Ensuring thread-safe usage of DateFormat.

DateFormat is inherently unsafe for multithreaded use. This patch adds
proper synchronization. The 'sLock' is re-used. To avoid two consecutive
lockings, locked version of initFormatStrings() method is created and
used where appropriate, i.e. in original method AND in added synchronized
block.

Change-Id: Id3c34613623e743e703aadb2342aa788679dda8a

1 files changed, 16 insertions, 10 deletions

diff --git a/core/java/android/text/format/DateUtils.java b/core/java/android/text/format/DateUtils.java
index a95dad7..353b628 100644
--- a/core/java/android/text/format/DateUtils.java
+++ b/core/java/android/text/format/DateUtils.java
@@ -642,14 +642,18 @@ public class DateUtils
 
     private static void initFormatStrings() {
         synchronized (sLock) {
-            Resources r = Resources.getSystem();
-            Configuration cfg = r.getConfiguration();
-            if (sLastConfig == null || !sLastConfig.equals(cfg)) {
-                sLastConfig = cfg;
-                sStatusTimeFormat = java.text.DateFormat.getTimeInstance(java.text.DateFormat.SHORT);
-                sElapsedFormatMMSS = r.getString(com.android.internal.R.string.elapsed_time_short_format_mm_ss);
-                sElapsedFormatHMMSS = r.getString(com.android.internal.R.string.elapsed_time_short_format_h_mm_ss);
-            }
+            initFormatStringsLocked();
+        }
+    }
+
+    private static void initFormatStringsLocked() {
+        Resources r = Resources.getSystem();
+        Configuration cfg = r.getConfiguration();
+        if (sLastConfig == null || !sLastConfig.equals(cfg)) {
+            sLastConfig = cfg;
+            sStatusTimeFormat = java.text.DateFormat.getTimeInstance(java.text.DateFormat.SHORT);
+            sElapsedFormatMMSS = r.getString(com.android.internal.R.string.elapsed_time_short_format_mm_ss);
+            sElapsedFormatHMMSS = r.getString(com.android.internal.R.string.elapsed_time_short_format_h_mm_ss);
         }
     }
 
@@ -659,8 +663,10 @@ public class DateUtils
      * @hide
      */
     public static final CharSequence timeString(long millis) {
-        initFormatStrings();
-        return sStatusTimeFormat.format(millis);
+        synchronized (sLock) {
+            initFormatStringsLocked();
+            return sStatusTimeFormat.format(millis);
+        }
     }
 
     /**