com.github.benmanes.caffeine.cache.simulator.parser.cache2k.Cache2kTraceReader.java Source code

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Here is the source code for com.github.benmanes.caffeine.cache.simulator.parser.cache2k.Cache2kTraceReader.java

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/*
 * Copyright 2016 Ben Manes. All Rights Reserved.
 *
 * 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 com.github.benmanes.caffeine.cache.simulator.parser.cache2k;

import static java.util.Objects.requireNonNull;

import java.io.BufferedInputStream;
import java.io.DataInputStream;
import java.io.EOFException;
import java.io.IOException;
import java.io.UncheckedIOException;
import java.util.List;
import java.util.NoSuchElementException;
import java.util.PrimitiveIterator;
import java.util.Spliterator;
import java.util.Spliterators;
import java.util.stream.LongStream;
import java.util.stream.StreamSupport;

import com.github.benmanes.caffeine.cache.simulator.parser.AbstractTraceReader;
import com.google.common.io.Closeables;

/**
 * A reader for the trace files provided by the author of cache2k. See
 * <a href="https://github.com/cache2k/cache2k-benchmark">traces</a>.
 *
 * @author ben.manes@gmail.com (Ben Manes)
 */
public final class Cache2kTraceReader extends AbstractTraceReader {

    public Cache2kTraceReader(List<String> filePaths) {
        super(filePaths);
    }

    @Override
    public LongStream events() throws IOException {
        DataInputStream input = new DataInputStream(new BufferedInputStream(readFiles()));
        LongStream stream = StreamSupport.longStream(
                Spliterators.spliteratorUnknownSize(new TraceIterator(input), Spliterator.ORDERED),
                /* parallel */ false);
        return stream.onClose(() -> Closeables.closeQuietly(input));
    }

    private static final class TraceIterator implements PrimitiveIterator.OfLong {
        final DataInputStream input;

        TraceIterator(DataInputStream input) {
            this.input = requireNonNull(input);
        }

        @Override
        public boolean hasNext() {
            try {
                input.mark(100);
                input.readInt();
                input.reset();
                return true;
            } catch (EOFException e) {
                return false;
            } catch (IOException e) {
                throw new UncheckedIOException(e);
            }
        }

        @Override
        public long nextLong() {
            if (!hasNext()) {
                throw new NoSuchElementException();
            }
            try {
                return input.readInt();
            } catch (IOException e) {
                throw new UncheckedIOException(e);
            }
        }
    }
}