org.bboxdb.storage.BloomFilterBuilder.java Source code

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Here is the source code for org.bboxdb.storage.BloomFilterBuilder.java

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/*******************************************************************************
 *
 *    Copyright (C) 2015-2016
 *  
 *    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
 *  
 *      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.bboxdb.storage;

import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;

import com.google.common.base.Charsets;
import com.google.common.hash.BloomFilter;
import com.google.common.hash.Funnel;
import com.google.common.hash.PrimitiveSink;

public class BloomFilterBuilder {

    private static final class TupleKeyFunnel implements Funnel<String> {
        /**
         * 
         */
        private static final long serialVersionUID = -2545258829029691131L;

        @Override
        public void funnel(final String argument, final PrimitiveSink into) {
            into.putString(argument, Charsets.UTF_8);
        }
    }

    /**
     * Create a bloom filter for a given number of keys
     * @param entries
     * @return
     */
    public static BloomFilter<String> buildBloomFilter(final long entries) {
        return BloomFilter.create(new TupleKeyFunnel(), entries);
    }

    /**
     * Load a persistent bloom filter into memory
     * @param file
     * @return 
     * @throws IOException
     */
    public static BloomFilter<String> loadBloomFilterFromFile(final File file) throws IOException {

        try (final InputStream inputStream = new BufferedInputStream(new FileInputStream(file));) {
            return BloomFilter.readFrom(inputStream, new TupleKeyFunnel());
        } catch (IOException e) {
            throw e;
        }
    }
}