SQLite

**
*************************************************************************
**
** This file contains code use to implement an in-memory rollback journal.
** The in-memory rollback journal is used to journal transactions for
** ":memory:" databases and when the journal_mode=MEMORY pragma is used.
**
** @(#) $Id: memjournal.c,v 1.9 2009/04/01 23:09:44 drh Exp $
*/
#include "sqliteInt.h"

/* Forward references to internal structures */
typedef struct MemJournal MemJournal;
typedef struct FilePoint FilePoint;
typedef struct FileChunk FileChunk;

/* Space to hold the rollback journal is allocated in increments of
** this many bytes.
**
** The size chosen is a little less than a power of two.  That way,
** the FileChunk object will have a size that almost exactly fills
** a power-of-two allocation.  This mimimizes wasted space in power-of-two
** memory allocators.
*/
#define JOURNAL_CHUNKSIZE (1024-sizeof(FileChunk*))

/* Macro to find the minimum of two numeric values.
*/
#ifndef MIN
# define MIN(x,y) ((x)<(y)?(x):(y))
#endif

  sqlite3_io_methods *pMethod;    /* Parent class. MUST BE FIRST */
  FileChunk *pFirst;              /* Head of in-memory chunk-list */
  FilePoint endpoint;             /* Pointer to the end of the file */
  FilePoint readpoint;            /* Pointer to the end of the last xRead() */
};

/*
** Read data from the in-memory journal file.  This is the implementation
** of the sqlite3_vfs.xRead method.
*/
static int memjrnlRead(
  sqlite3_file *pJfd,    /* The journal file from which to read */
  void *zBuf,            /* Put the results here */
  int iAmt,              /* Number of bytes to read */
  sqlite_int64 iOfst     /* Begin reading at this offset */
){
  MemJournal *p = (MemJournal *)pJfd;
  u8 *zOut = zBuf;
  int nRead = iAmt;
  int iChunkOffset;
  FileChunk *pChunk;

  /* SQLite never tries to read past the end of a rollback journal file */
  assert( iOfst+iAmt<=p->endpoint.iOffset );

  if( p->readpoint.iOffset!=iOfst || iOfst==0 ){
    sqlite3_int64 iOff = 0;
    for(pChunk=p->pFirst; 
        ALWAYS(pChunk) && (iOff+JOURNAL_CHUNKSIZE)<=iOfst;
        pChunk=pChunk->pNext
    ){
      iOff += JOURNAL_CHUNKSIZE;
    }
  }else{
    pChunk = p->readpoint.pChunk;
  }

  memjrnlTruncate(pJfd, 0);
  return SQLITE_OK;
}


/*
** Sync the file.
**
** Syncing an in-memory journal is a no-op.  And, in fact, this routine
** is never called in a working implementation.  This implementation
** exists purely as a contingency, in case some malfunction in some other
** part of SQLite causes Sync to be called by mistake.
*/
static int memjrnlSync(sqlite3_file *NotUsed, int NotUsed2){   /*NO_TEST*/
  UNUSED_PARAMETER2(NotUsed, NotUsed2);                        /*NO_TEST*/
  assert( 0 );                                                 /*NO_TEST*/
  return SQLITE_OK;                                            /*NO_TEST*/

}                                                              /*NO_TEST*/

/*
** Query the size of the file in bytes.
*/
static int memjrnlFileSize(sqlite3_file *pJfd, sqlite_int64 *pSize){
  MemJournal *p = (MemJournal *)pJfd;
  *pSize = (sqlite_int64) p->endpoint.iOffset;

# 2008 June 21
#
# The author disclaims copyright to this source code.  In place of
# a legal notice, here is a blessing:
#
#    May you do good and not evil.
#    May you find forgiveness for yourself and forgive others.
#    May you share freely, never taking more than you give.
#
#***********************************************************************
#
# $Id: permutations.test,v 1.46 2009/04/01 23:09:44 drh Exp $

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

# Argument processing.
#
#puts "PERM-DEBUG: argv=$argv"

  set ::perm::testmode [list persistent_journal no_journal autovacuum_ioerr]
  set ISQUICK 1
}
if {$::perm::testmode eq "all" || $::perm::testmode eq ""} {
  set ::perm::testmode {
    memsubsys1 memsubsys2 singlethread multithread onefile utf16 exclusive
    persistent_journal persistent_journal_error no_journal no_journal_error
    autovacuum_ioerr no_mutex_try fullmutex journaltest inmemory_journal
  }
}
if {$::perm::testmode eq "targets"} { 
  puts ""
  puts -nonewline "veryquick            "
  puts "Same as persistent_journal and no_journal"
  puts -nonewline "quick                "

  Run tests with an in-memory journal file.
} -presql {
  pragma journal_mode = 'memory'
} -exclude {
  # Exclude all tests that simulate IO errors.
  autovacuum_ioerr2.test incrvacuum_ioerr.test ioerr.test
  ioerr.test ioerr2.test ioerr3.test ioerr4.test ioerr5.test
  vacuum3.test incrblob_err.test diskfull.test backup_ioerr.test

  # Exclude test scripts that use tcl IO to access journal files or count
  # the number of fsync() calls.
  pager.test exclusive.test jrnlmode.test sync.test misc1.test 
  journal1.test conflict.test crash8.test tkt3457.test
}

ifcapable mem3 {
  run_tests "memsys3" -description {
    Run tests using the allocator in mem3.c.
  } -exclude {
    autovacuum.test           delete3.test              manydb.test