pg_iovec.h File Reference

#include <limits.h>
#include <sys/uio.h>
#include <unistd.h>

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Macros
#define	PG_IOV_MAX   Min(IOV_MAX, 128)

Functions
static ssize_t	pg_preadv (int fd, const struct iovec *iov, int iovcnt, off_t offset)
static ssize_t	pg_pwritev (int fd, const struct iovec *iov, int iovcnt, off_t offset)

Macro Definition Documentation

PG_IOV_MAX

#define PG_IOV_MAX   Min(IOV_MAX, 128)

Definition at line 41 of file pg_iovec.h.

Function Documentation

pg_preadv()

static ssize_t pg_preadv ( int  fd, const struct iovec *  iov, int  iovcnt, off_t  offset  )

inlinestatic

Definition at line 48 of file pg_iovec.h.

{
#if HAVE_DECL_PREADV
    /*
     * Avoid a small amount of argument copying overhead in the kernel if
     * there is only one iovec.
     */
    if (iovcnt == 1)
        return pread(fd, iov[0].iov_base, iov[0].iov_len, offset);
    else
        return preadv(fd, iov, iovcnt, offset);
#else
    ssize_t     sum = 0;
    ssize_t     part;
 
    for (int i = 0; i < iovcnt; ++i)
    {
        part = pg_pread(fd, iov[i].iov_base, iov[i].iov_len, offset);
        if (part < 0)
        {
            if (i == 0)
                return -1;
            else
                return sum;
        }
        sum += part;
        offset += part;
        if ((size_t) part < iov[i].iov_len)
            return sum;
    }
    return sum;
#endif
}

References fd(), i, and pg_pread.

Referenced by FileReadV(), and pgaio_io_perform_synchronously().

pg_pwritev()

static ssize_t pg_pwritev ( int  fd, const struct iovec *  iov, int  iovcnt, off_t  offset  )

inlinestatic

Definition at line 87 of file pg_iovec.h.

{
#if HAVE_DECL_PWRITEV
    /*
     * Avoid a small amount of argument copying overhead in the kernel if
     * there is only one iovec.
     */
    if (iovcnt == 1)
        return pwrite(fd, iov[0].iov_base, iov[0].iov_len, offset);
    else
        return pwritev(fd, iov, iovcnt, offset);
#else
    ssize_t     sum = 0;
    ssize_t     part;
 
    for (int i = 0; i < iovcnt; ++i)
    {
        part = pg_pwrite(fd, iov[i].iov_base, iov[i].iov_len, offset);
        if (part < 0)
        {
            if (i == 0)
                return -1;
            else
                return sum;
        }
        sum += part;
        offset += part;
        if ((size_t) part < iov[i].iov_len)
            return sum;
    }
    return sum;
#endif
}

References fd(), i, and pg_pwrite.

Referenced by FileWriteV(), pg_pwritev_with_retry(), and pgaio_io_perform_synchronously().