001/*
002 * (C) Copyright 2006-2011 Nuxeo SA (http://nuxeo.com/) and others.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *     http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 *
016 * Contributors:
017 *     Florent Guillaume
018 */
019
020package org.nuxeo.ecm.core.storage.sql;
021
022import java.io.Serializable;
023import java.util.Arrays;
024
025import org.nuxeo.ecm.core.storage.sql.RowMapper.RowUpdate;
026
027/**
028 * A type of fragment corresponding to several rows with the same id.
029 */
030public class CollectionFragment extends Fragment {
031
032    private static final long serialVersionUID = 1L;
033
034    /**
035     * Constructs a {@link CollectionFragment} from a {@link Row}.
036     *
037     * @param row the row
038     * @param state the initial state for the fragment
039     * @param context the persistence context to which the fragment is tied, or {@code null}
040     */
041    public CollectionFragment(Row row, State state, PersistenceContext context) {
042        super(row, state, context);
043    }
044
045    /**
046     * Sets a collection value.
047     *
048     * @param value the value
049     */
050    public void set(Serializable[] value) {
051        // unless invalidated (in which case don't try to refetch the value just
052        // to compare state), don't mark modified or dirty if there is no change
053        if (getState() != State.INVALIDATED_MODIFIED) {
054            // not invalidated, so no need to call accessed()
055            if (Arrays.equals(row.values, value)) {
056                return;
057            }
058        }
059        row.values = value.clone();
060        markModified();
061    }
062
063    /**
064     * Gets the collection value.
065     *
066     * @return the value
067     */
068    public Serializable[] get() {
069        accessed();
070        return row.values.clone();
071    }
072
073    /**
074     * Checks if the array is dirty (values changed since last clear).
075     *
076     * @return {@code true} if the array changed
077     */
078    public boolean isDirty() {
079        return !Arrays.equals(row.values, oldvalues);
080    }
081
082    @Override
083    public RowUpdate getRowUpdate() {
084        if (Arrays.equals(row.values, oldvalues)) {
085            return null;
086        }
087        // check if we have a list append
088        if (oldvalues == null) {
089            // row.values != null otherwise we would have returned already
090            return new RowUpdate(row, 0);
091        } else if (row.values != null && isPrefix(oldvalues, row.values)) {
092            return new RowUpdate(row, oldvalues.length);
093        } else {
094            // full update, row.values may be null
095            return new RowUpdate(row);
096        }
097    }
098
099    /**
100     * Checks if the left array is a strict prefix of the right one.
101     *
102     * @since 8.3
103     */
104    public static boolean isPrefix(Serializable[] left, Serializable[] right) {
105        if (left.length >= right.length) {
106            return false;
107        }
108        for (int i = 0; i < left.length; i++) {
109            Serializable o1 = left[i];
110            Serializable o2 = right[i];
111            if (!(o1 == null ? o2 == null : o1.equals(o2))) {
112                return false;
113            }
114        }
115        return true;
116    }
117
118    @Override
119    protected State refetch() {
120        row.values = context.mapper.readCollectionRowArray(row);
121        clearDirty();
122        return State.PRISTINE;
123    }
124
125    @Override
126    protected State refetchDeleted() {
127        row.values = context.model.getCollectionFragmentType(row.tableName).getEmptyArray();
128        clearDirty();
129        return State.PRISTINE;
130    }
131
132}