// ----------------------------------------------------------------------
// File: LinuxStat.hh
// Author: Andreas-Joachim Peters - CERN
// ----------------------------------------------------------------------

/************************************************************************
 * EOS - the CERN Disk Storage System                                   *
 * Copyright (C) 2011 CERN/ASwitzerland                                  *
 *                                                                      *
 * This program is free software: you can redistribute it and/or modify *
 * it under the terms of the GNU General Public License as published by *
 * the Free Software Foundation, either version 3 of the License, or    *
 * (at your option) any later version.                                  *
 *                                                                      *
 * 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, see <http://www.gnu.org/licenses/>.*
 ************************************************************************/

/**
 * @file   LinuxStat.hh
 *
 * @brief  Class getting process statistics from the linux proc filesystem
 *
 */

#ifndef __EOSCOMMON__LINUXSTAT__HH
#define __EOSCOMMON__LINUXSTAT__HH

#include "common/Namespace.hh"
#include <sys/param.h>

EOSCOMMONNAMESPACE_BEGIN

/*----------------------------------------------------------------------------*/
//! Static Class to measure memory consumption
//!
//! Example: linux_stat_t st; GetStat(st);
//!
/*----------------------------------------------------------------------------*/
class LinuxStat
{
public:
  typedef struct {
    // TODO! in 2.6. kernels we see 3 more entries (unknown for the meanwhile)
    unsigned long long pid;
    char tcomm[PATH_MAX];
    char state;
    unsigned long long ppid;
    unsigned long long pgid;
    unsigned long long sid;
    unsigned long long tty_nr;
    unsigned long long tty_pgrp;
    unsigned long long flags;
    unsigned long long min_flt;

    unsigned long long cmin_flt;
    unsigned long long maj_flt;
    unsigned long long cmaj_flt;
    unsigned long long utime;
    unsigned long long stime;
    unsigned long long cutime;
    unsigned long long cstime;
    unsigned long long priority;
    unsigned long long nicev;
    unsigned long long threads;

    unsigned long long it_real_value;
    unsigned long long start_time;
    unsigned long long vsize;
    unsigned long long rss;
    unsigned long long rsslim;
    unsigned long long start_code;
    unsigned long long end_code;
    unsigned long long start_stack;
    unsigned long long esp;
    unsigned long long eip;

    unsigned long long pending;
    unsigned long long blocked;
    unsigned long long sigign;
    unsigned long long sigcatch;
    unsigned long long wchan;
    unsigned long long zero1;
    unsigned long long zero2;
    unsigned long long exit_signal;
    unsigned long long cpu;
    unsigned long long rt_priority;

    unsigned long long policy;

  } linux_stat_t;

  static bool GetStat(linux_stat_t& result)
  {
    const char* stat_path = "/proc/self/stat";
    result.tcomm[0] = 0;
    result.state = 0;
    result.pid = result.ppid = result.pgid = result.sid = result.tty_nr =
                                 result.tty_pgrp = result.flags = result.min_flt = result.cmin_flt =
                                       result.maj_flt = result.cmaj_flt = result.utime = result.stime = result.cutime =
                                           result.cstime = result.priority = result.nicev = result.threads =
                                               result.it_real_value = result.start_time = result.vsize = result.rss =
                                                   result.rsslim = result.start_code = result.end_code = result.start_stack =
                                                       result.esp = result.eip = result.pending = result.blocked = result.sigign =
                                                           result.sigcatch = result.wchan = result.zero1 = result.zero2 =
                                                               result.exit_signal = result.cpu = result.rt_priority = result.policy = 0;
    FILE* f = fopen(stat_path, "r");

    if (!f) {
      perror(stat_path);
      return false;
    }

    if (41 != fscanf(f, "%lld %s %c %lld %lld %lld %lld %lld %lld %lld %lld "
                     "%lld %lld %lld %lld %lld %lld %lld %lld %lld %lld %lld "
                     "%lld %lld %lld %lld %lld %lld %lld %lld %lld %lld %lld "
                     "%lld %lld %lld %lld %lld %lld %lld %lld\n",
                     &result.pid, result.tcomm, &result.state, &result.ppid, &result.pgid,
                     &result.sid, &result.tty_nr, &result.tty_pgrp, &result.flags, &result.min_flt,
                     &result.cmin_flt, &result.maj_flt, &result.cmaj_flt, &result.utime,
                     &result.stime, &result.cutime, &result.cstime, &result.priority, &result.nicev,
                     &result.threads, &result.it_real_value, &result.start_time, &result.vsize,
                     &result.rss, &result.rsslim, &result.start_code, &result.end_code,
                     &result.start_stack, &result.esp, &result.eip, &result.pending, &result.blocked,
                     &result.sigign, &result.sigcatch, &result.wchan, &result.zero1, &result.zero2,
                     &result.exit_signal, &result.cpu, &result.rt_priority, &result.policy)) {
      perror(stat_path);
      fclose(f);
      return false;
    }

    result.rss *= 4096; // comes in 4k pages on Linux
    fclose(f);
    return true;
  }
};

EOSCOMMONNAMESPACE_END

#endif