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

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Here is the source code for hudson.plugins.timestamper.io.TimeShiftsReader.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 java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.Serializable;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;

import javax.annotation.CheckForNull;

import com.google.common.base.Optional;
import com.google.common.collect.ImmutableMap;
import com.google.common.io.Closeables;
import com.google.common.io.CountingInputStream;

import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;

/**
 * Read the time-shifts for a build from disk.
 * <p>
 * The time-shifts files were written by earlier versions of this plug-in.
 * 
 * @author Steven G. Brown
 */
class TimeShiftsReader implements Serializable {

    private static final long serialVersionUID = 1L;

    private final File timeShiftsFile;

    /**
     * Cache of the time shifts for each entry.
     * <p>
     * Transient: derived from the contents of {@link #timeShiftsFile}.
     */
    @CheckForNull
    @SuppressFBWarnings("SE_TRANSIENT_FIELD_NOT_RESTORED")
    private transient Map<Long, Long> timeShifts;

    TimeShiftsReader(Run<?, ?> build) {
        this.timeShiftsFile = TimestamperPaths.timeShiftsFile(build);
    }

    /**
     * Get the time recorded for the given time-stamp entry.
     * 
     * @return the recorded number of milliseconds since the epoch, or
     *         {@link Optional#absent()} if no time shift was recorded for that
     *         time-stamp entry
     * @throws IOException
     */
    Optional<Long> getTime(long timestampEntry) throws IOException {
        if (timeShifts == null) {
            timeShifts = ImmutableMap.copyOf(readTimeShifts());
        }
        return Optional.fromNullable(timeShifts.get(timestampEntry));
    }

    private Map<Long, Long> readTimeShifts() throws IOException {
        if (!timeShiftsFile.isFile()) {
            return Collections.emptyMap();
        }
        Map<Long, Long> timeShifts = new HashMap<Long, Long>();
        CountingInputStream inputStream = new CountingInputStream(
                new BufferedInputStream(new FileInputStream(timeShiftsFile)));
        boolean threw = true;
        try {
            while (inputStream.getCount() < timeShiftsFile.length()) {
                long entry = Varint.read(inputStream);
                long shift = Varint.read(inputStream);
                timeShifts.put(entry, shift);
            }
            threw = false;
        } finally {
            Closeables.close(inputStream, threw);
        }
        return timeShifts;
    }
}