SQLite

** The pager is used to access a database disk file.  It implements
** atomic commit and rollback through the use of a journal file that
** is separate from the database file.  The pager also implements file
** locking to prevent two processes from writing the same database
** file simultaneously, or one process from reading the database while
** another is writing.
**
** @(#) $Id: pager.c,v 1.343 2007/06/13 15:22:28 danielk1977 Exp $
*/
#ifndef SQLITE_OMIT_DISKIO
#include "sqliteInt.h"
#include "os.h"
#include "pager.h"
#include <assert.h>
#include <string.h>

    pPg->pPager = pPager;
    pPg->pNextAll = pPager->pAll;
    pPager->pAll = pPg;
    pPager->nPage++;
  }else{
    /* Recycle an existing page with a zero ref-count. */
    rc = pager_recycle(pPager, 1, &pPg);
    if( rc==SQLITE_BUSY ){
      rc = SQLITE_IOERR_BLOCKED;
    }
    if( rc!=SQLITE_OK ){
      goto pager_allocate_out;
    }
    assert( pPager->state>=SHARED_LOCK );
    assert(pPg);
  }
  *ppPg = pPg;

    pPager->state = PAGER_SYNCED;
  }else if( MEMDB && nTrunc!=0 ){
    rc = sqlite3PagerTruncate(pPager, nTrunc);
  }

sync_exit:
  if( rc==SQLITE_IOERR_BLOCKED ){
    /* pager_incr_changecounter() may attempt to obtain an exclusive
     * lock to spill the cache and return IOERR_BLOCKED. But since 
     * there is no chance the cache is inconsistent, it's
     * better to return SQLITE_BUSY.
     */
    rc = SQLITE_BUSY;
  }
  return rc;
}


/*
** Commit all changes to the database and release the write lock.
**

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This header file defines the interface that the SQLite library
** presents to client programs.
**
** @(#) $Id: sqlite.h.in,v 1.211 2007/06/13 15:22:28 danielk1977 Exp $
*/
#ifndef _SQLITE3_H_
#define _SQLITE3_H_
#include <stdarg.h>     /* Needed for the definition of va_list */

/*
** Make sure we can call this stuff from C++.

#define SQLITE_IOERR_FSYNC         (SQLITE_IOERR | (4<<8))
#define SQLITE_IOERR_DIR_FSYNC     (SQLITE_IOERR | (5<<8))
#define SQLITE_IOERR_TRUNCATE      (SQLITE_IOERR | (6<<8))
#define SQLITE_IOERR_FSTAT         (SQLITE_IOERR | (7<<8))
#define SQLITE_IOERR_UNLOCK        (SQLITE_IOERR | (8<<8))
#define SQLITE_IOERR_RDLOCK        (SQLITE_IOERR | (9<<8))
#define SQLITE_IOERR_DELETE        (SQLITE_IOERR | (10<<8))
#define SQLITE_IOERR_BLOCKED       (SQLITE_IOERR | (11<<8))

/*
** Enable or disable the extended result codes.
*/
int sqlite3_extended_result_codes(sqlite3*, int onoff);

/*

        }
      }
  
      /* If the query was read-only, we need do no rollback at all. Otherwise,
      ** proceed with the special handling.
      */
      if( !isReadOnly ){
        if( p->rc==SQLITE_IOERR_BLOCKED && isStatement ){
          xFunc = sqlite3BtreeRollbackStmt;
          p->rc = SQLITE_BUSY;
        } else if( p->rc==SQLITE_NOMEM && isStatement ){
          xFunc = sqlite3BtreeRollbackStmt;
        }else{
          /* We are forced to roll back the active transaction. Before doing
          ** so, abort any other statements this handle currently has active.
          */
          sqlite3AbortOtherActiveVdbes(db, p);
          sqlite3RollbackAll(db);

# 2007 June 13
#
# 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.
#
#***********************************************************************
# This file implements regression tests for SQLite library.
#
# This file implements tests to verify that ticket #2409 has been
# fixed. More specifically, they verify that if SQLite cannot
# obtain an EXCLUSIVE lock while trying to spill the cache during
# any statement other than a COMMIT, an I/O error is returned instead
# of SQLITE_BUSY.
#
# $Id: tkt2409.test,v 1.1 2007/06/13 15:22:28 danielk1977 Exp $

# Test Outline:
#
#   tkt-2409-1.*: Cause a cache-spill during an INSERT that is within
#       a db transaction but does not start a statement transaction.
#       Verify that the transaction is automatically rolled back
#       and SQLITE_IOERR_BLOCKED is returned
#
#   tkt-2409-2.*: Cause a cache-spill while updating the change-counter
#       during a database COMMIT. Verify that the transaction is not
#       rolled back and SQLITE_BUSY is returned.
#
#   tkt-2409-3.*: Similar to 2409-1.*, but using many INSERT statements
#       within a transaction instead of just one.
#
#   tkt-2409-4.*: Similar to 2409-1.*, but rig it so that the
#       INSERT statement starts a statement transaction. Verify that
#       SQLOTE_BUSY is returned and the transaction is not rolled back.
#

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

sqlite3_extended_result_codes $::DB 1

# Aquire a read-lock on the database using handle [db2].
#
proc read_lock_db {} {
  if {$::STMT eq ""} {
    set ::STMT [sqlite3_prepare db2 {SELECT rowid FROM sqlite_master} -1 TAIL]
    set rc [sqlite3_step $::STMT]
    if {$rc eq "SQLITE_ERROR"} {
      unread_lock_db
      read_lock_db
    }
  }
}

# Release any read-lock obtained using [read_lock_db]
#
proc unread_lock_db {} {
  if {$::STMT ne ""} {
    sqlite3_finalize $::STMT
    set ::STMT ""
  }
}

# Open the db handle used by [read_lock_db].
#
sqlite3 db2 test.db
set ::STMT ""

do_test tkt2409-1.1 {
  execsql {
    PRAGMA cache_size=10;
    CREATE TABLE t1(x TEXT UNIQUE NOT NULL, y BLOB);
  }
  read_lock_db
  set ::zShort [string repeat 0123456789 1]
  set ::zLong  [string repeat 0123456789 1500]
  catchsql {
    BEGIN;
    INSERT INTO t1 VALUES($::zShort, $::zLong);
  }
} {1 {disk I/O error}}

do_test tkt2409-1.2 {
  sqlite3_errcode $::DB
} {SQLITE_IOERR+11}

# Check the integrity of the cache.
#
integrity_check tkt2409-1.3

# Check that the transaction was rolled back. Because the INSERT
# statement in which the "I/O error" occured did not open a statement
# transaction, SQLite had no choice but to roll back the transaction.
#
do_test tkt2409-1.4 {
  unread_lock_db
  catchsql { ROLLBACK }
} {1 {cannot rollback - no transaction is active}}


set ::zShort [string repeat 0123456789 1]
set ::zLong  [string repeat 0123456789 1500]
set ::rc 1
for {set iCache 10} {$::rc} {incr iCache} {
  execsql "PRAGMA cache_size = $iCache"
  do_test tkt2409-2.1.$iCache {
    read_lock_db
    set ::rc [catch {
      execsql {
        BEGIN;
        INSERT INTO t1 VALUES($::zShort, $::zLong);
      }
    } msg]
    expr {($::rc == 1 && $msg eq "disk I/O error") || $::rc == 0}
  } {1}
}

do_test tkt2409-2.2 {
  catchsql {
    ROLLBACK;
    BEGIN;
    INSERT INTO t1 VALUES($::zShort, $::zLong);
    COMMIT;
  }
} {1 {database is locked}}

do_test tkt2409-2.3 {
  unread_lock_db
  catchsql {
    COMMIT;
  }
} {0 {}}

do_test tkt2409-3.1 {
  db close
  set ::DB [sqlite3 db test.db; sqlite3_connection_pointer db]
  sqlite3_extended_result_codes $::DB 1
  execsql {
    PRAGMA cache_size=10;
    DELETE FROM t1;
  }
  read_lock_db
  set ::zShort [string repeat 0123456789 1]
  set ::zLong  [string repeat 0123456789 1500]
  catchsql {
    BEGIN;
    INSERT INTO t1 SELECT $::zShort, $::zLong;
  }
} {1 {database is locked}}

do_test tkt2409-3.2 {
  sqlite3_errcode $::DB
} {SQLITE_BUSY}

# Check the integrity of the cache.
#
integrity_check tkt2409-3.3

# Check that the transaction was rolled back. Because the INSERT
# statement in which the "I/O error" occured did not open a statement
# transaction, SQLite had no choice but to roll back the transaction.
#
do_test tkt2409-3.4 {
  unread_lock_db
  catchsql { ROLLBACK }
} {0 {}}


do_test tkt2409-4.1 {
  execsql {
    PRAGMA cache_size=20;
    DROP TABLE t1;
    CREATE TABLE t1 (x TEXT UNIQUE NOT NULL);
  }

  unset -nocomplain t1
  array unset t1
  set t1(0) 1
  set sql ""
  for {set i 0} {$i<5000} {incr i} {
    set r 0
    while {[info exists t1($r)]} {
      set r [expr {int(rand()*1000000000)}]
    }
    set t1($r) 1
    append sql "INSERT INTO t1 VALUES('some-text-$r');"
  }

  read_lock_db
  execsql BEGIN
  catchsql $sql
} {1 {disk I/O error}}

do_test tkt2409-4.2 {
  sqlite3_errcode $::DB
} {SQLITE_IOERR+11}

# Check the integrity of the cache.
#
integrity_check tkt2409-4.3

do_test tkt2409-4.4 {
  catchsql { ROLLBACK }
} {1 {cannot rollback - no transaction is active}}


unread_lock_db
db2 close
finish_test