neoremind commented on a change in pull request #1875: [CALCITE-3873] Use
global caching for ReflectiveVisitDispatcher implementation
URL: https://github.com/apache/calcite/pull/1875#discussion_r398291034
##########
File path: core/src/main/java/org/apache/calcite/util/ReflectUtil.java
##########
@@ -403,71 +403,40 @@ private static Method lookupVisitMethod(
}
/**
- * Creates a dispatcher for calls to {@link #lookupVisitMethod}. The
- * dispatcher caches methods between invocations.
+ * Creates a dispatcher for calls to {@link #lookupVisitMethod}. By default
the
+ * dispatcher caches methods globally. If caching methods between invocations
+ * is preferred, use the overridden method {@link #createDispatcher(Class,
Class, boolean)}.
*
- * @param visitorBaseClazz Visitor base class
- * @param visiteeBaseClazz Visitee base class
+ * @param visitorBaseClazz Visitor base class
+ * @param visiteeBaseClazz Visitee base class
* @return cache of methods
*/
public static <R extends ReflectiveVisitor, E> ReflectiveVisitDispatcher<R,
E> createDispatcher(
final Class<R> visitorBaseClazz,
final Class<E> visiteeBaseClazz) {
+ return createDispatcher(visitorBaseClazz, visiteeBaseClazz, true);
+ }
+
+ /**
+ * Creates a dispatcher for calls to {@link #lookupVisitMethod}.
+ *
+ * @param visitorBaseClazz Visitor base class
+ * @param visiteeBaseClazz Visitee base class
+ * @param useGlobalMethodCache If set to true, the created dispatchers
will
+ * share a globally cache to store methods to
+ * mitigating reflection invocation overhead
+ * when looking up method. If set to false,
every
+ * dispatcher instance will only cache methods
+ * between invocations individually.
+ * @return cache of methods
+ */
+ public static <R extends ReflectiveVisitor, E> ReflectiveVisitDispatcher<R,
E> createDispatcher(
+ final Class<R> visitorBaseClazz,
+ final Class<E> visiteeBaseClazz,
+ final boolean useGlobalMethodCache) {
Review comment:
To maintain backward compatibility, I add one param boolean
`useGlobalMethodCache` to method `ReflectiveVisitDispatcher<R, E>
createDispatcher(..)` and provide an overridden method to make
`useGlobalMethodCache=true` by default, so anywhere else won't be changed, but
the underlying behavior will enable global caching. In case there might be
situations where `ReflectiveVisitDispatcher` is likely to cache per instance
and does not want to bother the global cache, so to make that flexibility
possible I made such change.
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