;
-  private BatchingCuratorDataSegmentAnnouncer segmentAnnouncer;
+  private BatchingDataSegmentAnnouncer segmentAnnouncer;
   private Set<DataSegment> testSegments;
 
   @Before
@@ -84,7 +84,7 @@ public class BatchingCuratorDataSegmentAnnouncerTest
     announcer.start();
 
     segmentReader = new SegmentReader(cf, jsonMapper);
-    segmentAnnouncer = new BatchingCuratorDataSegmentAnnouncer(
+    segmentAnnouncer = new BatchingDataSegmentAnnouncer(
         new DruidServerMetadata(
             "id",
             "host",

client/src/test/java/com/metamx/druid/curator/announcement/AnnouncerTest.java

@@ -27,6 +27,8 @@ import org.apache.curator.framework.api.CuratorEvent;
 import org.apache.curator.framework.api.CuratorEventType;
 import org.apache.curator.framework.api.CuratorListener;
 import org.apache.curator.test.KillSession;
+import org.apache.curator.utils.ZKPaths;
+import org.apache.zookeeper.data.Stat;
 import org.junit.After;
 import org.junit.Assert;
 import org.junit.Before;
@@ -60,7 +62,6 @@ public class AnnouncerTest extends CuratorTestBase
   public void testSanity() throws Exception
   {
     curator.start();
-    curator.create().forPath("/somewhere");
     Announcer announcer = new Announcer(curator, exec);
 
     final byte[] billy = "billy".getBytes();
@@ -163,4 +164,54 @@ public class AnnouncerTest extends CuratorTestBase
       announcer.stop();
     }
   }
+
+  @Test
+  public void testCleansUpItsLittleTurdlings() throws Exception
+  {
+    curator.start();
+    Announcer announcer = new Announcer(curator, exec);
+
+    final byte[] billy = "billy".getBytes();
+    final String testPath = "/somewhere/test2";
+    final String parent = ZKPaths.getPathAndNode(testPath).getPath();
+
+    announcer.start();
+
+    Assert.assertNull(curator.checkExists().forPath(parent));
+
+    announcer.announce(testPath, billy);
+
+    Assert.assertNotNull(curator.checkExists().forPath(parent));
+
+    announcer.stop();
+
+    Assert.assertNull(curator.checkExists().forPath(parent));
+  }
+
+  @Test
+  public void testLeavesBehindTurdlingsThatAlreadyExisted() throws Exception
+  {
+    curator.start();
+    Announcer announcer = new Announcer(curator, exec);
+
+    final byte[] billy = "billy".getBytes();
+    final String testPath = "/somewhere/test2";
+    final String parent = ZKPaths.getPathAndNode(testPath).getPath();
+
+    curator.create().forPath(parent);
+    final Stat initialStat = curator.checkExists().forPath(parent);
+
+    announcer.start();
+
+    Assert.assertEquals(initialStat.getMzxid(), curator.checkExists().forPath(parent).getMzxid());
+
+    announcer.announce(testPath, billy);
+
+    Assert.assertEquals(initialStat.getMzxid(), curator.checkExists().forPath(parent).getMzxid());
+
+    announcer.stop();
+
+    Assert.assertEquals(initialStat.getMzxid(), curator.checkExists().forPath(parent).getMzxid());
+  }
+
 }

server/src/test/java/com/metamx/druid/coordination/ZkCoordinatorTest.java

@@ -93,7 +93,7 @@ public class ZkCoordinatorTest extends CuratorTestBase
       }
     };
 
-    announcer = new CuratorDataSegmentAnnouncer(
+    announcer = new SingleDataSegmentAnnouncer(
         me, zkPaths, new Announcer(curator, Execs.singleThreaded("blah")), jsonMapper
     );