subprojects/s4-core/src/main/java/org/apache/s4/core/ft/CheckpointId.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.s4.core.ft;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

import org.apache.s4.core.ProcessingElement;

/**
 * <p>
 * Identifier of PEs. It is used to identify checkpointed PEs in the storage backend.
 * </p>
 * <p>
 * The storage backend is responsible for converting this identifier to whatever internal representation is most
 * suitable for it.
 * </p>
 * <p>
 * This class provides methods for getting a compact String representation of the identifier and for creating an
 * identifier from a String representation.
 * </p>
 *
 */
public class CheckpointId {

    private String prototypeId;
    private String key;

    private static final Pattern STRING_REPRESENTATION_PATTERN = Pattern.compile("\\[(\\S*)\\];\\[(\\S*)\\]");

    public CheckpointId() {
    }

    public CheckpointId(ProcessingElement pe) {
        this.prototypeId = pe.getPrototype().getClass().getName();
        this.key = pe.getId();
    }

    /**
     *
     * @param prototypeID
     *            id of the PE as returned by {@link ProcessingElement#getId() getId()} method
     * @param key
     *            keyed attribute(s)
     */
    public CheckpointId(String prototypeID, String key) {
        super();
        this.prototypeId = prototypeID;
        this.key = key;
    }

    public CheckpointId(String keyAsString) {
        Matcher matcher = STRING_REPRESENTATION_PATTERN.matcher(keyAsString);

        try {
            matcher.find();
            prototypeId = "".equals(matcher.group(1)) ? null : matcher.group(1);
            key = "".equals(matcher.group(2)) ? null : matcher.group(2);
        } catch (IndexOutOfBoundsException e) {

        }

    }

    public String getKey() {
        return key;
    }

    public String getPrototypeId() {
        return prototypeId;
    }

    public String toString() {
        return "[PROTO_ID];[KEY] --> " + getStringRepresentation();
    }

    public String getStringRepresentation() {
        return "[" + (prototypeId == null ? "" : prototypeId) + "];[" + (key == null ? "" : key) + "]";
    }

    @Override
    public int hashCode() {
        return getStringRepresentation().hashCode();
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj) {
            return true;
        }
        if ((obj == null) || (getClass() != obj.getClass())) {
            return false;
        }

        CheckpointId other = (CheckpointId) obj;
        if (key == null) {
            if (other.key != null)
                return false;
        } else if (!key.equals(other.key))
            return false;
        if (prototypeId == null) {
            if (other.prototypeId != null)
                return false;
        } else if (!prototypeId.equals(other.prototypeId))
            return false;
        return true;
    }

}