Mercurial > dive4elements > river
view artifacts/src/main/java/org/dive4elements/river/artifacts/CollectionMonitor.java @ 7471:fff862f4ef76
Experimental caching of datacage recommendations. The respective hook is called a lot and running the datacage over and over again when loading data can be expensive. So the generated recommendations are cached for some time.
Hopefully this improves the overall speed of loading data from the datacage.
author | Sascha L. Teichmann <teichmann@intevation.de> |
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date | Wed, 30 Oct 2013 15:26:21 +0100 |
parents | f16dce7a2407 |
children | f8e1af4e2f69 |
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/* Copyright (C) 2011, 2012, 2013 by Bundesanstalt für Gewässerkunde * Software engineering by Intevation GmbH * * This file is Free Software under the GNU AGPL (>=v3) * and comes with ABSOLUTELY NO WARRANTY! Check out the * documentation coming with Dive4Elements River for details. */ package org.dive4elements.river.artifacts; import java.util.HashMap; import java.util.List; import java.util.Map; import net.sf.ehcache.Cache; import org.w3c.dom.Document; import org.w3c.dom.Element; import org.w3c.dom.Node; import org.w3c.dom.NodeList; import org.dive4elements.artifacts.Artifact; import org.dive4elements.artifacts.ArtifactNamespaceContext; import org.dive4elements.artifacts.CallContext; import org.dive4elements.artifacts.Hook; import org.dive4elements.artifacts.common.utils.XMLUtils; import org.dive4elements.artifacts.common.utils.XMLUtils.ElementCreator; import org.dive4elements.artifactdatabase.state.Output; import org.dive4elements.river.artifacts.cache.CacheFactory; import org.dive4elements.river.artifacts.datacage.Recommendations; /** Monitors collection changes. */ public class CollectionMonitor implements Hook { public static final String CACHE_NAME = "recommendations"; @Override public void setup(Node cfg) { } @Override public void execute(Artifact artifact, CallContext context, Document doc) { D4EArtifact flys = (D4EArtifact) artifact; // Do not generate recommendations for a loaded artifact. String out = flys.getBoundToOut(); if (out != null && !out.isEmpty()) { return; } NodeList results = doc.getElementsByTagNameNS( ArtifactNamespaceContext.NAMESPACE_URI, "result"); if (results.getLength() < 1) { return; } Element result = (Element)results.item(0); result.appendChild(getRecommendedElement(flys, context, doc)); } protected Element getRecommendedElement( D4EArtifact artifact, CallContext context, Document doc ) { String [] outs = extractOutputNames(artifact, context); Element recommendations = null; Cache cache = CacheFactory.getCache(CACHE_NAME); if (cache != null) { String key = generateCacheKey(artifact, outs); net.sf.ehcache.Element ce = cache.get(key); if (ce != null) { // Found in cache. Element e = (Element)ce.getValue(); // Sync to avoid thread issues with XML DOM docs. synchronized (e.getOwnerDocument()) { recommendations = (Element)doc.importNode(e, true); } } else { // Not found in cache -> generate it. Element r = createElement(XMLUtils.newDocument()); Recommendations.getInstance().recommend( artifact, null, outs, getNoneUserSpecificParameters(artifact, context), r); recommendations = (Element)doc.importNode(r, true); cache.put(new net.sf.ehcache.Element(key, r)); } } else { // No cache configured -> append directly. recommendations = createElement(doc); Recommendations.getInstance().recommend( artifact, null, outs, getNoneUserSpecificParameters(artifact, context), recommendations); } return recommendations; } private static final Element createElement(Document doc) { ElementCreator creator = new ElementCreator( doc, ArtifactNamespaceContext.NAMESPACE_URI, ArtifactNamespaceContext.NAMESPACE_PREFIX); return creator.create("recommended-artifacts"); } private static final String generateCacheKey(D4EArtifact artifact, String [] outs) { StringBuilder sb = new StringBuilder(artifact.hash()); // XXX: The hash really should be unique enough. for (String out: outs) { sb.append(';').append(out); } return sb.toString(); } /** * Get outputnames from current state (only the ones for which * facets exist). */ private static final String [] extractOutputNames( D4EArtifact flys, CallContext context) { if (flys instanceof ChartArtifact) { return new String[0]; } List<Output> outs = flys.getCurrentOutputs(context); int num = outs == null ? 0 : outs.size(); String[] names = new String[num]; for (int i = 0; i < num; i++) { names[i] = outs.get(i).getName(); } return names; } /** * Creates Map from Strings "recommended" to "true". */ private static final Map<String, Object> getNoneUserSpecificParameters( D4EArtifact flys, CallContext context) { Map<String, Object> params = new HashMap<String, Object>(); params.put("recommended", "true"); return params; } } // vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :