pstore::trailer Struct Reference

The transaction footer structure. More...

#include <file_header.hpp>

Collaboration diagram for pstore::trailer:

Classes
struct	body
	Represents the portion of the trailer structure which is covered by the computed CRC value. More...

Public Types
enum	indices : unsigned { last }
using	index_records_array = std::array< typed_address< index::header_block >, static_cast< std::underlying_type< indices >::type >(indices::last)>

Public Member Functions
bool	crc_is_valid () const noexcept
bool	signature_is_valid () const noexcept
std::uint32_t	get_crc () const noexcept
	Computes the trailer's CRC value.

Static Public Member Functions
static bool	validate (database const &db, typed_address< trailer > pos)
	Checks that the address given by 'pos' appears to point to a valid transaction trailer. More...

Public Attributes
body	a
std::uint32_t	crc = 0
	The fields of a transaction footer are not modified as the code interacts with the data store. More...
std::uint32_t	unused1 = 0
std::array< std::uint8_t, 8 >	signature2 = default_signature2

Static Public Attributes
static std::array< std::uint8_t, 8 > const	default_signature1
static std::array< std::uint8_t, 8 > const	default_signature2

Detailed Description

The transaction footer structure.

An copy of this structure is written to the data store at the end of each transaction block. pstore::header::footer_pos holds the address of the latest complete instance and is updated once a transaction has been completely written to memory. Once written it is read-only.

Member Function Documentation

validate()

bool pstore::trailer::validate ( database const &  db, typed_address< trailer >  pos  )

static

Checks that the address given by 'pos' appears to point to a valid transaction trailer.

Raises exception::footer_corrupt if not.

Member Data Documentation

crc

std::uint32_t pstore::trailer::crc = 0

The fields of a transaction footer are not modified as the code interacts with the data store.

The memory that is occupies as marked as read-only as soon as the host OS and hardware permits. Despite this guarantee it's useful to be able to ensure that the reverse-order linked list of transactions – whose head is given by header::footer_pos is intact and that we don't have a stray pointer.

default_signature1

std::array< std::uint8_t, 8 > const pstore::trailer::default_signature1

static

Initial value:

{
        {'h', 'P', 'P', 'y', 'f', 'o', 'o', 'T'}}

default_signature2

std::array< std::uint8_t, 8 > const pstore::trailer::default_signature2

static

Initial value:

{
        {'h', 'P', 'P', 'y', 'T', 'a', 'i', 'l'}}

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The documentation for this struct was generated from the following files:

• include/pstore/core/file_header.hpp
• lib/core/file_header.cpp