FEATURE: Add TCP connection keep-alive option.

src/main/java/net/spy/memcached/ConnectionFactory.java

@@ -107,6 +107,15 @@ MemcachedNode createMemcachedNode(String name,
    */
   boolean useNagleAlgorithm();
 
+  /**
+   * If true, keep alive will be used on connected sockets.
+   *
+   * <p>
+   * See {@link java.net.Socket#setKeepAlive(boolean)} for more information.
+   * </p>
+   */
+  boolean getKeepAlive();
+
   /**
    * Observers that should be established at the time of connection
    * instantiation.

src/main/java/net/spy/memcached/ConnectionFactoryBuilder.java

@@ -59,6 +59,7 @@ public class ConnectionFactoryBuilder {
   private boolean isDaemon = true;
   private boolean shouldOptimize = false;
   private boolean useNagle = false;
+  private boolean keepAlive = false;
   //private long maxReconnectDelay =
   //DefaultConnectionFactory.DEFAULT_MAX_RECONNECT_DELAY;
   private long maxReconnectDelay = 1;
@@ -467,6 +468,9 @@ public Map<APIType, ReadPriority> getAPIReadPriority() {
   }
   /* ENABLE_REPLICATION end */
 
+  public void setKeepAlive(boolean on) {
+    keepAlive = on;
+  }
   /**
    * Get the ConnectionFactory set up with the provided parameters.
    */
@@ -591,6 +595,11 @@ public boolean useNagleAlgorithm() {
         return useNagle;
       }
 
+      @Override
+      public boolean getKeepAlive() {
+        return keepAlive;
+      }
+
       @Override
       public long getMaxReconnectDelay() {
         return maxReconnectDelay;

src/main/java/net/spy/memcached/DefaultConnectionFactory.java

@@ -318,7 +318,10 @@ public Transcoder<Object> getDefaultCollectionTranscoder() {
   public boolean useNagleAlgorithm() {
     return false;
   }
-
+  @Override
+  public boolean getKeepAlive() {
+    return false;
+  }
   public boolean shouldOptimize() {
     return true;
   }

src/main/java/net/spy/memcached/MemcachedConnection.java

@@ -630,6 +630,7 @@ private MemcachedNode makeMemcachedNode(String name,
     SocketChannel ch = SocketChannel.open();
     ch.configureBlocking(false);
     ch.socket().setTcpNoDelay(!connFactory.useNagleAlgorithm());
+    ch.socket().setKeepAlive(connFactory.getKeepAlive());
     ch.socket().setReuseAddress(true);
     /* The codes above can be replaced by the codes below since java 1.7 */
     // ch.setOption(StandardSocketOptions.TCP_NODELAY, !f.useNagleAlgorithm());
@@ -1307,6 +1308,7 @@ private void attemptReconnects() {
         ch = SocketChannel.open();
         ch.configureBlocking(false);
         ch.socket().setTcpNoDelay(!connFactory.useNagleAlgorithm());
+        ch.socket().setKeepAlive(connFactory.getKeepAlive());
         ch.socket().setReuseAddress(true);
         /* The codes above can be replaced by the codes below since java 1.7 */
         // ch.setOption(StandardSocketOptions.TCP_NODELAY, !f.useNagleAlgorithm());

src/test/java/net/spy/memcached/ClientBaseCase.java

@@ -152,6 +152,11 @@ public boolean useNagleAlgorithm() {
           return inner.useNagleAlgorithm();
         }
 
+        @Override
+        public boolean getKeepAlive() {
+          return inner.getKeepAlive();
+        }
+
         @Override
         public Collection<ConnectionObserver> getInitialObservers() {
           return observers;