mongo::KVPrefix Class Reference

A KVPrefix may be prepended to the keys of entries in an underlying KV store. More...

#include <kv_prefix.h>

Detailed Description

A KVPrefix may be prepended to the keys of entries in an underlying KV store.

Prefixing keys as such allows multiple MongoDB collections share an underlying table. This can be a beneficial tradeoff for workloads that create many collections.

Public Member Functions
bool	isPrefixed () const
int64_t	toBSONValue () const
int64_t	repr () const
std::string	toString () const
bool	operator< (const KVPrefix &rhs) const
bool	operator== (const KVPrefix &rhs) const
bool	operator!= (const KVPrefix &rhs) const

Static Public Member Functions
static KVPrefix	fromBSONElement (const BSONElement value)
static void	setLargestPrefix (KVPrefix largestPrefix)
static KVPrefix	getNextPrefix (const NamespaceString &ns)
	Returns 'KVPrefix::kNotPrefixed' if 'storageGlobalParams.groupCollections' is false or the input 'ns' is a namespace disallowed for grouping. More...
static KVPrefix	generateNextPrefix ()
	Unconditionally returns a new prefix. More...

Static Public Attributes
static const KVPrefix	kNotPrefixed = KVPrefix(-1)

Private Member Functions
	KVPrefix (int64_t value)

Private Attributes
int64_t	_value

Static Private Attributes
static stdx::mutex	_nextValueMutex
static int64_t	_nextValue = 0

Constructor & Destructor Documentation

KVPrefix()

mongo::KVPrefix::KVPrefix ( int64_t  value )

inlineexplicitprivate

Member Function Documentation

fromBSONElement()

KVPrefix mongo::KVPrefix::fromBSONElement ( const BSONElement  value )

static

generateNextPrefix()

KVPrefix mongo::KVPrefix::generateNextPrefix ( )

static

Unconditionally returns a new prefix.

Only useful for testing.

getNextPrefix()

KVPrefix mongo::KVPrefix::getNextPrefix ( const NamespaceString &  ns )

static

Returns 'KVPrefix::kNotPrefixed' if 'storageGlobalParams.groupCollections' is false or the input 'ns' is a namespace disallowed for grouping.

Otherwise returns the next 'KVPrefix' ensuring it is unique with respect to active collections and indexes.

isPrefixed()

bool mongo::KVPrefix::isPrefixed ( ) const

inline

operator!=()

bool mongo::KVPrefix::operator!= ( const KVPrefix &  rhs ) const

inline

operator<()

bool mongo::KVPrefix::operator< ( const KVPrefix &  rhs ) const

inline

operator==()

bool mongo::KVPrefix::operator== ( const KVPrefix &  rhs ) const

inline

repr()

int64_t mongo::KVPrefix::repr ( ) const

inline

setLargestPrefix()

void mongo::KVPrefix::setLargestPrefix ( KVPrefix  largestPrefix )

static

toBSONValue()

int64_t mongo::KVPrefix::toBSONValue ( ) const

inline

toString()

std::string mongo::KVPrefix::toString

(

)

const

Member Data Documentation

_nextValue

int64_t mongo::KVPrefix::_nextValue = 0

staticprivate

_nextValueMutex

stdx::mutex mongo::KVPrefix::_nextValueMutex

staticprivate

_value

int64_t mongo::KVPrefix::_value

private

kNotPrefixed

const KVPrefix mongo::KVPrefix::kNotPrefixed = KVPrefix(-1)

static

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

• /home/louis/git/mongodbsource.github.io/src/src/mongo/db/storage/kv/kv_prefix.h
• /home/louis/git/mongodbsource.github.io/src/src/mongo/db/storage/kv/kv_prefix.cpp