mongo::Lock::DBLock Class Reference

Database lock with support for collection- and document-level locking. More...

#include <d_concurrency.h>

Detailed Description

Database lock with support for collection- and document-level locking.

This lock supports four modes (see Lock_Mode): MODE_IS: concurrent database access, requiring further collection read locks MODE_IX: concurrent database access, requiring further collection read or write locks MODE_S: shared read access to the database, blocking any writers MODE_X: exclusive access to the database, blocking all other readers and writers

For MODE_IS or MODE_S also acquires global lock in intent-shared (IS) mode, and for MODE_IX or MODE_X also acquires global lock in intent-exclusive (IX) mode. For storage engines that do not support collection-level locking, MODE_IS will be upgraded to MODE_S and MODE_IX will be upgraded to MODE_X.

Public Member Functions
	DBLock (OperationContext *opCtx, StringData db, LockMode mode, Date_t deadline=Date_t::max())
	DBLock (DBLock &&)
	~DBLock ()
void	relockWithMode (LockMode newMode)
	Releases the DBLock and reacquires it with the new mode. More...
bool	isLocked () const

Private Attributes
const ResourceId	_id
OperationContext *const	_opCtx
LockResult	_result
LockMode	_mode
GlobalLock	_globalLock

Constructor & Destructor Documentation

DBLock() [1/2]

mongo::Lock::DBLock::DBLock	(	OperationContext *	opCtx,
		StringData	db,
		LockMode	mode,
		Date_t	deadline = Date_t::max()
	)

DBLock() [2/2]

mongo::Lock::DBLock::DBLock

(

DBLock &&

otherLock

)

~DBLock()

mongo::Lock::DBLock::~DBLock

(

)

Member Function Documentation

isLocked()

bool mongo::Lock::DBLock::isLocked ( ) const

inline

relockWithMode()

void mongo::Lock::DBLock::relockWithMode

(

LockMode

newMode

)

Releases the DBLock and reacquires it with the new mode.

The global intent lock is retained (so the database can't disappear). Relocking from MODE_IS or MODE_S to MODE_IX or MODE_X is not allowed to avoid violating the global intent. Use relockWithMode() instead of upgrading to avoid deadlock.

Member Data Documentation

_globalLock

GlobalLock mongo::Lock::DBLock::_globalLock

private

_id

const ResourceId mongo::Lock::DBLock::_id

private

_mode

LockMode mongo::Lock::DBLock::_mode

private

_opCtx

OperationContext* const mongo::Lock::DBLock::_opCtx

private

_result

LockResult mongo::Lock::DBLock::_result

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/concurrency/d_concurrency.h
• /home/louis/git/mongodbsource.github.io/src/src/mongo/db/concurrency/d_concurrency.cpp