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ARQ is a SPARQL 1.1 query engine for Apache Jena
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/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * 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 org.apache.jena.riot.system;

import java.util.concurrent.ExecutionException ;

import org.apache.jena.ext.com.google.common.cache.Cache ;
import org.apache.jena.atlas.lib.cache.CacheInfo ;
import org.apache.jena.datatypes.RDFDatatype ;
import org.apache.jena.datatypes.xsd.XSDDatatype ;
import org.apache.jena.ext.com.google.common.cache.CacheBuilder ;
import org.apache.jena.ext.com.google.common.cache.CacheStats ;
import org.apache.jena.graph.Node ;
import org.apache.jena.riot.RiotException ;
import org.apache.jena.riot.lang.LabelToNode ;
import org.apache.jena.sparql.graph.NodeConst ;

/** Adds some caching of created nodes - the caching is tuned to RIOT parser usage */
public class FactoryRDFCaching extends FactoryRDFStd {
    public static final int DftNodeCacheSize = 5000 ;

    // Control the setup - for one thread; start size = 50% of full size, no stats
    private final Cache cache ;

    public FactoryRDFCaching() {
        this(DftNodeCacheSize, SyntaxLabels.createLabelToNode());
    }

    public FactoryRDFCaching(int cacheSize, LabelToNode labelMapping) {
        super(labelMapping) ;
        cache = setCache(cacheSize) ;
    }

    private Cache setCache(int cacheSize) {
        return CacheBuilder.newBuilder()
            .maximumSize(cacheSize)
            .initialCapacity(cacheSize/2)
            //.recordStats()
            .concurrencyLevel(1)
            .build() ;
    }

    @Override
    public Node createURI(String uriStr) {
        try {
            return cache.get(uriStr, ()->RiotLib.createIRIorBNode(uriStr)) ;
        }
        catch (ExecutionException e) {
            throw new RiotException("Execution exception filling cache <"+uriStr+">", e) ;
        }
    }

    // A few constants

    @Override
    public Node createTypedLiteral(String lexical, RDFDatatype datatype) {
        if ( XSDDatatype.XSDinteger.equals(datatype) ) {
            switch(lexical) {
                case "0" : return NodeConst.nodeZero ;
                case "1" : return NodeConst.nodeOne ;
                case "2" : return NodeConst.nodeTwo ;
                case "-1" : return NodeConst.nodeMinusOne ;
            }
            // fallthrough.
        } else if ( XSDDatatype.XSDboolean.equals(datatype) ) {
            switch(lexical) {
                case "true" : return NodeConst.nodeTrue ;
                case "false" : return NodeConst.nodeFalse ;
            }
            // fallthrough.
        }
        return super.createTypedLiteral(lexical, datatype) ;
    }

    @Override
    public Node createStringLiteral(String lexical) {
        if ( lexical.isEmpty() )
            return NodeConst.emptyString ;
        return super.createStringLiteral(lexical) ;
    }

    // The cache is not reset.  It can be carried across parser runs.
//    @Override
//    public void reset() {
//        super.reset();
//    }

    public CacheInfo stats() {
        CacheStats stats = cache.stats() ;
        if ( stats.missCount() == 0 && stats.hitCount() == 0 )
            // Stats not enabled - all counts zero.
            return null ;
        return new CacheInfo(DftNodeCacheSize, stats) ;
    }
}