firebird-mirror/src/jrd/btn.h

/*
 *	PROGRAM:	JRD Access Method
 *	MODULE:		btn.h
 *	DESCRIPTION:	B-tree management code
 *
 *  The contents of this file are subject to the Initial
 *  Developer's Public License Version 1.0 (the "License");
 *  you may not use this file except in compliance with the
 *  License. You may obtain a copy of the License at
 *  http://www.ibphoenix.com/main.nfs?a=ibphoenix&page=ibp_idpl.
 *
 *  Software distributed under the License is distributed AS IS,
 *  WITHOUT WARRANTY OF ANY KIND, either express or implied.
 *  See the License for the specific language governing rights
 *  and limitations under the License.
 *
 *  The Original Code was created by Arno Brinkman
 *  for the Firebird Open Source RDBMS project.
 *
 *  Copyright (c) 2003 Arno Brinkman and all contributors
 *  signed below.
 *
 *  All Rights Reserved.
 *  Contributor(s): ______________________________________.
 */

#ifndef JRD_BTN_H
#define JRD_BTN_H

#include "firebird.h"			// needed for get_long
#include "memory_routines.h"	// needed for get_long

#include "../common/common.h"
#include "../jrd/ods.h"
#include "../common/classes/array.h"

// Flags (3-bits) used for index node
const int BTN_NORMAL_FLAG					= 0;
const int BTN_END_LEVEL_FLAG				= 1;
const int BTN_END_BUCKET_FLAG				= 2;
const int BTN_ZERO_PREFIX_ZERO_LENGTH_FLAG	= 3;
const int BTN_ZERO_LENGTH_FLAG				= 4;
const int BTN_ONE_LENGTH_FLAG				= 5;
//const int BTN_ZERO_PREFIX_ONE_LENGTH_FLAG	= 6;
//const int BTN_GET_MORE_FLAGS	= 7;

struct dynKey
{
	USHORT keyLength;
	UCHAR* keyData;
};

typedef Firebird::Array<dynKey*> keyList;
typedef Firebird::HalfStaticArray<Ods::IndexJumpNode, 32> jumpNodeList;

namespace BTreeNode {

	USHORT computePrefix(const UCHAR* prevString, USHORT prevLength,
				const UCHAR* string, USHORT length);

	SLONG findPageInDuplicates(const Ods::btree_page* page, UCHAR* pointer,
				SLONG previousNumber, RecordNumber findRecordNumber);

	USHORT getJumpNodeSize(const Ods::IndexJumpNode* jumpNode);
	USHORT getNodeSize(const Ods::IndexNode* indexNode, bool leafNode = true);
	UCHAR* getPointerFirstNode(Ods::btree_page* page, Ods::IndexJumpInfo* jumpInfo = NULL);

	bool keyEquality(USHORT length, const UCHAR* data, const Ods::IndexNode* indexNode);

	UCHAR* readJumpInfo(Ods::IndexJumpInfo* jumpInfo, UCHAR* pagePointer);
	UCHAR* readJumpNode(Ods::IndexJumpNode* jumpNode, UCHAR* pagePointer);
	inline UCHAR* readNode(Ods::IndexNode* indexNode, UCHAR* pagePointer, bool leafNode);

	UCHAR* writeJumpInfo(Ods::btree_page* page, const Ods::IndexJumpInfo* jumpInfo);
	UCHAR* writeJumpNode(Ods::IndexJumpNode* jumpNode, UCHAR* pagePointer);
	UCHAR* writeNode(Ods::IndexNode* indexNode, UCHAR* pagePointer, bool leafNode, bool withData = true);

	void setEndBucket(Ods::IndexNode* indexNode); //, bool leafNode = true);
	void setEndLevel(Ods::IndexNode* indexNode); //, bool leafNode = true);
	void setNode(Ods::IndexNode* indexNode, USHORT prefix = 0, USHORT length = 0,
		RecordNumber recordNumber = RecordNumber(0), SLONG pageNumber = 0,
		bool isEndBucket = false, bool isEndLevel = false);

} // namespace BTreeNode

inline UCHAR* BTreeNode::readNode(Ods::IndexNode* indexNode, UCHAR* pagePointer, bool leafNode)
{
/**************************************
 *
 *	r e a d N o d e
 *
 **************************************
 *
 * Functional description
 *	Read a leaf/page node from the page by the
 *  given pagePointer and the return the
 *  remaining position after the read.
 *
 **************************************/
	indexNode->nodePointer = pagePointer;

	// Get first byte that contains internal flags and 6 bits from number
	UCHAR* localPointer = pagePointer;
	UCHAR internalFlags = *localPointer++;
	SINT64 number = (internalFlags & 0x1F);
	internalFlags = ((internalFlags & 0xE0) >> 5);

	indexNode->isEndLevel = (internalFlags == BTN_END_LEVEL_FLAG);
	indexNode->isEndBucket = (internalFlags == BTN_END_BUCKET_FLAG);

	// If this is a END_LEVEL marker then we're done
	if (indexNode->isEndLevel)
	{
		indexNode->prefix = 0;
		indexNode->length = 0;
		indexNode->recordNumber.setValue(0);
		indexNode->pageNumber = 0;
		return localPointer;
	}

	// Get remaining bits for number
	ULONG tmp = *localPointer++;
	number |= (tmp & 0x7F) << 5;
	if (tmp >= 128)
	{
		tmp = *localPointer++;
		number |= (tmp & 0x7F) << 12;
		if (tmp >= 128)
		{
			tmp = *localPointer++;
			number |= (tmp & 0x7F) << 19;
			if (tmp >= 128)
			{
				tmp = *localPointer++;
				number |= (FB_UINT64) (tmp & 0x7F) << 26;
				if (tmp >= 128)
				{
					tmp = *localPointer++;
					number |= (FB_UINT64) (tmp & 0x7F) << 33;
/*
	Uncomment this if you need more bits in record number
						if (tmp >= 128)
						{
							tmp = *localPointer++;
							number |= (FB_UINT64) (tmp & 0x7F) << 40;
							if (tmp >= 128)
							{
								tmp = *localPointer++;
								number |= (FB_UINT64) (tmp & 0x7F) << 47;
								if (tmp >= 128)
								{
									tmp = *localPointer++;
									number |= (FB_UINT64) (tmp & 0x7F) << 54; // We get 61 bits at this point!
								}
							}
						}
*/
				}
			}
		}
	}
	indexNode->recordNumber.setValue(number);

	if (!leafNode)
	{
		// Get page number for non-leaf pages
		tmp = *localPointer++;
		number = (tmp & 0x7F);
		if (tmp >= 128)
		{
			tmp = *localPointer++;
			number |= (tmp & 0x7F) << 7;
			if (tmp >= 128)
			{
				tmp = *localPointer++;
				number |= (tmp & 0x7F) << 14;
				if (tmp >= 128)
				{
					tmp = *localPointer++;
					number |= (tmp & 0x7F) << 21;
					if (tmp >= 128)
					{
						tmp = *localPointer++;
						number |= (tmp & 0x0F) << 28;
					}
				}
			}
		}
		indexNode->pageNumber = number;
	}

	if (internalFlags == BTN_ZERO_PREFIX_ZERO_LENGTH_FLAG)
	{
		// Prefix is zero
		indexNode->prefix = 0;
	}
	else
	{
		// Get prefix
		tmp = *localPointer++;
		indexNode->prefix = (tmp & 0x7F);
		if (tmp & 0x80)
		{
			tmp = *localPointer++;
			indexNode->prefix |= (tmp & 0x7F) << 7; // We get 14 bits at this point
		}
	}

	if ((internalFlags == BTN_ZERO_LENGTH_FLAG) ||
		(internalFlags == BTN_ZERO_PREFIX_ZERO_LENGTH_FLAG))
	{
		// Length is zero
		indexNode->length = 0;
	}
	else if (internalFlags == BTN_ONE_LENGTH_FLAG)
	{
		// Length is one
		indexNode->length = 1;
	}
	else
	{
		// Get length
		tmp = *localPointer++;
		indexNode->length = (tmp & 0x7F);
		if (tmp & 0x80)
		{
			tmp = *localPointer++;
			indexNode->length |= (tmp & 0x7F) << 7; // We get 14 bits at this point
		}
	}

	// Get pointer where data starts
	indexNode->data = localPointer;
	localPointer += indexNode->length;

	return localPointer;
}

#endif // JRD_BTN_H