hudson.plugins.timestamper.io.TimestampsReader.java Source code

Introduction

Here is the source code for hudson.plugins.timestamper.io.TimestampsReader.java

Source

/*
 * The MIT License
 * 
 * Copyright (c) 2013 Steven G. Brown
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
package hudson.plugins.timestamper.io;

import hudson.model.Run;
import hudson.plugins.timestamper.Timestamp;

import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;

import com.google.common.base.Optional;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Iterators;
import com.google.common.io.ByteStreams;
import com.google.common.io.Closeables;
import com.google.common.io.CountingInputStream;

/**
 * Read the time-stamps for a build from disk.
 * 
 * @author Steven G. Brown
 */
public final class TimestampsReader implements Serializable {

    private static final long serialVersionUID = 1L;

    private final File timestampsFile;

    private long filePointer;

    private long elapsedMillis;

    private long millisSinceEpoch;

    private long entry;

    private final TimeShiftsReader timeShiftsReader;

    /**
     * Create a time-stamps reader for the given build.
     * 
     * @param build
     */
    public TimestampsReader(Run<?, ?> build) {
        this.timestampsFile = TimestamperPaths.timestampsFile(build);
        this.timeShiftsReader = new TimeShiftsReader(build);
        this.millisSinceEpoch = build.getTimeInMillis();
    }

    /**
     * Skip past the given number of time-stamp entries.
     * 
     * @param count
     *          the number of time-stamp entries to skip
     * @throws IOException
     */
    public void skip(int count) throws IOException {
        read(count, Optional.<List<Timestamp>>absent());
    }

    /**
     * Read the next time-stamp.
     * 
     * @return the next time-stamp, or {@link Optional#absent()} if there are no
     *         more to read
     * @throws IOException
     */
    public Optional<Timestamp> read() throws IOException {
        List<Timestamp> timestamps = new ArrayList<Timestamp>();
        read(1, Optional.of(timestamps));
        return Optional.fromNullable(Iterators.getOnlyElement(timestamps.iterator(), null));
    }

    /**
     * Read several time-stamps.
     * 
     * @param count
     *          the number of time-stamps to read
     * @return a list containing {@code count} time-stamps, or fewer if there are
     *         no more to read
     * @throws IOException
     */
    public List<Timestamp> read(int count) throws IOException {
        List<Timestamp> timestamps = new ArrayList<Timestamp>();
        read(count, Optional.of(timestamps));
        return ImmutableList.copyOf(timestamps);
    }

    /**
     * Read up to {@code count} time-stamps and add them to the given list.
     * 
     * @param count
     *          the number of time-stamps to read
     * @param timestamps
     *          the list that will contain the time-stamps (optional)
     * @throws IOException
     */
    private void read(int count, Optional<List<Timestamp>> timestamps) throws IOException {
        if (count < 1 || !timestampsFile.isFile()) {
            return;
        }
        InputStream inputStream = new FileInputStream(timestampsFile);
        boolean threw = true;
        try {
            ByteStreams.skipFully(inputStream, filePointer);
            inputStream = new BufferedInputStream(inputStream);
            int i = 0;
            while (i < count && filePointer < timestampsFile.length()) {
                Timestamp timestamp = readNext(inputStream);
                if (timestamps.isPresent()) {
                    timestamps.get().add(timestamp);
                }
                i++;
            }
            threw = false;
        } finally {
            Closeables.close(inputStream, threw);
        }
    }

    /**
     * Read the next time-stamp from the given input stream.
     * 
     * @param inputStream
     * @return the next time-stamp
     */
    private Timestamp readNext(InputStream inputStream) throws IOException {
        CountingInputStream countingInputStream = new CountingInputStream(inputStream);
        long elapsedMillisDiff = Varint.read(countingInputStream);

        elapsedMillis += elapsedMillisDiff;
        millisSinceEpoch = timeShiftsReader.getTime(entry).or(millisSinceEpoch + elapsedMillisDiff);
        filePointer += countingInputStream.getCount();
        entry++;
        return new Timestamp(elapsedMillis, millisSinceEpoch);
    }
}