[MINOR] Add javadoc to SchedulerConfGenerator and Code clean

hudi-utilities/src/main/java/org/apache/hudi/utilities/deltastreamer/SchedulerConfGenerator.java

@@ -44,6 +44,7 @@ public class SchedulerConfGenerator {
   public static final String DELTASYNC_POOL_NAME = "hoodiedeltasync";
   public static final String COMPACT_POOL_NAME = "hoodiecompact";
   public static final String SPARK_SCHEDULER_MODE_KEY = "spark.scheduler.mode";
+  public static final String SPARK_SCHEDULER_FAIR_MODE = "FAIR";
   public static final String SPARK_SCHEDULER_ALLOCATION_FILE_KEY = "spark.scheduler.allocation.file";
 
   private static final String SPARK_SCHEDULING_PATTERN =
@@ -52,36 +53,55 @@ public class SchedulerConfGenerator {
           + "  </pool>\n  <pool name=\"%s\">\n    <schedulingMode>%s</schedulingMode>\n"
           + "    <weight>%s</weight>\n    <minShare>%s</minShare>\n  </pool>\n</allocations>";
 
+  /**
+   * Helper to generate spark scheduling configs in XML format with input params.
+   *
+   * @param deltaSyncWeight Scheduling weight for delta sync
+   * @param compactionWeight Scheduling weight for compaction
+   * @param deltaSyncMinShare Minshare for delta sync
+   * @param compactionMinShare Minshare for compaction
+   * @return Spark scheduling configs
+   */
   private static String generateConfig(Integer deltaSyncWeight, Integer compactionWeight, Integer deltaSyncMinShare,
       Integer compactionMinShare) {
-    return String.format(SPARK_SCHEDULING_PATTERN, DELTASYNC_POOL_NAME, "FAIR", deltaSyncWeight.toString(),
-        deltaSyncMinShare.toString(), COMPACT_POOL_NAME, "FAIR", compactionWeight.toString(),
-        compactionMinShare.toString());
+    return String.format(SPARK_SCHEDULING_PATTERN, DELTASYNC_POOL_NAME, SPARK_SCHEDULER_FAIR_MODE,
+        deltaSyncWeight.toString(), deltaSyncMinShare.toString(), COMPACT_POOL_NAME, SPARK_SCHEDULER_FAIR_MODE,
+        compactionWeight.toString(), compactionMinShare.toString());
   }
 
   /**
    * Helper to set Spark Scheduling Configs dynamically.
    *
-   * @param cfg Config
+   * @param cfg Config for HoodieDeltaStreamer
    */
   public static Map<String, String> getSparkSchedulingConfigs(HoodieDeltaStreamer.Config cfg) throws Exception {
     scala.Option<String> scheduleModeKeyOption = new SparkConf().getOption(SPARK_SCHEDULER_MODE_KEY);
     final Option<String> sparkSchedulerMode =
         scheduleModeKeyOption.isDefined() ? Option.of(scheduleModeKeyOption.get()) : Option.empty();
 
-    Map<String, String> additionalSparkConfigs = new HashMap<>();
-    if (sparkSchedulerMode.isPresent() && "FAIR".equals(sparkSchedulerMode.get()) && cfg.continuousMode
-        && cfg.tableType.equals(HoodieTableType.MERGE_ON_READ.name())) {
+    Map<String, String> additionalSparkConfigs = new HashMap<>(1);
+    if (sparkSchedulerMode.isPresent() && SPARK_SCHEDULER_FAIR_MODE.equals(sparkSchedulerMode.get())
+        && cfg.continuousMode && cfg.tableType.equals(HoodieTableType.MERGE_ON_READ.name())) {
       String sparkSchedulingConfFile = generateAndStoreConfig(cfg.deltaSyncSchedulingWeight,
           cfg.compactSchedulingWeight, cfg.deltaSyncSchedulingMinShare, cfg.compactSchedulingMinShare);
       additionalSparkConfigs.put(SPARK_SCHEDULER_ALLOCATION_FILE_KEY, sparkSchedulingConfFile);
     } else {
       LOG.warn("Job Scheduling Configs will not be in effect as spark.scheduler.mode "
-          + "is not set to FAIR at instatiation time. Continuing without scheduling configs");
+          + "is not set to FAIR at instantiation time. Continuing without scheduling configs");
     }
     return additionalSparkConfigs;
   }
 
+  /**
+   * Generate spark scheduling configs and store it to a randomly generated tmp file.
+   *
+   * @param deltaSyncWeight Scheduling weight for delta sync
+   * @param compactionWeight Scheduling weight for compaction
+   * @param deltaSyncMinShare Minshare for delta sync
+   * @param compactionMinShare Minshare for compaction
+   * @return Return the absolute path of the tmp file which stores the spark schedule configs
+   * @throws IOException Throws an IOException when write configs to file failed
+   */
   private static String generateAndStoreConfig(Integer deltaSyncWeight, Integer compactionWeight,
       Integer deltaSyncMinShare, Integer compactionMinShare) throws IOException {
     File tempConfigFile = File.createTempFile(UUID.randomUUID().toString(), ".xml");