enable snappy compression for memcached results

client/pom.xml

@@ -181,6 +181,10 @@
             <groupId>com.metamx</groupId>
             <artifactId>bytebuffer-collections</artifactId>
         </dependency>
+        <dependency>
+          <groupId>org.xerial.snappy</groupId>
+          <artifactId>snappy-java</artifactId>
+        </dependency>
 
         <!-- Tests -->
         <dependency>

client/src/main/java/com/metamx/druid/client/cache/MemcachedCache.java

@@ -53,9 +53,10 @@ public class MemcachedCache implements Cache
   public static MemcachedCache create(final MemcachedCacheConfig config)
   {
     try {
-      SerializingTranscoder transcoder = new SerializingTranscoder(config.getMaxObjectSize());
+      SnappyTranscoder transcoder = new SnappyTranscoder(config.getMaxObjectSize());
-      // disable compression
+
-      transcoder.setCompressionThreshold(Integer.MAX_VALUE);
+      // always use compression
+      transcoder.setCompressionThreshold(0);
 
       return new MemcachedCache(
         new MemcachedClient(

client/src/main/java/com/metamx/druid/client/cache/SnappyTranscoder.java

@@ -0,0 +1,50 @@
+package com.metamx.druid.client.cache;
+
+import net.spy.memcached.transcoders.SerializingTranscoder;
+import org.xerial.snappy.Snappy;
+
+import java.io.IOException;
+
+public class SnappyTranscoder extends SerializingTranscoder
+{
+  public SnappyTranscoder()
+  {
+    super();
+  }
+
+  public SnappyTranscoder(int max)
+  {
+    super(max);
+  }
+
+  @Override
+  protected byte[] compress(byte[] in)
+  {
+    if (in == null) {
+      throw new NullPointerException("Can't compress null");
+    }
+
+    byte[] out;
+    try {
+      out = Snappy.compress(in);
+    } catch(IOException e) {
+      throw new RuntimeException("IO exception compressing data", e);
+    }
+    getLogger().debug("Compressed %d bytes to %d", in.length, out.length);
+    return out;
+  }
+
+  @Override
+  protected byte[] decompress(byte[] in)
+  {
+    byte[] out = null;
+    if(in != null) {
+      try {
+        out = Snappy.uncompress(in);
+      } catch (IOException e) {
+        getLogger().warn("Failed to decompress data", e);
+      }
+    }
+    return out == null ? null : out;
+  }
+}

pom.xml

@@ -320,6 +320,12 @@
                 <artifactId>jackson-mapper-asl</artifactId>
                 <version>1.9.11</version>
             </dependency>
+            <dependency>
+                <groupId>org.xerial.snappy</groupId>
+                <artifactId>snappy-java</artifactId>
+                <version>1.0.5</version>
+            </dependency>
+
 
             <!-- Test Scope -->
             <dependency>