add BlockedHealthBalncingPolicy

core/src/main/java/me/prettyprint/cassandra/connection/BlockedHealthBalncingPolicy

@@ -0,0 +1,72 @@
+package me.prettyprint.cassandra.connection;
+
+import java.util.Collection;
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Set;
+
+import me.prettyprint.cassandra.connection.factory.HClientFactory;
+import me.prettyprint.cassandra.service.CassandraHost;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import com.google.common.collect.Lists;
+
+public class BlockedHealthBalncingPolicy implements LoadBalancingPolicy {
+
+	private static final long serialVersionUID = 4216966823555634515L;
+	private static final Logger log = LoggerFactory.getLogger(BlockedHealthBalncingPolicy.class);
+	private static final int ZERO_VALUE = 0;
+
+	private final class FilteringCompare implements Comparator<HClientPool> {
+
+		public int compare(HClientPool o1, HClientPool o2) {
+
+			if ( log.isDebugEnabled() ) {
+				log.debug("comparing 1: {} / count {} / Blocked {} / availableClientQueue {} with 2: {} / count {} / Blocked {} / availableClientQueue {} ",
+						new Object[]{o1.getCassandraHost(), o1.getNumActive(), o1.getNumBlockedThreads(), o1.getNumIdle(),  
+						o2.getCassandraHost(), o2.getNumActive(), o2.getNumBlockedThreads(), o2.getNumIdle()});
+			}
+
+			if(o2.getNumIdle() == ZERO_VALUE || o2.getNumIdle() == ZERO_VALUE){
+				log.warn("finding 0 hector pool {}:{} /{}:{}",
+						new Object[]{o1.getCassandraHost(), o1.getNumIdle(), o2.getCassandraHost(), o2.getNumIdle()});
+			}
+
+			if(o1.getNumBlockedThreads() != o2.getNumBlockedThreads()){
+				return o1.getNumBlockedThreads() - o2.getNumBlockedThreads();
+			} else {
+				return o2.getNumIdle() - o1.getNumIdle();
+			}
+		}
+	}
+
+	public HClientPool getPool(Collection<HClientPool> pools, Set<CassandraHost> excludeHosts) {
+
+		List<HClientPool> hClientPoolList = Lists.newArrayList(pools);
+		Collections.shuffle(hClientPoolList);
+		Collections.sort(hClientPoolList, new FilteringCompare());
+
+		Iterator<HClientPool> iterator = hClientPoolList.iterator();
+		HClientPool concurrentHClientPool = iterator.next();
+
+		if ( excludeHosts != null && excludeHosts.size() > 0 ) {
+			while (iterator.hasNext()) {        
+				if ( !excludeHosts.contains(concurrentHClientPool.getCassandraHost()) ) {
+					break;
+				}
+				concurrentHClientPool = (ConcurrentHClientPool) iterator.next();
+			}
+		}
+
+		return concurrentHClientPool;
+	}
+
+	public HClientPool createConnection(HClientFactory clientFactory, CassandraHost host) {
+		return new ConcurrentHClientPool(clientFactory, host);
+	}
+
+}