// Copyright 2017 JanusGraph Authors
//
// Licensed 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.janusgraph.hadoop.compat;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import org.apache.hadoop.util.VersionInfo;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class HadoopCompatLoader {
private static final Logger log =
LoggerFactory.getLogger(HadoopCompatLoader.class);
public static final HadoopCompat DEFAULT_COMPAT = getCompat();
// TODO add a string argument that allows specifying a class instead of relying heuristics around VersionInfo.getVersion()
// TODO add threadsafe caching that is aware of the string argument and instantiates a compat for each argument at most once (assuming the instantiation succeeds)
public static HadoopCompat getCompat() {
String ver = VersionInfo.getVersion();
log.debug("Read Hadoop VersionInfo string {}", ver);
final String pkgName = HadoopCompatLoader.class.getPackage().getName();
final String className;
if (ver.startsWith("1.")) {
className = pkgName + ".h1.Hadoop1Compat";
} else {
className = pkgName + ".h2.Hadoop2Compat";
}
log.debug("Attempting to load class {} and instantiate with nullary constructor", className);
try {
Constructor<?> ctor = Class.forName(className).getConstructor();
log.debug("Invoking constructor {}", ctor);
return (HadoopCompat)ctor.newInstance();
} catch (NoSuchMethodException e) {
throw new RuntimeException(e);
} catch (SecurityException e) {
throw new RuntimeException(e);
} catch (ClassNotFoundException e) {
throw new RuntimeException(e);
} catch (InstantiationException e) {
throw new RuntimeException(e);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
} catch (IllegalArgumentException e) {
throw new RuntimeException(e);
} catch (InvocationTargetException e) {
throw new RuntimeException(e);
}
}
}