mongo::SavedCursorRegistry Class Reference

Class that stores active cursors that have been saved (as part of yielding) to allow them to be invalidated if the thing they pointed at goes away. More...

#include <record_store_v1_base.h>

Detailed Description

Class that stores active cursors that have been saved (as part of yielding) to allow them to be invalidated if the thing they pointed at goes away.

The registry is thread-safe, as readers may concurrently register and remove their cursors. Contention is expected to be very low, as yielding is infrequent. This logically belongs to the RecordStore, but is not contained in it to facilitate unit testing.

Classes
struct	SavedCursor
	The destructor ensures the cursor is unregistered when an exception is thrown. More...

Public Member Functions
	~SavedCursorRegistry ()
void	registerCursor (SavedCursor *cursor)
	Adds given saved cursor to SavedCursorRegistry. More...
bool	unregisterCursor (SavedCursor *cursor)
	Removes given saved cursor. More...
void	invalidateCursorsForBucket (DiskLoc bucket)
	When a btree-bucket disappears due to merge/split or similar, this invalidates all cursors that point at the same bucket by removing them from the registry. More...

Private Types
typedef stdx::unordered_set< SavedCursor * >	SavedCursorSet

Private Attributes
SpinLock	_mutex
SavedCursorSet	_cursors

Member Typedef Documentation

SavedCursorSet

typedef stdx::unordered_set<SavedCursor*> mongo::SavedCursorRegistry::SavedCursorSet

private

Constructor & Destructor Documentation

~SavedCursorRegistry()

mongo::SavedCursorRegistry::~SavedCursorRegistry

(

)

Member Function Documentation

invalidateCursorsForBucket()

void mongo::SavedCursorRegistry::invalidateCursorsForBucket

(

DiskLoc

bucket

)

When a btree-bucket disappears due to merge/split or similar, this invalidates all cursors that point at the same bucket by removing them from the registry.

registerCursor()

void mongo::SavedCursorRegistry::registerCursor

(

SavedCursor *

cursor

)

Adds given saved cursor to SavedCursorRegistry.

Doesn't take ownership.

unregisterCursor()

bool mongo::SavedCursorRegistry::unregisterCursor

(

SavedCursor *

cursor

)

Removes given saved cursor.

Returns true if the cursor was still present, and false if it had already been removed due to invalidation. Doesn't take ownership.

Member Data Documentation

_cursors

SavedCursorSet mongo::SavedCursorRegistry::_cursors

private

_mutex

SpinLock mongo::SavedCursorRegistry::_mutex

private

---

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

• /home/louis/git/mongodbsource.github.io/src/src/mongo/db/storage/mmap_v1/record_store_v1_base.h
• /home/louis/git/mongodbsource.github.io/src/src/mongo/db/storage/mmap_v1/record_store_v1_base.cpp