VisorEither.java

/*
 * 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.ignite.internal.visor;

import java.io.Externalizable;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectOutput;
import org.apache.ignite.internal.util.typedef.internal.S;

/**
 * Base class for Visor result with error.
 *
 * @param <T> Result type.
 */
public class VisorEither<T> implements Externalizable {
    /** */
    private static final long serialVersionUID = 0L;

    /** Exception on execution. */
    private Throwable error;

    /** Result. */
    private T res;

    /**
     * Default constructor.
     */
    public VisorEither() {
        // No-op.
    }

    /**
     * @param error Exception on execution.
     */
    public VisorEither(Throwable error) {
        this.error = error;
    }

    /**
     * @param res Result.
     */
    public VisorEither(T res) {
        this.res = res;
    }

    /**
     * @return {@code true} If failed on execution.
     */
    public boolean failed() {
        return error != null;
    }

    /**
     * @return Exception on execution.
     */
    public Throwable getError() {
        return error;
    }

    /**
     * @return Result.
     */
    public T getResult() {
        return res;
    }

    /** {@inheritDoc} */
    @Override public void writeExternal(ObjectOutput out) throws IOException {
        boolean failed = failed();

        out.writeBoolean(failed);
        out.writeObject(failed ? error : res);
    }

    /** {@inheritDoc} */
    @Override public void readExternal(ObjectInput in) throws IOException, ClassNotFoundException {
        if (in.readBoolean())
            error = (Throwable)in.readObject();
        else
            res = (T)in.readObject();
    }

    /** {@inheritDoc} */
    @Override public String toString() {
        return S.toString(VisorEither.class, this);
    }
}