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/*
*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*
*/
/**
* \file txn_hdr.h
*
* Qpid asynchronous store plugin library
*
* File containing code for class mrg::journal::txn_hdr (transaction
* record header), used to start a transaction (commit or abort) record.
*
* \author Kim van der Riet
*/
#ifndef QPID_LEGACYSTORE_JRNL_TXN_HDR_H
#define QPID_LEGACYSTORE_JRNL_TXN_HDR_H
#include <cstddef>
#include "qpid/legacystore/jrnl/rec_hdr.h"
namespace mrg
{
namespace journal
{
#pragma pack(1)
/**
* \brief Struct for transaction commit and abort records.
*
* Struct for DTX commit and abort records. Only the magic distinguishes between them. Since
* this record must be used in the context of a valid XID, the xidsize field must not be zero.
* Immediately following this record is the XID itself which is xidsize bytes long, followed by
* a rec_tail.
*
* Note that this record had its own rid distinct from the rids of the record(s) making up the
* transaction it is committing or aborting.
*
* Record header info in binary format (24 bytes):
* <pre>
* 0 7
* +---+---+---+---+---+---+---+---+ -+
* | magic | v | e | flags | |
* +---+---+---+---+---+---+---+---+ | struct hdr
* | rid | |
* +---+---+---+---+---+---+---+---+ -+
* | xidsize |
* +---+---+---+---+---+---+---+---+
* v = file version (If the format or encoding of this file changes, then this
* number should be incremented)
* e = endian flag, false (0x00) for little endian, true (0x01) for big endian
* </pre>
*
* Note that journal files should be transferable between 32- and 64-bit
* hardware of the same endianness, but not between hardware of opposite
* entianness without some sort of binary conversion utility. Thus buffering
* will be needed for types that change size between 32- and 64-bit compiles.
*/
struct txn_hdr : rec_hdr
{
#if defined(JRNL_BIG_ENDIAN) && defined(JRNL_32_BIT)
u_int32_t _filler0; ///< Big-endian filler for 32-bit size_t
#endif
std::size_t _xidsize; ///< XID size
#if defined(JRNL_LITTLE_ENDIAN) && defined(JRNL_32_BIT)
u_int32_t _filler0; ///< Little-endian filler for 32-bit size_t
#endif
/**
* \brief Default constructor, which sets all values to 0.
*/
txn_hdr(): rec_hdr(),
#if defined(JRNL_BIG_ENDIAN) && defined(JRNL_32_BIT)
_filler0(0),
#endif
_xidsize(0)
#if defined(JRNL_LITTLE_ENDIAN) && defined(JRNL_32_BIT)
, _filler0(0)
#endif
{}
/**
* \brief Convenience constructor which initializes values during construction.
*/
txn_hdr(const u_int32_t magic, const u_int8_t version, const u_int64_t rid,
const std::size_t xidsize, const bool owi): rec_hdr(magic, version, rid, owi),
#if defined(JRNL_BIG_ENDIAN) && defined(JRNL_32_BIT)
_filler0(0),
#endif
_xidsize(xidsize)
#if defined(JRNL_LITTLE_ENDIAN) && defined(JRNL_32_BIT)
, _filler0(0)
#endif
{}
/**
* \brief Returns the size of the header in bytes.
*/
inline static std::size_t size() { return sizeof(txn_hdr); }
};
#pragma pack()
} // namespace journal
} // namespace mrg
#endif // ifndef QPID_LEGACYSTORE_JRNL_TXN_HDR_H
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