JaQu: the static map Db.TOKENS was not synchronized.

h2/src/tools/org/h2/jaqu/Db.java

@@ -12,6 +12,7 @@ import java.sql.PreparedStatement;
 import java.sql.ResultSet;
 import java.sql.SQLException;
 import java.sql.Statement;
+import java.util.Collections;
 import java.util.List;
 import java.util.Map;
 import java.util.Properties;
@@ -28,8 +29,14 @@ import org.h2.util.JdbcUtils;
 //## Java 1.5 begin ##
 public class Db {
 
-    private static final WeakIdentityHashMap<Object, Token> TOKENS =
-        Utils.newWeakIdentityHashMap();
+    /**
+     * This map It holds unique tokens that are generated by functions such as
+     * Function.sum(..) in "db.from(p).select(Function.sum(p.unitPrice))". It
+     * doesn't actually hold column tokens, as those are bound to the query
+     * itself.
+     */
+    private static final Map<Object, Token> TOKENS =
+        Collections.synchronizedMap(new WeakIdentityHashMap<Object, Token>());
 
     private final Connection conn;
     private final Map<Class<?>, TableDefinition<?>> classMap =

h2/src/tools/org/h2/jaqu/util/Utils.java

@@ -44,10 +44,6 @@ public class Utils {
         return Collections.synchronizedMap(map);
     }
 
-    public static <A, B> WeakIdentityHashMap<A, B> newWeakIdentityHashMap() {
-        return new WeakIdentityHashMap<A, B>();
-    }
-
     public static <A, B> IdentityHashMap<A, B> newIdentityHashMap() {
         return new IdentityHashMap<A, B>();
     }

h2/src/tools/org/h2/jaqu/util/WeakIdentityHashMap.java

@@ -16,13 +16,15 @@ import java.util.Set;
 /**
  * This hash map uses weak references, so that elements that are no longer
  * referenced elsewhere can be garbage collected. It also uses object identity
- * to compare keys.
+ * to compare keys. The garbage collection happens when trying to add new data,
+ * or when resizing.
  *
  * @param <K> the keys
  * @param <V> the value
  */
 //## Java 1.5 begin ##
 public class WeakIdentityHashMap<K, V> implements Map<K, V> {
+
     private static final int MAX_LOAD = 90;
     private static final WeakReference<Object> DELETED_KEY =
         new WeakReference<Object>(null);