mongo::KVStorageEngine Class Reference

#include <kv_storage_engine.h>

Inheritance diagram for mongo::KVStorageEngine:

Classes
class	RemoveDBChange

Public Member Functions
	KVStorageEngine (KVEngine *engine, const KVStorageEngineOptions &options=KVStorageEngineOptions(), stdx::function< KVDatabaseCatalogEntryFactory > databaseCatalogEntryFactory=defaultDatabaseCatalogEntryFactory)
virtual	~KVStorageEngine ()
virtual void	finishInit ()
	Called after the globalStorageEngine pointer has been set up, before any other methods are called. More...
virtual RecoveryUnit *	newRecoveryUnit ()
	Returns a new interface to the storage engine's recovery unit. More...
virtual void	listDatabases (std::vector< std::string > *out) const
	List the databases stored in this storage engine. More...
KVDatabaseCatalogEntryBase *	getDatabaseCatalogEntry (OperationContext *opCtx, StringData db) override
	Return the DatabaseCatalogEntry that describes the database indicated by 'db'. More...
virtual bool	supportsDocLocking () const
	Returns whether the storage engine supports its own locking locking below the collection level. More...
virtual bool	supportsDBLocking () const
	Returns whether the storage engine supports locking at a database level. More...
virtual bool	supportsCappedCollections () const
	Returns whether the storage engine supports capped collections. More...
virtual Status	closeDatabase (OperationContext *opCtx, StringData db)
	Closes all file handles associated with a database. More...
virtual Status	dropDatabase (OperationContext *opCtx, StringData db)
	Deletes all data and metadata for a database. More...
virtual int	flushAllFiles (OperationContext *opCtx, bool sync)
virtual Status	beginBackup (OperationContext *opCtx)
	Transitions the storage engine into backup mode. More...
virtual void	endBackup (OperationContext *opCtx)
	Transitions the storage engine out of backup mode. More...
virtual bool	isDurable () const
	Returns whether the engine supports a journalling concept or not. More...
virtual bool	isEphemeral () const
	Returns true if the engine does not persist data to disk; false otherwise. More...
virtual Status	repairRecordStore (OperationContext *opCtx, const std::string &ns)
	Recover as much data as possible from a potentially corrupt RecordStore. More...
virtual void	cleanShutdown ()
	This method will be called before there is a clean shutdown. More...
virtual void	setStableTimestamp (Timestamp stableTimestamp) override
	Sets the highest timestamp at which the storage engine is allowed to take a checkpoint. More...
virtual void	setInitialDataTimestamp (Timestamp initialDataTimestamp) override
	Tells the storage engine the timestamp of the data at startup. More...
virtual void	setOldestTimestampFromStable () override
	Uses the current stable timestamp to set the oldest timestamp for which the storage engine must maintain snapshot history through. More...
virtual void	setOldestTimestamp (Timestamp newOldestTimestamp) override
	Sets the oldest timestamp for which the storage engine must maintain snapshot history through. More...
virtual bool	isCacheUnderPressure (OperationContext *opCtx) const override
	Indicates whether the storage engine cache is under pressure. More...
virtual void	setCachePressureForTest (int pressure) override
	For unit tests only. More...
virtual bool	supportsRecoverToStableTimestamp () const override
	Returns whether the storage engine supports "recover to stable timestamp". More...
virtual StatusWith< Timestamp >	recoverToStableTimestamp (OperationContext *opCtx) override
	Recovers the storage engine state to the last stable timestamp. More...
virtual boost::optional< Timestamp >	getRecoveryTimestamp () const override
	Returns the stable timestamp that the storage engine recovered to on startup. More...
virtual boost::optional< Timestamp >	getLastStableCheckpointTimestamp () const override
	Returns a timestamp that is guaranteed to be persisted to disk in a checkpoint. More...
virtual Timestamp	getAllCommittedTimestamp () const override
	Returns the all committed timestamp. More...
bool	supportsReadConcernSnapshot () const final
	Returns true if the storage engine supports the readConcern level "snapshot". More...
virtual void	replicationBatchIsComplete () const override
	Notifies the storage engine that a replication batch has completed. More...
SnapshotManager *	getSnapshotManager () const final
	Returns the SnapshotManager for this StorageEngine or NULL if not supported. More...
void	setJournalListener (JournalListener *jl) final
	Sets a new JournalListener, which is used by the storage engine to alert the rest of the system about journaled write progress. More...
KVEngine *	getEngine ()
const KVEngine *	getEngine () const
KVCatalog *	getCatalog ()
const KVCatalog *	getCatalog () const
StatusWith< std::vector< StorageEngine::CollectionIndexNamePair > >	reconcileCatalogAndIdents (OperationContext *opCtx) override
	Drop abandoned idents. More...
void	loadCatalog (OperationContext *opCtx) final
	When loading after an unclean shutdown, this performs cleanup on the KVCatalog and unsets the startingAfterUncleanShutdown decoration on the global ServiceContext. More...
void	closeCatalog (OperationContext *opCtx) final
Public Member Functions inherited from mongo::StorageEngine
virtual	~StorageEngine ()
	The destructor should only be called if we are tearing down but not exiting the process. More...
virtual bool	isMmapV1 () const
	Only MMAPv1 should override this and return true to trigger MMAPv1-specific behavior. More...

Private Types
using	CollIter = std::list< std::string >::iterator
typedef std::map< std::string, KVDatabaseCatalogEntryBase * >	DBMap

Private Member Functions
Status	_dropCollectionsNoTimestamp (OperationContext *opCtx, KVDatabaseCatalogEntryBase *dbce, CollIter begin, CollIter end)
	Returns the first dropCollection error that this method encounters. More...
Status	_dropCollectionsWithTimestamp (OperationContext *opCtx, KVDatabaseCatalogEntryBase *dbce, std::list< std::string > &toDrop, CollIter begin, CollIter end)
void	_dumpCatalog (OperationContext *opCtx)

Private Attributes
stdx::function< KVDatabaseCatalogEntryFactory >	_databaseCatalogEntryFactory
KVStorageEngineOptions	_options
std::unique_ptr< KVEngine >	_engine
const bool	_supportsDocLocking
const bool	_supportsDBLocking
const bool	_supportsCappedCollections
Timestamp	_initialDataTimestamp = Timestamp::kAllowUnstableCheckpointsSentinel
std::unique_ptr< RecordStore >	_catalogRecordStore
std::unique_ptr< KVCatalog >	_catalog
DBMap	_dbs
stdx::mutex	_dbsLock
bool	_inBackupMode = false

Additional Inherited Members
Public Types inherited from mongo::StorageEngine
typedef std::pair< std::string, std::string >	CollectionIndexNamePair

Member Typedef Documentation

CollIter

using mongo::KVStorageEngine::CollIter = std::list<std::string>::iterator

private

DBMap

typedef std::map<std::string, KVDatabaseCatalogEntryBase*> mongo::KVStorageEngine::DBMap

private

Constructor & Destructor Documentation

KVStorageEngine()

mongo::KVStorageEngine::KVStorageEngine	(	KVEngine *	engine,
		const KVStorageEngineOptions &	options = KVStorageEngineOptions(),
		stdx::function< KVDatabaseCatalogEntryFactory >	databaseCatalogEntryFactory = defaultDatabaseCatalogEntryFactory
	)

Parameters

engine

- ownership passes to me

~KVStorageEngine()

mongo::KVStorageEngine::~KVStorageEngine ( )

virtual

Member Function Documentation

_dropCollectionsNoTimestamp()

Status mongo::KVStorageEngine::_dropCollectionsNoTimestamp ( OperationContext *  opCtx, KVDatabaseCatalogEntryBase *  dbce, CollIter  begin, CollIter  end  )

private

Returns the first dropCollection error that this method encounters.

This method will attempt to drop all collections, regardless of the error status.

_dropCollectionsWithTimestamp()

Status mongo::KVStorageEngine::_dropCollectionsWithTimestamp ( OperationContext *  opCtx, KVDatabaseCatalogEntryBase *  dbce, std::list< std::string > &  toDrop, CollIter  begin, CollIter  end  )

private

_dumpCatalog()

void mongo::KVStorageEngine::_dumpCatalog ( OperationContext *  opCtx )

private

beginBackup()

Status mongo::KVStorageEngine::beginBackup ( OperationContext *  opCtx )

virtual

Transitions the storage engine into backup mode.

During backup mode the storage engine must stabilize its on-disk files, and avoid any internal processing that may involve file I/O, such as online compaction, so a filesystem level backup may be performed.

Storage engines that do not support this feature should use the default implementation. Storage engines that implement this must also implement endBackup().

For Storage engines that implement beginBackup the _inBackupMode variable is provided to avoid multiple instance enterting/leaving backup concurrently.

If this function returns an OK status, MongoDB can call endBackup to signal the storage engine that filesystem writes may continue. This function should return a non-OK status if filesystem changes cannot be stopped to allow for online backup. If the function should be retried, returns a non-OK status. This function may throw a WriteConflictException, which should trigger a retry by the caller. All other exceptions should be treated as errors.

Reimplemented from mongo::StorageEngine.

cleanShutdown()

void mongo::KVStorageEngine::cleanShutdown ( )

virtual

This method will be called before there is a clean shutdown.

Storage engines should override this method if they have clean-up to do that is different from unclean shutdown. MongoDB will not call into the storage subsystem after calling this function.

On error, the storage engine should assert and crash. There is intentionally no uncleanShutdown().

Implements mongo::StorageEngine.

closeCatalog()

void mongo::KVStorageEngine::closeCatalog ( OperationContext *  opCtx )

finalvirtual

Reimplemented from mongo::StorageEngine.

closeDatabase()

Status mongo::KVStorageEngine::closeDatabase ( OperationContext *  opCtx, StringData  db  )

virtual

Closes all file handles associated with a database.

Implements mongo::StorageEngine.

dropDatabase()

Status mongo::KVStorageEngine::dropDatabase ( OperationContext *  opCtx, StringData  db  )

virtual

Deletes all data and metadata for a database.

Implements mongo::StorageEngine.

endBackup()

void mongo::KVStorageEngine::endBackup ( OperationContext *  opCtx )

virtual

Transitions the storage engine out of backup mode.

Storage engines that do not support this feature should use the default implementation.

Storage engines implementing this feature should fassert when unable to leave backup mode.

Reimplemented from mongo::StorageEngine.

finishInit()

void mongo::KVStorageEngine::finishInit ( )

virtual

Called after the globalStorageEngine pointer has been set up, before any other methods are called.

Any initialization work that requires the ability to create OperationContexts should be done here rather than in the constructor.

Reimplemented from mongo::StorageEngine.

flushAllFiles()

int mongo::KVStorageEngine::flushAllFiles ( OperationContext *  opCtx, bool  sync  )

virtual

Returns

number of files flushed

Implements mongo::StorageEngine.

getAllCommittedTimestamp()

Timestamp mongo::KVStorageEngine::getAllCommittedTimestamp ( ) const

overridevirtual

Returns the all committed timestamp.

All transactions with timestamps earlier than the all committed timestamp are committed. Only storage engines that support document level locking must provide an implementation. Other storage engines may provide a no-op implementation.

Implements mongo::StorageEngine.

getCatalog() [1/2]

KVCatalog* mongo::KVStorageEngine::getCatalog ( )

inline

getCatalog() [2/2]

const KVCatalog* mongo::KVStorageEngine::getCatalog ( ) const

inline

getDatabaseCatalogEntry()

KVDatabaseCatalogEntryBase * mongo::KVStorageEngine::getDatabaseCatalogEntry ( OperationContext *  opCtx, StringData  db  )

overridevirtual

Return the DatabaseCatalogEntry that describes the database indicated by 'db'.

StorageEngine owns returned pointer. It should not be deleted by any caller.

Implements mongo::StorageEngine.

getEngine() [1/2]

KVEngine* mongo::KVStorageEngine::getEngine ( )

inline

getEngine() [2/2]

const KVEngine* mongo::KVStorageEngine::getEngine ( ) const

inline

getLastStableCheckpointTimestamp()

boost::optional< Timestamp > mongo::KVStorageEngine::getLastStableCheckpointTimestamp ( ) const

overridevirtual

Returns a timestamp that is guaranteed to be persisted to disk in a checkpoint.

Returns boost::none if there is no stable checkpoint. This method should return at least the value of getRecoveryTimestamp if the node started from a stable checkpoint. fasserts if StorageEngine::supportsRecoverToStableTimestamp() would return false.

Reimplemented from mongo::StorageEngine.

getRecoveryTimestamp()

boost::optional< Timestamp > mongo::KVStorageEngine::getRecoveryTimestamp ( ) const

overridevirtual

Returns the stable timestamp that the storage engine recovered to on startup.

If the recovery point was not stable, returns "none". fasserts if StorageEngine::supportsRecoverToStableTimestamp() would return false.

Reimplemented from mongo::StorageEngine.

getSnapshotManager()

SnapshotManager * mongo::KVStorageEngine::getSnapshotManager ( ) const

finalvirtual

Returns the SnapshotManager for this StorageEngine or NULL if not supported.

Pointer remains owned by the StorageEngine, not the caller.

Reimplemented from mongo::StorageEngine.

isCacheUnderPressure()

bool mongo::KVStorageEngine::isCacheUnderPressure ( OperationContext *  opCtx ) const

overridevirtual

Indicates whether the storage engine cache is under pressure.

Retrieves a cache pressure value in the range [0, 100] from the storage engine, and compares it against storageGlobalParams.cachePressureThreshold, a dynamic server parameter, to determine whether cache pressure is too high.

Reimplemented from mongo::StorageEngine.

isDurable()

bool mongo::KVStorageEngine::isDurable ( ) const

virtual

Returns whether the engine supports a journalling concept or not.

Implements mongo::StorageEngine.

isEphemeral()

bool mongo::KVStorageEngine::isEphemeral ( ) const

virtual

Returns true if the engine does not persist data to disk; false otherwise.

Implements mongo::StorageEngine.

listDatabases()

void mongo::KVStorageEngine::listDatabases ( std::vector< std::string > *  out ) const

virtual

List the databases stored in this storage engine.

XXX: why doesn't this take OpCtx?

Implements mongo::StorageEngine.

loadCatalog()

void mongo::KVStorageEngine::loadCatalog ( OperationContext *  opCtx )

finalvirtual

When loading after an unclean shutdown, this performs cleanup on the KVCatalog and unsets the startingAfterUncleanShutdown decoration on the global ServiceContext.

Reimplemented from mongo::StorageEngine.

newRecoveryUnit()

RecoveryUnit * mongo::KVStorageEngine::newRecoveryUnit ( )

virtual

Returns a new interface to the storage engine's recovery unit.

The recovery unit is the durability interface. For details, see recovery_unit.h

Caller owns the returned pointer.

Implements mongo::StorageEngine.

reconcileCatalogAndIdents()

StatusWith< std::vector< StorageEngine::CollectionIndexNamePair > > mongo::KVStorageEngine::reconcileCatalogAndIdents ( OperationContext *  opCtx )

overridevirtual

Drop abandoned idents.

This method reconciles differences between idents the KVEngine is aware of and the KVCatalog.

Returns a parallel list of index name, index spec pairs to rebuild.

There are three differences to consider:

First, a KVEngine may know of an ident that the KVCatalog does not. This method will drop the ident from the KVEngine.

Second, a KVCatalog may have a collection ident that the KVEngine does not. This is an illegal state and this method fasserts.

Third, a KVCatalog may have an index ident that the KVEngine does not. This method will rebuild the index.

Reimplemented from mongo::StorageEngine.

recoverToStableTimestamp()

StatusWith< Timestamp > mongo::KVStorageEngine::recoverToStableTimestamp ( OperationContext *  opCtx )

overridevirtual

Recovers the storage engine state to the last stable timestamp.

"Stable" in this case refers to a timestamp that is guaranteed to never be rolled back. The stable timestamp used should be one provided by StorageEngine::setStableTimestamp().

The "local" database is exempt and should not roll back any state except for "local.replset.minvalid" which must roll back to the last stable timestamp.

If successful, returns the timestamp that the storage engine recovered to.

fasserts if StorageEngine::supportsRecoverToStableTimestamp() would return false. Returns a bad status if there is no stable timestamp to recover to.

It is illegal to call this concurrently with setStableTimestamp or setInitialDataTimestamp.

Reimplemented from mongo::StorageEngine.

repairRecordStore()

Status mongo::KVStorageEngine::repairRecordStore ( OperationContext *  opCtx, const std::string &  ns  )

virtual

Recover as much data as possible from a potentially corrupt RecordStore.

This only recovers the record data, not indexes or anything else.

Generally, this method should not be called directly except by the repairDatabase() free function.

NOTE: MMAPv1 does not support this method and has its own repairDatabase() method.

Implements mongo::StorageEngine.

replicationBatchIsComplete()

void mongo::KVStorageEngine::replicationBatchIsComplete ( ) const

overridevirtual

Notifies the storage engine that a replication batch has completed.

This means that all the writes associated with the oplog entries in the batch are finished and no new writes with timestamps associated with those oplog entries will show up in the future. This function can be used to ensure oplog visibility rules are not broken, for example.

Reimplemented from mongo::StorageEngine.

setCachePressureForTest()

void mongo::KVStorageEngine::setCachePressureForTest ( int  pressure )

overridevirtual

For unit tests only.

Sets the cache pressure value with which isCacheUnderPressure() evalutates to 'pressure'.

Reimplemented from mongo::StorageEngine.

setInitialDataTimestamp()

void mongo::KVStorageEngine::setInitialDataTimestamp ( Timestamp  timestamp )

overridevirtual

Tells the storage engine the timestamp of the data at startup.

This is necessary because timestamps are not persisted in the storage layer.

Reimplemented from mongo::StorageEngine.

setJournalListener()

void mongo::KVStorageEngine::setJournalListener ( JournalListener *  jl )

finalvirtual

Sets a new JournalListener, which is used by the storage engine to alert the rest of the system about journaled write progress.

Implements mongo::StorageEngine.

setOldestTimestamp()

void mongo::KVStorageEngine::setOldestTimestamp ( Timestamp  timestamp )

overridevirtual

Sets the oldest timestamp for which the storage engine must maintain snapshot history through.

Additionally, all future writes must be newer or equal to this value.

Reimplemented from mongo::StorageEngine.

setOldestTimestampFromStable()

void mongo::KVStorageEngine::setOldestTimestampFromStable ( )

overridevirtual

Uses the current stable timestamp to set the oldest timestamp for which the storage engine must maintain snapshot history through.

oldest_timestamp will be set to stable_timestamp adjusted by 'targetSnapshotHistoryWindowInSeconds' to create a window of available snapshots on the storage engine from oldest to stable. Furthermore, oldest_timestamp will never be set ahead of the oplog read timestamp, ensuring the oplog reader's 'read_timestamp' can always be serviced.

Reimplemented from mongo::StorageEngine.

setStableTimestamp()

void mongo::KVStorageEngine::setStableTimestamp ( Timestamp  timestamp )

overridevirtual

Sets the highest timestamp at which the storage engine is allowed to take a checkpoint.

This timestamp can never decrease, and thus should be a timestamp that can never roll back.

Reimplemented from mongo::StorageEngine.

supportsCappedCollections()

virtual bool mongo::KVStorageEngine::supportsCappedCollections ( ) const

inlinevirtual

Returns whether the storage engine supports capped collections.

Reimplemented from mongo::StorageEngine.

supportsDBLocking()

virtual bool mongo::KVStorageEngine::supportsDBLocking ( ) const

inlinevirtual

Returns whether the storage engine supports locking at a database level.

Reimplemented from mongo::StorageEngine.

supportsDocLocking()

virtual bool mongo::KVStorageEngine::supportsDocLocking ( ) const

inlinevirtual

Returns whether the storage engine supports its own locking locking below the collection level.

If the engine returns true, MongoDB will acquire intent locks down to the collection level and will assume that the engine will ensure consistency at the level of documents. If false, MongoDB will lock the entire collection in Shared/Exclusive mode for read/write operations respectively.

Implements mongo::StorageEngine.

supportsReadConcernSnapshot()

bool mongo::KVStorageEngine::supportsReadConcernSnapshot ( ) const

finalvirtual

Returns true if the storage engine supports the readConcern level "snapshot".

Reimplemented from mongo::StorageEngine.

supportsRecoverToStableTimestamp()

bool mongo::KVStorageEngine::supportsRecoverToStableTimestamp ( ) const

overridevirtual

Returns whether the storage engine supports "recover to stable timestamp".

Returns true if the storage engine supports "recover to stable timestamp" but does not currently have a stable timestamp. In that case StorageEngine::recoverToStableTimestamp() will return a bad status.

Reimplemented from mongo::StorageEngine.

Member Data Documentation

_catalog

std::unique_ptr<KVCatalog> mongo::KVStorageEngine::_catalog

private

_catalogRecordStore

std::unique_ptr<RecordStore> mongo::KVStorageEngine::_catalogRecordStore

private

_databaseCatalogEntryFactory

stdx::function<KVDatabaseCatalogEntryFactory> mongo::KVStorageEngine::_databaseCatalogEntryFactory

private

_dbs

DBMap mongo::KVStorageEngine::_dbs

private

_dbsLock

stdx::mutex mongo::KVStorageEngine::_dbsLock

mutableprivate

_engine

std::unique_ptr<KVEngine> mongo::KVStorageEngine::_engine

private

_inBackupMode

bool mongo::KVStorageEngine::_inBackupMode = false

private

_initialDataTimestamp

Timestamp mongo::KVStorageEngine::_initialDataTimestamp = Timestamp::kAllowUnstableCheckpointsSentinel

private

_options

KVStorageEngineOptions mongo::KVStorageEngine::_options

private

_supportsCappedCollections

const bool mongo::KVStorageEngine::_supportsCappedCollections

private

_supportsDBLocking

const bool mongo::KVStorageEngine::_supportsDBLocking

private

_supportsDocLocking

const bool mongo::KVStorageEngine::_supportsDocLocking

private

---

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

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