mongo::WiredTigerSizeStorer Class Reference

The WiredTigerSizeStorer class serves as a write buffer to durably store size information for MongoDB collections. More...

#include <wiredtiger_size_storer.h>

Detailed Description

The WiredTigerSizeStorer class serves as a write buffer to durably store size information for MongoDB collections.

The size storer uses a separate WiredTiger table as key-value store, where the URI serves as key and the value is a BSON document with numRecords and dataSize fields. This buffering is neccessary to allow concurrent updates of size information without causing write conflicts. The dirty size information is periodically stored written back to the table, including on clean shutdown and/or catalog reload. Crashes or replica-set fail-overs may result in size updates to be lost, so size information is only approximate. Reads use the buffer for pending stores, or otherwise read directly from the WiredTiger table using a dedicated session and cursor.

Classes
struct	SizeInfo
	SizeInfo is a thread-safe buffer for keeping track of the number of documents in a collection and their data size. More...

Public Member Functions
	WiredTigerSizeStorer (WT_CONNECTION *conn, const std::string &storageUri, const bool readOnly=false)
	~WiredTigerSizeStorer ()
void	store (StringData uri, std::shared_ptr< SizeInfo > sizeInfo)
	Ensure that the shared SizeInfo will be stored by the next call to flush. More...
std::shared_ptr< SizeInfo >	load (StringData uri) const
void	flush (bool syncToDisk)
	Writes all changes to the underlying table. More...

Private Types
using	Buffer = StringMap< std::shared_ptr< SizeInfo > >

Private Attributes
const WiredTigerSession	_session
const bool	_readOnly
stdx::mutex	_cursorMutex
WT_CURSOR *	_cursor
stdx::mutex	_bufferMutex
Buffer	_buffer

Member Typedef Documentation

Buffer

using mongo::WiredTigerSizeStorer::Buffer = StringMap<std::shared_ptr<SizeInfo> >

private

Constructor & Destructor Documentation

WiredTigerSizeStorer()

mongo::WiredTigerSizeStorer::WiredTigerSizeStorer	(	WT_CONNECTION *	conn,
		const std::string &	storageUri,
		const bool	readOnly = false
	)

~WiredTigerSizeStorer()

mongo::WiredTigerSizeStorer::~WiredTigerSizeStorer

(

)

Member Function Documentation

flush()

void mongo::WiredTigerSizeStorer::flush

(

bool

syncToDisk

)

Writes all changes to the underlying table.

load()

std::shared_ptr< WiredTigerSizeStorer::SizeInfo > mongo::WiredTigerSizeStorer::load

(

StringData

uri

)

const

store()

void mongo::WiredTigerSizeStorer::store	(	StringData	uri,
		std::shared_ptr< SizeInfo >	sizeInfo
	)

Ensure that the shared SizeInfo will be stored by the next call to flush.

Values stored are no older than the values at time of this call, but may be newer.

Member Data Documentation

_buffer

Buffer mongo::WiredTigerSizeStorer::_buffer

private

_bufferMutex

stdx::mutex mongo::WiredTigerSizeStorer::_bufferMutex

mutableprivate

_cursor

WT_CURSOR* mongo::WiredTigerSizeStorer::_cursor

private

_cursorMutex

stdx::mutex mongo::WiredTigerSizeStorer::_cursorMutex

mutableprivate

_readOnly

const bool mongo::WiredTigerSizeStorer::_readOnly

private

_session

const WiredTigerSession mongo::WiredTigerSizeStorer::_session

private

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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/wiredtiger/wiredtiger_size_storer.h
• /home/louis/git/mongodbsource.github.io/src/src/mongo/db/storage/wiredtiger/wiredtiger_size_storer.cpp