optimize javadoc.

Author: hfutatzhanghb

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/common/DataNodeLockManager.java

@@ -24,8 +24,12 @@
 public interface DataNodeLockManager<T extends AutoCloseDataSetLock> {
 
   /**
-   * Acquire block pool level first if you want to Acquire volume lock.
+   * Acquire block pool level and volume level lock first if you want to acquire dir lock.
    * Or only acquire block pool level lock.
+   * There are several locking sequential patterns as below:
+   * 1. block pool
+   * 2. block poll -> volume
+   * 3. block pool level -> volume -> dir
    */
   enum LockLevel {
     BLOCK_POOl,

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DataNodeLayoutSubLockStrategy.java

@@ -27,7 +27,7 @@ public String blockIdToSubLock(long blockid) {
   }
 
   @Override
-  public List<String> getAllSubLockName() {
+  public List<String> getAllSubLockNames() {
     return DatanodeUtil.getAllSubDirNameForDataSetLock();
   }
 }

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DataSetSubLockStrategy.java

@@ -32,5 +32,5 @@ public interface DataSetSubLockStrategy {
    */
   String blockIdToSubLock(long blockid);
 
-  List<String> getAllSubLockName();
+  List<String> getAllSubLockNames();
 }

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DatanodeUtil.java

@@ -119,7 +119,7 @@ public static boolean dirNoFilesRecursive(
   /**
    * Take an example.
    * We hava a block with blockid mapping to:
-   * "/data1/hadoop/hdfs/datanode/current/BP-xxxx/current/finalized/subdir0/subdir0"
+   * "/data1/hadoop/hdfs/datanode/current/BP-xxxx/current/finalized/subdir0/subdir1"
    * We return "subdir0/subdir0".
    * @param blockId the block id.
    * @return two-level subdir string where block will be stored.

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/fsdataset/impl/FsDatasetImpl.java

@@ -436,7 +436,7 @@ private synchronized void activateVolume(
       FsVolumeReference ref) throws IOException {
     for (String bp : volumeMap.getBlockPoolList()) {
       lockManager.addLock(LockLevel.VOLUME, bp, ref.getVolume().getStorageID());
-      List<String> allSubDirNameForDataSetLock = datasetSubLockStrategy.getAllSubLockName();
+      List<String> allSubDirNameForDataSetLock = datasetSubLockStrategy.getAllSubLockNames();
       for (String dir : allSubDirNameForDataSetLock) {
         lockManager.addLock(LockLevel.DIR, bp, ref.getVolume().getStorageID(), dir);
         LOG.info("Added DIR lock for bpid:{}, volume storageid:{}, dir:{}",
@@ -641,7 +641,7 @@ public void removeVolumes(
       for (String storageUuid : storageToRemove) {
         storageMap.remove(storageUuid);
         for (String bp : volumeMap.getBlockPoolList()) {
-          List<String> allSubDirNameForDataSetLock = datasetSubLockStrategy.getAllSubLockName();
+          List<String> allSubDirNameForDataSetLock = datasetSubLockStrategy.getAllSubLockNames();
           for (String dir : allSubDirNameForDataSetLock) {
             lockManager.removeLock(LockLevel.DIR, bp, storageUuid, dir);
             LOG.info("Removed DIR lock for bpid:{}, volume storageid:{}, dir:{}",
@@ -3294,7 +3294,7 @@ public void addBlockPool(String bpid, Configuration conf)
       Set<String> vols = storageMap.keySet();
       for (String v : vols) {
         lockManager.addLock(LockLevel.VOLUME, bpid, v);
-        List<String> allSubDirNameForDataSetLock = datasetSubLockStrategy.getAllSubLockName();
+        List<String> allSubDirNameForDataSetLock = datasetSubLockStrategy.getAllSubLockNames();
         for (String dir : allSubDirNameForDataSetLock) {
           lockManager.addLock(LockLevel.DIR, bpid, v, dir);
           LOG.info("Added DIR lock for bpid:{}, volume storageid:{}, dir:{}",