sdisk.cpp

/* -*- mode:C++; c-basic-offset:4 -*-
     Shore-MT -- Multi-threaded port of the SHORE storage manager
   
                       Copyright (c) 2007-2009
      Data Intensive Applications and Systems Labaratory (DIAS)
               Ecole Polytechnique Federale de Lausanne
   
                         All Rights Reserved.
   
   Permission to use, copy, modify and distribute this software and
   its documentation is hereby granted, provided that both the
   copyright notice and this permission notice appear in all copies of
   the software, derivative works or modified versions, and any
   portions thereof, and that both notices appear in supporting
   documentation.
   
   This code is distributed in the hope that it will be useful, but
   WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. THE AUTHORS
   DISCLAIM ANY LIABILITY OF ANY KIND FOR ANY DAMAGES WHATSOEVER
   RESULTING FROM THE USE OF THIS SOFTWARE.
*/

/*<std-header orig-src='shore'>

 $Id: sdisk.cpp,v 1.9 2010/05/26 01:21:28 nhall Exp $

SHORE -- Scalable Heterogeneous Object REpository

Copyright (c) 1994-99 Computer Sciences Department, University of
                      Wisconsin -- Madison
All Rights Reserved.

Permission to use, copy, modify and distribute this software and its
documentation is hereby granted, provided that both the copyright
notice and this permission notice appear in all copies of the
software, derivative works or modified versions, and any portions
thereof, and that both notices appear in supporting documentation.

THE AUTHORS AND THE COMPUTER SCIENCES DEPARTMENT OF THE UNIVERSITY
OF WISCONSIN - MADISON ALLOW FREE USE OF THIS SOFTWARE IN ITS
"AS IS" CONDITION, AND THEY DISCLAIM ANY LIABILITY OF ANY KIND
FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.

This software was developed with support by the Advanced Research
Project Agency, ARPA order number 018 (formerly 8230), monitored by
the U.S. Army Research Laboratory under contract DAAB07-91-C-Q518.
Further funding for this work was provided by DARPA through
Rome Research Laboratory Contract No. F30602-97-2-0247.

*/

#include "w_defines.h"

/*  -- do not edit anything above this line --   </std-header>*/

/**\cond skip */

/*
 *   NewThreads I/O is Copyright 1995, 1996, 1997, 1998 by:
 *
 *    Josef Burger    <bolo@cs.wisc.edu>
 *
 *   All Rights Reserved.
 *
 *   NewThreads I/O may be freely used as long as credit is given
 *   to the above author(s) and the above copyright is maintained.
 */

#include <w.h>
#include <sdisk.h>

#include <sthread.h>    /* XXX for error codes */


const    int    stSHORTSEEK = sthread_base_t::stSHORTSEEK;


int    sdisk_base_t::vsize(const iovec_t *iov, int iovcnt)
{
    int    total = 0;

    for (int i = 0; i < iovcnt; i++)
        total += iov[i].iov_len;

    return total;
}


int    sdisk_t::modeBits(int mode)
{
    return mode & MODE_FLAGS;
}


/* open mode is a 1-of-n choice */
bool    sdisk_t::hasMode(int mode, int wanted)
{
    mode = modeBits(mode);
    return mode == wanted;
}

/* options are one-of-many; true if all wanted are found */
bool    sdisk_t::hasOption(int mode, int wanted)
{
    mode &= OPTION_FLAGS;
    return (mode & wanted) == wanted;
}


/* Emulate vector I/O operations on thos boxes which don't
   support it. Either an error or a short transfer will
   abort the I/O and return the transfer count. */

w_rc_t    sdisk_t::readv(const iovec_t *iov, int iovcnt, int &transfered)
{
    int    total = 0;
    int    done = 0;
    int    n;
    int    i;
    w_rc_t    e;

    total = vsize(iov, iovcnt);

    for (i = 0; i < iovcnt; i++) {
        e = read(iov[i].iov_base, iov[i].iov_len, n);
        if (e.is_error())
            break;
        done += n;
        if (size_t(n) != iov[i].iov_len)
            break;
    }

    transfered = done;

    return e;
}


w_rc_t    sdisk_t::writev(const iovec_t *iov, int iovcnt, int &transfered)
{
    int    total = 0;
    int    done = 0;
    int    n;
    int    i;
    w_rc_t    e;

    total = vsize(iov, iovcnt);

    for (i = 0; i < iovcnt; i++) {
        e = write(iov[i].iov_base, iov[i].iov_len, n);
        if (e.is_error())
            break;
        done += n;
        if (size_t(n) != iov[i].iov_len)
            break;
    }

    transfered = done;

    return e;
}

/* Emulate positioned I/O operations on thos boxes which don't
   support it.  It isn't "race safe", that is a difficult problem
   to deal with.  Pread/Pwrite don't move the file pointer, but
   that is difficult to do if the OS doens't support them.  We 
   seek to where the I/O is supposed to be, execute it, and
   then restore the old position.  */

w_rc_t    sdisk_t::pread(void *buf, int size, fileoff_t pos,
               int &transfered)
{
  // make it safe or don't do it at all.
  return RC(fcNOTIMPLEMENTED);
  
    fileoff_t    was;
    fileoff_t    newpos;
    int        n;
    w_rc_t        e;
    w_rc_t        es;

    W_DO(seek(0, SEEK_AT_CUR, was));
    /* Only move if it needs to */
    if (pos != was) {
        W_DO(seek(pos, SEEK_AT_SET, newpos));
        if (newpos != pos) {
            es = seek(was, SEEK_AT_SET, newpos);
            if (es.is_error())
                cerr << "Warning: pread reposition failed!"
                    << endl << e << endl;
            return RC(stSHORTSEEK);
        }
    }

    e = read(buf, size, n);

    es = seek(was, SEEK_AT_SET, newpos);
    /* XXX should a reposition error make the I/O fail? */
    if (es.is_error() || newpos != was)
        cerr << "Warning: pread reposition failed!"
            << endl << e << endl;

    transfered = n;

    return e;
}

w_rc_t    sdisk_t::pwrite(const void *buf, int size, fileoff_t pos,
               int &transfered)
{
  // make it safe or don't do it at all.
  return RC(fcNOTIMPLEMENTED);
  
    fileoff_t    was;
    fileoff_t    newpos;
    int        n;
    w_rc_t        e;
    w_rc_t        es;

    W_DO(seek(0, SEEK_AT_CUR, was));
    /* Only move if it needs to */
    if (pos != was) {
        W_DO(seek(pos, SEEK_AT_SET, newpos));
        if (newpos != pos) {
            es = seek(was, SEEK_AT_SET, newpos);
            if (es.is_error())
                cerr << "Warning: pwrite reposition failed!"
                    << endl << e << endl;
            return RC(stSHORTSEEK);
        }
    }

    e = write(buf, size, n);

    es = seek(was, SEEK_AT_SET, newpos);
    /* XXX should a reposition error make the I/O fail? */
    if (es.is_error() || newpos != was)
        cerr << "Warning: pwrite reposition failed!"
            << endl << e << endl;

    transfered = n;

    return e;
}


/* a no-op file-sync if the underlying implementation doesn't support it. */
w_rc_t    sdisk_t::sync()
{
    return RCOK;
}


w_rc_t    sdisk_t::stat(filestat_t &)
{
    return RC(fcNOTIMPLEMENTED);
}
/**\endcond skip */

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