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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 EventHeader.h
*
* List of journal record structs:
* struct DequeueHeader
* struct EnqueueHeader
* struct EventHeader <-- This file
* struct FileHeader
* 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_EventHeader_h_
#define qpid_asyncStore_jrnl2_EventHeader_h_
#include "RecordHeader.h"
namespace qpid {
namespace asyncStore {
namespace jrnl2 {
#pragma pack(1)
/**
* \brief Struct for an event record header. Event records can be used to record
* system events in the store.
*
* The EventHeader record type may be used to store events into the journal which do
* not constitute data content but changes of state in the broker. These can be
* recovered and used to set appropriate state in the broker.
*
* This record is almost identical to EnqueueRecord, but without the flags. It
* precedes the xid and stored event data in journal files, and unless there is
* no xid and no data (both with 0 length), is followed by a RecordTail.
*
* \todo TODO: I am uncertain at this time whether it is necessary to set an XID on an event
* record, but in case, I have left this feature in. In any event, there is only a
* 1 byte size penalty in the header size for doing so.
*
* Record layout in binary format (32 bytes):
* <pre>
* 0x0 0x7
* +-----+-----+-----+-----+-----+-----+-----+-----+ -+
* 0x00 | m_magic | v | e | m_flags | |
* +-----+-----+-----+-----+-----+-----+-----+-----+ | struct RecordHeader
* 0x08 | m_recordId | |
* +-----+-----+-----+-----+-----+-----+-----+-----+ -+
* 0x10 | m_xidSize |
* +-----+-----+-----+-----+-----+-----+-----+-----+
* 0x18 | m_dataSize |
* +-----+-----+-----+-----+-----+-----+-----+-----+
* </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>
* <pre>
* No content (ie m_xidSize==0 AND m_dataSize==0):
* +---------+
* | event |
* | header |
* +---------+
* <-- 32 --->
*
* With content:
* +---------+----------------+---------------------------+--------+
* | event | XID | Event data | record |
* | header | | | tail |
* +---------+----------------+---------------------------+--------+
* <-- 32 ---><-- m_xidSize --><------ m_dataSize -------><-- 16 -->
* </pre>
*/
class EventHeader : public RecordHeader
{
public:
uint64_t m_xidSize; ///< XID size
uint64_t m_dataSize; ///< Record data size
/**
* \brief Default constructor, which sets all values to 0.
*/
EventHeader();
/**
* \brief Convenience constructor which initializes values during construction.
*
* \param magic The magic for this record
* \param version Version of this record
* \param recordId Record identifier for this record
* \param xidSize Size of the transaction (or distributed transaction) ID for this record
* \param dataSize Size of the opaque data block for this record
* \param overwriteIndicator Flag indicating the present value of the overwrite indicator when writing this
* record
*/
EventHeader(const uint32_t magic,
const uint8_t version,
const uint64_t recordId,
const uint64_t xidSize,
const uint64_t dataSize,
const bool overwriteIndicator);
/**
* \brief Copy constructor
*
* \param eh Instance to be copied
*/
EventHeader(const EventHeader& eh);
/**
* \brief Virtual destructor
*/
virtual ~EventHeader();
/**
* \brief Convenience copy method.
*/
virtual void copy(const EventHeader& eh);
/**
* \brief Reset this record to default values (mostly 0)
*/
virtual 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.
*
* \returns Size of record body in bytes.
*/
virtual uint64_t getBodySize() const;
/**
* \brief Return total size of this record in bytes, being in the case of the enqueue record the size of the
* header, the size of the body (xid and data) and the size of the tail.
*
* \returns Total size of record in bytes.
*/
virtual uint64_t getRecordSize() const;
};
#pragma pack()
}}} // namespace qpid::asyncStore::jrnl2
#endif // qpid_asyncStore_jrnl2_EventHeader_h_
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