Github user paul-rogers commented on a diff in the pull request:
https://github.com/apache/drill/pull/660#discussion_r91632144
--- Diff:
exec/java-exec/src/main/java/org/apache/drill/exec/compile/CachedClassLoader.java
---
@@ -0,0 +1,70 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.drill.exec.compile;
+
+import java.net.URL;
+import java.net.URLClassLoader;
+import java.util.Map;
+import java.util.concurrent.ConcurrentMap;
+
+import com.google.common.collect.MapMaker;
+
+/**
+ * Class loader for "plain-old Java" generated classes.
+ * Very basic implementation: allows defining a class from
+ * byte codes and finding the loaded classes. Delegates
+ * all other class requests to the thread context class
+ * loader. This structure ensures that a generated class can
+ * find both its own inner classes as well as all the standard
+ * Drill implementation classes.
+ */
+
+public class CachedClassLoader extends URLClassLoader {
+
+ /**
+ * Cache of generated classes. Semantics: a single thread defines
+ * the classes, many threads may access the classes.
+ */
+
+ private ConcurrentMap<String, Class<?>> cache = new
MapMaker().concurrencyLevel(4).makeMap();
+
+ public CachedClassLoader( ) {
+ super(new URL[0], Thread.currentThread().getContextClassLoader());
+ }
+
+ public void addClass( String fqcn, byte[] byteCodes ) {
+
+ assert ! cache.containsKey( fqcn );
--- End diff --
Done. Preconditions is compiled in, meaning it executes in production.
Asserts fire only in debug. I'll follow the drill standard here, despite the
cost.
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