Add comments to the tools

src/java/voldemort/tools/PartitionAnalysisCLI.java

@@ -36,6 +36,11 @@
 
 import com.google.common.base.Joiner;
 
+/*
+ * Analyzes the partition layout of a cluster based on the storage definitions
+ * for that cluster and determines how well balanced the partition layout is.
+ */
+
 public class PartitionAnalysisCLI {
 
     private final static Logger logger = Logger.getLogger(PartitionAnalysisCLI.class);

src/java/voldemort/tools/RebalanceControllerCLI.java

@@ -39,6 +39,10 @@
 
 import com.google.common.base.Joiner;
 
+/*
+ * Executes the actual rebalance operation againt a server.
+ */
+
 public class RebalanceControllerCLI {
 
     private final static Logger logger = Logger.getLogger(RebalanceControllerCLI.class);

src/java/voldemort/tools/RebalancePlanCLI.java

@@ -37,6 +37,12 @@
 
 import com.google.common.base.Joiner;
 
+/*
+ * This tool generates a rebalance plan based on current and final xml. The plan
+ * will contain steps on how to rebalance the server such that its layout
+ * changes from the 'current' state to the 'final' state.
+ */
+
 public class RebalancePlanCLI {
 
     private final static Logger logger = Logger.getLogger(RebalancePlanCLI.class);
@@ -75,8 +81,9 @@ private static void setupParser() {
     private static void printUsage() {
         StringBuilder help = new StringBuilder();
         help.append("RebalancePlanCLI\n");
-        help.append("  Moves partitions to achieve better balance. This can be done for shuffling (improve balance among existing nodes),"
-                    + " cluster expansion (adding nodes to some zones), and zone expansion (adding an entire new zone).\n");
+        help.append("Generates a rebalance plan based on current and final xml. The plan will "
+                    + "contain steps  on how to rebalance the server such that its layout"
+                    + "changes from current to final state");
         help.append("Options:\n");
         help.append("  Required:\n");
         help.append("    --current-cluster <clusterXML>\n");

src/java/voldemort/tools/RepartitionerCLI.java

@@ -37,6 +37,19 @@
 
 import com.google.common.base.Joiner;
 
+/*
+ * This tool accepts an existing cluster.xml and generates a new cluster.xml.
+ * 
+ * The tool reads the existing cluster.xml to understand the partition layout.
+ * It then moves the partitions around (according to some intelligent mechanism)
+ * with the goal of achieving a better balanced state. A new cluster.xml is then
+ * generated according to what the tool believes is a better partition layout.
+ * 
+ * A better balanced state might be needed for : (1) Improving balance among
+ * existing nodes (2) Cluster expansion (adding nodes to some zones) (3) Zone
+ * expansion (adding an entire new zone)
+ */
+
 public class RepartitionerCLI {
 
     private final static Logger logger = Logger.getLogger(RepartitionerCLI.class);