HostInfo.h

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// # HostInfo.h: Miscellaneous information about this host and process.
// # Copyright (C) 1997,2002
// # 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: casa-feedback@nrao.edu.
// #        Postal address: AIPS++ Project Office
// #                        National Radio Astronomy Observatory
// #                        520 Edgemont Road
// #                        Charlottesville, VA 22903-2475 USA
 
#ifndef CASA_HOSTINFO_H
#define CASA_HOSTINFO_H
 
#include <casacore/casa/aips.h>
#include <cstring>
#include <cstddef>
 
namespace casacore {  // # NAMESPACE CASACORE - BEGIN
 
class String;
class HostMachineInfo;
 
// <summary>
// Miscellaneous information about this host and process.
// </summary>
 
// <use visibility=export>
 
// <reviewed reviewer="UNKNOWN" date="before2004/08/25" tests="" demos="">
// </reviewed>
 
// <prerequisite>
//   <li> None
// </prerequisite>
//
// <synopsis>
// This class is meant to encapsulate miscellaneous information about the
// environment that the current process is running in.
//
// At present, the class can be used to obtain the name of the host on which
// this process is running, the process id of this process, the amount of
// physical memory (total, used, & free) on this host, the amount of swap
// space (total, used, and free), the number of CPUs on this host, and a
// count of the number of seconds from January 1, 1970. Generally you
// should use the classes <linkto class=Time>Time</linkto> and
// <linkto class=MVTime>MVTime</linkto> if your primary interest is related
// to time and dates. If your interest is in timing, you would generally use
// class <linkto class=Timer>Timer</linkto>, which can also report CPU times
// as well as "clock" times.
//
// Determination of the number of CPUs, swap space, and physical memory is
// particularly OS dependent. In cases where this functionality has not yet
// been implemented, the memory and swap functions will return -1 and the
// CPU function will return 0.
// </synopsis>
//
// <example>
// <srcblock>
// cout << "I am process #" << HostInfo::processID() << " running on host " <<
//         HostInfo::hostName() << ", which has " << HostInfor::numCPUs( ) << " CPUs." << endl;
// cout << "This host has " << HostInfo::memoryTotal( ) << "K of memory [ " <<
//         HostInfo::memoryUsed( ) << " used, " <<
//         HostInfo::memoryFree( ) << " free ]." << endl;
// cout << "This host has " << HostInfo::swapTotal( ) << "K of swap space [ " <<
//         HostInfo::swapUsed( ) << " used, " <<
//         HostInfo::swapFree( ) << " free ]." << endl;
// Double now = HostInfo::secondsFrom1970();
// doSomething();
// cout << "Function doSomething() took " <<
//         HostInfo::secondsFrom1970() - now << " seconds to execute."  << endl;
// </srcblock>
// </example>
//
// <motivation>
// The <linkto class=ObjectID>ObjectID</linkto> class uses a combination of
// hostname, process id, time, and a sequence number to ensure that ObjectID's
// are distinct. This class encapsulates the way the first three of those items
// are obtained.
// </motivation>
//
// <todo asof="2002/08/01">
//   <li> OS version?
// </todo>
 
class HostInfo {
 public:
  static String hostName();
  static Int processID();
  static Double secondsFrom1970();
 
  // Returns True for big endian machines (like SUN).
  // Returns False for little endian machines (like PC).
  static Bool bigEndian();
 
  // Returns 0 if unable to determine the number of CPUs.
  static Int numCPUs(bool use_aipsrc = false);
 
  // Get memory info (in KBytes).
  // Returns -1 if unable to determine memory info.
  // <group>
  static ptrdiff_t memoryTotal(bool use_aipsrc = false);
  static ptrdiff_t memoryUsed();
  static ptrdiff_t memoryFree();
  // </group>
 
  // Get swap space info (in KBytes).
  // Returns -1 if unable to determine swap info.
  // <group>
  static ptrdiff_t swapTotal();
  static ptrdiff_t swapUsed();
  static ptrdiff_t swapFree();
  // </group>
 
  // Allows to set custom resource values overriding the
  // existing .apisrc setting and/or system defaults
  // Expected unit are KiB for memory total
  // and percentage (%) for memory fraction
  // Returns the value previously stored
  // <group>
  static ptrdiff_t setMemoryTotal(ptrdiff_t memory);
  static Int setMemoryFraction(Int memfrac);
  static Int setNumCPUs(Int numCPUs);
  // </group>
 
 private:
  // we don't want folks creating these...
  HostInfo();
  const HostInfo &operator=(const HostInfo &);
 
  static HostMachineInfo *info;
  static ptrdiff_t resources_memory;
  static Int resources_memfrac;
  static Int resources_numCPUs;
};
 
inline Bool HostInfo::bigEndian() {
#if defined(AIPS_LITTLE_ENDIAN)
  return False;
#else
  return True;
#endif
}
 
}  // namespace casacore
 
#endif