Class Description

This class extends class ThreadLock, adding functionality to register 'acquirers' of type ThreadLock. Only with the second acquirer added, the lock is activated using ThreadLock.setSafeness(Safeness.Safe). The goal is to not use a mutex, when such use is not needed. In occasions with very high frequency of acquisition, this can provide a performance benefit.

The following rules apply:

An instance of this type must not be acquired before an acquirer is registered.
The acquirers have to be in recursive mode.
If acquirers are locked in a nested fashion, then they have to be added in the same order they are locked and removed in reverse order
An acquirer must not be added twice. (This is not a technical restriction, but a chosen design. While a second addition is ignored, in debug versions of the code, an ALib Error Report is written (by default this triggers an assertion).

Using nulled acquirers:
Sometimes it is useful to add a null as an acquirer. A sample for this is found and explained with ALIB.stdOutputStreamsLock. If the first acquirer is null, the second should be added in a thread-safe way. This means, the code invoking addAcquirer needs to care for itself, that this object is not acquired during this process. E.g. it can be done in the bootstrap section of a process, when no parallel threads were started. For further acquirers, such care does not need to be taken. While an acquirer must not be attached twice, 'anonymous' (null) acquirers may. For each anonymous invocation of addAcquirer, a corresponding call removeAcquirer is needed, to get back to Safeness.Unsafe.

Public Methods
	SmartLock ()

int	addAcquirer (ThreadLock newAcquirer)

int	cntAcquirers ()

int	removeAcquirer (ThreadLock acquirerToRemove)

Public Methods inherited from ThreadLock
	ThreadLock ()

	ThreadLock (LockMode lockMode)

	ThreadLock (LockMode lockMode, Safeness safeness)

void	acquire ()

int	dbgCountAcquirements (Thread thread)

LockMode	getMode ()

Safeness	getSafeness ()

void	release ()

void	setSafeness (Safeness safeness)

String	toString ()

boolean	willRelease ()

Protected Fields
ArrayList< ThreadLock >	acquirers = new ArrayList<ThreadLock>()

Protected Fields inherited from ThreadLock
int	cntAcquirements

boolean	createOwnerStackTrace = false

LockMode	lockMode

Object	mutex

Thread	owner

Exception	ownerException

Ticks	waitTime = new Ticks()

Additional Inherited Members
Public Fields inherited from ThreadLock
int	recursionWarningThreshold = 10

int	waitWarningTimeLimitInMillis = 1000

Package Access Methods inherited from ThreadLock
void	constructor (LockMode lockMode, Safeness safeness)

Constructor & Destructor Documentation

◆ SmartLock()

SmartLock ( )

Constructs an SmartLock. Parent ThreadLock is initialized to Unsafe mode.

Member Function Documentation

◆ addAcquirer()

int addAcquirer ( ThreadLock newAcquirer )

Adds an acquirer.

Parameters

newAcquirer The acquirer to add.

Returns: The new number of acquirers set.

Reimplemented in TextLogger.

◆ cntAcquirers()

int cntAcquirers ( )

Returns the number of acquirers. This is for debug and statistics purposes.

Returns: The number of acquirers set.

◆ removeAcquirer()

int removeAcquirer ( ThreadLock acquirerToRemove )

Removes an acquirer.

Parameters

acquirerToRemove The acquirer to remove.

Returns: The new number of acquirers set.

Reimplemented in TextLogger.

Member Data Documentation

◆ acquirers

ArrayList<ThreadLock> acquirers = new ArrayList<ThreadLock>()

protected

The list of acquirers.

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

SmartLock.java