/*
     This file is part of GNUnet.
     Copyright (C) 2008--2013 GNUnet e.V.

     GNUnet is free software: you can redistribute it and/or modify it
     under the terms of the GNU Affero General Public License as published
     by the Free Software Foundation, either version 3 of the License,
     or (at your option) any later version.

     GNUnet 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
     Affero General Public License for more details.

     You should have received a copy of the GNU Affero General Public License
     along with this program.  If not, see <http://www.gnu.org/licenses/>.

     SPDX-License-Identifier: AGPL3.0-or-later
 */

/**
 * @file testbed/gnunet-service-testbed_cpustatus.c
 * @brief calls to determine current CPU load
 * @author Tzvetan Horozov
 * @author Christian Grothoff
 * @author Igor Wronsky
 * @author Alex Harper (OS X portion)
 * @author Sree Harsha Totakura
 */

#include "platform.h"
#include "gnunet_util_lib.h"
#include "gnunet-service-testbed_meminfo.h"

#if SOLARIS
#if HAVE_KSTAT_H
#include <kstat.h>
#endif
#if HAVE_SYS_SYSINFO_H
#include <sys/sysinfo.h>
#endif
#if HAVE_KVM_H
#include <kvm.h>
#endif
#endif
#ifdef BSD
#if HAVE_KVM_H
#include <kvm.h>
#endif
#endif

#ifdef OSX
#include <mach/mach.h>

static processor_cpu_load_info_t prev_cpu_load;
#endif

#define DEBUG_STATUSCALLS GNUNET_NO

#ifdef __linux__
static FILE *proc_stat;
#endif

/**
 * Current CPU load, as percentage of CPU cycles not idle or
 * blocked on IO.
 */
static int currentCPULoad;

static double agedCPULoad = -1;

/**
 * Current IO load, as percentage of CPU cycles blocked on IO.
 */
static int currentIOLoad;

static double agedIOLoad = -1;


/**
 * hanlde to the file to write the load statistics to
 */
struct GNUNET_BIO_WriteHandle *bw;

struct GNUNET_SCHEDULER_Task *sample_load_task_id;


#ifdef OSX
static int
initMachCpuStats ()
{
  unsigned int cpu_count;
  processor_cpu_load_info_t cpu_load;
  mach_msg_type_number_t cpu_msg_count;
  kern_return_t kret;
  int i, j;

  kret = host_processor_info (mach_host_self (),
                              PROCESSOR_CPU_LOAD_INFO,
                              &cpu_count,
                              (processor_info_array_t *) &cpu_load,
                              &cpu_msg_count);
  if (kret != KERN_SUCCESS)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_WARNING, "host_processor_info failed.");
    return GNUNET_SYSERR;
  }
  prev_cpu_load = GNUNET_malloc (cpu_count * sizeof(*prev_cpu_load));
  for (i = 0; i < cpu_count; i++)
  {
    for (j = 0; j < CPU_STATE_MAX; j++)
    {
      prev_cpu_load[i].cpu_ticks[j] = cpu_load[i].cpu_ticks[j];
    }
  }
  vm_deallocate (mach_task_self (),
                 (vm_address_t) cpu_load,
                 (vm_size_t) (cpu_msg_count * sizeof(*cpu_load)));
  return GNUNET_OK;
}


#endif

/**
 * Update the currentCPU and currentIO load (and on Linux, memory) values.
 *
 * Before its first invocation the method initStatusCalls() must be called.
 * If there is an error the method returns -1.
 */
static int
updateUsage ()
{
  currentIOLoad = -1;
  currentCPULoad = -1;
#ifdef __linux__
  /* under linux, first try %idle/usage using /proc/stat;
     if that does not work, disable /proc/stat for the future
     by closing the file and use the next-best method. */
  if (proc_stat != NULL)
  {
    static unsigned long long last_cpu_results[5] = { 0, 0, 0, 0, 0 };
    static int have_last_cpu = GNUNET_NO;
    int ret;
    char line[256];
    unsigned long long user_read, system_read, nice_read, idle_read,
                       iowait_read;
    unsigned long long user, system, nice, idle, iowait;
    unsigned long long usage_time = 0, total_time = 1;

    /* Get the first line with the data */
    rewind (proc_stat);
    fflush (proc_stat);
    if (NULL == fgets (line, 256, proc_stat))
    {
      GNUNET_log_strerror_file (GNUNET_ERROR_TYPE_WARNING,
                                "fgets", "/proc/stat");
      proc_stat = NULL;         /* don't try again */
    }
    else
    {
      iowait_read = 0;
      ret = sscanf (line, "%*s %llu %llu %llu %llu %llu",
                    &user_read,
                    &system_read, &nice_read, &idle_read, &iowait_read);
      if (ret < 4)
      {
        GNUNET_log_strerror_file (GNUNET_ERROR_TYPE_WARNING,
                                  "fgets-sscanf", "/proc/stat");
        fclose (proc_stat);
        proc_stat = NULL;       /* don't try again */
        have_last_cpu = GNUNET_NO;
      }
      else
      {
        /* Store the current usage */
        user = user_read - last_cpu_results[0];
        system = system_read - last_cpu_results[1];
        nice = nice_read - last_cpu_results[2];
        idle = idle_read - last_cpu_results[3];
        iowait = iowait_read - last_cpu_results[4];
        /* Calculate the % usage */
        usage_time = user + system + nice;
        total_time = usage_time + idle + iowait;
        if ((total_time > 0) && (have_last_cpu == GNUNET_YES))
        {
          currentCPULoad = (int) (100L * usage_time / total_time);
          if (ret > 4)
            currentIOLoad = (int) (100L * iowait / total_time);
          else
            currentIOLoad = -1;         /* 2.4 kernel */
        }
        /* Store the values for the next calculation */
        last_cpu_results[0] = user_read;
        last_cpu_results[1] = system_read;
        last_cpu_results[2] = nice_read;
        last_cpu_results[3] = idle_read;
        last_cpu_results[4] = iowait_read;
        have_last_cpu = GNUNET_YES;
        return GNUNET_OK;
      }
    }
  }
#endif

#ifdef OSX
  {
    unsigned int cpu_count;
    processor_cpu_load_info_t cpu_load;
    mach_msg_type_number_t cpu_msg_count;
    unsigned long long t_sys, t_user, t_nice, t_idle, t_total;
    unsigned long long t_idle_all, t_total_all;
    kern_return_t kret;
    int i, j;

    t_idle_all = t_total_all = 0;
    kret = host_processor_info (mach_host_self (), PROCESSOR_CPU_LOAD_INFO,
                                &cpu_count,
                                (processor_info_array_t *) &cpu_load,
                                &cpu_msg_count);
    if (kret == KERN_SUCCESS)
    {
      for (i = 0; i < cpu_count; i++)
      {
        if (cpu_load[i].cpu_ticks[CPU_STATE_SYSTEM] >=
            prev_cpu_load[i].cpu_ticks[CPU_STATE_SYSTEM])
        {
          t_sys = cpu_load[i].cpu_ticks[CPU_STATE_SYSTEM]
                  - prev_cpu_load[i].cpu_ticks[CPU_STATE_SYSTEM];
        }
        else
        {
          t_sys = cpu_load[i].cpu_ticks[CPU_STATE_SYSTEM]
                  + (ULONG_MAX - prev_cpu_load[i].cpu_ticks[CPU_STATE_SYSTEM]
                     + 1);
        }

        if (cpu_load[i].cpu_ticks[CPU_STATE_USER] >=
            prev_cpu_load[i].cpu_ticks[CPU_STATE_USER])
        {
          t_user = cpu_load[i].cpu_ticks[CPU_STATE_USER]
                   - prev_cpu_load[i].cpu_ticks[CPU_STATE_USER];
        }
        else
        {
          t_user = cpu_load[i].cpu_ticks[CPU_STATE_USER]
                   + (ULONG_MAX - prev_cpu_load[i].cpu_ticks[CPU_STATE_USER]
                      + 1);
        }

        if (cpu_load[i].cpu_ticks[CPU_STATE_NICE] >=
            prev_cpu_load[i].cpu_ticks[CPU_STATE_NICE])
        {
          t_nice = cpu_load[i].cpu_ticks[CPU_STATE_NICE]
                   - prev_cpu_load[i].cpu_ticks[CPU_STATE_NICE];
        }
        else
        {
          t_nice = cpu_load[i].cpu_ticks[CPU_STATE_NICE]
                   + (ULONG_MAX - prev_cpu_load[i].cpu_ticks[CPU_STATE_NICE]
                      + 1);
        }

        if (cpu_load[i].cpu_ticks[CPU_STATE_IDLE] >=
            prev_cpu_load[i].cpu_ticks[CPU_STATE_IDLE])
        {
          t_idle = cpu_load[i].cpu_ticks[CPU_STATE_IDLE]
                   - prev_cpu_load[i].cpu_ticks[CPU_STATE_IDLE];
        }
        else
        {
          t_idle = cpu_load[i].cpu_ticks[CPU_STATE_IDLE]
                   + (ULONG_MAX - prev_cpu_load[i].cpu_ticks[CPU_STATE_IDLE]
                      + 1);
        }
        t_total = t_sys + t_user + t_nice + t_idle;
        t_idle_all += t_idle;
        t_total_all += t_total;
      }
      for (i = 0; i < cpu_count; i++)
      {
        for (j = 0; j < CPU_STATE_MAX; j++)
        {
          prev_cpu_load[i].cpu_ticks[j] = cpu_load[i].cpu_ticks[j];
        }
      }
      if (t_total_all > 0)
        currentCPULoad = 100 - (100 * t_idle_all) / t_total_all;
      else
        currentCPULoad = -1;
      vm_deallocate (mach_task_self (),
                     (vm_address_t) cpu_load,
                     (vm_size_t) (cpu_msg_count * sizeof(*cpu_load)));
      currentIOLoad = -1;       /* FIXME-OSX! */
      return GNUNET_OK;
    }
    else
    {
      GNUNET_log (GNUNET_ERROR_TYPE_WARNING, "host_processor_info failed.");
      return GNUNET_SYSERR;
    }
  }
#endif
  /* try kstat (Solaris only) */
#if SOLARIS && HAVE_KSTAT_H && HAVE_SYS_SYSINFO_H
  {
    static long long last_idlecount;
    static long long last_totalcount;
    static int kstat_once;      /* if open fails, don't keep
                                   trying */
    kstat_ctl_t *kc;
    kstat_t *khelper;
    long long idlecount;
    long long totalcount;
    long long deltaidle;
    long long deltatotal;

    if (kstat_once == 1)
      goto ABORT_KSTAT;
    kc = kstat_open ();
    if (kc == NULL)
    {
      GNUNET_log_strerror (GNUNET_ERROR_TYPE_WARNING, "kstat_close");
      goto ABORT_KSTAT;
    }

    idlecount = 0;
    totalcount = 0;
    for (khelper = kc->kc_chain; khelper != NULL; khelper = khelper->ks_next)
    {
      cpu_stat_t stats;

      if (0 != strncmp (khelper->ks_name, "cpu_stat", strlen ("cpu_stat")))
        continue;
      if (khelper->ks_data_size > sizeof(cpu_stat_t))
        continue;               /* better save then sorry! */
      if (-1 != kstat_read (kc, khelper, &stats))
      {
        idlecount += stats.cpu_sysinfo.cpu[CPU_IDLE];
        totalcount
          += stats.cpu_sysinfo.cpu[CPU_IDLE]
             + stats.cpu_sysinfo.cpu[CPU_USER]
             + stats.cpu_sysinfo.cpu[CPU_KERNEL]
             + stats.cpu_sysinfo.cpu[CPU_WAIT];
      }
    }
    if (0 != kstat_close (kc))
      GNUNET_log_strerror (GNUNET_ERROR_TYPE_WARNING, "kstat_close");
    if ((idlecount == 0) && (totalcount == 0))
      goto ABORT_KSTAT;         /* no stats found => abort */
    deltaidle = idlecount - last_idlecount;
    deltatotal = totalcount - last_totalcount;
    if ((deltatotal > 0) && (last_totalcount > 0))
    {
      currentCPULoad = (unsigned int) (100.0 * deltaidle / deltatotal);
      if (currentCPULoad > 100)
        currentCPULoad = 100;   /* odd */
      if (currentCPULoad < 0)
        currentCPULoad = 0;     /* odd */
      currentCPULoad = 100 - currentCPULoad;    /* computed idle-load before! */
    }
    else
      currentCPULoad = -1;
    currentIOLoad = -1;         /* FIXME-SOLARIS! */
    last_idlecount = idlecount;
    last_totalcount = totalcount;
    return GNUNET_OK;
ABORT_KSTAT:
    kstat_once = 1;             /* failed, don't try again */
    return GNUNET_SYSERR;
  }
#endif

  /* insert methods better than getloadavg for
     other platforms HERE! */

  /* ok, maybe we have getloadavg on this platform */
#if HAVE_GETLOADAVG
  {
    static int warnOnce = 0;
    double loadavg;
    if (1 != getloadavg (&loadavg, 1))
    {
      /* only warn once, if there is a problem with
         getloadavg, we're going to hit it frequently... */
      if (warnOnce == 0)
      {
        warnOnce = 1;
        GNUNET_log_strerror (GNUNET_ERROR_TYPE_WARNING, "getloadavg");
      }
      return GNUNET_SYSERR;
    }
    else
    {
      /* success with getloadavg */
      currentCPULoad = (int) (100 * loadavg);
      currentIOLoad = -1;       /* FIXME */
      return GNUNET_OK;
    }
  }
#endif

  /* loadaverage not defined and no platform
     specific alternative defined
     => default: error
   */
  return GNUNET_SYSERR;
}


/**
 * Update load values (if enough time has expired),
 * including computation of averages.  Code assumes
 * that lock has already been obtained.
 */
static void
updateAgedLoad ()
{
  static struct GNUNET_TIME_Absolute lastCall;
  struct GNUNET_TIME_Relative age;

  age = GNUNET_TIME_absolute_get_duration (lastCall);
  if ((agedCPULoad == -1)
      || (age.rel_value_us > 500000))
  {
    /* use smoothing, but do NOT update lastRet at frequencies higher
       than 500ms; this makes the smoothing (mostly) independent from
       the frequency at which getCPULoad is called (and we don't spend
       more time measuring CPU than actually computing something). */
    lastCall = GNUNET_TIME_absolute_get ();
    updateUsage ();
    if (currentCPULoad == -1)
    {
      agedCPULoad = -1;
    }
    else
    {
      if (agedCPULoad == -1)
      {
        agedCPULoad = currentCPULoad;
      }
      else
      {
        /* for CPU, we don't do the 'fast increase' since CPU is much
           more jitterish to begin with */
        agedCPULoad = (agedCPULoad * 31 + currentCPULoad) / 32;
      }
    }
    if (currentIOLoad == -1)
    {
      agedIOLoad = -1;
    }
    else
    {
      if (agedIOLoad == -1)
      {
        agedIOLoad = currentIOLoad;
      }
      else
      {
        /* for IO, we don't do the 'fast increase' since IO is much
           more jitterish to begin with */
        agedIOLoad = (agedIOLoad * 31 + currentIOLoad) / 32;
      }
    }
  }
}


/**
 * Get the load of the CPU relative to what is allowed.
 * @return the CPU load as a percentage of allowed
 *        (100 is equivalent to full load)
 */
static int
cpu_get_load ()
{
  updateAgedLoad ();
  return (int) agedCPULoad;
}


/**
 * Get the load of the CPU relative to what is allowed.
 * @return the CPU load as a percentage of allowed
 *        (100 is equivalent to full load)
 */
static int
disk_get_load ()
{
  updateAgedLoad ();
  return (int) agedIOLoad;
}


/**
 * Get the percentage of memory used
 *
 * @return the percentage of memory used
 */
static unsigned int
mem_get_usage ()
{
  double percentage;

  meminfo ();
  percentage = (((double) kb_main_used) / ((double) kb_main_total) * 100.0);
  return (unsigned int) percentage;
}


#ifdef __linux__
#include <dirent.h>
/**
 * Returns the number of processes
 *
 * @return the number of processes
 */
static unsigned int
get_nproc ()
{
  DIR *dir;
  struct dirent *ent;
  unsigned int nproc;

  dir = opendir ("/proc");
  if (NULL == dir)
    return 0;
  nproc = 0;
  while (NULL != (ent = readdir (dir)))
  {
    if ((*ent->d_name > '0') && (*ent->d_name <= '9'))
      nproc++;
  }
  closedir (dir);
  return nproc;
}


#endif


static void
sample_load_task (void *cls)
{
  struct GNUNET_TIME_Absolute now;
  char *str;
  int nbs;
  int ld_cpu;
  int ld_disk;
  unsigned int mem_usage;
  unsigned int nproc;

  sample_load_task_id = NULL;
  ld_cpu = cpu_get_load ();
  ld_disk = disk_get_load ();
  if ((-1 == ld_cpu) || (-1 == ld_disk))
    goto reschedule;
  mem_usage = mem_get_usage ();
#ifdef __linux__
  nproc = get_nproc ();
#else
  nproc = 0;
#endif
  now = GNUNET_TIME_absolute_get ();
  nbs = GNUNET_asprintf (&str, "%llu %d %d %u %u\n", now.abs_value_us / 1000LL
                         / 1000LL,
                         ld_cpu, ld_disk, mem_usage, nproc);
  if (0 < nbs)
  {
    GNUNET_BIO_write (bw, "sample load task", str, nbs);
  }
  else
    GNUNET_break (0);
  GNUNET_free (str);

reschedule:
  sample_load_task_id =
    GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_UNIT_SECONDS,
                                  &sample_load_task, NULL);
}


/**
 * Initialize logging CPU and IO statisticfs.  Checks the configuration for
 * "STATS_DIR" and logs to a file in that directory.  The file is name is
 * generated from the hostname and the process's PID.
 */
void
GST_stats_init (const struct GNUNET_CONFIGURATION_Handle *cfg)
{
  char *hostname;
  char *stats_dir;
  char *fn;
  size_t len;

  if (GNUNET_OK !=
      GNUNET_CONFIGURATION_get_value_filename (cfg, "testbed",
                                               "STATS_DIR", &stats_dir))
    return;
  len = GNUNET_OS_get_hostname_max_length ();
  hostname = GNUNET_malloc (len);
  if (0 != gethostname (hostname, len))
  {
    GNUNET_log_strerror (GNUNET_ERROR_TYPE_WARNING, "gethostname");
    GNUNET_free (stats_dir);
    GNUNET_free (hostname);
    return;
  }
  fn = NULL;
  (void) GNUNET_asprintf (&fn, "%s/%.*s-%jd.dat", stats_dir, (int)len,
                          hostname, (intmax_t) getpid ());
  GNUNET_free (stats_dir);
  GNUNET_free (hostname);
  if (NULL == (bw = GNUNET_BIO_write_open_file (fn)))
  {
    GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                _ ("Cannot open %s for writing load statistics.  "
                   "Not logging load statistics\n"), fn);
    GNUNET_free (fn);
    return;
  }
  GNUNET_free (fn);
  sample_load_task_id = GNUNET_SCHEDULER_add_now (&sample_load_task, NULL);
#ifdef __linux__
  proc_stat = fopen ("/proc/stat", "r");
  if (NULL == proc_stat)
    GNUNET_log_strerror_file (GNUNET_ERROR_TYPE_WARNING,
                              "fopen", "/proc/stat");
#elif OSX
  initMachCpuStats ();
#endif
  updateUsage ();                /* initialize */
}


/**
 * Shutdown the status calls module.
 */
void
GST_stats_destroy ()
{
  if (NULL == bw)
    return;
#ifdef __linux__
  if (proc_stat != NULL)
  {
    fclose (proc_stat);
    proc_stat = NULL;
  }
#elif OSX
  GNUNET_free (prev_cpu_load);
#endif
  if (NULL != sample_load_task_id)
  {
    GNUNET_SCHEDULER_cancel (sample_load_task_id);
    sample_load_task_id = NULL;
  }
  GNUNET_break (GNUNET_OK == GNUNET_BIO_write_close (bw, NULL));
  bw = NULL;
}


/* end of cpustatus.c */