Merge pull request mongodb#59 from rwallace/master

Use COW in BSON.java to eliminate contention

Author: bwmcadams

src/main/org/bson/BSON.java

@@ -22,7 +22,7 @@
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
-import java.util.Vector;
+import java.util.concurrent.CopyOnWriteArrayList;
 import java.util.logging.Logger;
 import java.util.regex.Pattern;
 
@@ -175,7 +175,7 @@ public static void addEncodingHook( Class c , Transformer t ){
         _encodeHooks = true;
         List<Transformer> l = _encodingHooks.get( c );
         if ( l == null ){
-            l = new Vector<Transformer>();
+            l = new CopyOnWriteArrayList<Transformer>();
             _encodingHooks.put( c , l );
         }
         l.add( t );
@@ -185,7 +185,7 @@ public static void addDecodingHook( Class c , Transformer t ){
         _decodeHooks = true;
         List<Transformer> l = _decodingHooks.get( c );
         if ( l == null ){
-            l = new Vector<Transformer>();
+            l = new CopyOnWriteArrayList<Transformer>();
             _decodingHooks.put( c , l );
         }
         l.add( t );