1/*-
2 * See the file LICENSE for redistribution information.
3 *
4 * Copyright (c) 2002,2008 Oracle.  All rights reserved.
5 *
6 * $Id: MultipleKeyNIODataEntry.java,v 1.8 2008/04/02 13:43:38 bschmeck Exp $
7 */
8
9package com.sleepycat.db;
10
11import com.sleepycat.db.internal.DbConstants;
12import com.sleepycat.db.internal.DbUtil;
13
14import java.nio.ByteBuffer;
15
16/**
17A DatabaseEntry that holds multiple key/data pairs returned by a single
18{@link com.sleepycat.db.Database Database} or {@link com.sleepycat.db.Cursor Cursor} get call.
19*/
20public class MultipleKeyNIODataEntry extends MultipleEntry {
21    /**
22    Construct an entry with no data. The object must be configured
23    before use with the {@link com.sleepycat.db.DatabaseEntry#setDataNIO DatabaseEntry.setDataNIO} method.
24    */
25    public MultipleKeyNIODataEntry() {
26        super(null);
27    }
28
29    /**
30    Construct an entry with a given java.nio.ByteBuffer.  The offset is
31    set to zero; the size is set to the length of the buffer.
32    <p>
33    @param data
34    ByteBuffer wrapped by the entry.
35    */
36    public MultipleKeyNIODataEntry(final ByteBuffer data) {
37        super(data);
38    }
39
40    /**
41     * Return the bulk retrieval flag and reset the entry position so that the
42     * next set of key/data can be returned.
43     */
44    /* package */
45    int getMultiFlag() {
46        pos = 0;
47        return DbConstants.DB_MULTIPLE_KEY;
48    }
49
50    /**
51    Get the next key/data pair in the returned set.  This method may only
52    be called after a successful call to a {@link com.sleepycat.db.Database Database} or
53    {@link com.sleepycat.db.Cursor Cursor} get method with this object as the data parameter.
54    <p>
55    @param key
56    an entry that is set to refer to the next key element in the returned
57    set.
58    <p>
59    @param data
60    an entry that is set to refer to the next data element in the returned
61    set.
62    <p>
63    @return
64    indicates whether a value was found.  A return of <code>false</code>
65    indicates that the end of the set was reached.
66    */
67   public boolean next(final DatabaseEntry key, final DatabaseEntry data) {
68        byte[] intarr;
69        int saveoffset;
70        if (pos == 0)
71            pos = ulen - INT32SZ;
72
73        // pull the offsets out of the ByteBuffer.
74        if(this.data_nio.capacity() < 16)
75            return false;
76        intarr = new byte[16];
77        saveoffset = this.data_nio.position();
78        this.data_nio.position(pos - INT32SZ*3);
79        this.data_nio.get(intarr, 0, 16);
80        this.data_nio.position(saveoffset);
81
82        final int keyoff = DbUtil.array2int(intarr, 12);
83
84        // crack out the key and data offsets and lengths.
85        if (keyoff < 0)
86            return false;
87
88        final int keysz = DbUtil.array2int(intarr, 8);
89        final int dataoff = DbUtil.array2int(intarr, 4);
90        final int datasz = DbUtil.array2int(intarr, 0);
91
92        // move the position to one before the last offset read.
93        pos -= INT32SZ*4;
94
95        key.setDataNIO(this.data_nio);
96        key.setOffset(keyoff);
97        key.setSize(keysz);
98
99        data.setDataNIO(this.data_nio);
100        data.setOffset(dataoff);
101        data.setSize(datasz);
102
103        return true;
104    }
105}
106