[SPARK-3797] Minor addendum to Yarn shuffle service

I did not realize there was a `network.util.JavaUtils` when I wrote this code. This PR moves the `ByteBuffer` string conversion to the appropriate place. I tested the changes on a stable yarn cluster.

Author: Andrew Or <andrew@databricks.com>

Closes #3144 from andrewor14/yarn-shuffle-util and squashes the following commits:

b6c08bf [Andrew Or] Remove unused import
94e205c [Andrew Or] Use netty Unpooled
85202a5 [Andrew Or] Use guava Charsets
057135b [Andrew Or] Reword comment
adf186d [Andrew Or] Move byte buffer String conversion logic to JavaUtils

1 files changed, 20 insertions, 0 deletions

diff --git a/network/common/src/main/java/org/apache/spark/network/util/JavaUtils.java b/network/common/src/main/java/org/apache/spark/network/util/JavaUtils.java
index 40b71b0c87..2856d1c8c9 100644
--- a/network/common/src/main/java/org/apache/spark/network/util/JavaUtils.java
+++ b/network/common/src/main/java/org/apache/spark/network/util/JavaUtils.java
@@ -17,6 +17,8 @@
 
 package org.apache.spark.network.util;
 
+import java.nio.ByteBuffer;
+
 import java.io.ByteArrayInputStream;
 import java.io.ByteArrayOutputStream;
 import java.io.Closeable;
@@ -25,6 +27,8 @@ import java.io.ObjectInputStream;
 import java.io.ObjectOutputStream;
 
 import com.google.common.io.Closeables;
+import com.google.common.base.Charsets;
+import io.netty.buffer.Unpooled;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -73,4 +77,20 @@ public class JavaUtils {
     int hash = obj.hashCode();
     return hash != Integer.MIN_VALUE ? Math.abs(hash) : 0;
   }
+
+  /**
+   * Convert the given string to a byte buffer. The resulting buffer can be
+   * converted back to the same string through {@link #bytesToString(ByteBuffer)}.
+   */
+  public static ByteBuffer stringToBytes(String s) {
+    return Unpooled.wrappedBuffer(s.getBytes(Charsets.UTF_8)).nioBuffer();
+  }
+
+  /**
+   * Convert the given byte buffer to a string. The resulting string can be
+   * converted back to the same byte buffer through {@link #stringToBytes(String)}.
+   */
+  public static String bytesToString(ByteBuffer b) {
+    return Unpooled.wrappedBuffer(b).toString(Charsets.UTF_8);
+  }
 }