SQLite

*************************************************************************
** This is the implementation of the page cache subsystem.
** 
** The page cache is used to access a database file.  The pager journals
** all writes in order to support rollback.  Locking is used to limit
** access to one or more reader or on writer.
**
** @(#) $Id: pager.c,v 1.3 2001/04/15 00:37:09 drh Exp $
** @(#) $Id: pager.c,v 1.4 2001/04/15 02:27:25 drh Exp $
*/
#include "sqliteInt.h"
#include "pager.h"
#include <fcntl.h>
#include <sys/stat.h>
#include <unistd.h>
#include <assert.h>

  strcpy(pPager->zJournal, zFilename);
  strcpy(&pPager->zJournal[nameLen], "-journal");
  pPager->fd = fd;
  pPager->jfd = -1;
  pPager->nRef = 0;
  pPager->dbSize = -1;
  pPager->nPage = 0;
  pPager->mxPage = mxPage>10 ? mxPage : 10;
  pPager->mxPage = mxPage>5 ? mxPage : 10;
  pPager->state = SQLITE_UNLOCK;
  pPager->errMask = 0;
  pPager->pFirst = 0;
  pPager->pLast = 0;
  memset(pPager->aHash, 0, sizeof(pPager->aHash));
  *ppPager = pPager;
  return SQLITE_OK;

      }
      pPg->pPager = pPager;
      pPg->pNextAll = pPager->pAll;
      if( pPager->pAll ){
        pPager->pAll->pPrevAll = pPg;
      }
      pPg->pPrevAll = 0;
      pPager->pAll = pPg;
      pPager->nPage++;
    }else{
      /* Recycle an older page.  First locate the page to be recycled.
      ** Try to find one that is not dirty and is near the head of
      ** of the free list */
      int cnt = 4;
      pPg = pPager->pFirst;

** All subsequent write attempts also return SQLITE_FULL until there
** is a call to sqlitepager_commit() or sqlitepager_rollback() to
** reset.
*/
int sqlitepager_write(void *pData){
  PgHdr *pPg = DATA_TO_PGHDR(pData);
  Pager *pPager = pPg->pPager;
  int rc;
  int rc = SQLITE_OK;

  if( pPager->errMask ){ 
    return pager_errcode(pPager);
  }
  pPg->dirty = 1;
  if( pPg->inJournal ){ return SQLITE_OK; }
  assert( pPager->state!=SQLITE_UNLOCK );

#   drh@hwaci.com
#   http://www.hwaci.com/drh/
#
#***********************************************************************
# This file implements regression tests for SQLite library.  The
# focus of this script is page cache subsystem.
#
# $Id: pager.test,v 1.1 2001/04/15 00:37:21 drh Exp $
# $Id: pager.test,v 1.2 2001/04/15 02:27:25 drh Exp $


set testdir [file dirname $argv0]
source $testdir/tester.tcl

if {$dbprefix!="mem:" && [info commands pager_open]!=""} {

    pager_rollback $::p1
  } msg]
  lappend v $msg
} {0 {}}
do_test pager-2.29 {
  page_read $::g1
} {Page-One}
do_test pager-2.99 {
  pager_close $::p1
} {}

do_test pager-3.1 {
  set v [catch {
    set ::p1 [pager_open ptf1.db 5]
  } msg]
  if {$v} {lappend v $msg}
  set v
} {0}
do_test pager-3.2 {
  pager_pagecount $::p1
} {1}
do_test pager-3.3 {
  set v [catch {
    set ::g(1) [page_get $::p1 1]
  } msg]
  if {$v} {lappend v $msg}
  set v
} {0}
do_test pager-3.4 {
  page_read $::g(1)
} {Page-One}
do_test pager-3.5 {
  for {set i 2} {$i<=20} {incr i} {
    set gx [page_get $::p1 $i]
    page_write $gx "Page-$i"
    page_unref $gx
  }
  pager_commit $::p1
} {}
for {set i 2} {$i<=20} {incr i} {
  do_test pager-3.6.[expr {$i-1}] [subst {
    set gx \[page_get $::p1 $i\]
    set v \[page_read \$gx\]
    page_unref \$gx
    set v
  }] "Page-$i"
}
do_test pager-2.99 {
do_test pager-3.99 {
  pager_close $::p1
} {}


} ;# end if( not mem: and has pager_open command );

finish_test