SQLite

  ** has to create a wrapper sqlite3_file of the same version.  Hence
  ** there are two I/O method structures, one for version 1 and the other
  ** for version 2.
  */
  sqlite3_io_methods sIoMethodsV1;
  sqlite3_io_methods sIoMethodsV2;

  /* True when this shim has been initialized.
  */
  int isInitialized;

  /* For run-time access any of the other global data structures in this
  ** shim, the following mutex must be held.
  */
  sqlite3_mutex *pMutex;

  /* List of multiplexGroup objects.
  */
  multiplexGroup *pGroups;

  /* Chunk params.
  */
  int nChunkSize;
  int nMaxChunks;

} gMultiplex;

/************************* Utility Routines *********************************/

  }

  /* We need to create a group structure and manage
  ** access to this group of files.
  */
  multiplexEnter();
  pMultiplexOpen = (multiplexConn*)pConn;
  /* allocate space for group, file handles, 
  ** and file name (+ extra for "-0000\0") 
  */
  pGroup = sqlite3_malloc( sizeof(multiplexGroup) + (pOrigVfs->szOsFile*gMultiplex.nMaxChunks) + nName + 6 );
  if( pGroup==0 ){
    rc=SQLITE_NOMEM;
  }else{
    pMultiplexOpen->pGroup = pGroup;
    memset(pGroup, 0, sizeof(multiplexGroup) + (pOrigVfs->szOsFile*gMultiplex.nMaxChunks) + nName + 6);
    /* assign pointers to extra space for file handles */
    for(i=0; i<gMultiplex.nMaxChunks; i++){
      pGroup->pReal[i] = (sqlite3_file *)((char *)&pGroup[1] + (pOrigVfs->szOsFile*i));
    }
    pGroup->zName = (char *)&pGroup[1] + (pOrigVfs->szOsFile*gMultiplex.nMaxChunks);
    memcpy(pGroup->zName, zName, nName+1);
    pGroup->nName = nName;
    pGroup->flags = flags;

  sqlite3_free(pGroup);
  multiplexLeave();
  return rc;
}

/* Pass xRead requests thru to the original VFS after
** determining the correct chunk to operate on.
** Break up reads across chunk boundaries.
*/
static int multiplexRead(
  sqlite3_file *pConn,
  void *pBuf,
  int iAmt,
  sqlite3_int64 iOfst
){

  }
  multiplexLeave();
  return rc;
}

/* Pass xWrite requests thru to the original VFS after
** determining the correct chunk to operate on.
** Break up writes across chunk boundaries.
*/
static int multiplexWrite(
  sqlite3_file *pConn,
  const void *pBuf,
  int iAmt,
  sqlite3_int64 iOfst
){

  int rc2;
  int i;
  sqlite3_file *pSubOpen;
  sqlite3_vfs *pOrigVfs = gMultiplex.pOrigVfs;   /* Real VFS */
  multiplexEnter();
  /* delete the chunks above the truncate limit */
  for(i=(int)(size/gMultiplex.nChunkSize)+1; i<gMultiplex.nMaxChunks; i++){
    /* close any open chunks before deleting them */
    if( pGroup->bOpen[i] ){
      pSubOpen = pGroup->pReal[i];
      rc2 = pSubOpen->pMethods->xClose(pSubOpen);
      if( rc2!=SQLITE_OK ) rc = SQLITE_IOERR_TRUNCATE;
    }

    if( i ) sqlite3_snprintf(pGroup->nName+6, pGroup->zName+pGroup->nName, "-%04d", i);
    rc2 = pOrigVfs->xDelete(pOrigVfs, pGroup->zName, 0);
    if( rc2!=SQLITE_OK ) rc = SQLITE_IOERR_TRUNCATE;
  }
  pSubOpen = multiplexSubOpen(p, (int)(size/gMultiplex.nChunkSize), &rc2, NULL);
  if( pSubOpen ){
    rc2 = pSubOpen->pMethods->xTruncate(pSubOpen, size%gMultiplex.nChunkSize);

  int rc = SQLITE_OK;
  int rc2;
  int i;
  multiplexEnter();
  *pSize = 0;
  for(i=0; i<gMultiplex.nMaxChunks; i++){
    sqlite3_file *pSubOpen = NULL;

    /* if not opened already, check to see if the chunk exists */
    if( pGroup->bOpen[i] ){
      pSubOpen = pGroup->pReal[i];
    }else{
      sqlite3_vfs *pOrigVfs = gMultiplex.pOrigVfs;   /* Real VFS */
      int exists = 0;
      pGroup->zName[pGroup->nName] = '\0';
      if( i ) sqlite3_snprintf(pGroup->nName+6, pGroup->zName+pGroup->nName, "-%04d", i);
      rc2 = pOrigVfs->xAccess(pOrigVfs, pGroup->zName, SQLITE_ACCESS_EXISTS, &exists);
      if( rc2==SQLITE_OK && exists){
        /* if it exists, open it */
        pSubOpen = multiplexSubOpen(p, i, &rc, NULL);
      }else{
        /* stop at first "gap" */
        break;
      }
    }
    if( pSubOpen ){
      sqlite3_int64 sz;
      rc2 = pSubOpen->pMethods->xFileSize(pSubOpen, &sz);
      if( rc2!=SQLITE_OK ){
        rc = rc2;
      }else{
        *pSize += sz;
      }
    }else{

  for {set i 1} {$i<=15} {incr i} {
    file delete -force $name-000$i
    file delete -force $name-00$i
  }
}

db close

#-------------------------------------------------------------------------
#   multiplex-1.1.*: Test initialize and shutdown.

do_test multiplex-1.1 { sqlite3_multiplex_initialize nosuchvfs 1 } {SQLITE_ERROR}
do_test multiplex-1.2 { sqlite3_multiplex_initialize "" 1 }        {SQLITE_OK}
do_test multiplex-1.3 { sqlite3_multiplex_initialize "" 1 }        {SQLITE_MISUSE}
do_test multiplex-1.4 { sqlite3_multiplex_shutdown }               {SQLITE_OK}

do_test multiplex-1.5 { sqlite3_multiplex_initialize "" 0 }        {SQLITE_OK}

#   multiplex-2.3.*: Open and close a second db.
#
#   multiplex-2.4.*: Try to shutdown the multiplex system before closing the db
#                file. Check that this fails and the multiplex system still works
#                afterwards. Then close the database and successfully shut
#                down the multiplex system.
#
#   multiplex-2.5.*: More reading/writing with small chunk size.

sqlite3_multiplex_initialize "" 1
sqlite3_multiplex_set 0x8000 16

do_test multiplex-2.1.2 {
  sqlite3 db test.db
  execsql {

  sqlite3_multiplex_shutdown
} {SQLITE_MISUSE}
do_test multiplex-2.4.2 {
  execsql { INSERT INTO t1 VALUES(3, randomblob(1100)) }
} {}
do_test multiplex-2.4.4 { file size test.db } {7168}
do_test multiplex-2.4.99 {
  db close
  sqlite3_multiplex_shutdown
} {SQLITE_OK}


do_test multiplex-2.5.1 {
  multiplex_delete test.db
  sqlite3_multiplex_initialize "" 1
  sqlite3_multiplex_set 0x1000 16
} {SQLITE_OK}

do_test multiplex-2.5.2 {
  sqlite3 db test.db
  execsql {
    PRAGMA page_size = 1024;
    PRAGMA journal_mode = delete;
    PRAGMA auto_vacuum = off;
    CREATE TABLE t1(a PRIMARY KEY, b);
  }
} {delete}

do_test multiplex-2.5.3 { 
  execsql { 
    INSERT INTO t1 VALUES(1, 'one');
    INSERT INTO t1 VALUES(2, randomblob(4000));
    INSERT INTO t1 VALUES(3, 'three');
    INSERT INTO t1 VALUES(4, randomblob(4000));
    INSERT INTO t1 VALUES(5, 'five') 
  }
} {}

do_test multiplex-2.5.4 {
  db eval {SELECT * FROM t1 WHERE a=1}
} {1 one}

do_test multiplex-2.5.5 {
  db eval {SELECT * FROM t1 WHERE a=3}
} {3 three}

do_test multiplex-2.5.6 {
  db eval {SELECT * FROM t1 WHERE a=5}
} {5 five}

do_test multiplex-2.5.7 {
  db eval {SELECT a,length(b) FROM t1 WHERE a=2}
} {2 4000}

do_test multiplex-2.5.8 {
  db eval {SELECT a,length(b) FROM t1 WHERE a=4}
} {4 4000}

do_test multiplex-2.5.99 {
  db close
  sqlite3_multiplex_shutdown
} {SQLITE_OK}

#-------------------------------------------------------------------------
# Try some tests with more than one connection to a database file. Still
# in rollback mode.