#define _GNU_SOURCE

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <unistd.h>
#include <dirent.h>
#include <fcntl.h>
#include <string.h>
#include <errno.h>

#include <libaio.h>

#define FASTWRITER_SYNCIO_ALIGN 512

#define SYNC_MODE
#define AIO_MODE 2
#define EXTRA_BUFFERS 2
#define WRITE_INTERVAL 1

#define RAID_STRIP_SIZE 	256
#define RAID_DISKS		8
#define STRIPS_AT_ONCE		2

#ifdef AIO_MODE
# define SYNC_MODE
#endif /* AIO_MODE */

#ifdef SYNC_MODE
# define BLOCK_SIZE (1024 * RAID_STRIP_SIZE * RAID_DISKS * STRIPS_AT_ONCE)
#else /* SYNC_MODE */
# define BLOCK_SIZE 16384
#endif /* SYNC_MODE */

#ifdef AIO_MODE
# define BUFSIZE (BLOCK_SIZE * (AIO_MODE + EXTRA_BUFFERS))
#else /* AIO_MODE */
# define BUFSIZE BLOCK_SIZE
#endif /* AIO_MODE */


int main(int argc, char *argv[]) {
    int err;
    size_t SKIP = 1;
    DIR *dir;
    struct dirent *ent;
    struct timeval start, tv;
    size_t us;
    size_t files = 0;
    size_t total_size = 0;
    size_t last_write = 0;
    size_t last_size = 0;
    size_t skip;
    size_t run;
    size_t ready;
    ssize_t res;
    size_t max_size = (size_t)-1;
    char *buffer;//[BUFSIZE];
    long double mcoef = 1000000. / (1024 * 1024);
    int flags = O_RDONLY|O_NOATIME|O_LARGEFILE;

#ifdef AIO_MODE
    int i;
    size_t curio, schedio;
    int done[AIO_MODE + EXTRA_BUFFERS];
    
    io_context_t aio;
    struct iocb io[AIO_MODE], *ioptr[AIO_MODE];

    int events;
    struct io_event ev[AIO_MODE];
#endif /* AIO_MODE */

#ifdef SYNC_MODE
    flags |= O_DIRECT;
#endif

    printf("Used buffer: %i MB, Block: %i KB\n", BUFSIZE / 1024 / 1024, BLOCK_SIZE/1024);

    posix_memalign((void**)&buffer, FASTWRITER_SYNCIO_ALIGN, BUFSIZE);
    
    if (argc < 2) {
	printf("Usage: %s <directory|device> [skip|size]\n", argv[0]);
	exit(0);
    }
    
    if (strstr(argv[1], "/dev/")) {
	if (argc > 2) {
	    max_size = atol(argv[2]);
	    max_size *= 1024 * 1024 * 1024;
	}

	int fd = open(argv[1], flags, 0);
	if (fd < 0) {
	    printf("Unable to open device %s\n", argv[1]);
	    exit(1);
	}

	size_t size = BLOCK_SIZE;

#ifdef AIO_MODE	
	memset(done, 0, sizeof(done));
	memset(&aio, 0, sizeof(aio));
	io_queue_init(AIO_MODE, &aio);
	for (i = 0; i < AIO_MODE; i++) {
	    ioptr[i] = &io[i];
	    memset(ioptr[i], 0, sizeof(struct iocb));
	    io_prep_pread(ioptr[i], fd, buffer + i * BLOCK_SIZE, BLOCK_SIZE, i * BLOCK_SIZE);
	    io_set_callback(ioptr[i], (void*)(uintptr_t)i);
	}

	curio = 0;
	schedio = AIO_MODE;
	events = 0;
#endif /* AIO_MODE */
	
	gettimeofday(&start, NULL);

#ifdef AIO_MODE	
        err = io_submit(aio, AIO_MODE, ioptr);
        if (err != AIO_MODE) {
    	    printf("io_submit returned %i\n", err);
    	    perror("Failed to submit initial AIO jobs");
	}
#endif /* AIO_MODE */
	
#ifdef AIO_MODE	
	ready = 0;
	while (1) {
	    if (!done[curio%(AIO_MODE + EXTRA_BUFFERS)]) {
    		err = io_getevents(aio, 1, AIO_MODE - events, &ev[events], NULL);
		if (err < 0) perror("Error waiting for AIO\n");
		
		if ((!ready)&&(err > 1)) {
		    printf("*** Multiple read requests (%i of %i) are finished simultaneously. It is either:\n", err, AIO_MODE);
		    printf("      Small buffer size (%i KB)\n", BLOCK_SIZE/1024);
		    printf("      More parallel AIOs (%i) than supported by kernel, try %i\n", AIO_MODE, AIO_MODE - err);
		}
		
		for (i = 0; i < err; i++) {
		    struct io_event *ep = &ev[events + i];
		    int doneio = (uintptr_t)ep->data;
	    	    if (ep->res2 || (ep->res != BLOCK_SIZE)) perror("Error in async IO");
		    done[doneio%(AIO_MODE + EXTRA_BUFFERS)] = 1;
//		    printf("done (%i): %i\n", i, doneio);
		}
		
		events += err;
		
		for (i = events - 1; (i >= 0)&&((schedio - curio) < (AIO_MODE + EXTRA_BUFFERS)); i--) {
		    struct iocb *newio = (struct iocb *)ev[i].obj;
		    memset(newio, 0, sizeof(struct iocb));
		    io_prep_pread(newio, fd, buffer + (schedio % (AIO_MODE + EXTRA_BUFFERS)) * BLOCK_SIZE, BLOCK_SIZE, schedio * BLOCK_SIZE);
		    io_set_callback(newio, (void*)(uintptr_t)schedio);
		    err = io_submit(aio, 1, &newio);
		    if (err != 1) perror("Failed to submit AIO jobs");
		    schedio++;
		}
		events = i + 1;
		
		if (events) {
		    printf("*** Unprocessed events (%i), probably not enough buffer space...\n", events);
//		    printf("      curio (%zu), schedio (%zu)\n", curio, schedio);
		}

		ready = 1;
		continue;
	    }

	    done[curio%(AIO_MODE + EXTRA_BUFFERS)] = 0;
	    curio++;

	    res = BLOCK_SIZE;
#else /* AIO_MODE */
        res = read(fd, buffer, size);
	while (res > 0) {
#endif /* AIO_MODE */

	    if (res != size) {
		printf("Incomplete read: %zu bytes read instead of %zu\n", res, size);
		exit(-1);
	    }
	    total_size += res;

	    gettimeofday(&tv, NULL);
	    us = (tv.tv_sec - start.tv_sec) * 1000000 + (tv.tv_usec - start.tv_usec);
	    if ((us - last_write) > WRITE_INTERVAL * 1000000) {
		printf("Reading: %s (%lu GB),  Measured speed: %zu MB/s, Current speed: %zu MB/s\n", argv[0], total_size / 1024 / 1024 / 1024, (size_t)(mcoef * total_size / us), (size_t)(mcoef * (total_size - last_size) / (us - last_write)));
		last_write = us;
		last_size = total_size;
	    }
	    
	    if (total_size > max_size) {
		printf("Reading: %s (%lu GB),  Measured speed: %zu MB/s\n", argv[0], total_size / 1024 / 1024 / 1024, (size_t)(mcoef * total_size / us));
		break;
	    }
	
#ifndef AIO_MODE	
	    res = read(fd, buffer, size);
#endif /* AIO_MODE */
	}
	
#ifdef AIO_MODE	
	io_queue_release(aio);
#endif /* AIO_MODE */

	close(fd);

	if (res < 0) {
	    printf("Read failed with errno %i\n", errno);
	    exit(-1);
	}

	free(buffer);
	
	return 0;
    }

    chdir(argv[1]);

    if (argc > 2) {
	SKIP = atoi(argv[2]);
	
	printf("Skip %zu\n", SKIP);
    }

    gettimeofday(&start, NULL);
    for (run = 0; run < SKIP; run++) {
      skip = 0;
      dir = opendir(".");
      while ((ent = readdir(dir))) {
	struct stat st;
	
	if (((skip++)%SKIP) != run) continue;

	if (stat(ent->d_name, &st)) continue;
	if (!S_ISREG(st.st_mode)) continue;

#ifdef F_MODE
	FILE *f = fopen(ent->d_name, "r");
	if (!f) continue;
#else	
	int fd = open(ent->d_name, flags, 0);
	if (fd < 0) continue;
#endif	
	
	int size = st.st_blksize;
	
	if (size > BUFSIZE) {
	    printf("Buffer too small\n");
	    exit(1);
	}


#ifdef F_MODE
	while (!feof(f)) {
	    err = fread(buffer, 1, size, f);
	    if (err < 0) break;
	}
#else
# ifdef SYNC_MODE
	if (size < BLOCK_SIZE) size = BLOCK_SIZE;
# endif
        err = read(fd, buffer, size);
        while (err > 0) {
	    err = read(fd, buffer, size);
	}
#endif

	if (err < 0) {
	    printf("Read failed\n");
	    exit(1);
	}

#ifdef F_MODE
	fclose(f);
#else
	close(fd);
#endif

	total_size += st.st_size;
	files++;
	
	gettimeofday(&tv, NULL);
	us = (tv.tv_sec - start.tv_sec) * 1000000 + (tv.tv_usec - start.tv_usec);
	printf("Reading: %s (%lu MB), Read: %lu files (%lu GB),  Measured speed: %zu MB/s\n", ent->d_name, st.st_size/1024/1024, files, total_size / 1024 / 1024 / 1024, (size_t)(mcoef * total_size / us));
      }
      closedir(dir);
    }
    
    free(buffer);

}