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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 rec_hdr.h
*
* Qpid asynchronous store plugin library
*
* File containing code for class mrg::journal::rec_hdr (record header),
* which is a common initial header used for all journal record structures
* except the record tail (rec_tail).
*
* \author Kim van der Riet
*/
#ifndef QPID_LEGACYSTORE_JRNL_REC_HDR_H
#define QPID_LEGACYSTORE_JRNL_REC_HDR_H
#include <cstddef>
#include "qpid/legacystore/jrnl/jcfg.h"
#include <sys/types.h>
namespace mrg
{
namespace journal
{
#pragma pack(1)
/**
* \brief Struct for data common to the head of all journal files and records.
* This includes identification for the file type, the encoding version, endian
* indicator and a record ID.
*
* File header info in binary format (16 bytes):
* <pre>
* 0 7
* +---+---+---+---+---+---+---+---+
* | magic | v | e | flags |
* +---+---+---+---+---+---+---+---+
* | rid |
* +---+---+---+---+---+---+---+---+
* 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 rec_hdr
{
u_int32_t _magic; ///< File type identifier (magic number)
u_int8_t _version; ///< File encoding version
u_int8_t _eflag; ///< Flag for determining endianness
u_int16_t _uflag; ///< User-defined flags
u_int64_t _rid; ///< Record ID (rotating 64-bit counter)
// Global flags
static const u_int16_t HDR_OVERWRITE_INDICATOR_MASK = 0x1;
// Convenience constructors and methods
/**
* \brief Default constructor, which sets all values to 0.
*/
inline rec_hdr(): _magic(0), _version(0), _eflag(0), _uflag(0), _rid(0) {}
/**
* \brief Convenience constructor which initializes values during construction.
*/
inline rec_hdr(const u_int32_t magic, const u_int8_t version, const u_int64_t rid,
const bool owi): _magic(magic), _version(version),
#if defined(JRNL_BIG_ENDIAN)
_eflag(RHM_BENDIAN_FLAG),
#else
_eflag(RHM_LENDIAN_FLAG),
#endif
_uflag(owi ? HDR_OVERWRITE_INDICATOR_MASK : 0), _rid(rid) {}
/**
* \brief Convenience copy method.
*/
inline void hdr_copy(const rec_hdr& h)
{
_magic = h._magic;
_version = h._version;
_eflag = h._eflag;
_uflag = h._uflag;
_rid =h._rid;
}
/**
* \brief Resets all fields to 0
*/
inline void reset()
{
_magic = 0;
_version = 0;
_eflag = 0;
_uflag = 0;
_rid = 0;
}
inline bool get_owi() const { return _uflag & HDR_OVERWRITE_INDICATOR_MASK; }
inline void set_owi(const bool owi)
{
_uflag = owi ? _uflag | HDR_OVERWRITE_INDICATOR_MASK :
_uflag & (~HDR_OVERWRITE_INDICATOR_MASK);
}
/**
* \brief Returns the size of the header in bytes.
*/
inline static std::size_t size() { return sizeof(rec_hdr); }
}; // struct rec_hdr
#pragma pack()
} // namespace journal
} // namespace mrg
#endif // ifndef QPID_LEGACYSTORE_JRNL_REC_HDR_H
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