SQLite

/*
** 2004 April 6
**
** 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: btree.c,v 1.572 2009/03/12 14:43:28 danielk1977 Exp $
**
** This file implements a external (disk-based) database using BTrees.
** See the header comment on "btreeInt.h" for additional information.
** Including a description of file format and an overview of operation.
*/
#include "btreeInt.h"

}

/*
** Commit the statment subtransaction currently in progress.  If no
** subtransaction is active, this is a no-op.
*/
int sqlite3BtreeCommitStmt(Btree *p){
  int rc = SQLITE_OK;
  BtShared *pBt = p->pBt;
  sqlite3BtreeEnter(p);
  pBt->db = p->db;

  if( p->inTrans==TRANS_WRITE && pBt->inStmt ){
    int iStmtpoint = p->db->nSavepoint;
    assert( pBt->readOnly==0 );
    rc = sqlite3PagerSavepoint(pBt->pPager, SAVEPOINT_RELEASE, iStmtpoint);

    pBt->inStmt = 0;
  }

  sqlite3BtreeLeave(p);
  return rc;
}

/*
** Rollback the active statement subtransaction.  If no subtransaction
** is active this routine is a no-op.
**
** All cursors will be invalidated by this operation.  Any attempt
** to use a cursor that was open at the beginning of this operation
** will result in an error.
*/
int sqlite3BtreeRollbackStmt(Btree *p){
  int rc = SQLITE_OK;
  BtShared *pBt = p->pBt;
  sqlite3BtreeEnter(p);
  pBt->db = p->db;

  if( p->inTrans==TRANS_WRITE && pBt->inStmt ){
    int iStmtpoint = p->db->nSavepoint;
    assert( pBt->readOnly==0 );
    rc = sqlite3PagerSavepoint(pBt->pPager, SAVEPOINT_ROLLBACK, iStmtpoint);
    if( rc==SQLITE_OK ){
      rc = sqlite3PagerSavepoint(pBt->pPager, SAVEPOINT_RELEASE, iStmtpoint);
    }
    pBt->inStmt = 0;
  }
  sqlite3BtreeLeave(p);

#
#    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 runs all tests.
#
# $Id: quick.test,v 1.94 2009/03/12 14:43:28 danielk1977 Exp $

proc lshift {lvar} {
  upvar $lvar l
  set ret [lindex $l 0]
  set l [lrange $l 1 end]
  return $ret
}

  speed4p.test
  sqllimits1.test
  tkt2686.test
  thread001.test
  thread002.test
  thread003.test
  thread004.test
  thread005.test
  trans2.test
  vacuum3.test

  incrvacuum_ioerr.test
  autovacuum_crash.test
  btree8.test
  shared_err.test

#    May you share freely, never taking more than you give.
#
#***********************************************************************
#
#   This file contains tests that attempt to break the pcache module
#   by bombarding it with simultaneous requests from multiple threads.
#     
# $Id: thread003.test,v 1.7 2009/03/12 14:43:28 danielk1977 Exp $

set testdir [file dirname $argv0]

source $testdir/tester.tcl
source $testdir/thread_common.tcl
if {[info commands sqlthread] eq ""} {
  finish_test

} {0}

# In this test case, one thread is continually querying the database.
# The other thread does not have a database connection, but calls
# sqlite3_release_memory() over and over again.
#
set nSecond 30
puts "Starting thread003.4 (should run for ~$nSecond seconds)"
unset -nocomplain finished(1)
unset -nocomplain finished(2)
do_test thread003.4 {
  thread_spawn finished(1) $thread_procs [format {
    set iEnd [expr {[clock_seconds] + %d}]
    set ::DB [sqlthread open test.db]

# 2009 March 11
#
# 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.
#
#***********************************************************************
#
# Test a race-condition that shows up in shared-cache mode.
#
# $Id: thread005.test,v 1.1 2009/03/12 14:43:28 danielk1977 Exp $

set testdir [file dirname $argv0]

source $testdir/tester.tcl
ifcapable !mutex||!shared_cache {
  return
}
source $testdir/thread_common.tcl
if {[info commands sqlthread] eq ""} {
  return
}

#-------------------------------------------------------------------------
# This test tries to exercise a race-condition that existed in shared-cache
# mode at one point. The test uses two threads; each has a database connection
# open on the same shared cache. The schema of the database is:
#
#    CREATE TABLE t1(a INTEGER PRIMARY KEY, b UNIQUE);
#
# One thread is a reader and the other thread a reader and a writer. The 
# writer thread repeats the following transaction as fast as possible:
# 
#      BEGIN;
#        DELETE FROM t1 WHERE a = (SELECT max(a) FROM t1);
#        INSERT INTO t1 VALUES(NULL, NULL);
#        UPDATE t1 SET b = a WHERE a = (SELECT max(a) FROM t1);
#        SELECT count(*) FROM t1 WHERE b IS NULL;
#      COMMIT;
#
# The reader thread does the following over and over as fast as possible:
#
#      BEGIN;
#        SELECT count(*) FROM t1 WHERE b IS NULL;
#      COMMIT;
#
# The test runs for 20 seconds or until one of the "SELECT count(*)" 
# statements returns a non-zero value. If an SQLITE_LOCKED error occurs,
# the connection issues a ROLLBACK immediately to abandon the current
# transaction.
#
# If everything is working correctly, the "SELECT count(*)" statements 
# should never return a value other than 0. The "INSERT" statement 
# executed by the writer adds a row with "b IS NULL" to the table, but
# the subsequent UPDATE statement sets its "b" value to an integer
# immediately afterwards.
#
# However, before the race-condition was fixed, if the reader's SELECT
# statement hit an error (say an SQLITE_LOCKED) at the same time as the
# writer was executing the UPDATE statement, then it could incorrectly
# rollback the statement-transaction belonging to the UPDATE statement.
# The UPDATE statement would still be reported as successful to the user,
# but it would have no effect on the database contents.
# 
# Note that it has so far only proved possible to hit this race-condition
# when using an ATTACHed database. There doesn't seem to be any reason
# for this, other than that operating on an ATTACHed database means there
# are a few more mutex grabs and releases during the window of time open
# for the race-condition. Maybe this encourages the scheduler to context
# switch or something...
#

# Use shared-cache mode for this test.
# 
db close
set ::enable_shared_cache [sqlite3_enable_shared_cache]
sqlite3_enable_shared_cache 1

file delete -force test.db test2.db

do_test thread005-1.1 {
  sqlite3 db test.db
  execsql { ATTACH 'test2.db' AS aux }
  execsql {
    CREATE TABLE aux.t1(a INTEGER PRIMARY KEY, b UNIQUE);
    INSERT INTO t1 VALUES(1, 1);
    INSERT INTO t1 VALUES(2, 2);
  }
  db close
} {}

set ThreadProgram {
  proc execsql {zSql {db {}}} {
    if {$db eq ""} {set db $::DB}

    set lRes [list]
    set rc SQLITE_OK

    while {$rc=="SQLITE_OK" && $zSql ne ""} {
      set STMT [sqlite3_prepare_v2 $db $zSql -1 zSql]
      while {[set rc [sqlite3_step $STMT]] eq "SQLITE_ROW"} {
        for {set i 0} {$i < [sqlite3_column_count $STMT]} {incr i} {
          lappend lRes [sqlite3_column_text $STMT 0]
        }
      }
      set rc [sqlite3_finalize $STMT]
    }

    if {$rc != "SQLITE_OK"} { error "$rc [sqlite3_errmsg $db]" }
    return $lRes
  }

  if {$isWriter} {
    set Sql {
      BEGIN;
        DELETE FROM t1 WHERE a = (SELECT max(a) FROM t1);
        INSERT INTO t1 VALUES(NULL, NULL);
        UPDATE t1 SET b = a WHERE a = (SELECT max(a) FROM t1);
        SELECT count(*) FROM t1 WHERE b IS NULL;
      COMMIT;
    }
  } else {
    set Sql {
      BEGIN;
      SELECT count(*) FROM t1 WHERE b IS NULL;
      COMMIT;
    }
  }

  set ::DB [sqlite3_open test.db]

  execsql { ATTACH 'test2.db' AS aux }

  set result "ok"
  set finish [expr [clock_seconds]+5]
  while {$result eq "ok" && [clock_seconds] < $finish} {
    set rc [catch {execsql $Sql} msg]
    if {$rc} {
      if {[string match "SQLITE_LOCKED*" $msg]} {
        catch { execsql ROLLBACK }
      } else {
        error $msg
      }
    } elseif {$msg ne "0"} {
      set result "failed"
    }
  }

  sqlite3_close $::DB
  set result
}

puts "Running thread-tests for ~20 seconds"
thread_spawn finished(0) {set isWriter 0} $ThreadProgram
thread_spawn finished(1) {set isWriter 1} $ThreadProgram
if {![info exists finished(0)]} { vwait finished(0) }
if {![info exists finished(1)]} { vwait finished(1) }

do_test thread005-1.2 {
  list $finished(0) $finished(1)
} {ok ok}

do_test thread005-1.3 {
  sqlite3 db test.db
  execsql { ATTACH 'test2.db' AS aux }
  execsql { SELECT count(*) FROM t1 WHERE b IS NULL }
} {0}

sqlite3_enable_shared_cache $::enable_shared_cache
finish_test