Append-only, mmap-backed vector of elements of type T. More...

#include "MMappedVector.h"

Collaboration diagram for MMappedVector< T >:

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Classes
struct	data_t
	On-disk layout stored at the start of the backing file. More...

Public Member Functions
	MMappedVector (const char *filename, bool read_only, uint64_t magic, uint16_t version=1)
	Open (or create) the mmap-backed vector.
	~MMappedVector ()
	Sync and unmap the file.
const T &	operator[] (unsigned long k) const
	Read-only element access by index.
T &	operator[] (unsigned long k)
	Read-write element access by index.
void	add (const T &value)
	Append an element to the end of the vector.
unsigned long	nbElements () const
	Return the number of elements currently stored.
uint16_t	version () const
	Return the format version stamped in the file's header.
void	setVersion (uint16_t v)
	Stamp `v` into the header, declaring the file upgraded.
void	sync ()
	Flush the backing region to its file (`MappedRegion::sync()`).
void	flush ()
	Force the backing file to stable storage (`MappedRegion::flush()`).
bool	uncleanShutdown () const
	Whether this file still had `FLAG_DIRTY` set when it was opened, i.e.

Static Public Attributes
static constexpr uint32_t	FLAG_DIRTY = 1u
	Bit of `data_t::flags` set while the file is open for writing.

Private Member Functions
void	grow ()
	Double the backing region and refresh `data`.
void	set (pg_uuid_t u, unsigned long i)
	Unused overload kept for interface compatibility.

Private Attributes
MappedRegion	region
	Backing storage (shared mmap, or heap buffer).
data_t *	data
	Typed view of `region.base()`.
bool	read_only_ = false
	Mapped read-only: the header must not be written.
bool	unclean_ = false
	The previous run left the dirty bit set.

Static Private Attributes
static constexpr unsigned	STARTING_CAPACITY =(1u << 16)
	Initial number of element slots allocated.

Detailed Description

template<typename T>
class MMappedVector< T >

Append-only, mmap-backed vector of elements of type T.

Template Parameters

T	The element type. Must be trivially copyable.

Definition at line 39 of file MMappedVector.h.

Constructor & Destructor Documentation

◆ MMappedVector()

template<typename T>

MMappedVector< T >::MMappedVector	(	const char *	filename,
		bool	read_only,
		uint64_t	magic,
		uint16_t	version = 1 )

Open (or create) the mmap-backed vector.

A file created here is stamped with version; an existing file is accepted when its stamp is at most version, so a build that understands version n keeps reading the files an older one wrote. The caller reads the stamp back with version() to decide how to interpret fields whose meaning changed.

Parameters

filename	Path to the backing file (created with `STARTING_CAPACITY` slots if absent).
read_only	If `true`, map the file read-only.
magic	Expected magic value for format validation.
version	Highest format version this build writes and reads.

Definition at line 41 of file MMappedVector.hpp.

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◆ ~MMappedVector()

template<typename T>

MMappedVector< T >::~MMappedVector ( )

Sync and unmap the file.

Definition at line 91 of file MMappedVector.hpp.

Member Function Documentation

◆ add()

template<typename T>

void MMappedVector< T >::add ( const T & value )

Append an element to the end of the vector.

Grows the backing file if the current capacity is exhausted.

Parameters

value Element to append.

Definition at line 111 of file MMappedVector.hpp.

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◆ flush()

template<typename T>

void MMappedVector< T >::flush ( )

Force the backing file to stable storage (MappedRegion::flush()).

Definition at line 126 of file MMappedVector.hpp.

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◆ grow()

template<typename T>

void MMappedVector< T >::grow ( )

private

Double the backing region and refresh data.

Definition at line 82 of file MMappedVector.hpp.

◆ nbElements()

template<typename T>

unsigned long MMappedVector< T >::nbElements ( ) const

inline

Return the number of elements currently stored.

Returns: Element count.

Definition at line 120 of file MMappedVector.h.

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◆ operator[]() [1/2]

template<typename T>

T & MMappedVector< T >::operator[] ( unsigned long k )

inline

Read-write element access by index.

Parameters

k	Zero-based element index.

Returns: Reference to element k.

Definition at line 105 of file MMappedVector.hpp.

◆ operator[]() [2/2]

template<typename T>

const T & MMappedVector< T >::operator[] ( unsigned long k ) const

inline

Read-only element access by index.

Parameters

k	Zero-based element index.

Returns: Const reference to element k.

Definition at line 99 of file MMappedVector.hpp.

◆ set()

template<typename T>

void MMappedVector< T >::set	(	pg_uuid_t	u,
		unsigned long	i )

private

Unused overload kept for interface compatibility.

Parameters

u	Ignored UUID parameter.
i	Ignored integer parameter.

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◆ setVersion()

template<typename T>

void MMappedVector< T >::setVersion ( uint16_t v )

inline

Stamp v into the header, declaring the file upgraded.

Only a pass that has rewritten every record to the new version's conventions may call this.

Definition at line 133 of file MMappedVector.h.

◆ sync()

template<typename T>

void MMappedVector< T >::sync ( )

Flush the backing region to its file (MappedRegion::sync()).

Definition at line 120 of file MMappedVector.hpp.

◆ uncleanShutdown()

template<typename T>

bool MMappedVector< T >::uncleanShutdown ( ) const

inline

Whether this file still had FLAG_DIRTY set when it was opened, i.e.

whoever wrote it last did not close it.

Definition at line 156 of file MMappedVector.h.

◆ version()

template<typename T>

uint16_t MMappedVector< T >::version ( ) const

inline

Return the format version stamped in the file's header.

Definition at line 125 of file MMappedVector.h.

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Member Data Documentation

◆ data

template<typename T>

data_t* MMappedVector< T >::data

private

Typed view of region.base().

Definition at line 56 of file MMappedVector.h.

◆ FLAG_DIRTY

template<typename T>

uint32_t MMappedVector< T >::FLAG_DIRTY = 1u

staticconstexpr

Bit of data_t::flags set while the file is open for writing.

Cleared on a clean close, so a file found with it still set was left behind by a process that died (or by an immediate shutdown). The header layout is unchanged: the bit lives in what used to be reserved padding, which older builds neither read nor write.

Definition at line 152 of file MMappedVector.h.

◆ read_only_

template<typename T>

bool MMappedVector< T >::read_only_ = false

private

Mapped read-only: the header must not be written.

Definition at line 57 of file MMappedVector.h.

◆ region

template<typename T>

MappedRegion MMappedVector< T >::region

private

Backing storage (shared mmap, or heap buffer).

Definition at line 55 of file MMappedVector.h.

◆ STARTING_CAPACITY

template<typename T>

unsigned MMappedVector< T >::STARTING_CAPACITY =(1u << 16)

staticconstexprprivate

Initial number of element slots allocated.

Definition at line 61 of file MMappedVector.h.

◆ unclean_

template<typename T>

bool MMappedVector< T >::unclean_ = false

private

The previous run left the dirty bit set.

Definition at line 58 of file MMappedVector.h.

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

/home/senellar/git/software/provsql/src/MMappedVector.h
/home/senellar/git/software/provsql/src/MMappedVector.hpp

Classes

Public Member Functions

Static Public Attributes

Private Member Functions

Private Attributes

Static Private Attributes

Detailed Description

Constructor & Destructor Documentation

◆ MMappedVector()

◆ ~MMappedVector()

Member Function Documentation

◆ add()

◆ flush()

◆ grow()

◆ nbElements()

◆ operator[]() [1/2]

◆ operator[]() [2/2]

◆ set()

◆ setVersion()

◆ sync()

◆ uncleanShutdown()

◆ version()

Member Data Documentation

◆ data

◆ FLAG_DIRTY

◆ read_only_

◆ region

◆ STARTING_CAPACITY

◆ unclean_