Added touch operation

Added an operation to reset the expiration time of a key. I have
tested this code thoughly and will check in the unit tests in a
later commit.

Change-Id: Iee3045bdb58142dd44c9e8c723dffe7abdbcb230
Reviewed-on: http://review.couchbase.org/6753
Tested-by: Michael Wiederhold <mike@couchbase.com>
Reviewed-by: Matt Ingenthron <matt@couchbase.com>

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

@@ -342,6 +342,50 @@ public void complete() {
 		return rv;
 	}
 
+	/**
+	 * Touch the given key to reset its expiration time with the default
+	 * transcoder.
+	 *
+	 * @param key the key to fetch
+	 * @param exp the new expiration to set for the given key
+	 * @return a future that will hold the return value of whether or not
+	 * the fetch succeeded
+	 * @throws IllegalStateException in the rare circumstance where queue
+	 *         is too full to accept any more requests
+	 */
+	public <T> Future<Boolean> touch(final String key, final int exp) {
+		return touch(key, exp, transcoder);
+	}
+
+	/**
+	 * Touch the given key to reset its expiration time.
+	 *
+	 * @param key the key to fetch
+	 * @param exp the new expiration to set for the given key
+	 * @param tc the transcoder to serialize and unserialize value
+	 * @return a future that will hold the return value of whether or not
+	 * the fetch succeeded
+	 * @throws IllegalStateException in the rare circumstance where queue
+	 *         is too full to accept any more requests
+	 */
+	public <T> Future<Boolean> touch(final String key, final int exp,
+			final Transcoder<T> tc) {
+		final CountDownLatch latch=new CountDownLatch(1);
+		final OperationFuture<Boolean> rv=new OperationFuture<Boolean>(latch,
+				operationTimeout);
+
+		Operation op=opFact.touch(key, exp, new OperationCallback() {
+			public void receivedStatus(OperationStatus status) {
+				rv.set(status.isSuccess());
+		}
+			public void complete() {
+				latch.countDown();
+			}});
+		rv.setOperation(op);
+		addOp(key, op);
+		return rv;
+	}
+
 	/**
 	 * Append to an existing value in the cache.
 	 *

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

@@ -122,6 +122,15 @@ MutatorOperation mutate(Mutator m, String key, int by,
 	StoreOperation store(StoreType storeType, String key, int flags, int exp,
 			byte[] data, OperationCallback cb);
 
+	/**
+	 * Resets a keys expiration time
+	 * @param key The key whose expiration time is to be reset.
+	 * @param expiration The new expiration time for the key
+	 * @param cb The status callback
+	 * @return A touch operation
+	 */
+	KeyedOperation touch(String key, int expiration, OperationCallback cb);
+
 	/**
 	 * Get a concatenation operation.
 	 *

src/main/java/net/spy/memcached/protocol/ascii/AsciiOperationFactory.java

@@ -68,6 +68,11 @@ public StoreOperation store(StoreType storeType, String key, int flags,
 		return new StoreOperationImpl(storeType, key, flags, exp, data, cb);
 	}
 
+	public KeyedOperation touch(String key, int expiration, OperationCallback cb) {
+		throw new UnsupportedOperationException("Touch is only supported in" +
+				" the binary protocol");
+	}
+
 	public VersionOperation version(OperationCallback cb) {
 		return new VersionOperationImpl(cb);
 	}

src/main/java/net/spy/memcached/protocol/binary/BinaryOperationFactory.java

@@ -72,6 +72,10 @@ public StoreOperation store(StoreType storeType, String key, int flags,
 		return new StoreOperationImpl(storeType, key, flags, exp, data, 0, cb);
 	}
 
+	public KeyedOperation touch(String key, int expiration, OperationCallback cb) {
+		return new TouchOperationImpl(key, expiration, cb);
+	}
+
 	public VersionOperation version(OperationCallback cb) {
 		return new VersionOperationImpl(cb);
 	}

src/main/java/net/spy/memcached/protocol/binary/TouchOperationImpl.java

@@ -0,0 +1,58 @@
+package net.spy.memcached.protocol.binary;
+
+import java.util.Collection;
+import java.util.Collections;
+
+import net.spy.memcached.ops.KeyedOperation;
+import net.spy.memcached.ops.OperationCallback;
+import net.spy.memcached.ops.OperationStatus;
+
+/**
+ * Operation to reset a timeout in Membase server.
+ */
+public class TouchOperationImpl extends OperationImpl
+	implements KeyedOperation {
+
+	static final int CMD=28;
+
+	private final String key;
+	private final int exp;
+
+	protected TouchOperationImpl(String k, int e, OperationCallback cb) {
+		super(CMD, generateOpaque(), cb);
+		key=k;
+		exp=e;
+	}
+
+	@Override
+	public Collection<String> getKeys() {
+		return Collections.singleton(key);
+	}
+
+	@Override
+	protected OperationStatus getStatusForErrorCode(int errCode, byte[] errPl) {
+        OperationStatus baseStatus = super.getStatusForErrorCode(errCode, errPl);
+        if (baseStatus != null) {
+            return baseStatus;
+        }
+		OperationStatus rv=null;
+		switch(errCode) {
+			case ERR_EXISTS:
+				rv=EXISTS_STATUS;
+				break;
+			case ERR_NOT_FOUND:
+				rv=NOT_FOUND_STATUS;
+				break;
+			case ERR_TEMP_FAIL:
+				rv=TEMP_FAIL;
+				break;
+		}
+		return rv;
+	}
+
+	@Override
+	public void initialize() {
+		prepareBuffer(key, 0, EMPTY_BYTES, exp);
+	}
+
+}