[Imporve][Master] Refine the doselect annotation of the distribution policy (#16149)

dolphinscheduler-master/src/main/java/org/apache/dolphinscheduler/server/master/dispatch/host/assign/LowerWeightRoundRobin.java

@@ -25,10 +25,12 @@ import java.util.Collection;
 public class LowerWeightRoundRobin extends AbstractSelector<HostWeight> {
 
     /**
-     * select
+     * Selects a HostWeight from a collection of HostWeight objects.
+     * The selection is based on the current weight of each HostWeight.
+     * The HostWeight with the smallest current weight is selected.
      *
-     * @param sources sources
+     * @param sources A collection of HostWeight objects to select from.
-     * @return HostWeight
+     * @return The selected HostWeight with the smallest current weight.
      */
     @Override
     public HostWeight doSelect(Collection<HostWeight> sources) {

dolphinscheduler-master/src/main/java/org/apache/dolphinscheduler/server/master/dispatch/host/assign/RandomSelector.java

@@ -27,6 +27,14 @@ import java.util.concurrent.ThreadLocalRandom;
  */
 public class RandomSelector extends AbstractSelector<HostWorker> {
 
+    /**
+     * This method selects a HostWorker from a collection of HostWorker objects using a weighted random algorithm.
+     * The selection is based on the weight of each HostWorker.
+     * A random number is generated and the HostWorker whose weight spans this random number is selected.
+     *
+     * @param source A collection of HostWorker objects to select from.
+     * @return The selected HostWorker based on the weighted random algorithm.
+     */
     @Override
     public HostWorker doSelect(final Collection<HostWorker> source) {
 

dolphinscheduler-master/src/main/java/org/apache/dolphinscheduler/server/master/dispatch/host/assign/RoundRobinSelector.java

@@ -73,6 +73,14 @@ public class RoundRobinSelector extends AbstractSelector<HostWorker> {
 
     }
 
+    /**
+     * This method selects a HostWorker from a collection of HostWorker objects using a weighted round-robin algorithm.
+     * The selection is based on the current weight of each HostWorker.
+     * The HostWorker with the highest current weight is selected.
+     *
+     * @param source A collection of HostWorker objects to select from.
+     * @return The selected HostWorker with the highest current weight.
+     */
     @Override
     public HostWorker doSelect(Collection<HostWorker> source) {