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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 FileHeader.h
*
* List of journal record structs:
* struct DequeueHeader
* struct EnqueueHeader
* struct EventHeader
* struct FileHeader <-- This file
* struct RecordHeader
* struct RecordTail
* struct TransactionHeader
*
* Overview of journal record structs:
*
* <pre>
* +------------+ +--------------+
* | RecordTail | | RecordHeader |
* +------------+ | (abstract) |
* +--------------+
* ^
* |
* +----------------+---------+-------+-------------------+
* | | | |
* +------------+ +-------------+ +---------------+ +-------------------+
* | FileHeader | | EventHeader | | DequeueHeader | | TransactionHeader |
* +------------+ +-------------+ +---------------+ +-------------------+
* ^
* |
* +---------------+
* | EnqueueHeader |
* +---------------+
* </pre>
*/
#ifndef qpid_asyncStore_jrnl2_FileHeader_h_
#define qpid_asyncStore_jrnl2_FileHeader_h_
#include "qpid/asyncStore/jrnl2/RecordHeader.h"
struct timespec;
namespace qpid {
namespace asyncStore {
namespace jrnl2 {
#pragma pack(1)
/**
* \brief Struct for the data written to the head of all journal files.
*
* In addition to the fields inherited from RecordHeader, this struct includes the
* unique record ID for this record and an offset of the first record in the file.
* There is also a field for a nanosecond-resolution time stamp which records the
* time that this file was first written in each cycle.
*
* This header precedes all data in journal files and occupies the first complete
* block in the file. The fields in this record are updated as necessary each time
* the file is written or overwritten.
*
* File layout in binary format (48 bytes):
* <pre>
* 0x0 0x7
* +-----+-----+-----+-----+-----+-----+-----+-----+ -+
* 0x00 | m_magic | v | e | m_flags | |
* +-----+-----+-----+-----+-----+-----+-----+-----+ | struct RecordHeader
* 0x08 | m_recordId (used to show first rid in file) | |
* +-----+-----+-----+-----+-----+-----+-----+-----+ -+
* 0x10 | m_physicalFileId | m_logicalFileId |
* +-----+-----+-----+-----+-----+-----+-----+-----+
* 0x18 | m_firstRecordOffset |
* +-----+-----+-----+-----+-----+-----+-----+-----+
* 0x20 | m_timestampSeconds |
* +-----+-----+-----+-----+-----+-----+-----+-----+
* 0x28 |m_timestampNanoSeconds | m_reserved |
* +-----+-----+-----+-----+-----+-----+-----+-----+
* </pre>
* <table>
* <tr>
* <td>v</td>
* <td>file version [ <code>_version</code> ] (If the format or encoding of
* this file changes, then this number should be incremented)</td>
* </tr>
* <tr>
* <td>e</td>
* <td>endian flag [ <code>_bigEndianFlag</code> ], <b>false</b> (0x00) for
* little endian, <b>true</b> (0x01) for big endian</td>
* </tr>
* </table>
* General journal file structure:
* <pre>
* <----------------------------- Journal File ----------------------------------->
* +--------+ +-----------------+ +---------+ +---------+ +-------------------+
* | file | | continuation of | | first | | second | ... | last record |
* | header | | record from | | record | | record | | (or part thereof) |
* | | | prev. file (opt)| | in file | | in file | | in file |
* +--------+ +-----------------+ +---------+ +---------+ +-------------------+
* ^
* |
* m_firstRecordOffset -----------+
* </pre>
*/
class FileHeader : public RecordHeader
{
public:
uint32_t m_physicalFileId; ///< Physical file ID (pfid)
uint32_t m_logicalFileId; ///< Logical file ID (lfid)
uint64_t m_firstRecordOffset;///< First record offset (fro)
uint64_t m_timestampSeconds; ///< Timestamp of journal initialization, seconds component
uint32_t m_timestampNanoSeconds;///< Timestamp of journal initialization, nanoseconds component
uint32_t m_reserved; ///< Little-endian filler for uint32_t
/**
* \brief Default constructor, which sets all values to 0.
*/
FileHeader();
/**
* \brief Convenience constructor which initializes values during construction.
* \param magic Magic for this record
* \param version Version of this record
* \param recordId RecordId for this record
* \param overwriteIndicator Overwrite indicator for this record
* \param physicalFileId Physical file ID (file number on disk)
* \param logicalFileId Logical file ID (file number as seen by circular file buffer)
* \param firstRecordOffset First record offset in bytes from beginning of file
* \param setTimestampFlag If true, causes the timestamp to be initialized with the current system time
*/
FileHeader(const uint32_t magic,
const uint8_t version,
const uint64_t recordId,
const bool overwriteIndicator,
const uint16_t physicalFileId,
const uint16_t logicalFileId,
const uint64_t firstRecordOffset,
const bool setTimestampFlag = false);
/**
* \brief Copy constructor.
* \param fh FileHeader instance to be copied
*/
FileHeader(const FileHeader& fh);
/**
* \brief Destructor.
*/
virtual ~FileHeader();
/**
* \brief Convenience copy method.
* \param fh FileHeader instance to be copied
*/
void copy(const FileHeader& fh);
/**
* \brief Resets all fields to default values (mostly 0).
*/
void reset();
/**
* \brief Return the header size of this record in bytes.
* \returns Size of record header in bytes.
*/
static uint64_t getHeaderSize();
/**
* \brief Return the body (data) size of this record in bytes, which in the case of a FileHeader is always 0.
* \returns Size of record body in bytes. By definition, a FileHeader has no body.
*/
uint64_t getBodySize() const;
/**
* \brief Return total size of this record in bytes, being in the case of the
* FileHeader the size of the header itself only.
* \returns Total size of record in bytes.
*/
uint64_t getRecordSize() const;
/**
* \brief Gets the current time from the system clock and sets the timestamp in the struct.
*/
void setTimestamp();
/**
* \brief Sets the timestamp in the struct to the provided value (in seconds and nanoseconds).
* \param ts Timestamp from which the file header time stamp is to be copied
*/
void setTimestamp(const timespec& ts);
};
#pragma pack()
}}} // namespace qpid::asyncStore::jrnl2
#endif // qpid_asyncStore_jrnl2_FileHeader_h_
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