001/**
002 * Copyright (c) 2011, The University of Southampton and the individual contributors.
003 * All rights reserved.
004 *
005 * Redistribution and use in source and binary forms, with or without modification,
006 * are permitted provided that the following conditions are met:
007 *
008 *   *  Redistributions of source code must retain the above copyright notice,
009 *      this list of conditions and the following disclaimer.
010 *
011 *   *  Redistributions in binary form must reproduce the above copyright notice,
012 *      this list of conditions and the following disclaimer in the documentation
013 *      and/or other materials provided with the distribution.
014 *
015 *   *  Neither the name of the University of Southampton nor the names of its
016 *      contributors may be used to endorse or promote products derived from this
017 *      software without specific prior written permission.
018 *
019 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
020 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
021 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
022 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
023 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
024 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
025 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
026 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
027 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
028 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
029 */
030package org.openimaj.hadoop.sequencefile;
031
032import java.util.Arrays;
033
034import org.apache.hadoop.io.SequenceFile;
035import org.openimaj.data.RandomData;
036
037/**
038 * The state describing the extraction process from {@link SequenceFile}.
039 * Basically, this class stores the current state of the extraction and
040 * determines whether the next item should be extracted or not.
041 *
042 * @author Sina Samangooei (ss@ecs.soton.ac.uk)
043 * @author Jonathon Hare (jsh2@ecs.soton.ac.uk)
044 */
045public class ExtractionState {
046        private int count = 0;
047        private int max = -1;
048        private int[] randomInts = null;
049
050        /**
051         * @return the number of items that have been extracted
052         */
053        public int getCount() {
054                return count;
055        }
056
057        /**
058         * @return true if the next record is allowed; false otherwise
059         */
060        protected boolean allowNext() {
061                if (this.max != -1 && this.count >= this.max)
062                        return false;
063                if (this.randomInts == null)
064                        return true;
065
066                final int thingLocation = Arrays.binarySearch(randomInts, this.count);
067
068                return thingLocation >= 0;
069        }
070
071        /**
072         * @return true if the extraction is finished; i.e. the maximum number of
073         *         records has been reached
074         */
075        public boolean isFinished() {
076                return this.max != -1 && this.count >= this.max;
077        }
078
079        protected void tick() {
080                this.count++;
081        }
082
083        /**
084         * Instruct the state to extract number records from the file randomly.
085         *
086         * @param number
087         *            number of records to extract
088         * @param total
089         *            total number of records in the file
090         */
091        public void setRandomSelection(int number, int total) {
092                this.randomInts = RandomData.getUniqueRandomInts(number, 0, total);
093                Arrays.sort(randomInts);
094                System.out.println(this.randomInts.length + " random ints selected");
095                System.out.println(Arrays.toString(randomInts));
096        }
097
098        /**
099         * Set the maximum allowed number of records to extract.
100         *
101         * @param max
102         *            the number of records.
103         */
104        public void setMaxFileExtract(int max) {
105                this.max = max;
106        }
107}