/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * Copyright by The HDF Group.                                               *
 * All rights reserved.                                                      *
 *                                                                           *
 * This file is part of HDF5.  The full HDF5 copyright notice, including     *
 * terms governing use, modification, and redistribution, is contained in    *
 * the COPYING file, which can be found at the root of the source code       *
 * distribution tree, or in https://support.hdfgroup.org/ftp/HDF5/releases.  *
 * If you do not have access to either file, you may request a copy from     *
 * help@hdfgroup.org.                                                        *
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
/*-------------------------------------------------------------------------
 *
 * Created:     atomic_reader.c
 *
 * Purpose:     This is the "reader" part of the standalone test to check
 *              atomic read-write operation on a system.
 *              a) atomic_reader.c--the reader (this file)
 *              a) atomic_writer.c--the writer
 *              c) atomic_data--the name of the data file used by writer and reader
 *
 *-------------------------------------------------------------------------
 */

/***********/
/* Headers */
/***********/

#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#if !defined(WIN32) && !defined(__MINGW32__)

#include <fcntl.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>

/****************/
/* Local Macros */
/****************/

#define FILENAME "atomic_data"
#define READ_TRIES 20
#define OPEN_TRIES 50

/********************/
/* Local Prototypes */
/********************/

static void usage(void);
int verify(int fd, unsigned int k);
void print_info(int *info, unsigned int lastr, unsigned iteration);



/*-------------------------------------------------------------------------
 * Function:    usage
 *
 * Purpose:     To print the command line options
 *
 * Parameters:  None
 *
 * Return: 	void
 *
 *-------------------------------------------------------------------------
 */
static void
usage(void)
{
    printf("\n");
    printf("Usage error!\n");
    printf("Usage: atomic_reader -n <number of integers to read> -i <number of iterations for reader>\n");
    printf("       Note**The number of integers for option n has to be positive\n");
    printf("       Note**The number of integers for option i has to be positive\n");
    printf("\n");
} /* usage() */


/*-------------------------------------------------------------------------
 * Function:    verify
 *
 * Purpose:     To verify that the data read is the pattern expected.
 *              Each integer read should be the same as the index.
 *              When a difference is encountered, the remaining integers 
 *              read should be the same as the previous index.
 *              For example, the pattern expected should be either:
 *              a) 01234567....n-1
 *                  or
 *              b) if at index 4, a difference is encountered,
 *                 the remaining integers should be all "3"s as:
 *                 012333333333333
 *
 * Parameters:  
 *              fd -- the file descriptor
 *              k -- the number of integers to read
 *
 * Return:      
 *              positive on success
 *              negative on failure
 *
 *-------------------------------------------------------------------------
 */
int
verify(int fd, unsigned int k)
{
    unsigned int i;		/* local index variable */
    ssize_t bytes_read;		/* the number of bytes read */
    unsigned int *buf = NULL;	/* buffer to hold data read */

    /* Allocate buffer for data read */
    if((buf = (unsigned int *)malloc(k * sizeof(unsigned int))) == NULL) {
        printf("READER: error from malloc\n");
        goto error;
    } /* end if */

    /* Position the file at the beginning */
    if(lseek(fd, (off_t)0, SEEK_SET) < 0) {
        printf("READER: error from lseek\n");
        goto error;
    } /* end if */

    /* Read the whole file */
    if((bytes_read = read(fd, buf, (k * sizeof(unsigned int)))) < 0) {
        printf("READER: error from read\n");
        goto error;
    } /* end if */

    /* Verify the bytes read are correct */
    if(bytes_read != (ssize_t)(k*sizeof(unsigned int))) {
        printf("READER: error from bytes read=%lu\n", (unsigned long)bytes_read);
        goto error;
    } /* end if */

    /* Verify data read */
    for(i=0; i < k; i++)  {
        if(buf[i] != i)
            break;
    } /* end for */

    if(i < k) {
        /* Compare the beginning and ending sentinel values */
        if(buf[k-1] != (i-1)) {
            printf("FAIL IN READER: ...beginning sentinel value=%u, i=%u\n", (i-1), i);
            printf("FAIL IN READER: buf[%u]=%u\n", i-1, buf[i-1]);
            printf("FAIL IN READER: buf[%u]=%u\n", i, buf[i]);
            printf("FAIL IN READER: buf[%u]=%u\n", i+1, buf[i+1]);
            printf("FAIL IN READER: ...ending sentinel value=%u\n", buf[k-1]);
            goto error;
        } /* end if */
    } /* end if */

    /* Free the buffer */
    if(buf)
        free(buf);
    return 0;

error:
    /* Free the buffer */
    if(buf)
        free(buf);
    return -1;
} /* end verify() */



/*-------------------------------------------------------------------------
 * Function:    print_info
 *
 * Purpose:     To print the statistics gathered for re-reads
 *
 * Parameters: 
 *              info -- the array storing the statistics for re-reads
 *              lastr -- the last read completed
 *              iteration -- the current iteration
 *
 * Return:      void
 *
 *-------------------------------------------------------------------------
 */
void
print_info(int *info, unsigned int lastr, unsigned iteration)
{
    unsigned j;	/* local index variable */

    printf("--------statistics for %u reads (iteration %u)--------\n", lastr, iteration);

    for(j = 0; j <= READ_TRIES; j++)
        printf("# of %u re-tries = %u\n", j, info[j]);

    printf("--------end statistics for %u reads (iteration %u)--------\n", lastr, iteration);
} /* print_info() */


/*-------------------------------------------------------------------------
 * Function:    main
 *
 * Purpose:     To verify that the data read is the pattern expected.
 *              (1) Make sure the file opens successfully and the # of bytes read is as expected	
 *              (2) Iterate the reader with i iterations 
 *              (3) Read and verify n integers for each iteration
 *              (4) On verification error, re-read the data at most READ_TRIES
 *                  times to see if correct data can be obtained
 *              (5) Print out statistics for the number of re-retries for each iteration
 *
 * Note:
 *      (a) The # of integers (via -n option) used by the writer and reader should be the same.
 *      (b) The data file used by the writer and reader should be the same.
 *
 * Future enhancement:
 *      1) Provide default values for n and i and allow user to run with either 0 or 1 option
 *      2) Use HDF library HD<system calls> instead of the system calls
 *      3) Handle large sized buffer (gigabytes) if needed
 *
 * Return:      Success:    EXIT_SUCCESS
 *              Failure:    EXIT_FAILURE
 *
 *-------------------------------------------------------------------------
 */
int
main(int argc, char *argv[])
{
    int fd = -1;                    /* file descriptor                      */
    unsigned int j=0, i=0, m=0;     /* local index variables                */
    int temp;                       /* temporary variable                   */
    unsigned int iterations = 0;    /* the input for "-i"                   */
    unsigned num = 0;               /* the input for "-n"                   */
    int opt = 0;                    /* option char                          */
    int info[READ_TRIES+1];         /* re-tries statistics                  */

    /* Ensure the expected # of arguments */
    if(argc != 5) {
        usage();
        exit(EXIT_FAILURE);
    } /* end if */

    /* Parse command line options */
    while((opt = getopt(argc, argv, "n:i:")) != -1) {
        switch(opt) {
            case 'n':
                if((temp = atoi(optarg)) < 0) {
                    usage();
                    exit(EXIT_FAILURE);
                } /* end if */
                num = (unsigned int)temp;
                break;
            case 'i':
                if((temp = atoi(optarg)) < 0) {
                    usage();
                    exit(EXIT_FAILURE);
                } /* end if */
                iterations = (unsigned int)temp;
                break;
            default:
                printf("Invalid option encountered\n");
                break;
        } /* end switch */
    } /* end while */

    printf("READER: number of integers to read = %u; # of iterations = %d\n", num, iterations);

    printf("\n");
    for(i = 1; i <= iterations; i++) {
        unsigned opens = OPEN_TRIES;

        printf("READER: *****start iteration %u*****\n", i);

        /* Ensure open and file size are done properly */
        while(opens--) {
            struct stat sinfo;

            memset(&sinfo, 0, sizeof(sinfo));

            if((fd = open(FILENAME, O_RDONLY, 0644)) < 0) {
                printf("READER: error from open--retry open again\n");
            } else {
                printf("READER: open succeed\n");

                if((fstat(fd, &sinfo) == 0) &&
                        (sinfo.st_size == (off_t)(num * sizeof(unsigned int)))) {
                    printf("READER: file size is correct--%u\n", (unsigned int)sinfo.st_size);
                    break;
                } /* end if */

                printf("READER: error from fstat or file size of %u is incorrect--retry open again\n", (unsigned int)sinfo.st_size);
                if(close(fd) < 0) {
                    printf("READER: error from close\n");
                    return EXIT_FAILURE;
                } /* end if */
                fd = -1;
            } /* end else */

        } /* end while */

        if(fd < 0) {
            printf("READER: *****open failure/incorrect file size for all %u tries, continue next iteration*****\n\n", OPEN_TRIES);
            continue;
        } /* end if */

        memset(info, 0, sizeof(info));

        /* Read and verify data */
        for(j = 1; j <= num; j++) {

            printf("READER: doing read %u\n", j);
            if(verify(fd, num) < 0) {
                printf("READER: error from read %u\n", j);

                /* Perform re-read to see if correct data is obtained */
                for(m = 1; m <= READ_TRIES; m++) {
                    printf("READER: ===============going to do re-read try %u\n", m);
                    if(verify(fd, num) < 0)
                        printf("READER: ===============error from re-read try %u\n", m);
                    else {
                        ++info[m];
                        printf("READER: ===============SUCCESS from re-read try %u\n", m);
                        break;
                    } /* end else */
                } /* end for */

                if(m > READ_TRIES) {
                    printf("READER: ===============error from all re-read tries: %u\n", READ_TRIES);
                    printf("READER:*****ERROR--stop on read %u\n", j);
                    break;
                } /* end if */
            } else {
                ++info[0];
                printf("READER: success from read %u\n", j);
            } /* end else */

        } /* end for */

        /* Print the statistics for re-reads */
        print_info(info, j-1, i);

        /* Close the file */
        if(close(fd) < 0) {
            printf("READER: error from close\n");
            return EXIT_FAILURE;
        } /* end if */

        printf("READER: *****end iteration %u*****\n\n", i);

    } /* end for */

    return EXIT_SUCCESS;
}

#else /* WIN32 / MINGW32 */

int
main(void)
{
    printf("Non-POSIX platform. Exiting.\n");
    return EXIT_FAILURE;
} /* end main() */

#endif /* WIN32 / MINGW32 */

