HierarchicalFacets.java

/**
 * Copyright (c) 2015 Lemur Consulting Ltd.
 * <p/>
 * Licensed 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
 * <p/>
 * http://www.apache.org/licenses/LICENSE-2.0
 * <p/>
 * 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 uk.co.flax.biosolr;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Executor;
import java.util.concurrent.Future;
import java.util.concurrent.FutureTask;
import java.util.concurrent.RunnableFuture;
import java.util.concurrent.Semaphore;
import java.util.concurrent.SynchronousQueue;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;

import org.apache.solr.common.SolrException;
import org.apache.solr.common.SolrException.ErrorCode;
import org.apache.solr.common.params.FacetParams;
import org.apache.solr.common.params.SolrParams;
import org.apache.solr.common.util.NamedList;
import org.apache.solr.common.util.SimpleOrderedMap;
import org.apache.solr.handler.component.ResponseBuilder;
import org.apache.solr.request.SimpleFacets;
import org.apache.solr.request.SolrQueryRequest;
import org.apache.solr.search.DocSet;
import org.apache.solr.search.QueryParsing;
import org.apache.solr.search.SyntaxError;
import org.apache.solr.util.DefaultSolrThreadFactory;

import uk.co.flax.biosolr.builders.FacetTreeBuilder;
import uk.co.flax.biosolr.builders.FacetTreeBuilderFactory;
import uk.co.flax.biosolr.pruning.PrunerFactory;

/**
 * Facet generator to process and build one or more hierarchical facet
 * trees. This deals with the parameter processing and retrieving the
 * base facet values, before handing over to {@link FacetTreeGenerator}
 * instances to actually build the facet tree.
 * 
 * @author mlp
 */
public class HierarchicalFacets extends SimpleFacets {

	private final FacetTreeParameters parameters;

	static final Executor directExecutor = new Executor() {
		@Override
		public void execute(Runnable r) {
			r.run();
		}
	};

	static final Executor facetExecutor = new ThreadPoolExecutor(0, Integer.MAX_VALUE, 
			10, TimeUnit.SECONDS, // terminate idle threads after 10 sec
			new SynchronousQueue<Runnable>(), // directly hand off tasks
			new DefaultSolrThreadFactory("facetExecutor"));

	public HierarchicalFacets(SolrQueryRequest req, DocSet docs, SolrParams params, ResponseBuilder rb, FacetTreeParameters ftParams) {
		super(req, docs, params, rb);
		this.parameters = ftParams;
	}

	@SuppressWarnings({ "rawtypes", "unchecked" })
	public SimpleOrderedMap<NamedList> process(String[] facetTrees) throws IOException {
		if (!rb.doFacets || facetTrees == null || facetTrees.length == 0) {
			return null;
		}

		int maxThreads = req.getParams().getInt(FacetParams.FACET_THREADS, 0);
		Executor executor = maxThreads == 0 ? directExecutor : facetExecutor;
		final Semaphore semaphore = new Semaphore((maxThreads <= 0) ? Integer.MAX_VALUE : maxThreads);
		List<Future<NamedList>> futures = new ArrayList<>(facetTrees.length);

		SimpleOrderedMap<NamedList> treeResponse = new SimpleOrderedMap<>();
		try {
			FacetTreeBuilderFactory treeBuilderFactory = new FacetTreeBuilderFactory();
			PrunerFactory prunerFactory = new PrunerFactory(parameters);
			
			for (String fTree : facetTrees) {
				try {
					ParsedParams parsedParams = parseParams(FacetTreeParameters.LOCAL_PARAM_TYPE, fTree);
					SolrParams localParams = parsedParams.localParams;
					FacetTreeBuilder treeBuilder = treeBuilderFactory.constructFacetTreeBuilder(localParams);
					final String localKey = localParams.get(QueryParsing.V);
					
					final FacetTreeGenerator generator = new FacetTreeGenerator(treeBuilder, 
							localParams.get(FacetTreeParameters.COLLECTION_PARAM, null),
							prunerFactory.constructPruner(localParams));
					final NamedList<Integer> termCounts = getTermCounts(localKey, parsedParams);
					Callable<NamedList> callable = new Callable<NamedList>() {
						@Override
						public NamedList call() throws Exception {
							try {
								List<SimpleOrderedMap<Object>> tree = generator.generateTree(rb, termCounts);
								NamedList<List<SimpleOrderedMap<Object>>> nl = new NamedList<>();
								nl.add(localKey, tree);
								return nl;
							} finally {
								semaphore.release();
							}
						}
					};

					RunnableFuture<NamedList> runnableFuture = new FutureTask<>(callable);
					semaphore.acquire();// may block and/or interrupt
					executor.execute(runnableFuture);// releases semaphore when done
					futures.add(runnableFuture);
				} catch (SyntaxError e) {
					throw new SolrException(ErrorCode.BAD_REQUEST, e);
				}
			}

			// Loop over futures to get the values. The order is the same as
			// facetTrees but shouldn't matter.
			for (Future<NamedList> future : futures) {
				treeResponse.addAll(future.get());
			}
		} catch (InterruptedException e) {
			throw new SolrException(SolrException.ErrorCode.SERVER_ERROR,
					"Error while processing facet tree fields: InterruptedException", e);
		} catch (ExecutionException ee) {
			Throwable e = ee.getCause();// unwrap
			if (e instanceof RuntimeException) {
				throw (RuntimeException) e;
			}
			throw new SolrException(SolrException.ErrorCode.SERVER_ERROR, "Error while processing facet tree fields: "
					+ e.toString(), e);
		}

		return treeResponse;
	}

}