svn commit: r1325207 - in /avro/trunk: CHANGES.txt lang/java/avro/src/main/java/org/apache/avro/SchemaNormalization.java

[thiru]

Author: thiru
Date: Thu Apr 12 11:24:41 2012
New Revision: 1325207

URL: http://svn.apache.org/viewvc?rev=1325207&view=rev
Log:
AVRO-1055. Race condition in Java fingerprinting code

Modified:
    avro/trunk/CHANGES.txt
    
avro/trunk/lang/java/avro/src/main/java/org/apache/avro/SchemaNormalization.java

Modified: avro/trunk/CHANGES.txt
URL: 
http://svn.apache.org/viewvc/avro/trunk/CHANGES.txt?rev=1325207&r1=1325206&r2=1325207&view=diff
==============================================================================
--- avro/trunk/CHANGES.txt (original)
+++ avro/trunk/CHANGES.txt Thu Apr 12 11:24:41 2012
@@ -20,6 +20,8 @@ Avro 1.7.0 (unreleased)
     AVRO-1045. Java: Fix a bug in GenericData#deepCopy() of ByteBuffer values.
     (cutting)
 
+    AVRO-1055. Race condition in Java fingerprinting code (thiru)
+
 Avro 1.6.3 (5 March 2012)
 
   IMPROVEMENTS

Modified: 
avro/trunk/lang/java/avro/src/main/java/org/apache/avro/SchemaNormalization.java
URL: 
http://svn.apache.org/viewvc/avro/trunk/lang/java/avro/src/main/java/org/apache/avro/SchemaNormalization.java?rev=1325207&r1=1325206&r2=1325207&view=diff
==============================================================================
--- 
avro/trunk/lang/java/avro/src/main/java/org/apache/avro/SchemaNormalization.java
 (original)
+++ 
avro/trunk/lang/java/avro/src/main/java/org/apache/avro/SchemaNormalization.java
 Thu Apr 12 11:24:41 2012
@@ -78,10 +78,9 @@ public class SchemaNormalization {
   /** Returns the 64-bit Rabin Fingerprint (as recommended in the Avro
     * spec) of a byte string. */
   public static long fingerprint64(byte[] data) {
-    if (fpTable64 == null) fillFPTable64();
     long result = EMPTY64;
     for (byte b: data)
-      result = (result >>> 8) ^ fpTable64[(int)(result ^ b) & 0xff];
+      result = (result >>> 8) ^ FP64.FP_TABLE[(int)(result ^ b) & 0xff];
     return result;
   }
 
@@ -157,17 +156,19 @@ public class SchemaNormalization {
   }
 
   final static long EMPTY64 = 0xc15d213aa4d7a795L;
-  private static long[] fpTable64 = null;
 
-  private static void fillFPTable64() {
-    fpTable64 = new long[256];
-    for (int i = 0; i < 256; i++) {
-      long fp = i;
-      for (int j = 0; j < 8; j++) {
-        long mask = -(fp & 1L);
-        fp = (fp >>> 1) ^ (EMPTY64 & mask);
+  /* An inner class ensures that FP_TABLE initialized only when needed. */
+  private static class FP64 {
+    private static final long[] FP_TABLE = new long[256];
+    static {
+      for (int i = 0; i < 256; i++) {
+        long fp = i;
+        for (int j = 0; j < 8; j++) {
+          long mask = -(fp & 1L);
+          fp = (fp >>> 1) ^ (EMPTY64 & mask);
+        }
+        FP_TABLE[i] = fp;
       }
-      fpTable64[i] = fp;
     }
   }
 }