From a4325e55597da54e3400ac5704f4437d637771d3 Mon Sep 17 00:00:00 2001
From: Henri Yandell <bayard@apache.org>
Date: Tue, 7 Jul 2009 07:10:02 +0000
Subject: [PATCH] Moving availableLocaleSet and availableLocaleList to both
 lazily initialize in a separate synchronized method. This brings the two
 pieces of code into line with each other, allows availableLocaleSet() to be
 unsynchronized as desired in LANG-488 and removes the static initialization
 of availableLocaleList() as requested in LANG-511

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/lang/trunk@791726 13f79535-47bb-0310-9956-ffa450edef68
---
 .../org/apache/commons/lang/LocaleUtils.java  | 47 ++++++++++++++-----
 1 file changed, 35 insertions(+), 12 deletions(-)

diff --git a/src/java/org/apache/commons/lang/LocaleUtils.java b/src/java/org/apache/commons/lang/LocaleUtils.java
index 8635b2e8f..553baeeb4 100644
--- a/src/java/org/apache/commons/lang/LocaleUtils.java
+++ b/src/java/org/apache/commons/lang/LocaleUtils.java
@@ -40,18 +40,18 @@ import java.util.Set;
 public class LocaleUtils {
 
     /** Unmodifiable list of available locales. */
-    private static final List<Locale> cAvailableLocaleList;
+    //@GuardedBy("this")
+    private static List<Locale> cAvailableLocaleList; // lazily created by availableLocaleList()
+
     /** Unmodifiable set of available locales. */
     //@GuardedBy("this")
-    private static Set<Locale> cAvailableLocaleSet; // lazily created by availableLocaleSet()
+    private static Set<Locale> cAvailableLocaleSet;   // lazily created by availableLocaleSet()
+
     /** Unmodifiable map of language locales by country. */
     private static final Map<String, List<Locale>> cLanguagesByCountry = Collections.synchronizedMap(new HashMap<String, List<Locale>>());
+
     /** Unmodifiable map of country locales by language. */
     private static final Map<String, List<Locale>> cCountriesByLanguage = Collections.synchronizedMap(new HashMap<String, List<Locale>>());
-    static {
-        List<Locale> list = Arrays.asList(Locale.getAvailableLocales());
-        cAvailableLocaleList = Collections.unmodifiableList(list);
-    }
 
     /**
      * <p><code>LocaleUtils</code> instances should NOT be constructed in standard programming.
@@ -193,9 +193,24 @@ public class LocaleUtils {
      * @return the unmodifiable list of available locales
      */
     public static List<Locale> availableLocaleList() {
+        if(cAvailableLocaleList == null) { 
+            initAvailableLocaleList(); 
+        }
         return cAvailableLocaleList;
     }
 
+    /**
+     * Initializes the availableLocaleList. It is separate from availableLocaleList() 
+     * to avoid the synchronized block affecting normal use, yet synchronized and 
+     * lazy loading to avoid a static block affecting other methods in this class. 
+     */
+    private static synchronized void initAvailableLocaleList() {
+        if(cAvailableLocaleList == null) {
+            List<Locale> list = Arrays.asList(Locale.getAvailableLocales());
+            cAvailableLocaleList = Collections.unmodifiableList(list);
+        }
+    }
+
     //-----------------------------------------------------------------------
     /**
      * <p>Obtains an unmodifiable set of installed locales.</p>
@@ -207,13 +222,21 @@ public class LocaleUtils {
      * @return the unmodifiable set of available locales
      */
     public static synchronized Set<Locale> availableLocaleSet() {
-        Set<Locale> set = cAvailableLocaleSet;
-        if (set == null) {
-            set = new HashSet<Locale>(availableLocaleList());
-            set = Collections.unmodifiableSet(set);
-            cAvailableLocaleSet = set;
+        if(cAvailableLocaleSet == null) { 
+            initAvailableLocaleSet(); 
+        }
+        return cAvailableLocaleSet;
+    }
+
+    /**
+     * Initializes the availableLocaleSet. It is separate from availableLocaleSet() 
+     * to avoid the synchronized block affecting normal use, yet synchronized and 
+     * lazy loading to avoid a static block affecting other methods in this class. 
+     */
+    private static synchronized void initAvailableLocaleSet() {
+        if(cAvailableLocaleSet == null) {
+            cAvailableLocaleSet = Collections.unmodifiableSet( new HashSet<Locale>(availableLocaleList()) );
         }
-        return set;
     }
 
     //-----------------------------------------------------------------------