Module dk.cloudcreate.essentials.components.foundation

Package dk.cloudcreate.essentials.components.foundation.fencedlock

Interface FencedLockStorage<UOW extends UnitOfWork,LOCK extends DBFencedLock>

public interface FencedLockStorage<UOW extends UnitOfWork,LOCK extends DBFencedLock>

Method Summary

Modifier and Type	Method	Description
boolean	confirmLockInDB(DBFencedLockManager<UOW,LOCK> lockManager, UOW uow, LOCK fencedLock, OffsetDateTime confirmedTimestamp)	Update the database status for the lock as being confirmed by this lock manager instance
LOCK	createInitializedLock(DBFencedLockManager<UOW,LOCK> lockManager, LockName name, long currentToken, String lockedByLockManagerInstanceId, OffsetDateTime lockAcquiredTimestamp, OffsetDateTime lockLastConfirmedTimestamp)	Create an initialized lock
LOCK	createUninitializedLock(DBFencedLockManager<UOW,LOCK> lockManager, LockName lockName)	Create an un-initialized lock (with a default DB specific un-initialized value for the DBFencedLock.getCurrentToken())
void	deleteAllLocksInDB(DBFencedLockManager<UOW,LOCK> lockManager, UOW uow)	Delete all locks in the DB.
void	deleteLockInDB(DBFencedLockManager<UOW,LOCK> lockManager, UOW uow, LockName nameOfLockToDelete)	Delete a lock in the DB.
long	getInitialTokenValue()	Return the DB specific value for a FencedLock.getCurrentToken() that is being persisted the very first time
Long	getUninitializedTokenValue()	Return the DB specific uninitialized value for a FencedLock.getCurrentToken() that has yet to be persisted for the very first time
void	initializeLockStorage(DBFencedLockManager<UOW,LOCK> lockManager, UOW uow)	Initialize the database storage (e.g.
boolean	insertLockIntoDB(DBFencedLockManager<UOW,LOCK> lockManager, UOW uow, LOCK initialLock, OffsetDateTime lockAcquiredAndLastConfirmedTimestamp)	Insert the local into the DB for the very first time
Optional<LOCK>	lookupLockInDB(DBFencedLockManager<UOW,LOCK> lockManager, UOW uow, LockName lockName)	Lookup a Lock in the underlying database
boolean	releaseLockInDB(DBFencedLockManager<UOW,LOCK> lockManager, UOW uow, LOCK fencedLock)	Update the database status for the lock as being released
boolean	updateLockInDB(DBFencedLockManager<UOW,LOCK> lockManager, UOW uow, LOCK timedOutLock, LOCK newLockReadyToBeAcquiredLocally)	Update the lock in the DB.

Method Detail

initializeLockStorage

void initializeLockStorage(DBFencedLockManager<UOW,LOCK> lockManager,
                           UOW uow)

Initialize the database storage (e.g. create table, collection, etc.)

Parameters:

lockManager - the lock manager

uow - the active unit of work

confirmLockInDB

boolean confirmLockInDB(DBFencedLockManager<UOW,LOCK> lockManager,
                        UOW uow,
                        LOCK fencedLock,
                        OffsetDateTime confirmedTimestamp)

Update the database status for the lock as being confirmed by this lock manager instance

Parameters:

lockManager - the lock manager

uow - the active unit of work

fencedLock - the fenced lock instance that is being confirmed

confirmedTimestamp - the new confirmed timestamp

Returns:

true if the update in the DB was successful or false if we couldn't confirm the lock (e.g. because another lock manager instance had acquired the lock and updated the FencedLock.getCurrentToken() value in the DB

releaseLockInDB

boolean releaseLockInDB(DBFencedLockManager<UOW,LOCK> lockManager,
                        UOW uow,
                        LOCK fencedLock)

Update the database status for the lock as being released

Parameters:

lockManager - the lock manager

uow - the active unit of work

fencedLock - the fenced lock instance that is being released

Returns:

true if the update in the DB was successful or false if we couldn't release the lock (e.g. because another lock manager instance had acquired the lock and updated the FencedLock.getCurrentToken() value in the DB

lookupLockInDB

Optional<LOCK> lookupLockInDB(DBFencedLockManager<UOW,LOCK> lockManager,
                              UOW uow,
                              LockName lockName)

Lookup a Lock in the underlying database

Parameters:

lockManager - the lock manager

uow - the active unit of work

lockName - the name of the lock to find in the DB

Returns:

the result of the search

createUninitializedLock

LOCK createUninitializedLock(DBFencedLockManager<UOW,LOCK> lockManager,
                             LockName lockName)

Create an un-initialized lock (with a default DB specific un-initialized value for the DBFencedLock.getCurrentToken())

Parameters:

lockManager - the lock manager

lockName - the name of the lock

Returns:

the concrete DB specific DBFencedLock subclass

createInitializedLock

LOCK createInitializedLock(DBFencedLockManager<UOW,LOCK> lockManager,
                           LockName name,
                           long currentToken,
                           String lockedByLockManagerInstanceId,
                           OffsetDateTime lockAcquiredTimestamp,
                           OffsetDateTime lockLastConfirmedTimestamp)

Create an initialized lock

Parameters:

lockManager - the lock manager

name - the name of the lock

currentToken - the current token value

lockedByLockManagerInstanceId - the id (if any) of the local managed that has acquired the lock

lockAcquiredTimestamp - the lock Acquired Timestamp

lockLastConfirmedTimestamp - the lock Last Confirmed Timestamp

Returns:

the concrete DB specific DBFencedLock subclass

getUninitializedTokenValue

Long getUninitializedTokenValue()

Return the DB specific uninitialized value for a FencedLock.getCurrentToken() that has yet to be persisted for the very first time

Returns:

the DB specific uninitialized value for a FencedLock.getCurrentToken() that has yet to be persisted for the very first time

getInitialTokenValue

long getInitialTokenValue()

Return the DB specific value for a FencedLock.getCurrentToken() that is being persisted the very first time

Returns:

the DB specific value for a FencedLock.getCurrentToken() that is being persisted the very first time

insertLockIntoDB

boolean insertLockIntoDB(DBFencedLockManager<UOW,LOCK> lockManager,
                         UOW uow,
                         LOCK initialLock,
                         OffsetDateTime lockAcquiredAndLastConfirmedTimestamp)

Insert the local into the DB for the very first time

Parameters:

lockManager - the lock manager

uow - the unit of work

initialLock - the initial and no yet persisted lock (with no FencedLock.getCurrentToken() value set yet)

lockAcquiredAndLastConfirmedTimestamp - the timestamp of when the lock is being acquired and last confirmed

Returns:

updateLockInDB

boolean updateLockInDB(DBFencedLockManager<UOW,LOCK> lockManager,
                       UOW uow,
                       LOCK timedOutLock,
                       LOCK newLockReadyToBeAcquiredLocally)

Update the lock in the DB.

Parameters:

lockManager - the lock manager

uow - the unit of work

timedOutLock - the lock that has timed out

newLockReadyToBeAcquiredLocally - the lock that was acquired by this lock manager instance

Returns:

true if the update in the DB was successful or false if we couldn't confirm the lock (e.g. because another lock manager instance had acquired the lock)

deleteLockInDB

void deleteLockInDB(DBFencedLockManager<UOW,LOCK> lockManager,
                    UOW uow,
                    LockName nameOfLockToDelete)

Delete a lock in the DB. Should be used with caution (i.e. when you're sure that the lock is no longer used by any nodes

Parameters:

lockManager - the lock manager

uow - the unit of work

nameOfLockToDelete - the name of the lock to delete

deleteAllLocksInDB

void deleteAllLocksInDB(DBFencedLockManager<UOW,LOCK> lockManager,
                        UOW uow)

Delete all locks in the DB. Should be used with caution and typically only for testing purposes

Parameters:

lockManager - the lock manager

uow - the unit of work