From 252b42770d5a2c38626e4c2eeedd61cc113cba6f Mon Sep 17 00:00:00 2001
From: Simon Kitching <skitching@apache.org>
Date: Sun, 15 Oct 2006 03:11:19 +0000
Subject: [PATCH] Fix thread-safety bug (SimpleDateFormat.format is not
 thread-safe). Thanks to Martin Wilson of bright-interactive for the bug
 report.

git-svn-id: https://svn.apache.org/repos/asf/jakarta/commons/proper/logging/trunk@464108 13f79535-47bb-0310-9956-ffa450edef68
---
 .../apache/commons/logging/impl/SimpleLog.java | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/src/java/org/apache/commons/logging/impl/SimpleLog.java b/src/java/org/apache/commons/logging/impl/SimpleLog.java
index 509c600..f8e85c0 100644
--- a/src/java/org/apache/commons/logging/impl/SimpleLog.java
+++ b/src/java/org/apache/commons/logging/impl/SimpleLog.java
@@ -100,7 +100,15 @@ public class SimpleLog implements Log, Serializable {
     static protected boolean showDateTime = false;
     /** The date and time format to use in the log message */
     static protected String dateTimeFormat = DEFAULT_DATE_TIME_FORMAT;
-    /** Used to format times */
+
+    /**
+     * Used to format times.
+     * <p>
+     * Any code that accesses this object should first obtain a lock on it,
+     * ie use synchronized(dateFormatter); this requirement was introduced
+     * in 1.1.1 to fix an existing thread safety bug (SimpleDateFormat.format
+     * is not thread-safe).
+     */
     static protected DateFormat dateFormatter = null;
 
     // ---------------------------------------------------- Log Level Constants
@@ -179,7 +187,6 @@ public class SimpleLog implements Log, Serializable {
         }
     }
 
-
     // ------------------------------------------------------------- Attributes
 
     /** The name of this simple log instance */
@@ -281,7 +288,12 @@ public class SimpleLog implements Log, Serializable {
 
         // Append date-time if so configured
         if(showDateTime) {
-            buf.append(dateFormatter.format(new Date()));
+            Date now = new Date();
+            String dateText;
+            synchronized(dateFormatter) {
+                dateText = dateFormatter.format(now);
+            }
+            buf.append(dateText);
             buf.append(" ");
         }