001/*
002 * (C) Copyright 2015 Nuxeo SAS (http://nuxeo.com/) and contributors.
003 *
004 * All rights reserved. This program and the accompanying materials
005 * are made available under the terms of the GNU Lesser General Public License
006 * (LGPL) version 2.1 which accompanies this distribution, and is available at
007 * http://www.gnu.org/licenses/lgpl.html
008 *
009 * This library is distributed in the hope that it will be useful,
010 * but WITHOUT ANY WARRANTY; without even the implied warranty of
011 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
012 * Lesser General Public License for more details.
013 *
014 * Contributors:
015 * Nuxeo - initial API and implementation
016 */
017
018package org.nuxeo.ecm.platform.rendition.lazy;
019
020import java.security.MessageDigest;
021import java.security.NoSuchAlgorithmException;
022import java.util.ArrayList;
023import java.util.Calendar;
024import java.util.List;
025
026import org.apache.commons.logging.Log;
027import org.apache.commons.logging.LogFactory;
028import org.nuxeo.ecm.core.api.Blob;
029import org.nuxeo.ecm.core.api.DocumentModel;
030import org.nuxeo.ecm.core.api.NuxeoException;
031import org.nuxeo.ecm.core.api.impl.blob.StringBlob;
032import org.nuxeo.ecm.core.transientstore.api.TransientStore;
033import org.nuxeo.ecm.core.transientstore.api.TransientStoreService;
034import org.nuxeo.ecm.core.work.api.Work;
035import org.nuxeo.ecm.core.work.api.WorkManager;
036import org.nuxeo.ecm.platform.rendition.Rendition;
037import org.nuxeo.ecm.platform.rendition.extension.RenditionProvider;
038import org.nuxeo.ecm.platform.rendition.impl.LazyRendition;
039import org.nuxeo.ecm.platform.rendition.service.RenditionDefinition;
040import org.nuxeo.runtime.api.Framework;
041
042/**
043 * Default implementation of an asynchronous {@link RenditionProvider}
044 *
045 * @author <a href="mailto:tdelprat@nuxeo.com">Tiry</a>
046 * @since 7.2
047 */
048public abstract class AbstractLazyCachableRenditionProvider implements RenditionProvider {
049
050    public static final String WORKERID_KEY = "workerid";
051
052    public static final String CACHE_NAME = "LazyRenditionCache";
053
054    protected static Log log = LogFactory.getLog(AbstractLazyCachableRenditionProvider.class);
055
056    /**
057     * Define if rendition caching key should include the user login
058     *
059     * @return
060     */
061    protected abstract boolean perUserRendition();
062
063    @Override
064    public List<Blob> render(DocumentModel doc, RenditionDefinition def) {
065
066        // build the key
067        String key = buildRenditionKey(doc, def);
068
069        // see if rendition is already in process
070
071        TransientStoreService tss = Framework.getService(TransientStoreService.class);
072
073        TransientStore ts = tss.getStore(CACHE_NAME);
074
075        if (ts == null) {
076            throw new NuxeoException("Unable to find Transient Store  " + CACHE_NAME);
077        }
078
079        if (!ts.exists(key)) {
080            Work work = getRenditionWork(key, doc, def);
081            WorkManager wm = Framework.getService(WorkManager.class);
082            ts.putParameter(key, WORKERID_KEY, work.getId());
083            wm.schedule(work);
084        } else {
085            if (ts.isCompleted(key)) {
086                List<Blob> blobs = ts.getBlobs(key);
087                ts.release(key);
088                return blobs;
089            }
090        }
091        // return an empty Blob
092        List<Blob> blobs = new ArrayList<Blob>();
093        StringBlob emptyBlob = new StringBlob("");
094        emptyBlob.setFilename("inprogress");
095        emptyBlob.setMimeType("text/plain;" + LazyRendition.EMPTY_MARKER);
096        blobs.add(emptyBlob);
097        return blobs;
098    }
099
100    protected String buildRenditionKey(DocumentModel doc, RenditionDefinition def) {
101
102        StringBuffer sb = new StringBuffer(doc.getId());
103        sb.append("::");
104        String modificationDatePropertyName = def.getSourceDocumentModificationDatePropertyName();
105        Calendar modif = (Calendar) doc.getPropertyValue(modificationDatePropertyName);
106        if (modif != null) {
107            sb.append(modif.getTimeInMillis());
108            sb.append("::");
109        }
110        if (perUserRendition()) {
111            sb.append(doc.getCoreSession().getPrincipal().getName());
112            sb.append("::");
113        }
114        sb.append(def.getName());
115
116        return getDigest(sb.toString());
117    }
118
119    protected String getDigest(String key) {
120        MessageDigest digest;
121        try {
122            digest = MessageDigest.getInstance("MD5");
123        } catch (NoSuchAlgorithmException e) {
124            return key;
125        }
126        byte[] buf = digest.digest(key.getBytes());
127        return toHexString(buf);
128    }
129
130    private static final char[] HEX_DIGITS = "0123456789abcdef".toCharArray();
131
132    protected String toHexString(byte[] data) {
133        StringBuilder buf = new StringBuilder(2 * data.length);
134        for (byte b : data) {
135            buf.append(HEX_DIGITS[(0xF0 & b) >> 4]);
136            buf.append(HEX_DIGITS[0x0F & b]);
137        }
138        return buf.toString();
139    }
140
141    /**
142     * Return the {@link Work} that will compute the {@link Rendition}. {@link AbstractRenditionBuilderWork} can be used
143     * as a base class
144     *
145     * @param key the key used to rendition
146     * @param doc the target {@link DocumentModel}
147     * @param def the {@link RenditionDefinition}
148     * @return
149     */
150    protected abstract Work getRenditionWork(final String key, final DocumentModel doc, final RenditionDefinition def);
151
152}