/*-
* See the file LICENSE for redistribution information.
*
* Copyright (c) 2002, 2015 Oracle and/or its affiliates. All rights reserved.
*
* $Id$
*/
package com.sleepycat.db;
import com.sleepycat.db.internal.DbConstants;
import com.sleepycat.db.internal.DbUtil;
import java.nio.ByteBuffer;
/**
An abstract class representing a DatabaseEntry that holds multiple results
returned by a single {@link com.sleepycat.db.Cursor Cursor} get method. Use one of the concrete
subclasses depending on whether you need:
<ul>
<li>multiple data items only: {@link com.sleepycat.db.MultipleDataEntry MultipleDataEntry}</li>
<li>multiple key / data item pairs: {@link com.sleepycat.db.MultipleKeyDataEntry MultipleKeyDataEntry}</li>
<li>multiple record number / data item pairs:
{@link com.sleepycat.db.MultipleRecnoDataEntry MultipleRecnoDataEntry}</li>
</ul>
*/
public abstract class MultipleEntry extends DatabaseEntry {
/* package */ int pos;
/* package */ MultipleEntry(final byte[] data, final int offset, final int size) {
super(data, offset, size);
setUserBuffer((data != null) ? (data.length - offset) : 0, true);
flags |= DbConstants.DB_DBT_BULK;
}
/* package */ MultipleEntry(final ByteBuffer data) {
super(data);
flags |= DbConstants.DB_DBT_BULK;
}
public void setUserBuffer(final int length, final boolean usermem) {
if (!usermem)
throw new IllegalArgumentException("User buffer required");
super.setUserBuffer(length, usermem);
}
/*
* A helper function for building DataEntry classes that contain multiple
* entries.
*
* ASCII art representation of the memory layout of multi-dbts:
*
* |-----------------------------------------------------------
* | | | | | | | | | | |
* | D1 | D2 | D3 |-------> <-------|D3 |D3 |D2 |D2 |D1 |D1 |
* | | | | | sz|off| sz|off| sz|off|
* |-----------------------------------------------------------
*
* When they are key/data pairs. The keys are inserted first, followed by
* the data.
*/
protected boolean append_internal(
final byte[] newdata, int offset, int len, int recno)
throws DatabaseException {
int curr_off;
// If this is the first item start inserting indeces at the end.
if (pos == 0) {
pos = ulen;
curr_off = 0;
} else {
/* Read the offset and size from the last entry. */
curr_off = DbUtil.array2int(this.data, pos + INT32SZ);
curr_off += DbUtil.array2int(this.data, pos);
}
if (curr_off + len > pos - 3 * INT32SZ - (recno > 0 ? INT32SZ : 0))
return (false);
if (recno > 0) {
pos -= INT32SZ;
DbUtil.int2array(curr_off, this.data, pos);
}
pos -= INT32SZ;
DbUtil.int2array(curr_off, this.data, pos);
pos -= INT32SZ;
DbUtil.int2array(len, this.data, pos);
/* Add a terminator. */
DbUtil.int2array((recno > 0) ? 0 : -1, this.data, pos - INT32SZ);
for (int i = 0; i < len; i++)
this.data[curr_off + i] = newdata[i + offset];
return (true);
}
/*
* A helper function for building DataEntry classes that contain multiple
* entries. Simplifies the common case without a record number.
*/
protected boolean append_internal(
final byte[] newdata, int offset, int len)
throws DatabaseException {
return append_internal(newdata, offset, len, 0);
}
}