HDFS-16695. Improve code with Lambda in org.apache.hadoop.hdfs.servernamenode package

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/AclTransformation.java

@@ -246,19 +246,14 @@ private AclTransformation() {
    * All access ACL entries sort ahead of all default ACL entries.
    */
   static final Comparator<AclEntry> ACL_ENTRY_COMPARATOR =
-    new Comparator<AclEntry>() {
-      @Override
-      public int compare(AclEntry entry1, AclEntry entry2) {
-        return ComparisonChain.start()
+      (entry1, entry2) -> ComparisonChain.start()
           .compare(entry1.getScope(), entry2.getScope(),
-            Ordering.explicit(ACCESS, DEFAULT))
+              Ordering.explicit(ACCESS, DEFAULT))
           .compare(entry1.getType(), entry2.getType(),
-            Ordering.explicit(USER, GROUP, MASK, OTHER))
+              Ordering.explicit(USER, GROUP, MASK, OTHER))
           .compare(entry1.getName(), entry2.getName(),
-            Ordering.natural().nullsFirst())
+              Ordering.natural().nullsFirst())
           .result();
-      }
-    };
 
   /**
    * Builds the final list of ACL entries to return by trimming, sorting and

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/DefaultAuditLogger.java

@@ -39,12 +39,7 @@
 @InterfaceStability.Evolving
 public abstract class DefaultAuditLogger extends HdfsAuditLogger {
   protected static final ThreadLocal<StringBuilder> STRING_BUILDER =
-      new ThreadLocal<StringBuilder>() {
-        @Override
-        protected StringBuilder initialValue() {
-          return new StringBuilder();
-        }
-      };
+      ThreadLocal.withInitial(StringBuilder::new);
 
   protected volatile boolean isCallerContextEnabled;
 

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/EditLogFileInputStream.java

@@ -28,7 +28,6 @@
 import java.net.HttpURLConnection;
 import java.net.URL;
 import java.nio.file.Files;
-import java.security.PrivilegedExceptionAction;
 
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -478,41 +477,33 @@ public URLLog(URLConnectionFactory connectionFactory, URL url) {
 
     @Override
     public InputStream getInputStream() throws IOException {
-      return SecurityUtil.doAsCurrentUser(
-          new PrivilegedExceptionAction<InputStream>() {
-            @Override
-            public InputStream run() throws IOException {
-              HttpURLConnection connection;
-              try {
-                connection = (HttpURLConnection)
-                    connectionFactory.openConnection(url, isSpnegoEnabled);
-              } catch (AuthenticationException e) {
-                throw new IOException(e);
-              }
-
-              if (connection.getResponseCode() != HttpURLConnection.HTTP_OK) {
-                throw new HttpGetFailedException(
-                    "Fetch of " + url +
-                    " failed with status code " + connection.getResponseCode() +
-                    "\nResponse message:\n" + connection.getResponseMessage(),
-                    connection);
-              }
-
-              String contentLength = connection.getHeaderField(CONTENT_LENGTH);
-              if (contentLength != null) {
-                advertisedSize = Long.parseLong(contentLength);
-                if (advertisedSize <= 0) {
-                  throw new IOException("Invalid " + CONTENT_LENGTH + " header: " +
-                      contentLength);
-                }
-              } else {
-                throw new IOException(CONTENT_LENGTH + " header is not provided " +
-                                      "by the server when trying to fetch " + url);
-              }
-
-              return connection.getInputStream();
-            }
-          });
+      return SecurityUtil.doAsCurrentUser(() -> {
+        HttpURLConnection connection;
+        try {
+          connection = (HttpURLConnection) connectionFactory.openConnection(url, isSpnegoEnabled);
+        } catch (AuthenticationException e) {
+          throw new IOException(e);
+        }
+
+        if (connection.getResponseCode() != HttpURLConnection.HTTP_OK) {
+          throw new HttpGetFailedException("Fetch of " + url +
+              " failed with status code " + connection.getResponseCode() +
+              "\nResponse message:\n" + connection.getResponseMessage(), connection);
+        }
+
+        String contentLength = connection.getHeaderField(CONTENT_LENGTH);
+        if (contentLength != null) {
+          advertisedSize = Long.parseLong(contentLength);
+          if (advertisedSize <= 0) {
+            throw new IOException("Invalid " + CONTENT_LENGTH + " header: " + contentLength);
+          }
+        } else {
+          throw new IOException(CONTENT_LENGTH + " header is not provided " +
+              "by the server when trying to fetch " + url);
+        }
+
+        return connection.getInputStream();
+      });
     }
 
     @Override

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSDirEncryptionZoneOp.java

@@ -21,7 +21,6 @@
 
 import java.io.IOException;
 import java.security.GeneralSecurityException;
-import java.security.PrivilegedExceptionAction;
 import java.util.AbstractMap;
 import java.util.concurrent.ExecutorService;
 import java.util.EnumSet;
@@ -94,14 +93,11 @@ private static EncryptedKeyVersion generateEncryptedDataEncryptionKey(
     // KMS does not need configuration to allow non-hdfs user GENERATE_EEK
     // operation.
     EncryptedKeyVersion edek = SecurityUtil.doAsLoginUser(
-        new PrivilegedExceptionAction<EncryptedKeyVersion>() {
-          @Override
-          public EncryptedKeyVersion run() throws IOException {
-            try {
-              return fsd.getProvider().generateEncryptedKey(ezKeyName);
-            } catch (GeneralSecurityException e) {
-              throw new IOException(e);
-            }
+        () -> {
+          try {
+            return fsd.getProvider().generateEncryptedKey(ezKeyName);
+          } catch (GeneralSecurityException e) {
+            throw new IOException(e);
           }
         });
     long generateEDEKTime = monotonicNow() - generateEDEKStartTime;

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSDirErasureCodingOp.java

@@ -76,9 +76,7 @@ static ErasureCodingPolicy getEnabledErasureCodingPolicyByName(
         .getEnabledPolicyByName(ecPolicyName);
     if (ecPolicy == null) {
       final String sysPolicies =
-          Arrays.asList(
-              fsn.getErasureCodingPolicyManager().getEnabledPolicies())
-              .stream()
+          Arrays.stream(fsn.getErasureCodingPolicyManager().getEnabledPolicies())
               .map(ErasureCodingPolicy::getName)
               .collect(Collectors.joining(", "));
       final String message = String.format("Policy '%s' does not match any " +

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSEditLogOp.java

@@ -125,7 +125,6 @@
 import org.apache.hadoop.io.Text;
 import org.apache.hadoop.io.Writable;
 import org.apache.hadoop.io.WritableFactories;
-import org.apache.hadoop.io.WritableFactory;
 import org.apache.hadoop.io.erasurecode.ECSchema;
 import org.apache.hadoop.io.erasurecode.ErasureCodeConstants;
 import org.apache.hadoop.ipc.ClientId;
@@ -158,12 +157,7 @@ public abstract class FSEditLogOp {
 
   public static class OpInstanceCache {
     private static final ThreadLocal<OpInstanceCacheMap> CACHE =
-        new ThreadLocal<OpInstanceCacheMap>() {
-      @Override
-      protected OpInstanceCacheMap initialValue() {
-        return new OpInstanceCacheMap();
-      }
-    };
+        ThreadLocal.withInitial(OpInstanceCacheMap::new);
 
     @SuppressWarnings("serial")
     static final class OpInstanceCacheMap extends
@@ -4467,12 +4461,7 @@ static class BlockTwo implements Writable {
     long len;
 
     static {                                      // register a ctor
-      WritableFactories.setFactory
-        (BlockTwo.class,
-         new WritableFactory() {
-           @Override
-           public Writable newInstance() { return new BlockTwo(); }
-         });
+      WritableFactories.setFactory(BlockTwo.class, BlockTwo::new);
     }
 
 

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSImageFormatPBINode.java

@@ -307,20 +307,8 @@ private void fillUpInodeList(ArrayList<INode> inodeList, INode inode) {
 
     private void addToCacheAndBlockMap(final ArrayList<INode> inodeList) {
       final ArrayList<INode> inodes = new ArrayList<>(inodeList);
-      nameCacheUpdateExecutor.submit(
-          new Runnable() {
-            @Override
-            public void run() {
-              addToCacheInternal(inodes);
-            }
-          });
-      blocksMapUpdateExecutor.submit(
-          new Runnable() {
-            @Override
-            public void run() {
-              updateBlockMapInternal(inodes);
-            }
-          });
+      nameCacheUpdateExecutor.submit(() -> addToCacheInternal(inodes));
+      blocksMapUpdateExecutor.submit(() -> updateBlockMapInternal(inodes));
     }
 
     // update name cache with non-thread safe

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSImageFormatProtobuf.java

@@ -34,8 +34,6 @@
 import java.security.DigestOutputStream;
 import java.security.MessageDigest;
 import java.util.ArrayList;
-import java.util.Collections;
-import java.util.Comparator;
 import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
@@ -377,18 +375,15 @@ private void loadInternal(RandomAccessFile raFile, FileInputStream fin)
 
       ArrayList<FileSummary.Section> sections = Lists.newArrayList(summary
           .getSectionsList());
-      Collections.sort(sections, new Comparator<FileSummary.Section>() {
-        @Override
-        public int compare(FileSummary.Section s1, FileSummary.Section s2) {
-          SectionName n1 = SectionName.fromString(s1.getName());
-          SectionName n2 = SectionName.fromString(s2.getName());
-          if (n1 == null) {
-            return n2 == null ? 0 : -1;
-          } else if (n2 == null) {
-            return -1;
-          } else {
-            return n1.ordinal() - n2.ordinal();
-          }
+      sections.sort((s1, s2) -> {
+        SectionName n1 = SectionName.fromString(s1.getName());
+        SectionName n2 = SectionName.fromString(s2.getName());
+        if (n1 == null) {
+          return n2 == null ? 0 : -1;
+        } else if (n2 == null) {
+          return -1;
+        } else {
+          return n1.ordinal() - n2.ordinal();
         }
       });
 

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSImageSerialization.java

@@ -75,13 +75,7 @@ private FSImageSerialization() {}
    * in this class should be thread-safe since image-saving is multithreaded, so 
    * we need to keep the static objects in a thread-local.
    */
-  static private final ThreadLocal<TLData> TL_DATA =
-    new ThreadLocal<TLData>() {
-    @Override
-    protected TLData initialValue() {
-      return new TLData();
-    }
-  };
+  static private final ThreadLocal<TLData> TL_DATA = ThreadLocal.withInitial(TLData::new);
 
   /**
    * Simple container "struct" for threadlocal data.

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSNamesystem.java

@@ -6736,12 +6736,7 @@ public String getNodeUsage() {
         new HashMap<String, Map<String,Object>>();
     final List<DatanodeDescriptor> live = new ArrayList<DatanodeDescriptor>();
     blockManager.getDatanodeManager().fetchDatanodes(live, null, true);
-    for (Iterator<DatanodeDescriptor> it = live.iterator(); it.hasNext();) {
-      DatanodeDescriptor node = it.next();
-      if (!node.isInService()) {
-        it.remove();
-      }
-    }
+    live.removeIf(node -> !node.isInService());
 
     if (live.size() > 0) {
       float totalDfsUsed = 0;

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSNamesystemLock.java

@@ -93,12 +93,7 @@ class FSNamesystemLock {
    * many read locks held simultaneously.
    */
   private final ThreadLocal<Long> readLockHeldTimeStampNanos =
-      new ThreadLocal<Long>() {
-        @Override
-        public Long initialValue() {
-          return Long.MAX_VALUE;
-        }
-      };
+      ThreadLocal.withInitial(() -> Long.MAX_VALUE);
   private final AtomicInteger numReadLockWarningsSuppressed =
       new AtomicInteger(0);
   /** Time stamp (ms) of the last time a read lock report was written. */

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FileJournalManager.java

@@ -537,16 +537,11 @@ public static class EditLogFile {
     private boolean hasCorruptHeader = false;
     private final boolean isInProgress;
 
-    final static Comparator<EditLogFile> COMPARE_BY_START_TXID 
-      = new Comparator<EditLogFile>() {
-      @Override
-      public int compare(EditLogFile a, EditLogFile b) {
-        return ComparisonChain.start()
-        .compare(a.getFirstTxId(), b.getFirstTxId())
-        .compare(a.getLastTxId(), b.getLastTxId())
-        .result();
-      }
-    };
+    final static Comparator<EditLogFile> COMPARE_BY_START_TXID =
+        (a, b) -> ComparisonChain.start()
+            .compare(a.getFirstTxId(), b.getFirstTxId())
+            .compare(a.getLastTxId(), b.getLastTxId())
+            .result();
 
     EditLogFile(File file,
         long firstTxId, long lastTxId) {

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FsImageValidation.java

@@ -48,7 +48,6 @@
 import java.io.IOException;
 import java.util.Arrays;
 import java.util.Collections;
-import java.util.Iterator;
 import java.util.Timer;
 import java.util.TimerTask;
 import java.util.concurrent.atomic.AtomicInteger;
@@ -148,19 +147,16 @@ static String toCommaSeparatedNumber(long n) {
     /** @return a filter for the given type. */
     static FilenameFilter newFilenameFilter(NameNodeFile type) {
       final String prefix = type.getName() + "_";
-      return new FilenameFilter() {
-        @Override
-        public boolean accept(File dir, String name) {
-          if (!name.startsWith(prefix)) {
+      return (dir, name) -> {
+        if (!name.startsWith(prefix)) {
+          return false;
+        }
+        for (int i = prefix.length(); i < name.length(); i++) {
+          if (!Character.isDigit(name.charAt(i))) {
             return false;
           }
-          for (int i = prefix.length(); i < name.length(); i++) {
-            if (!Character.isDigit(name.charAt(i))) {
-              return false;
-            }
-          }
-          return true;
         }
+        return true;
       };
     }
   }
@@ -264,12 +260,7 @@ FSNamesystem checkINodeReference(Configuration conf,
 
   static class INodeMapValidation {
     static Iterable<INodeWithAdditionalFields> iterate(INodeMap map) {
-      return new Iterable<INodeWithAdditionalFields>() {
-        @Override
-        public Iterator<INodeWithAdditionalFields> iterator() {
-          return map.getMapIterator();
-        }
-      };
+      return map::getMapIterator;
     }
 
     static void run(FSDirectory fsdir, AtomicInteger errorCount) {

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/INodeReference.java

@@ -388,13 +388,8 @@ public static class WithCount extends INodeReference {
      * Compare snapshot with IDs, where null indicates the current status thus
      * is greater than any non-null snapshot.
      */
-    public static final Comparator<WithName> WITHNAME_COMPARATOR
-        = new Comparator<WithName>() {
-      @Override
-      public int compare(WithName left, WithName right) {
-        return left.lastSnapshotId - right.lastSnapshotId;
-      }
-    };
+    public static final Comparator<WithName> WITHNAME_COMPARATOR =
+        Comparator.comparingInt(left -> left.lastSnapshotId);
 
     public WithCount(INodeReference parent, INode referred) {
       super(parent, referred);