/*                                                                       */
/* Written by Roger Heflin roger.a.heflin@conoco.com rahmrh@cableone.net */ 
/*                                                                       */

/* Simulates an application writting multiple data streams to several    */
/* file to duplicate an application IO issues                            */
/* code tries to note when a write takes alot longer than expected       */
/* and does appear to be able to sometimes detect the bdflush deamon     */
/* under the correct conditions */

/* Quite a bit more error checking could be done at various points but
   is not done */

#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <sys/time.h>
#include <unistd.h>

double my_tod()
{
struct timeval t1;

gettimeofday(&t1,NULL);

return(t1.tv_sec + (double)t1.tv_usec/1e6);
}

int main(int argc,char **argv)
{
char *directory;
int write_size;
char filename[30][256];
int  *writebuffer;
long long num_writes;
long long max_writes;
FILE *fn[30];
int nfiles;
int i;
char hostname1[32];
unsigned long sleep_usec;
double delayt;
double write_time;
double bflush_time;
double start_time,end_time,start_time1,end_time1,start_time2,end_time2;
int cnt;
int num_slowwrite;

num_slowwrite = 0;

setlinebuf(stdout);

if (argc != 5)
  {
  fprintf(stderr,"Usage: %s directory size sleep_time numberoffiles\n",argv[0]);
  fprintf(stderr,"      directory - is the directory to work in\n");
  fprintf(stderr,"      size - is the block size to use for the writes\n");
  fprintf(stderr,"      sleep_time is the sleep time in second to sleep\n");
  fprintf(stderr,"             after writing to all files using really\n");
  fprintf(stderr,"             small numbers below the kernel resolution will not\n");
  fprintf(stderr,"             result in smaller times - decimals are allowed\n");
  fprintf(stderr,"      numberoffiles - number of write streams\n");
  exit(-1);
  }

write_size = atoi(argv[2]);
delayt = atof(argv[3]);
directory=argv[1];
nfiles=atoi(argv[4]);

printf("write size is %d sleep time is %f\n",write_size,delayt);
printf("with %d files\n",nfiles);

sleep_usec = delayt * 1000000;
writebuffer = malloc(write_size+4);

if (writebuffer == 0)
  {
  fprintf(stderr,"Malloc of %d bytes failed - error is %s\n",write_size,strerror(errno));
  exit(-1);
  }
chdir(directory);

for (i=0;i<write_size/4;i++)
  {
  writebuffer[i] = i;
  }
gethostname(hostname1,32);
for (i=0;i<nfiles;i++)
  {
  sprintf(filename[i],"%s/%s_%d.tmp_%d",directory,hostname1,getpid(),i);
  fprintf(stderr,"Using filename %s\n",filename[i]);
  }

/* max number of writes to do before doing a rewind */
/* the 2000 number is basically the max file size - adjusting
   it smaller will allow testing with more files on small disks */
max_writes = 2000*1024*1024 / write_size;
num_writes = 0;
write_time = 0;

for (i=0;i<nfiles;i++)
  {
  fn[i] = fopen(filename[i],"wb");
  if (fn[i] == NULL)
    {
    fprintf(stderr,"Failure opening file %s - error is %s\n",filename[i],strerror(errno));
    exit(-1);
    }
  setvbuf(fn[i],malloc(write_size),_IOFBF,write_size);
  }

cnt = 0;
start_time1 = my_tod();
start_time2 = start_time1;
bflush_time=start_time1;
while (1)
  {
  for (i=0;i<nfiles;i++)
    {
    if ((num_writes%max_writes) == 0)  
      {
      fprintf(stderr,"Rewinding file %d\n",i);
      fseek(fn[i],0,SEEK_SET);
      }
      
    start_time = my_tod();
    if (fwrite(writebuffer,write_size,1,fn[i]) != 1)
      {
      fprintf(stderr,"Error fwrite failure - error was %s\n",strerror(errno));
      exit(-1);
      }
    end_time = my_tod();
    write_time += (end_time - start_time);

    if (i==0)
      num_writes ++; 

    if (end_time-start_time > 1.0)
      {
      num_slowwrite ++;
      } 
    }

  /* Only sleep once per every nfiles writes of write_size */ 

    if (sleep_usec != 0)
      usleep(sleep_usec);

/* Print out a rate every xxx writes for each file*/
  if (cnt == 10)
    {
    end_time1 = my_tod();
    end_time2 = end_time1;
    printf("%s %8.1f secs - last wrt speed %8.2f MB/sec %10.2f GB written %8.2f MB/sec overall average %d slowwrites",
           hostname1,
           (end_time2-start_time2),
           ((cnt*write_size*nfiles) / (end_time1-start_time1))/(1024*1024),
           ((double)num_writes*(double)write_size*nfiles)/(1024*1024*1024),
           (((double)num_writes*(double)write_size*nfiles) / (end_time2-start_time2))/(1024*1024),num_slowwrite); 
    if ( ( end_time1 - start_time1) > 5 ) 
      {
      printf(" Buffer flush %5.2f - last was %f seconds ago\n",end_time1 - start_time1,start_time1 - bflush_time);
      bflush_time = start_time1;
      }
    else
      {
      printf("\n");
      }

    start_time1 = my_tod();
    cnt = 0;
    num_slowwrite = 0;
    }  
     
/*   if (access("QUIT_NOW",F_OK) == 0)
    {
    printf("Average time per write %s %f\n",hostname1,write_time/num_writes);
    for (i=0;i<nfiles;i++)
      fclose(fn[i]);
    exit(0);
    }   */
  cnt ++;
  }

}