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ExternalLockSync.h
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//# ExternalLockSync.h: Class to hold table lock data
//# Copyright (C) 1997,1998
//# Associated Universities, Inc. Washington DC, USA.
//#
//# This library is free software; you can redistribute it and/or modify it
//# under the terms of the GNU Library General Public License as published by
//# the Free Software Foundation; either version 2 of the License, or (at your
//# option) any later version.
//#
//# This library is distributed in the hope that it will be useful, but WITHOUT
//# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
//# FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public
//# License for more details.
//#
//# You should have received a copy of the GNU Library General Public License
//# along with this library; if not, write to the Free Software Foundation,
//# Inc., 675 Massachusetts Ave, Cambridge, MA 02139, USA.
//#
//# Correspondence concerning AIPS++ should be addressed as follows:
//# Internet email: casa-feedback@nrao.edu.
//# Postal address: AIPS++ Project Office
//# National Radio Astronomy Observatory
//# 520 Edgemont Road
//# Charlottesville, VA 22903-2475 USA
#ifndef TABLES_EXTERNALLOCKSYNC_H
#define TABLES_EXTERNALLOCKSYNC_H
//# Includes
#include <casacore/casa/aips.h>
#include <casacore/tables/Tables/TableLockData.h>
#include <casacore/tables/Tables/TableSyncData.h>
namespace casacore { //# NAMESPACE CASACORE - BEGIN
// <summary>
// Class to hold table lock data.
// </summary>
// <use visibility=local>
// <reviewed reviewer="UNKNOWN" date="before2004/08/25" tests="tTable" demos="">
// </reviewed>
// <prerequisite>
// <li> class <linkto class=Table>TableLock</linkto>
// </prerequisite>
// <synopsis>
// This class keeps the <src>LockFile</src> object used to do the
// actual locking/unlocking.
// It also keeps the synchronization information.
// </synopsis>
// <motivation>
// Encapsulate Table locking data.
// </motivation>
class ExternalLockSync
{
public:
// Construct from the given TableLock object.
ExternalLockSync (const TableLock& lockOptions);
~ExternalLockSync();
// Copy constructor is forbidden.
ExternalLockSync (const ExternalLockSync& that) = delete;
// Assignment is forbidden.
ExternalLockSync& operator= (const ExternalLockSync& that) = delete;
// Create the <src>LockFile</src> object and acquire a read or write
// lock when permanent locking is in effect.
// It throws an exception when acquiring the lock failed.
void makeLock (const String& tableName, Bool create, FileLocker::LockType);
// 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.
// <br>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.
Bool acquire (FileLocker::LockType = FileLocker::Write, uInt nattempts = 0);
// Get the current number of rows in this object.
rownr_t nrow() const;
// Release the lock and synchronize the table access.
// When autolocking is in effect, the lock is only released when
// the inspection-interval (see class
// <linkto class=TableLockData>TableLockData</linkto>) has expired.
// It does nothing when permanent locking is used.
// It throws an exception when the release failed.
void release (rownr_t nrrow);
// Check if the table has a read or write lock, thus if the table can
// be read or written safely.
Bool hasLock (FileLocker::LockType) const;
private:
// The callback function when releasing a lock.
static MemoryIO* releaseCallBack (void* lockSyncObject, Bool always);
// The member function executing the callback functionality.
MemoryIO* doReleaseCallBack (Bool always);
//# Define the lock and sync data objects.
TableLockData itsLock;
TableSyncData itsSync;
rownr_t itsNrrow;
};
inline Bool ExternalLockSync::hasLock (FileLocker::LockType type) const
{
return itsLock.hasLock (type);
}
inline void ExternalLockSync::release (rownr_t nrrow)
{
itsNrrow = nrrow;
itsLock.release();
}
inline MemoryIO* ExternalLockSync::doReleaseCallBack (Bool)
{
itsSync.write (itsNrrow);
return &(itsSync.memoryIO());
}
inline rownr_t ExternalLockSync::nrow() const
{
return itsNrrow;
}
} //# NAMESPACE CASACORE - END
#endif
casacore::type
casacore::ExternalLockSync::makeLock
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.
casacore::ExternalLockSync::release
void release(rownr_t nrrow)
Release the lock and synchronize the table access.
Definition ExternalLockSync.h:127
casacore::ExternalLockSync::itsSync
TableSyncData itsSync
Definition ExternalLockSync.h:118
casacore::ExternalLockSync::~ExternalLockSync
~ExternalLockSync()
casacore::ExternalLockSync::acquire
Bool acquire(FileLocker::LockType=FileLocker::Write, uInt nattempts=0)
Acquire a read or write lock (when needed).
casacore::ExternalLockSync::itsLock
TableLockData itsLock
Definition ExternalLockSync.h:117
casacore::ExternalLockSync::doReleaseCallBack
MemoryIO * doReleaseCallBack(Bool always)
The member function executing the callback functionality.
Definition ExternalLockSync.h:132
casacore::ExternalLockSync::hasLock
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.
Definition ExternalLockSync.h:123
casacore::ExternalLockSync::nrow
rownr_t nrow() const
Get the current number of rows in this object.
Definition ExternalLockSync.h:137
casacore::ExternalLockSync::itsNrrow
rownr_t itsNrrow
Definition ExternalLockSync.h:119
casacore::ExternalLockSync::releaseCallBack
static MemoryIO * releaseCallBack(void *lockSyncObject, Bool always)
The callback function when releasing a lock.
casacore::ExternalLockSync::ExternalLockSync
ExternalLockSync(const ExternalLockSync &that)=delete
Copy constructor is forbidden.
casacore::ExternalLockSync::ExternalLockSync
ExternalLockSync(const TableLock &lockOptions)
Construct from the given TableLock object.
casacore::ExternalLockSync::operator=
ExternalLockSync & operator=(const ExternalLockSync &that)=delete
Assignment is forbidden.
casacore::FileLocker::LockType
LockType
Define the possible lock types.
Definition FileLocker.h:93
casacore::FileLocker::Write
@ Write
Acquire a write lock.
Definition FileLocker.h:97
casacore::MemoryIO
Definition MemoryIO.h:123
casacore::String
String: the storage and methods of handling collections of characters.
Definition String.h:223
casacore::TableLockData
Definition TableLockData.h:62
casacore::TableLock
Definition TableLock.h:67
casacore::TableSyncData
Definition TableSyncData.h:77
casacore
this file contains all the compiler specific defines
Definition mainpage.dox:28
casacore::uInt
unsigned int uInt
Definition aipstype.h:49
casacore::Bool
bool Bool
Define the standard types used by Casacore.
Definition aipstype.h:40
casacore::rownr_t
uInt64 rownr_t
Define the type of a row number in a table.
Definition aipsxtype.h:44