casacore::ExternalLockSync Class Reference

Class to hold table lock data. More...

#include <ExternalLockSync.h>

Public Member Functions
	ExternalLockSync (const TableLock &lockOptions)
	Construct from the given TableLock object.
	~ExternalLockSync ()
void	makeLock (const String &tableName, Bool create, FileLocker::LockType)
	Create the `LockFile` object and acquire a read or write lock when permanent locking is in effect.
Bool	acquire (FileLocker::LockType=FileLocker::Write, uInt nattempts=0)
	Acquire a read or write lock (when needed).
uInt	nrow () const
	Get the current number of rows in this object.
void	release (uInt nrrow)
	Release the lock and synchronize the table access.
Bool	hasLock (FileLocker::LockType) const
	Check if the table has a read or write lock, thus if the table can be read or written safely.
Private Member Functions
	ExternalLockSync (const ExternalLockSync &that)
	Copy constructor is forbidden.
ExternalLockSync &	operator= (const ExternalLockSync &that)
	Assignment is forbidden.
MemoryIO *	doReleaseCallBack (Bool always)
	The member function executing the callback functionality.
Static Private Member Functions
static MemoryIO *	releaseCallBack (void *lockSyncObject, Bool always)
	The callback function when releasing a lock.
Private Attributes
TableLockData	itsLock
TableSyncData	itsSync
uInt	itsNrrow

Detailed Description

Class to hold table lock data.

Intended use:

Internal

Review Status

Reviewed By:: UNKNOWN
Date Reviewed:: before2004/08/25
Test programs:: tTable

Prerequisite

class TableLock

Synopsis

This class keeps the LockFile object used to do the actual locking/unlocking. It also keeps the synchronization information.

Motivation

Encapsulate Table locking data.

Definition at line 64 of file ExternalLockSync.h.

Constructor & Destructor Documentation

casacore::ExternalLockSync::ExternalLockSync ( const TableLock & lockOptions )

Construct from the given TableLock object.

casacore::ExternalLockSync::~ExternalLockSync ( )

casacore::ExternalLockSync::ExternalLockSync ( const ExternalLockSync & that ) [private]

Copy constructor is forbidden.

Member Function Documentation

Bool casacore::ExternalLockSync::acquire	(	FileLocker::LockType	= `FileLocker::Write`,
		uInt	nattempts = `0`
	)

Acquire a read or write lock (when needed).

Nattempts==0 indicates that it has to wait until the lock is acquired. Nattempts>0 indicates that it gives up acquiring the lock when nattempts have been done (with 1 second intervals). It throws an exception when acquire failed while it had to wait. It returns a false status when acquiring the lock failed while it does not have to wait.
When a lock is successfully acquired, the number of rows (see function nrrow() below) is reset as a result of synchronizing the access to the table.

MemoryIO * casacore::ExternalLockSync::doReleaseCallBack ( Bool always ) [inline, private]

The member function executing the callback functionality.

Definition at line 134 of file ExternalLockSync.h.

References itsNrrow, itsSync, casacore::TableSyncData::memoryIO(), and casacore::TableSyncData::write().

Bool casacore::ExternalLockSync::hasLock ( FileLocker::LockType type ) const [inline]

Check if the table has a read or write lock, thus if the table can be read or written safely.

Definition at line 125 of file ExternalLockSync.h.

References casacore::TableLockData::hasLock(), and itsLock.

void casacore::ExternalLockSync::makeLock	(	const String &	tableName,
		Bool	create,
		FileLocker::LockType
	)

Create the LockFile object and acquire a read or write lock when permanent locking is in effect.

It throws an exception when acquiring the lock failed.

uInt casacore::ExternalLockSync::nrow ( ) const [inline]

Get the current number of rows in this object.

Definition at line 139 of file ExternalLockSync.h.

References itsNrrow.

ExternalLockSync& casacore::ExternalLockSync::operator= ( const ExternalLockSync & that ) [private]

Assignment is forbidden.

void casacore::ExternalLockSync::release ( uInt nrrow ) [inline]

Release the lock and synchronize the table access.

When autolocking is in effect, the lock is only released when the inspection-interval (see class TableLockData ) has expired. It does nothing when permanent locking is used. It throws an exception when the release failed.

Definition at line 129 of file ExternalLockSync.h.

References itsLock, itsNrrow, and casacore::TableLockData::release().