Added some javadocs

Author: lutovich

driver/src/main/java/org/neo4j/driver/internal/cluster/loadbalancing/LeastConnectedLoadBalancingStrategy.java

@@ -21,6 +21,11 @@
 import org.neo4j.driver.internal.net.BoltServerAddress;
 import org.neo4j.driver.internal.spi.ConnectionPool;
 
+/**
+ * Load balancing strategy that finds server with least amount of active (checked out of the pool) connections from
+ * given readers or writers. It finds a start index for iteration in a round-robin fashion. This is done to prevent
+ * choosing same first address over and over when all addresses have same amount of active connections.
+ */
 public class LeastConnectedLoadBalancingStrategy implements LoadBalancingStrategy
 {
     private final RoundRobinArrayIndex readersIndex = new RoundRobinArrayIndex();
@@ -53,12 +58,14 @@ private BoltServerAddress select( BoltServerAddress[] addresses, RoundRobinArray
             return null;
         }
 
+        // choose start index for iteration in round-rodin fashion
         int startIndex = addressesIndex.next( size );
         int index = startIndex;
 
         BoltServerAddress leastConnectedAddress = null;
         int leastActiveConnections = Integer.MAX_VALUE;
 
+        // iterate over the array to find least connected address
         do
         {
             BoltServerAddress address = addresses[index];
@@ -70,6 +77,7 @@ private BoltServerAddress select( BoltServerAddress[] addresses, RoundRobinArray
                 leastActiveConnections = activeConnections;
             }
 
+            // loop over to the start of the array when end is reached
             if ( index == size - 1 )
             {
                 index = 0;

driver/src/main/java/org/neo4j/driver/internal/cluster/loadbalancing/LoadBalancingStrategy.java

@@ -20,9 +20,24 @@
 
 import org.neo4j.driver.internal.net.BoltServerAddress;
 
+/**
+ * A facility to select most appropriate reader or writer among the given addresses for request processing.
+ */
 public interface LoadBalancingStrategy
 {
+    /**
+     * Select most appropriate read address from the given array of addresses.
+     *
+     * @param knownReaders array of all known readers.
+     * @return most appropriate reader or {@code null} if it can't be selected.
+     */
     BoltServerAddress selectReader( BoltServerAddress[] knownReaders );
 
+    /**
+     * Select most appropriate write address from the given array of addresses.
+     *
+     * @param knownWriters array of all known writers.
+     * @return most appropriate writer or {@code null} if it can't be selected.
+     */
     BoltServerAddress selectWriter( BoltServerAddress[] knownWriters );
 }

driver/src/main/java/org/neo4j/driver/internal/cluster/loadbalancing/RoundRobinLoadBalancingStrategy.java

@@ -20,6 +20,10 @@
 
 import org.neo4j.driver.internal.net.BoltServerAddress;
 
+/**
+ * Load balancing strategy that selects addresses in round-robin fashion. It maintains separate indices for readers and
+ * writers.
+ */
 public class RoundRobinLoadBalancingStrategy implements LoadBalancingStrategy
 {
     private final RoundRobinArrayIndex readersIndex = new RoundRobinArrayIndex();