/*
 *  vmstat_dynix.c
 *  UCD SNMP module for systemStats section of UCD-SNMP-MIB for Dynix
 *  Patrick Hess <phess@phess.best.vwh.net>
 *
 *  This is just a port of the vmstat_solaris2 code Version 0.7
 *
 */

/* To make lint skip the debug code and stop complaining */
#ifdef __lint
#define SNMP_NO_DEBUGGING 1
#endif

#define __NO_ASM_MACRO 1

/* Includes start here */

/* Standard includes */
#include <sys/tmp_ctl.h>
#include <sys/sysperf.h>
#include <sys/vmmeter.h>
#include <unistd.h>
#include <string.h>
     
/* UCD-SNMP config details */
#include <config.h>

/* Includes needed for all modules */
#include "mibdefs.h"
#include "mibincl.h"

/* Utility functions for UCD-SNMP */
#include "util_funcs.h"
#include <snmp_alarm.h>

/* Header file for this module */
#include "vmstat.h"
#include "vmstat_dynix.h"

/* Includes end here */


/* Global structures start here */

/* A structure to save data gathered from the kernel kstat interface to.  */
/* We used to have the sys/sysinfo.h cpu_stat_t here but we did not need */
/* all of it, some in a different size and some additional ones so we build */
/* our own */
struct cpu_stat_snapshot
{
  time_t     		css_time;
  unsigned int 		css_cpus;
  unsigned long long 	css_swapin;
  unsigned long long	css_swapout;
  unsigned long long	css_blocks_read;
  unsigned long long	css_blocks_write;
  unsigned long long	css_interrupts;
  unsigned long long	css_context_sw;
  unsigned long long	css_cpu[V_CPU_STATES];
};
    
/* Global structures end here */


/* Global variables start here */

/* Variables for the calculated values, filled in update_stats    */
/* Need to be global since we need them in more than one function */
static ulong swapin;
static ulong swapout;
static ulong blocks_read;
static ulong blocks_write;
static ulong interrupts;
static ulong context_sw;

/* Since MIB wants V_CPU_SYSTEM, which is V_CPU_KERNEL + V_CPU_STREAM */
static long cpu_perc[V_CPU_STATES+1];

/* How many snapshots we have already taken, needed for the first */
/* POLL_INTERVAL * POLL_VALUES seconds of agent running */
static unsigned int number_of_snapshots;

/* The place to store the snapshots of system data in */
static struct cpu_stat_snapshot snapshot[POLL_VALUES+1];

/* And one for the raw counters, which we fill when the raw values are */
/* requested, as opposed to the absolute values, which are taken every */
/* POLL_INTERVAL seconds and calculated over POLL_INTERVAL * POLL_VALUES time */
static struct cpu_stat_snapshot raw_values;

/* Global variables end here */


/* Functions start here */

/* Function prototype */
static void update_stats(unsigned int registrationNumber, void *clientarg);
static int take_snapshot(struct cpu_stat_snapshot *css);

/* init_vmstat_dynix starts here */
/* Init function for this module, from prototype */
/* Defines variables handled by this module, defines root OID for */
/* this module and registers it with the agent */

static FindVarMethod var_extensible_vmstat;

void init_vmstat_dynix(void) 
{
  
  /* Which variables do we service ? */
  struct variable2 extensible_vmstat_variables[] = {
    {MIBINDEX, ASN_INTEGER, RONLY, var_extensible_vmstat, 1, {MIBINDEX }},
    {ERRORNAME, ASN_OCTET_STR, RONLY, var_extensible_vmstat, 1, {ERRORNAME }},
    {SWAPIN, ASN_INTEGER, RONLY, var_extensible_vmstat, 1, {SWAPIN }},
    {SWAPOUT, ASN_INTEGER, RONLY, var_extensible_vmstat, 1, {SWAPOUT}},
    {IOSENT, ASN_INTEGER, RONLY, var_extensible_vmstat, 1, {IOSENT}},
    {IORECEIVE, ASN_INTEGER, RONLY, var_extensible_vmstat, 1, {IORECEIVE}},
    {SYSINTERRUPTS, ASN_INTEGER, RONLY, var_extensible_vmstat, 1, {SYSINTERRUPTS}},
    {SYSCONTEXT, ASN_INTEGER, RONLY, var_extensible_vmstat, 1, {SYSCONTEXT}},
    {CPUUSER, ASN_INTEGER, RONLY, var_extensible_vmstat, 1, {CPUUSER}},
    {CPUSYSTEM, ASN_INTEGER, RONLY, var_extensible_vmstat, 1, {CPUSYSTEM}},
    {CPUIDLE, ASN_INTEGER, RONLY, var_extensible_vmstat, 1, {CPUIDLE}},
    {CPURAWUSER, ASN_COUNTER, RONLY, var_extensible_vmstat, 1, {CPURAWUSER}},
    {CPURAWSYSTEM, ASN_COUNTER, RONLY, var_extensible_vmstat, 1, {CPURAWSYSTEM}},
    {CPURAWIDLE, ASN_COUNTER, RONLY, var_extensible_vmstat, 1, {CPURAWIDLE}},
    {CPURAWWAIT, ASN_COUNTER, RONLY, var_extensible_vmstat, 1, {CPURAWWAIT}},
    {CPURAWKERNEL, ASN_COUNTER, RONLY, var_extensible_vmstat, 1, {CPURAWKERNEL}},
    {IORAWSENT, ASN_COUNTER, RONLY, var_extensible_vmstat, 1, {IORAWSENT}},
    {IORAWRECEIVE, ASN_COUNTER, RONLY, var_extensible_vmstat, 1, {IORAWRECEIVE}},
    /* Future use: */
    /*
      {ERRORFLAG, ASN_INTEGER, RONLY, var_extensible_vmstat, 1, {ERRORFLAG }},
      {ERRORMSG, ASN_OCTET_STR, RONLY, var_extensible_vmstat, 1, {ERRORMSG }}
      */    
  };
  
  /* Define the OID pointer to the top of the mib tree that we're */
  /* registering underneath */
  oid vmstat_variables_oid[] = {EXTENSIBLEMIB,11};
  
  /* register ourselves with the agent to handle our mib tree */
  /* LINTED Trust me, I know what I'm doing */
  REGISTER_MIB("ucd-snmp/vmstat", extensible_vmstat_variables, variable2, \
               vmstat_variables_oid);
  
  /* Start with some useful data */
  update_stats(0, NULL);
  
  /* update_stats is run every POLL_INTERVAL seconds using this routine */
  /* (see 'man snmp_alarm') */
  /* This is only executed once to get some useful data in the beginning */
  if (snmp_alarm_register(5, NULL, update_stats, NULL) == 0)
    {
      snmp_log(LOG_WARNING, "vmstat_dynix (init): snmp_alarm_register failed.\n");
    }  
  /* This is the one that runs update_stats every POLL_INTERVAL seconds */
  if (snmp_alarm_register(POLL_INTERVAL, SA_REPEAT, update_stats, NULL) == 0)
    {
      snmp_log(LOG_ERR, "vmstat_dynix (init): snmp_alarm_register failed, cannot service requests.\n");
    }  
    
} /* init_vmstat_dynix ends here */

/* Data collection function take_snapshot starts here */
/* Get data from kernel and save into the snapshot strutcs */
/* Argument is the snapshot struct to save to. Global anyway, but looks nicer */
static int take_snapshot(struct cpu_stat_snapshot *css)
{
  /* Variables start here */

  /* Counters */
  unsigned int cpu_num = 0;
  
  /* Low resolution time counter */
  time_t current_time;
  
  /* see sys/sysperf.h, holds CPU data */
  exp_vmmeter_t *cs, *origcs = 0;

  /* size of the cs struct */
  size_t vminfo_size;
  
  /* The usual stuff to count on, err, by */
  int i;
  int engnum = 0;

  /* Variables end here */

  /* Function starts here */

  /* Get time */
  current_time = time(0);
  
  /* If we have just gotten the data, return the values from last run (skip if-clause) */
  /* This happens on a snmpwalk request. */
  /* if we just did it less than 2 seconds ago */
  /* Jumps into if-clause either when snapshot is empty or when too old */
  
  if ((css->css_time == 0) || (current_time > css->css_time + 2))
  {
      /* Make sure we clean up before we put new data into snapshot */
      memset(css, 0, sizeof *css);
      
      /* Get the number of CPUs we gather data from */
      if ( (cpu_num = tmp_ctl(TMP_NENG,0)) < 0 ) {
          snmp_log(LOG_ERR, "vmstat_dynix: (take snapshot) bad tmp_ctl return\n");
          return(-1);
      }
      css->css_cpus = cpu_num;

      vminfo_size = cpu_num * sizeof(exp_vmmeter_t);

      if (! (cs = (exp_vmmeter_t *) malloc(vminfo_size)) ) {
          snmp_log(LOG_ERR, "vmstat_dynix: (take_snapshot) bad malloc return\n" );
          return (-1);
      }
      origcs = cs;
      
      /* Update timer */
      css->css_time = current_time;
      
      /* Read data from kernel into cs structure */
      /* cs is the buffer we are writing to and */
      /* vminfo_size is the size of the cs struct */
      if ( (getkerndata(VMMETER_DATAID, cs, vminfo_size)) < 0 )
        {
          snmp_log(LOG_ERR, "vmstat_dynix (take_snapshot): getkerndata failure.");
          return(-1);
        }

      /* Get the data from each CPU */
      /* We walk through the whole vmmeter struct and sum up all the found stats, */
      /* there's one for every CPU in a machine */
      /* Okay...  you can't laugh at this!  I'm a C-hack, not a C-coder. :)  */
      while (engnum < cpu_num)
	{ 
	      
	      /* Get the data from the cs structure and sum it up in our own structure */
	      css->css_swapin 		+= (unsigned long long) cs->v_swpin;
	      css->css_swapout 		+= (unsigned long long) cs->v_swpout;
	      css->css_blocks_read 	+= (unsigned long long) cs->v_phread;
	      css->css_blocks_write 	+= (unsigned long long) cs->v_phwrite;
	      css->css_interrupts 	+= (unsigned long long) cs->v_intr;
	      css->css_context_sw 	+= (unsigned long long) cs->v_swtch;	      

	      /* We need a for-loop for the CPU STATE values */
	      for (i=0; i<V_CPU_STATES; i++)
	        {
	          css->css_cpu[i]	+= (unsigned long long) cs->v_time[i];
	        } /* end for */ 

              cs++;
              engnum++;
	} /* end while */
    }

  free((void *) origcs);

  /* All engines running at warp speed, no problems (if there are any engines, that is) */
  return (cpu_num > 0 ? 0 : -1);
} /* take_snapshot ends here */
      
/* This gets called every POLL_INTERVAL seconds to update the snapshots.  It takes a new snapshot and */
/* drops the oldest one.  This way we move the time window so we always take the values over */
/* POLL_INTERVAL * POLL_VALUES seconds and update the data used every POLL_INTERVAL seconds */
/* The alarm timer is in the init function of this module (snmp_alarm_register) */
/* ARGSUSED0 */
static void update_stats(unsigned int registrationNumber, void *clientarg)
{
  /* The time between the samples we compare */
  time_t time_diff;
  
  /* Easier to use these than the snapshots, short hand pointers */
  struct cpu_stat_snapshot *css_old, *css_new;
  
  /* The usual stuff to count on, err, by */
  int i;

  /* The sum of the CPU ticks that have passed on the different CPU states, so we can calculate */
  /* the percentages of each state */
  unsigned long long cpu_sum = 0;
  
  DEBUGMSGTL(("ucd-snmp/vmstat_dynix.c:update_stats","updating stats\n"));

  /* Take the current snapshot */
  if (take_snapshot(&snapshot[0]) == -1)
    {
      snmp_log(LOG_WARNING, "vmstat_dynix (update_stats): Something went wrong with take_snapshot.");
      return;
    }
  
  /* Do we have some data we can use ?  An issue right after the start of the agent */
  if (number_of_snapshots > 0)
    {
      /* Huh, the number of CPUs changed during run time.  That is indeed s.th. worth noting, we */
      /* output a humorous (more or less) syslog message and need to retake the snapshots */
      if (snapshot[0].css_cpus != snapshot[1].css_cpus)
        {
          if (snapshot[0].css_cpus > snapshot[1].css_cpus)
            {
              snmp_log(LOG_NOTICE, "vmstat_dynix (update_stats): Cool ! Number of CPUs increased, must be hot-pluggable.");
            }
          else
            {
              snmp_log(LOG_NOTICE, "vmstat_dynix (update_stats): Lost at least one CPU, RIP.");
            }
	  /* Make all snapshots but the current one invalid */
          number_of_snapshots = 1;
	  /* Move the current one in the "first" [1] slot */
          memmove(&snapshot[1], &snapshot[0], sizeof snapshot[0]);
	  /* Erase the current one */
          memset(&snapshot[0], 0, sizeof snapshot[0]);
	  /* Try to get a new snapshot in five seconds so we can return s.th. useful */
          if (snmp_alarm_register(5, NULL, update_stats, NULL) == 0)
            {
              snmp_log(LOG_WARNING, "vmstat_dynix (update_stats): snmp_alarm_register failed.\n");
            }  
          return;
        }
            
      /* Short hand pointers */
      css_new = &snapshot[0];
      css_old = &snapshot[number_of_snapshots];

      /* How much time has passed between the snapshots we get the values from ? */
      /* Time is in seconds */
      time_diff = snapshot[0].css_time - snapshot[number_of_snapshots].css_time;

      if ( time_diff == 0 )
          DEBUGMSGTL(("ucd-snmp/vmstat_dynix.c:update_stats","time_diff is ZERO...  watch for the segfault\n"));

      DEBUGMSGTL(("ucd-snmp/vmstat_dynix.c:update_stats","time_diff: %lld\n", time_diff));
            
      /* swapin and swapout are in pages, MIB wants kB/s,so we just need to get kB and seconds */
      /* For the others we need to get value per second */
      /* decided to use sysconf(_SC_PAGESIZE) instead to get around an #ifndef (I don't like those) */
      /* LINTED cast needed, really */
      swapin       = (uint_t)((css_new->css_swapin - css_old->css_swapin) * (time_t) 1000
			* sysconf(_SC_PAGESIZE) / 1024 / time_diff ); 
      /* LINTED cast needed, really */
      swapout      = (uint_t)((css_new->css_swapout - css_old->css_swapout) * (time_t) 1000
			* sysconf(_SC_PAGESIZE) / 1024 / time_diff); 
      /* LINTED cast needed, really */
      blocks_read  = (uint_t)((css_new->css_blocks_read - css_old->css_blocks_read) * (time_t) 1000 / time_diff); 
      /* LINTED cast needed, really */
      blocks_write = (uint_t)((css_new->css_blocks_write - css_old->css_blocks_write) * (time_t) 1000 / time_diff); 
      /* LINTED cast needed, really */
      interrupts   = (uint_t)((css_new->css_interrupts - css_old->css_interrupts) * (time_t) 1000 / time_diff); 
      /* LINTED cast needed, really */
      context_sw   = (uint_t)((css_new->css_context_sw - css_old->css_context_sw) * (time_t) 1000 / time_diff); 
      
      /* Loop thru all the V_CPU_STATES and get the differences */
      for (i = 0; i < V_CPU_STATES; i++)
        {
          cpu_sum += (css_new->css_cpu[i] - css_old->css_cpu[i]);
        }

      /* Now calculate the absolute percentage values */
      /* Looks somewhat complicated sometimes but tries to get around using floats to increase speed */
      for (i = 0; i < V_CPU_STATES; i++)
        {
          /* Since we don't return fractions we use + 0.5 to get between 99 and 101 percent adding the values */
          /* together, otherwise we would get less than 100 most of the time */
          /* LINTED has to be 'long' */
          cpu_perc[i] = (long) (((css_new->css_cpu[i] - css_old->css_cpu[i]) * 100 + (cpu_sum / 2)) / cpu_sum);
        }

      /* As said before, MIB wants V_CPU_SYSTEM which is V_CPU_KERNEL + V_CPU_STREAM */
      /* LINTED has to be 'long' */
      cpu_perc[V_CPU_SYSTEM] = (long) ((((css_new->css_cpu[V_CPU_KERNEL] - css_old->css_cpu[V_CPU_KERNEL])
                                     + (css_new->css_cpu[V_CPU_STREAM]   - css_old->css_cpu[V_CPU_STREAM])) 
                                     *  100 + (cpu_sum / 2) ) / cpu_sum );
    }

  /* Make the current one the first one and move the whole thing one place down */
  memmove(&snapshot[1], &snapshot[0], (size_t)(((char *)&snapshot[POLL_VALUES]) - ((char *)&snapshot[0])));

  /* Erase the current one */
  memset(&snapshot[0], 0, sizeof snapshot[0]);

  /* Only important on start up, we keep track of how many snapshots we have taken so far */
  if (number_of_snapshots < POLL_VALUES)
    {
      number_of_snapshots++;
    }
} /* update_stats ends here */

/* *var_extensible_vmstat starts here */
/* The guts of the module, this routine gets called to service a request */
static unsigned char *var_extensible_vmstat(struct variable *vp,
                                            oid *name,
                                            size_t *length,
                                            int exact,
                                            size_t *var_len,
                                            WriteMethod **write_method)
{
  /* Needed for returning the values */
  static long long_ret; 
  static char errmsg[300];

  /* set to 0 as default */  
  long_ret = 0;  

  /* generic check whether the options passed make sense and whether the */
  /* right variable is requested */
  if (header_generic(vp,name,length,exact,var_len, write_method) != MATCH_SUCCEEDED)
    {
      return(NULL);
    }

  /* The function that actually returns s.th. */
  switch (vp->magic) {
  case MIBINDEX:
    long_ret = 1;
    return((u_char *) (&long_ret));
  case ERRORNAME:    /* dummy name */
    sprintf(errmsg,"systemStats");
    *var_len = strlen(errmsg);
    return((u_char *) (errmsg));
  case SWAPIN:
    return((u_char *) (&swapin));
  case SWAPOUT:
    return((u_char *) (&swapout));
  case IOSENT:
    return((u_char *) (&blocks_write));
  case IORECEIVE:
    return((u_char *) (&blocks_read));
  case SYSINTERRUPTS:
    return((u_char *) (&interrupts));
  case SYSCONTEXT:
    return((u_char *) (&context_sw));
  case CPUUSER:
    return((u_char *) (&cpu_perc[V_CPU_USER]));
  case CPUSYSTEM:
    return((u_char *) (&cpu_perc[V_CPU_SYSTEM]));
  case CPUIDLE:
    return((u_char *) (&cpu_perc[V_CPU_IDLE]));
  case CPURAWUSER:
    take_snapshot(&raw_values);
    /* LINTED has to be 'long' */
    long_ret = (long)(raw_values.css_cpu[V_CPU_USER] / raw_values.css_cpus);
    return((u_char *) (&long_ret));
  /* We are missing CPURAWNICE, Dynix does not account for this in the kernel so this OID can not */
  /* be returned.  Also, these values will roll over sooner or later and then return inaccurate data */
  /* but the MIB wants Integer32 so we cannot put a counter here */
  /* (Has been changed to Counter32 in the latest MIB version!) */
  case CPURAWSYSTEM:
    take_snapshot(&raw_values);
    /* LINTED has to be 'long' */
    long_ret = (long)((raw_values.css_cpu[V_CPU_KERNEL] + raw_values.css_cpu[V_CPU_STREAM]) / raw_values.css_cpus);
    return((u_char *) (&long_ret));
  case CPURAWIDLE:
    take_snapshot(&raw_values);
    /* LINTED has to be 'long' */
    long_ret = (long)(raw_values.css_cpu[V_CPU_IDLE] / raw_values.css_cpus);
    return((u_char *) (&long_ret));    
  case CPURAWWAIT:
    take_snapshot(&raw_values);
    /* LINTED has to be 'long' */
    long_ret = (long)(raw_values.css_cpu[V_CPU_STREAM] / raw_values.css_cpus);
    return((u_char *) (&long_ret));    
  case CPURAWKERNEL:
    take_snapshot(&raw_values);
    /* LINTED has to be 'long' */
    long_ret = (long)(raw_values.css_cpu[V_CPU_KERNEL] / raw_values.css_cpus);
    return((u_char *) (&long_ret));    
  case IORAWSENT:
    long_ret = (long)(raw_values.css_blocks_write);
    return((u_char *) (&long_ret));
  case IORAWRECEIVE:
    long_ret = (long)(raw_values.css_blocks_read);
    return((u_char *) (&long_ret));

    /* reserved for future use */
    /*
      case ERRORFLAG:
      return((u_char *) (&long_ret));
      case ERRORMSG:
      return((u_char *) (&long_ret));
      */
  default:
    snmp_log(LOG_ERR,"vmstat_dynix: Error in request, no match found.\n");
  }
  return(NULL);
} /* *var_extensible_vmstat ends here */

/* Functions end here */

/* Program ends here */
