/*
* LensKit, an open source recommender systems toolkit.
* Copyright 2010-2014 LensKit Contributors. See CONTRIBUTORS.md.
* Work on LensKit has been funded by the National Science Foundation under
* grants IIS 05-34939, 08-08692, 08-12148, and 10-17697.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
* FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
* details.
*
* You should have received a copy of the GNU General Public License along with
* this program; if not, write to the Free Software Foundation, Inc., 51
* Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
package org.grouplens.lenskit.inject;
import org.grouplens.grapht.Component;
import org.grouplens.grapht.Dependency;
import org.grouplens.grapht.InjectionException;
import org.grouplens.grapht.graph.DAGNode;
import org.grouplens.lenskit.RecommenderBuildException;
import org.grouplens.lenskit.core.LenskitConfiguration;
import org.grouplens.lenskit.core.RecommenderConfigurationException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.util.Set;
/**
* Process a recommender graph to deal with its shareable nodes.
*
* @since 1.2
* @compat Experimental
* @author <a href="http://www.grouplens.org">GroupLens Research</a>
*/
public final class RecommenderInstantiator {
private static final Logger logger = LoggerFactory.getLogger(RecommenderInstantiator.class);
private final DAGNode<Component, Dependency> graph;
private final NodeInstantiator instantiator;
public static RecommenderInstantiator create(DAGNode<Component,Dependency> g) {
return new RecommenderInstantiator(g, NodeInstantiator.create());
}
public static RecommenderInstantiator create(DAGNode<Component,Dependency> g,
NodeInstantiator instantiator) {
return new RecommenderInstantiator(g, instantiator);
}
@Deprecated
public static RecommenderInstantiator forConfig(LenskitConfiguration config) throws RecommenderConfigurationException {
return create(config.buildGraph());
}
private RecommenderInstantiator(DAGNode<Component, Dependency> g, NodeInstantiator inst) {
graph = g;
instantiator = inst;
}
/**
* Get the graph from this instantiator.
*
* @return The graph. This method returns a defensive copy, so modifying it will not modify the
* graph underlying this instantiator.
*/
public DAGNode<Component, Dependency> getGraph() {
return graph;
}
/**
* Instantiate the recommender graph. This requires the graph to have been resolved with a real
* DAO instance, not just a class, if anything references the DAO. Use {@link
* LenskitConfiguration#buildGraph()} to get such a graph.
*
* @return A new recommender graph with all shareable nodes pre-instantiated.
* @throws RecommenderBuildException If there is an error instantiating the graph.
*/
public DAGNode<Component,Dependency> instantiate() throws RecommenderBuildException {
try {
return replaceShareableNodes(NodeProcessors.instantiate(instantiator));
} catch (InjectionException e) {
throw new RecommenderBuildException("Recommender instantiation failed", e);
}
}
/**
* Simulate instantiating a graph.
* @return The simulated graph.
*/
public DAGNode<Component,Dependency> simulate() throws RecommenderBuildException {
try {
return replaceShareableNodes(NodeProcessors.simulateInstantiation());
} catch (InjectionException e) {
throw new RecommenderBuildException("Simulated instantiation failed", e);
}
}
/**
* Replace shareable nodes in a graph.
*
* @param replace A replacement function. For each shareable node, this function will
* be called; if it returns a node different from its input node, the
* new node will be used as a replacement for the old.
*/
private DAGNode<Component,Dependency> replaceShareableNodes(NodeProcessor replace) throws InjectionException {
logger.debug("replacing nodes in graph with {} nodes", graph.getReachableNodes().size());
Set<DAGNode<Component,Dependency>> toReplace = GraphtUtils.getShareableNodes(graph);
logger.debug("found {} shared nodes", toReplace.size());
DAGNode<Component, Dependency> result =
NodeProcessors.processNodes(graph, toReplace, replace);
logger.debug("final graph has {} nodes", result.getReachableNodes().size());
return result;
}
}