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HttpClient-based client for Riak
There is a newer version: 2.1.1
/*
 * This file is provided 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 com.basho.riak.client.query;

import java.io.IOException;
import java.util.LinkedList;

import com.basho.riak.client.IRiakClient;
import com.basho.riak.client.IRiakObject;
import com.basho.riak.client.RiakException;
import com.basho.riak.client.operations.RiakOperation;
import com.basho.riak.client.query.LinkWalkStep.Accumulate;
import com.basho.riak.client.raw.RawClient;
import com.basho.riak.client.raw.query.LinkWalkSpec;

/**
 * A Link Walk operation, build the operation by adding steps, then execute.
 * 
 * @author russell
 * 
 * @see IRiakClient#walk(IRiakObject)
 */
public class LinkWalk implements RiakOperation {

    private final RawClient client;
    private final String startBucket;
    private final String startKey;
    private final LinkedList steps = new LinkedList();

    /**
     * Create a Link Walk operation that will be executed with
     * client, starting from startObject
     * 
     * @param client
     *            the {@link RawClient} to use
     * @param startObject
     *            the {@link IRiakObject} to start from
     */
    public LinkWalk(final RawClient client, final IRiakObject startObject) {
        this.client = client;
        this.startBucket = startObject.getBucket();
        this.startKey = startObject.getKey();
    }

    /**
     * Run the Link Walk query on the {@link RawClient} the operation was constructed with.
     * 
     * @return a {@link WalkResult}
     */
    public WalkResult execute() throws RiakException {
        try {
            return client.linkWalk(new LinkWalkSpec(steps, startBucket, startKey));
        } catch (IOException e) {
            throw new RiakException(e);
        }
    }

    /**
     * Add a link walking step to this link walk
     *
     * @param bucket
     *            the bucket, a null, or empty string is treated as the wildcard
     * @param tag
     *            the tag of the link, a null or empty string is treated as the
     *            wildcard
     * @param accumulate
     *            to keep the result of this step or not
     * @return this
     */
    public LinkWalk addStep(String bucket, String tag, Accumulate accumulate) {
        synchronized (steps) {
            steps.add(new LinkWalkStep(bucket, tag, accumulate));
        }
        return this;
    }

    /**
     * Add a link walking step to this link walk
     *
     * @param bucket
     *            the bucket, a null, or empty string is treated as the wildcard _
     * @param tag
     *            the tag of the link, a null or empty string is treated as the
     *            wildcard
     * @param accumulate
     *            to keep the result of this step or not
     * @return this
     */
    public LinkWalk addStep(String bucket, String tag, boolean keep) {
        synchronized (steps) {
            steps.add(new LinkWalkStep(bucket, tag, keep));
        }
        return this;
    }

    /**
     * Add a link walking step to this link walk using the default accumulate
     * value for the step (NO for all steps accept last step)
     *
     * @param bucket
     *            the bucket, a null, or empty string is treated as the wildcard _
     * @param tag
     *            the tag of the link, a null or empty string is treated as the
     *            wildcard
     * @return this
     */
    public LinkWalk addStep(String bucket, String tag) {
        synchronized (steps) {
            steps.add(new LinkWalkStep(bucket, tag));
        }
        return this;
    }
}