SPY-8: Added a limit on how many gets can be optimized

We have a limit on the amount of sets that can be optimized so we
should have a limit on how many gets can be optimized as well. This
way people don't run into any issues with optimizing too many get
requests and having the client timeout as a result of the server
being too slow trying to fill all of the requests in the multi-
get.

The max number of gets that can be optimized into a single
request is 4096.

Change-Id: I23c107ca3459e3386270c53f9ce20450d7ee8830
Reviewed-on: http://review.couchbase.org/8599
Reviewed-by: Matt Ingenthron <matt@couchbase.com>
Tested-by: Michael Wiederhold <mike@couchbase.com>

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

@@ -17,6 +17,7 @@
  */
 public class BinaryMemcachedNodeImpl extends TCPMemcachedNodeImpl {
 
+	private final int MAX_GET_OPTIMIZATION_COUNT = 4096;
 	private final int MAX_SET_OPTIMIZATION_COUNT = 65535;
 	private final int MAX_SET_OPTIMIZATION_BYTES = 2 * 1024 * 1024;
 
@@ -47,7 +48,8 @@ private void optimizeGets() {
 					(GetOperation)optimizedOp);
 			optimizedOp=og;
 
-			while(writeQ.peek() instanceof GetOperation) {
+			while(writeQ.peek() instanceof GetOperation
+					&& og.size() < MAX_GET_OPTIMIZATION_COUNT) {
 				GetOperation o=(GetOperation) writeQ.remove();
 				if(!o.isCancelled()) {
 					og.addOperation(o);

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

@@ -33,4 +33,8 @@ public void addOperation(GetOperation o) {
 		}
 	}
 
+	public int size() {
+		return pcb.numKeys();
+	}
+
 }