/* -*-  Mode: C++; c-file-style: "gnu"; indent-tabs-mode:nil; -*- */
/*
 * Copyright (c) 2013 University of California, Los Angeles
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation;
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * Author: Alexander Afanasyev <alexander.afanasyev@ucla.edu>
 */

#ifndef MEM_USAGE_H
#define MEM_USAGE_H

#ifdef __linux__
// #include <proc/readproc.h>
// #include <unistd.h>
// // #include <sys/resource.h>
#include <sys/sysinfo.h>
#endif

#ifdef __APPLE__
#include <mach/task.h>
#include <mach/mach_traps.h>
#include <mach/mach.h>
#include <unistd.h>
#include <err.h>
#include <sys/param.h>
#include <mach-o/ldsyms.h>
#endif

/**
 * @ingroup ndn-helpers
 * @brief Utility class to evaluate current usage of RAM
 */
class MemUsage
{
public:
  /**
   * @brief Get memory utilization in bytes
   */
  static inline
  int64_t
  Get ()
  {
#if defined(__linux__)
/*
/proc/[pid]/statm
              Provides information about memory usage, measured in pages.  The
              columns are:

                  size       (1) total program size
                             (same as VmSize in /proc/[pid]/status)
                  resident   (2) resident set size
                             (same as VmRSS in /proc/[pid]/status)
                  share      (3) shared pages (i.e., backed by a file)
                  text       (4) text (code)
                  lib        (5) library (unused in Linux 2.6)
                  data       (6) data + stack
                  dt         (7) dirty pages (unused in Linux 2.6)

Reference: http://man7.org/linux/man-pages/man5/proc.5.html
*/
    std::ifstream is ("/proc/self/statm");
    if (!is.bad () && !is.eof ())
      {
        unsigned long vm;
	unsigned long rss;
        is >> vm   // the first number: virtual memory
           >> rss; // the second number: resident set size
        
        return rss * getpagesize ();
      }
    else
      {
        return -1;
      }

#elif defined(__APPLE__)
    struct task_basic_info t_info;
    mach_msg_type_number_t t_info_count = TASK_BASIC_INFO_COUNT;

    if (KERN_SUCCESS != task_info (mach_task_self (),
                                   TASK_BASIC_INFO, (task_info_t)&t_info, &t_info_count))
      {
        return -1; // something is wrong
      }

    return t_info.resident_size;
#endif
    // other systems are not yet supported
    return -1;
  }
};

#endif // MEM_USAGE_H