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//# TableLockData.cc: Class to hold table lock data
//# Copyright (C) 1997,1998,1999,2000,2001
//# 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: aips2-request@nrao.edu.
//# Postal address: AIPS++ Project Office
//# National Radio Astronomy Observatory
//# 520 Edgemont Road
//# Charlottesville, VA 22903-2475 USA
//#
//# $Id$
#include <casacore/tables/Tables/TableLockData.h>
#include <casacore/tables/Tables/TableError.h>
#include <casacore/casa/Logging/LogIO.h>
#include <unistd.h>
namespace casacore { //# NAMESPACE CASACORE - BEGIN
TableLockData::TableLockData (const TableLock& lockOptions,
TableLockData::ReleaseCallBack* releaseCallBack,
void* releaseParentObject)
: TableLock (lockOptions),
itsLock (0),
itsReleaseCallBack (releaseCallBack),
itsReleaseParent (releaseParentObject)
{}
TableLockData::~TableLockData()
{
delete itsLock;
}
void TableLockData::makeLock (const String& name, Bool create,
FileLocker::LockType type, uInt locknr)
{
//# Create lock file object only when not created yet.
//# It is acceptable that no lock file exists for a readonly table
//# (to be able to read older tables).
if (itsLock == 0) {
itsLock = new LockFile (name + "/table.lock", interval(), create,
True, False, locknr, isPermanent(),
option() == NoLocking);
}
//# Acquire a lock when permanent locking is in use.
if (isPermanent()) {
uInt nattempts = 1;
if (option() == PermanentLockingWait) {
nattempts = 0; // wait
}
if (! itsLock->acquire (type, nattempts)) {
throw (TableError ("Permanent lock on table " + name +
" could not be acquired (" +
itsLock->lastMessage() + ")"));
}
}
}
Bool TableLockData::acquire (MemoryIO* info,
FileLocker::LockType type, uInt nattempts)
{
//# Try to acquire a lock.
//# Show a message when we have to wait for a long time.
//# Start with n attempts, show a message and continue thereafter.
uInt n = 30;
if (nattempts > 0 && nattempts < n) {
n = nattempts;
}
Bool status = itsLock->acquire (info, type, n);
if (!status && n != nattempts) {
String s = "read";
if (type == FileLocker::Write) {
s = "write";
}
LogIO os;
os << "Process " << uInt(getpid()) << ": waiting for "
<< s << "-lock on file " << itsLock->name();
os.post();
if (nattempts > 0) {
nattempts -= n;
}
status = itsLock->acquire (info, type, nattempts);
if (status) {
os << "Process " << uInt(getpid()) << ": acquired "
<< s << "-lock on file " << itsLock->name();
os.post();
}else{
if (nattempts > 0) {
os << "Process " << uInt(getpid()) << ": gave up acquiring "
<< s << "-lock on file " << itsLock->name()
<< " after " << nattempts << " seconds";
os.post();
}
}
}
//# Throw exception when error while we had to wait forever.
if (!status) {
if (nattempts == 0) {
throw (TableError ("Error (" + itsLock->lastMessage() +
") when acquiring lock on " + itsLock->name()));
}
}
return status;
}
void TableLockData::release (Bool always)
{
//# Only release if not permanently locked.
if (always || !isPermanent()) {
MemoryIO* memIO = 0;
if (hasLock (FileLocker::Write)) {
if (itsReleaseCallBack != 0) {
memIO = itsReleaseCallBack (itsReleaseParent, always);
}
}
if (! itsLock->release (memIO)) {
throw (TableError ("Error (" + itsLock->lastMessage() +
") when releasing lock on " + itsLock->name()));
}
}
}
} //# NAMESPACE CASACORE - END
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