HDFS-10662. Optimize UTF8 string/byte conversions. Contributed by Daryn Sharp.

(cherry picked from commit 6ae39199dac6ac7be6802b31452552c76da16e24)

Conflicts:
	hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSDirWriteFileOp.java

(cherry picked from commit 77b61d1f4e34de9fed3dd6167fa93bb35e85e038)
(cherry picked from commit 58df27b87388dbb9729862a58dcdbe0b57e8b1ab)

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSUtil.java

@@ -37,7 +37,6 @@ import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_SERVER_HTTPS_KEYPASSWORD_
 import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_SERVER_HTTPS_KEYSTORE_PASSWORD_KEY;
 import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_SERVER_HTTPS_TRUSTSTORE_PASSWORD_KEY;
 
-import com.google.common.base.Charsets;
 import java.io.IOException;
 import java.io.PrintStream;
 import java.io.UnsupportedEncodingException;
@@ -45,6 +44,7 @@ import java.net.InetAddress;
 import java.net.InetSocketAddress;
 import java.net.URI;
 import java.net.URISyntaxException;
+import java.nio.charset.StandardCharsets;
 import java.security.SecureRandom;
 import java.text.SimpleDateFormat;
 import java.util.Arrays;
@@ -313,7 +313,11 @@ public class DFSUtil {
   public static String bytes2String(byte[] bytes) {
     return bytes2String(bytes, 0, bytes.length);
   }
-  
+
+  // Using the charset canonical name for String/byte[] conversions is much
+  // more efficient due to use of cached encoders/decoders.
+  private static final String UTF8_CSN = StandardCharsets.UTF_8.name();
+
   /**
    * Decode a specific range of bytes of the given byte array to a string
    * using UTF8.
@@ -325,18 +329,24 @@ public class DFSUtil {
    */
   public static String bytes2String(byte[] bytes, int offset, int length) {
     try {
-      return new String(bytes, offset, length, "UTF8");
-    } catch(UnsupportedEncodingException e) {
-      assert false : "UTF8 encoding is not supported ";
+      return new String(bytes, offset, length, UTF8_CSN);
+    } catch (UnsupportedEncodingException e) {
+      // should never happen!
+      throw new IllegalArgumentException("UTF8 encoding is not supported", e);
     }
-    return null;
   }
 
   /**
    * Converts a string to a byte array using UTF8 encoding.
    */
   public static byte[] string2Bytes(String str) {
-    return str.getBytes(Charsets.UTF_8);
+    try {
+      return str.getBytes(UTF8_CSN);
+    } catch (UnsupportedEncodingException e) {
+      // should never happen!
+      throw new IllegalArgumentException("UTF8 decoding is not supported", e);
+    }
+
   }
 
   /**

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

@@ -18,7 +18,6 @@
 package org.apache.hadoop.hdfs.server.namenode;
 
 import com.google.common.base.Preconditions;
-import org.apache.commons.io.Charsets;
 import org.apache.hadoop.fs.FileAlreadyExistsException;
 import org.apache.hadoop.fs.InvalidPathException;
 import org.apache.hadoop.fs.UnresolvedLinkException;
@@ -121,7 +120,7 @@ class FSDirMkdirOp {
   static Map.Entry<INodesInPath, String> createAncestorDirectories(
       FSDirectory fsd, INodesInPath iip, PermissionStatus permission)
       throws IOException {
-    final String last = new String(iip.getLastLocalName(), Charsets.UTF_8);
+    final String last = DFSUtil.bytes2String(iip.getLastLocalName());
     INodesInPath existing = iip.getExistingINodes();
     List<String> children = iip.getPath(existing.length(),
         iip.length() - existing.length());
@@ -189,7 +188,7 @@ class FSDirMkdirOp {
       throws IOException {
     assert fsd.hasWriteLock();
     existing = unprotectedMkdir(fsd, fsd.allocateNewInodeId(), existing,
-        localName.getBytes(Charsets.UTF_8), perm, null, now());
+        DFSUtil.string2Bytes(localName), perm, null, now());
     if (existing == null) {
       return null;
     }

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

@@ -19,7 +19,6 @@
 package org.apache.hadoop.hdfs.server.namenode;
 
 import com.google.common.base.Preconditions;
-import org.apache.commons.io.Charsets;
 import org.apache.hadoop.fs.ContentSummary;
 import org.apache.hadoop.fs.DirectoryListingStartAfterNotFoundException;
 import org.apache.hadoop.fs.FileEncryptionInfo;
@@ -51,7 +50,7 @@ class FSDirStatAndListingOp {
     FSPermissionChecker pc = fsd.getPermissionChecker();
     byte[][] pathComponents = FSDirectory
         .getPathComponentsForReservedPath(srcArg);
-    final String startAfterString = new String(startAfter, Charsets.UTF_8);
+    final String startAfterString = DFSUtil.bytes2String(startAfter);
     final String src = fsd.resolvePath(pc, srcArg, pathComponents);
     final INodesInPath iip = fsd.getINodesInPath(src, true);
 

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

@@ -18,7 +18,6 @@
 package org.apache.hadoop.hdfs.server.namenode;
 
 import com.google.common.annotations.VisibleForTesting;
-import com.google.common.base.Charsets;
 import com.google.common.base.Preconditions;
 import com.google.common.collect.Lists;
 import org.apache.hadoop.HadoopIllegalArgumentException;
@@ -26,6 +25,7 @@ import org.apache.hadoop.fs.XAttr;
 import org.apache.hadoop.fs.XAttrSetFlag;
 import org.apache.hadoop.fs.permission.FsAction;
 import org.apache.hadoop.hdfs.DFSConfigKeys;
+import org.apache.hadoop.hdfs.DFSUtil;
 import org.apache.hadoop.hdfs.XAttrHelper;
 import org.apache.hadoop.hdfs.protocol.HdfsFileStatus;
 import org.apache.hadoop.hdfs.protocol.proto.HdfsProtos;
@@ -421,7 +421,7 @@ class FSDirXAttrOp {
     if (fsd.getXattrMaxSize() == 0) {
       return;
     }
-    int size = xAttr.getName().getBytes(Charsets.UTF_8).length;
+    int size = DFSUtil.string2Bytes(xAttr.getName()).length;
     if (xAttr.getValue() != null) {
       size += xAttr.getValue().length;
     }

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

@@ -21,7 +21,6 @@ import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Preconditions;
 import com.google.common.collect.Lists;
 import com.google.protobuf.InvalidProtocolBufferException;
-import org.apache.commons.io.Charsets;
 import org.apache.hadoop.HadoopIllegalArgumentException;
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.conf.Configuration;
@@ -417,7 +416,7 @@ public class FSDirectory implements Closeable {
     long modTime = now();
     INodeFile newNode = newINodeFile(allocateNewInodeId(), permissions, modTime,
         modTime, replication, preferredBlockSize);
-    newNode.setLocalName(localName.getBytes(Charsets.UTF_8));
+    newNode.setLocalName(DFSUtil.string2Bytes(localName));
     newNode.toUnderConstruction(clientName, clientMachine);
 
     INodesInPath newiip;