org.apache.hadoop.hbase.procedure.ProcedureManagerHost.java Source code

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Here is the source code for org.apache.hadoop.hbase.procedure.ProcedureManagerHost.java

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/**
 * 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.hadoop.hbase.procedure;

import java.io.IOException;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.Set;
import java.util.List;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;

/**
 * Provides the common setup framework and runtime services for globally
 * barriered procedure invocation from HBase services.
 * @param <E> the specific procedure management extension that a concrete
 * implementation provides
 */
@InterfaceAudience.Private
@InterfaceStability.Evolving
public abstract class ProcedureManagerHost<E extends ProcedureManager> {

    public static final String REGIONSERVER_PROCEDURE_CONF_KEY = "hbase.procedure.regionserver.classes";
    public static final String MASTER_PROCEUDRE_CONF_KEY = "hbase.procedure.master.classes";

    private static final Log LOG = LogFactory.getLog(ProcedureManagerHost.class);

    protected Set<E> procedures = new HashSet<E>();

    /**
     * Load system procedures. Read the class names from configuration.
     * Called by constructor.
     */
    protected void loadUserProcedures(Configuration conf, String confKey) {
        Class<?> implClass = null;

        // load default procedures from configure file
        String[] defaultProcClasses = conf.getStrings(confKey);
        if (defaultProcClasses == null || defaultProcClasses.length == 0)
            return;

        List<E> configured = new ArrayList<E>();
        for (String className : defaultProcClasses) {
            className = className.trim();
            ClassLoader cl = this.getClass().getClassLoader();
            Thread.currentThread().setContextClassLoader(cl);
            try {
                implClass = cl.loadClass(className);
                configured.add(loadInstance(implClass));
                LOG.info("User procedure " + className + " was loaded successfully.");
            } catch (ClassNotFoundException e) {
                LOG.warn("Class " + className + " cannot be found. " + e.getMessage());
            } catch (IOException e) {
                LOG.warn("Load procedure " + className + " failed. " + e.getMessage());
            }
        }

        // add entire set to the collection
        procedures.addAll(configured);
    }

    @SuppressWarnings("unchecked")
    public E loadInstance(Class<?> implClass) throws IOException {
        // create the instance
        E impl;
        Object o = null;
        try {
            o = implClass.newInstance();
            impl = (E) o;
        } catch (InstantiationException e) {
            throw new IOException(e);
        } catch (IllegalAccessException e) {
            throw new IOException(e);
        }

        return impl;
    }

    // Register a procedure manager object
    public void register(E obj) {
        procedures.add(obj);
    }

    public Set<E> getProcedureManagers() {
        Set<E> returnValue = new HashSet<E>();
        for (E e : procedures) {
            returnValue.add(e);
        }
        return returnValue;
    }

    public abstract void loadProcedures(Configuration conf);
}