001 package org.wdssii.webindex.servlet;
002
003 import java.util.Arrays;
004 import java.util.Collection;
005
006 /**
007 * Transfer object containing a number of IndexRecordBeans corresponding to a
008 * source.
009 *
010 * @author Lakshman
011 * @version $Id: IndexRecordList.java,v 1.4 2007/10/29 20:46:15 lakshman Exp $
012 */
013 public class IndexRecordList {
014 private String source;
015 private IndexRecordBean[] records;
016 private long lastNumber;
017
018 /** Name of source */
019 public String getSource() {
020 return source;
021 }
022
023 /** The list can be empty, but it won't be null. */
024 public IndexRecordBean[] getRecords() {
025 return records;
026 }
027
028 /** returns -ve if no IndexRecords are here. */
029 public long getLastNumber() {
030 return lastNumber;
031 }
032
033 /** set state */
034 private void updateLast() {
035 if (records.length > 0) {
036 IndexRecordBean last = records[ records.length - 1 ];
037 this.lastNumber = last.getNumber();
038 } else {
039 // FIXME: need to distinguish in case directory got scoured
040 this.lastNumber = -1;
041 }
042 }
043
044 /** the IndexRecords should already be sorted. */
045 private IndexRecordList(String source, IndexRecordBean[] indexRecords, long lastNumber) {
046 this.source = source;
047 this.records = indexRecords;
048 this.lastNumber = lastNumber;
049 }
050
051 public static final int RETURN_ALL_RECORDS = -1;
052 public static final int RETURN_LATEST_ONLY = -2;
053
054 /**
055 * Returns a cloned copy of this TO, pruned to the number of the last
056 * IndexRecord specified.
057 */
058 @SuppressWarnings("unchecked")
059 public IndexRecordList newInstance(long lastRead) {
060 IndexRecordBean[] v = records; // for lastRead == RETURN_ALL_RECORDS
061 if (lastRead == RETURN_LATEST_ONLY && records.length > 0){
062 v = new IndexRecordBean[]{ records[records.length-1] };
063 } else if (lastRead > 0 ){
064 // the equality check is based purely on number, so this works
065 IndexRecordBean lastReadItem = new IndexRecordBean(null,null,lastRead);
066 int loc = Arrays.binarySearch(records,lastReadItem);
067 if ( loc >= 0 ){
068 v = getRecordsAfterIndex(loc+1);
069 }
070 // otherwise: not there, so return entire list
071 }
072 return new IndexRecordList(source, v, lastNumber);
073 }
074
075 private IndexRecordBean[] getRecordsAfterIndex(int start){
076 // subset array
077 IndexRecordBean[] v = new IndexRecordBean[ records.length - start ];
078 for (int i = start, j = 0; i < records.length; ++i,++j){
079 v[j] = records[i];
080 }
081 return v;
082 }
083
084 /** create empty TO */
085 public static IndexRecordList newInstance(String source) {
086 IndexRecordList to = new IndexRecordList(source,
087 new IndexRecordBean[0], -1);
088 return to;
089 }
090
091 @SuppressWarnings("unchecked")
092 public void setRecords(Collection<IndexRecordBean> c) {
093 // need to make sure that the IndexRecords array is ordered by number.
094 records = c.toArray(new IndexRecordBean[0]);
095 Arrays.sort(records);
096 updateLast();
097 }
098
099 public void pruneToMaxSize(long maxSize){
100 if ( records.length > maxSize ){
101 int start = records.length - (int) maxSize;
102 records = getRecordsAfterIndex(start);
103 }
104 }
105 }