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From ohe...@apache.org
Subject svn commit: r819146 - /commons/proper/lang/trunk/src/java/org/apache/commons/lang/concurrent/LazyInitializer.java
Date Sat, 26 Sep 2009 15:03:06 GMT
Author: oheger
Date: Sat Sep 26 15:03:06 2009
New Revision: 819146

URL: http://svn.apache.org/viewvc?rev=819146&view=rev
Log:
[LANG-496] Added a comment why a temporary variable is used in get().

Modified:
    commons/proper/lang/trunk/src/java/org/apache/commons/lang/concurrent/LazyInitializer.java

Modified: commons/proper/lang/trunk/src/java/org/apache/commons/lang/concurrent/LazyInitializer.java
URL: http://svn.apache.org/viewvc/commons/proper/lang/trunk/src/java/org/apache/commons/lang/concurrent/LazyInitializer.java?rev=819146&r1=819145&r2=819146&view=diff
==============================================================================
--- commons/proper/lang/trunk/src/java/org/apache/commons/lang/concurrent/LazyInitializer.java
(original)
+++ commons/proper/lang/trunk/src/java/org/apache/commons/lang/concurrent/LazyInitializer.java
Sat Sep 26 15:03:06 2009
@@ -42,9 +42,11 @@
  * to this class, a subclass of {@code LazyInitializer} has to be created:
  *
  * <pre>
- * public class ComplexObjectInitializer extends LazyInitializer&lt;ComplexObject&gt;
{
+ * public class ComplexObjectInitializer extends LazyInitializer&lt;ComplexObject&gt;
+ * {
  *     &#064;Override
- *     protected ComplexObject initialize() {
+ *     protected ComplexObject initialize()
+ *     {
  *         return new ComplexObject();
  *     }
  * }
@@ -75,7 +77,8 @@
  * @version $Id$
  * @param <T> the type of the object managed by this initializer class
  */
-public abstract class LazyInitializer<T> {
+public abstract class LazyInitializer<T>
+{
     /** Stores the managed object. */
     private volatile T object;
 
@@ -85,13 +88,19 @@
      *
      * @return the object initialized by this {@code LazyInitializer}
      */
-    public T get() {
+    public T get()
+    {
+        // use a temporary variable to reduce the number of reads of the
+        // volatile field
         T result = object;
 
-        if (result == null) {
-            synchronized (this) {
+        if (result == null)
+        {
+            synchronized (this)
+            {
                 result = object;
-                if (result == null) {
+                if (result == null)
+                {
                     object = result = initialize();
                 }
             }



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