//# TableLock.cc: Class to hold table lock options
//# Copyright (C) 1997,2000,2001,2002
//# 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/TableLock.h>
#include <casacore/tables/Tables/TableError.h>
#include <casacore/casa/System/AipsrcValue.h>


namespace casacore { //# NAMESPACE CASACORE - BEGIN

TableLock::TableLock (LockOption option)
: itsOption            (option),
  itsReadLocking       (True),
  itsMaxWait           (0),
  itsInterval          (5),
  itsIsDefaultLocking  (False),
  itsIsDefaultInterval (True)
{
  init();
}

TableLock::TableLock (LockOption option, double inspectionInterval,
		      uInt maxWait)
: itsOption            (option),
  itsReadLocking       (True),
  itsMaxWait           (maxWait),
  itsInterval          (inspectionInterval),
  itsIsDefaultLocking  (False),
  itsIsDefaultInterval (False)
{
  init();
}

TableLock::TableLock (const TableLock& that)
: itsOption            (that.itsOption),
  itsReadLocking       (that.itsReadLocking),
  itsMaxWait           (that.itsMaxWait),
  itsInterval          (that.itsInterval),
  itsIsDefaultLocking  (that.itsIsDefaultLocking),
  itsIsDefaultInterval (that.itsIsDefaultInterval)
{}

TableLock& TableLock::operator= (const TableLock& that)
{
  if (this != &that) {
    itsOption            = that.itsOption;
    itsReadLocking       = that.itsReadLocking;
    itsMaxWait           = that.itsMaxWait;
    itsInterval          = that.itsInterval;
    itsIsDefaultLocking  = that.itsIsDefaultLocking;
    itsIsDefaultInterval = that.itsIsDefaultInterval;
  }
  return *this;
}


void TableLock::init()
{
#ifdef AIPS_TABLE_NOLOCKING
  itsOption = NoLocking;
#else
  Bool opt;
  AipsrcValue<Bool>::find (opt, "table.nolocking", False);
  if (opt) {
    itsOption = NoLocking;
  } else {
    if (itsOption == DefaultLocking) {
      itsOption           = AutoLocking;
      itsIsDefaultLocking = True;
    } else if (itsOption == AutoNoReadLocking) {
      itsOption      = AutoLocking;
      itsReadLocking = False;
    } else if (itsOption == UserNoReadLocking) {
      itsOption      = UserLocking;
      itsReadLocking = False;
    }
  }
#endif
  if (itsOption == NoLocking) {
    itsReadLocking = False;
  }
}


void TableLock::merge (const TableLock& that)
{
  if (! that.itsIsDefaultLocking) {
    if (itsIsDefaultLocking  ||  that.itsOption <= itsOption) {
      itsOption  = that.itsOption;
      itsMaxWait = that.itsMaxWait;
      itsIsDefaultLocking = that.itsIsDefaultLocking;
    }
    if (itsIsDefaultLocking) {
      itsReadLocking = that.itsReadLocking;
    } else if (that.itsReadLocking) {
      itsReadLocking = True;
    }
    if (! that.itsIsDefaultInterval) {
      if (itsIsDefaultInterval  ||  itsInterval > that.itsInterval) {
	itsInterval = that.itsInterval;
      }
    }
  }
}

Bool TableLock::lockingDisabled()
{
#ifdef AIPS_TABLE_NOLOCKING
  return True;
#else
  Bool opt;
  AipsrcValue<Bool>::find (opt, "table.nolocking", False);
  return opt;
#endif
}

} //# NAMESPACE CASACORE - END