From d4a91bd0c0d9d438ffe95fafee0212499b0abcfd Mon Sep 17 00:00:00 2001
From: jteagles <jeagles@gmail.com>
Date: Mon, 2 May 2022 13:14:26 -0500
Subject: [PATCH] YARN-11116. Migrate Times util from SimpleDateFormat to
 thread-safe DateTimeFormatter class (#4242)

Co-authored-by: Jonathan Eagles <jeagles@verizonmedia.com>
Signed-off-by: Akira Ajisaka <aajisaka@apache.org>
---
 .../org/apache/hadoop/yarn/util/Times.java    | 33 ++++++++-----------
 .../apache/hadoop/yarn/util/TestTimes.java    | 17 ++++++++++
 2 files changed, 30 insertions(+), 20 deletions(-)

diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/src/main/java/org/apache/hadoop/yarn/util/Times.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/src/main/java/org/apache/hadoop/yarn/util/Times.java
index b6604eee12..2755026398 100644
--- a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/src/main/java/org/apache/hadoop/yarn/util/Times.java
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/src/main/java/org/apache/hadoop/yarn/util/Times.java
@@ -19,8 +19,9 @@
 package org.apache.hadoop.yarn.util;
 
 import java.text.ParseException;
-import java.text.SimpleDateFormat;
-import java.util.Date;
+import java.time.Instant;
+import java.time.ZoneId;
+import java.time.format.DateTimeFormatter;
 
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -31,23 +32,16 @@ public class Times {
   private static final Logger LOG =
       LoggerFactory.getLogger(Times.class);
 
-  static final String ISO8601DATEFORMAT = "yyyy-MM-dd'T'HH:mm:ss.SSSZ";
+  static final String ISO8601_DATE_FORMAT = "yyyy-MM-dd'T'HH:mm:ss.SSSZ";
 
   // This format should match the one used in yarn.dt.plugins.js
-  static final ThreadLocal<SimpleDateFormat> dateFormat =
-      new ThreadLocal<SimpleDateFormat>() {
-        @Override protected SimpleDateFormat initialValue() {
-          return new SimpleDateFormat("EEE MMM dd HH:mm:ss Z yyyy");
-        }
-      };
+  static final DateTimeFormatter DATE_FORMAT =
+      DateTimeFormatter.ofPattern("EEE MMM dd HH:mm:ss Z yyyy").withZone(
+          ZoneId.systemDefault());
 
-  static final ThreadLocal<SimpleDateFormat> isoFormat =
-      new ThreadLocal<SimpleDateFormat>() {
-        @Override
-        protected SimpleDateFormat initialValue() {
-          return new SimpleDateFormat(ISO8601DATEFORMAT);
-        }
-      };
+  static final DateTimeFormatter ISO_OFFSET_DATE_TIME =
+      DateTimeFormatter.ofPattern(ISO8601_DATE_FORMAT).withZone(
+          ZoneId.systemDefault());
 
   public static long elapsed(long started, long finished) {
     return Times.elapsed(started, finished, true);
@@ -83,8 +77,7 @@ public static long elapsed(long started, long finished, boolean isRunning) {
   }
 
   public static String format(long ts) {
-    return ts > 0 ? String.valueOf(dateFormat.get().format(new Date(ts)))
-                  : "N/A";
+    return ts > 0 ? DATE_FORMAT.format(Instant.ofEpochMilli(ts)) : "N/A";
   }
 
   /**
@@ -94,7 +87,7 @@ public static String format(long ts) {
    * @return ISO 8601 formatted string.
    */
   public static String formatISO8601(long ts) {
-    return isoFormat.get().format(new Date(ts));
+    return ISO_OFFSET_DATE_TIME.format(Instant.ofEpochMilli(ts));
   }
 
   /**
@@ -109,6 +102,6 @@ public static long parseISO8601ToLocalTimeInMillis(String isoString)
     if (isoString == null) {
       throw new ParseException("Invalid input.", -1);
     }
-    return isoFormat.get().parse(isoString).getTime();
+    return Instant.from(ISO_OFFSET_DATE_TIME.parse(isoString)).toEpochMilli();
   }
 }
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/src/test/java/org/apache/hadoop/yarn/util/TestTimes.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/src/test/java/org/apache/hadoop/yarn/util/TestTimes.java
index 918743d02f..36b94bad55 100644
--- a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/src/test/java/org/apache/hadoop/yarn/util/TestTimes.java
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/src/test/java/org/apache/hadoop/yarn/util/TestTimes.java
@@ -21,6 +21,12 @@
 import org.junit.Assert;
 import org.junit.Test;
 
+import java.io.IOException;
+import java.text.SimpleDateFormat;
+import java.util.Date;
+
+import static org.apache.hadoop.yarn.util.Times.ISO8601_DATE_FORMAT;
+
 public class TestTimes {
 
   @Test
@@ -61,4 +67,15 @@ public void testFinishTimesAheadOfStartTimes() {
     elapsed = Times.elapsed(Long.MAX_VALUE, 0, true);
     Assert.assertEquals("Elapsed time is not -1", -1, elapsed);
   }
+
+  @Test
+  public void validateISO() throws IOException {
+    SimpleDateFormat isoFormat = new SimpleDateFormat(ISO8601_DATE_FORMAT);
+    for (int i = 0; i < 1000; i++) {
+      long now = System.currentTimeMillis();
+      String instant =  Times.formatISO8601(now);
+      String date = isoFormat.format(new Date(now));
+      Assert.assertEquals(date, instant);
+    }
+  }
 }
\ No newline at end of file