/* This program is a speed test for linearly accessing a drive.
 * You give it the devicename, blocksize to read, and how many blocks,
 * and it will then use asynchronous IO to get the data.
 *
 * In theory, this should allow a drive with tagged queueing to maximize
 * throughput. Assuming the driver also supports tagged queueing!
 *
 * compile with   $CC -o aioread aioread.c -laio
 * Usage:  aioread /dev/rpath blocksize blockcount
 */

#include <aio.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/dkio.h>
#include <sys/vtoc.h>
#include <errno.h>

#include <stdio.h>


void usage(){
	fprintf(stderr,"aioread\n");
	fprintf(stderr,"Usage:   aioread /dev/path blocksize blockcount\n");
	fprintf(stderr,"  Async reads  blockcount number of blocks from device\n");
	fprintf(stderr,"  Specifically makes blockcount number of separate requests\n");
}

#define MAXCOUNT 1000

int main(int argc, char *argv[]){
	int  fd;
	char *buffers[MAXCOUNT];
	aio_result_t resultstat[MAXCOUNT];
	struct timeval timeout;
	int blockcount, blocksize,errflag=0;
	int bcount;

	timeout.tv_sec=3;

	if(argc<4){
		usage();
		exit(1);
	}
	blocksize=atoi(argv[2]);
	blockcount=atoi(argv[3]);
	if(blockcount>=MAXCOUNT){
		fprintf(stderr,"Sorry, can only handle less than %d blocks\n",
		       MAXCOUNT);
		return 1;
	}

	fd=open(argv[1],O_RDONLY);

	if(fd==-1){
		perror("could not open device");
		exit(errno);
	}

	for(bcount=0;bcount<blockcount;bcount++){
		buffers[bcount]=(char*)malloc(blocksize);
		if(buffers[bcount]==NULL){
			fprintf(stderr,"could not malloc block buffer #%d\n",
			       bcount);
			exit(1);
		}
	}

	for(bcount=0;bcount<blockcount;bcount++){
		aioread(fd, buffers[bcount], blocksize, bcount*blocksize,
			SEEK_SET, &resultstat[bcount]);
	}

	for(bcount=0;bcount<blockcount;bcount++){
		int retval=aiowait(&timeout);
		if(retval == 0){
			if(errno==EINVAL){
				fprintf(stderr,"Hey.. timeout because all DONE?!");
			} else {
				perror("Error in aiowait");
				errflag=1;
			}
			fprintf(stderr,"Timeout for aioread\n");
			
		}
		if(retval==-1){
			if(errno==EINVAL){
				fprintf(stderr,
					"all requests already done, at count %d\n",
				       bcount);
				return 0;
			}
			perror("error in aiowait()");
		}
	}

	if(errflag!=0){
		fprintf(stderr,"quitting without trying to write\n");
		fprintf(stderr,"THe driver may still be hung\n");
		exit(0);
	}
	fprintf(stderr,"All reads done\n");
	for(bcount=0;bcount<blockcount;bcount++){
		write(1,buffers[bcount],blocksize);
	}
	return 0;
}