/* njmon / nimon -- internal data collector */  #ifdef EXTRA_TEST  #include <stdio.h>  #include <stdlib.h>  #include <unistd.h>  #include <string.h>    void psection(char *s) { printf("\"%s\": {\n",s); }  void psectionend() { printf("}\n"); }  void pstring(char *name, char *s) { printf("\t\"%s\": \"%s\",\n",name,s); }  void plong(char *name, long value) { printf("\t\"%s\": %ld,\n",name,value); }  void pdouble(char *name, double value) { printf("\t\"%s\": %.3lf,\n",name,value); }    extern void extra_init();  extern void extra_data(double elapsed);  int main()  {          extra_init();          extra_data(2.0);          return 0;  }  #endif /* EXTRA_TEST */    void extra_init()  {          /* If necessary, use this function to              initialise any data structures */  }    void extra_data(double elapsed)  {      FILE * pop;      char    string[4096];      double  rperf = 0.0;        if ( (pop = popen("/home/nag/rperf/rperf 2>/dev/null", "r") ) != NULL ) {          if ( fgets(string, 4095, pop) != NULL) {                  /* Sample result->54.85 rPerf estimated based on 2.00 Virtual CPU cores<- */                  sscanf(string, "%lf rPerf", &rperf );                  string[strlen(string)-1] = 0; /* remove newline at the end */          }          pclose(pop);      }      if(rperf > 0.0) { /* If the command failed, dont send the data */          psection("extra");          pdouble("rperf",rperf);          pstring("rperf_string",string);          plong("meaning_of_life", 42);           psectionend();      }  }  

1. Everything between "#ifdef EXTRA_TEST" and "#endif /* EXTRA_TEST */" is the code used for stand-alone testing of your two new functions.
2. These lines are compiled in by adding the -D EXTRA_TEST option to the compiler.
3. In this example case, we do not need the extra_init() function so it is empty but must be present.
4. The extra_data() function has a parameter, which is the double floating point number called "elapsed". Elapsed is the number of seconds since this function was called (or the extra_init() function on the first time).  In this example case, it is not used.  If your data is an incrementing measure, then elapsed time is used to convert the statistics into measure per second.  An example would be a data rate.  If the previous value was 100 KB and current value is 120 KB, then the data rate would be "(120 - 100)/elapsed KB per second."
5. This example, uses the popen() function to run the Korn shell script "rperf" from the directory "/home/nag/rperf/".  There is a large assumption here that every target server has the rperf command in that directory.  If I was rolling out this new feature across servers, I would probably put the rperf script in /usr/lbin (AIX) or /usr/local/bin (Linux).
6. The comment in the code shows the output of the script: 54.85 rPerf estimated based on 2.00 Virtual CPU cores
7. The sscanf() function captures the 54.85 into the double variable rperf.
8. Next, we strip off the newline character - YOU CAN'T HAVE ANY CONTROL CHARACTERS IN STRINGS in JSON nor InfluxDB Line Protocol. The newline would mess up the test mode output. The full njmon or nimon program removes control characters for us.
9. The pclose() function cleans up the open file. Not cleaning up, would create a memory leak.
10. We now have a double variable called rperf and a string variable called rperf_string to save to the Time-Series database.  In a real working case, the string variable is rather pointless as you cannot graph a string -that is only numbers.
11. Finally, check the data is good.  If the extra functions fail to read the data, do not attempt to save the data. Missing data is handled well in Time-Series databases.
12. In the example, we use a section name of "extra" and save a double, string and "fake" integer just as an illustration.
    You can section any name that is not already in use.  Select a name to make the data content obvious. Perhaps the example would be better to have "estimated_rperf". Other examples: "rdbms", or RDBMS vendors name or "payroll_statistics " or "app_transaction_rates".
13. The function psectionend() informs njmon or nimon that to end the data called "extra" (or whatever you want to call it).

  $ cc extra.c -o extra -D EXTRA_TEST    

    $ ./extra  "extra": {          "rperf": 54.850,          "rperf_string": "54.85 rPerf estimated based on 2.00 Virtual CPU cores",          "meaning_of_life": 42,  }  $   

  cc njmon_aix_v63.c -o nimon_aix722_v63 -D NIMON -g -O3 -lperfstat -lm  -qstrict  cc njmon_aix_v63.c -o njmon_aix722_v63 -D NJMON -g -O3 -lperfstat -lm  -qstrict

  cc njmon_aix_v63.c -o nimon_aix722_v63 -D NIMON -g -O3 -lperfstat -lm  -qstrict -D EXTRA  cc njmon_aix_v63.c -o njmon_aix722_v63 -D NJMON -g -O3 -lperfstat -lm  -qstrict -D EXTRA

  #ifdef EXTRA    #include "extra.c"    #endif /* EXTRA */  

  #ifdef EXTRA      extra_init();  #endif /* EXTRA */  

  #ifdef EXTRA          extra_data(elapsed);  #endif /* EXTRA */  

  ./nimon_aix722_v63 -s1 -c1 -f

  $ tail -1 blue_20200511_2236.influxlp  extra,host=blue,os=AIX,architecture=POWER8_COMPAT_mode,serial_no=7804930,mtm=IBM-9009-42A rperf=54.850,rperf_string="54.85 rPerf estimated based on 2.00 Virtual CPU cores",meaning_of_life=42i     $ 

  # influx  Connected to http://localhost:8086 version 1.7.7  InfluxDB shell version: 1.7.7  > use njmon  Using database njmon  > select * from extra  name: extra  time                architecture       host meaning_of_life mtm          os  rperf rperf_string                                          serial_no  ----                ------------       ---- --------------- ---          --  ----- ------------                                          ---------  1589225676653374913 POWER8_COMPAT_mode blue 42              IBM-9009-42A AIX 54.85 54.85 rPerf estimated based on 2.00 Virtual CPU cores 7804930  1589225687042766744 POWER8_COMPAT_mode blue 42              IBM-9009-42A AIX 54.85 54.85 rPerf estimated based on 2.00 Virtual CPU cores 7804930  

  > select rperf,meaning_of_life,rperf_string from extra  name: extra  time                rperf meaning_of_life rperf_string  ----                ----- --------------- ------------  1589225676653374913 54.85 42              54.85 rPerf estimated based on 2.00 Virtual CPU cores  1589225687042766744 54.85 42              54.85 rPerf estimated based on 2.00 Virtual CPU cores  1589225697429213338 54.85 42              54.85 rPerf estimated based on 2.00 Virtual CPU cores  1589225707969159256 54.85 42              54.85 rPerf estimated based on 2.00 Virtual CPU cores  1589225717355288209 54.85 42              54.85 rPerf estimated based on 2.00 Virtual CPU cores  

• The upper left shows the current value in a "Single Stat" panel.
• The middle graph shows the rPerf values.
• The lower graph shows the Virtual and CPU consumed with real work.