SQLite

** references.  Or if the writeOnly flag is set to 1, then only
** trip write cursors and leave read cursors unchanged.
**
** Every cursor is a candidate to be tripped, including cursors
** that belong to other database connections that happen to be
** sharing the cache with pBtree.
**
** This routine gets called when a rollback occurs. If the writeOnly
** flag is true, then only write-cursors need be tripped - read-only
** cursors save their current positions so that they may continue 
** following the rollback. Or, if writeOnly is false, all cursors are 
** tripped. In general, writeOnly is false if the transaction being
** rolled back modified the database schema. In this case b-tree root
** pages may be moved or deleted from the database altogether, making
** it unsafe for read cursors to continue.
**
** If the writeOnly flag is true and an error is encountered while 
** saving the current position of a read-only cursor, all cursors, 
** including all read-cursors are tripped.
**
** SQLITE_OK is returned if successful, or if an error occurs while
** saving a cursor position, an SQLite error code.
*/
int sqlite3BtreeTripAllCursors(Btree *pBtree, int errCode, int writeOnly){
  BtCursor *p;
  int rc = SQLITE_OK;

  assert( (writeOnly==0 || writeOnly==1) && BTCF_WriteFlag==1 );
  if( pBtree ){
    sqlite3BtreeEnter(pBtree);
    for(p=pBtree->pBt->pCursor; p; p=p->pNext){
      int i;
      if( writeOnly && (p->curFlags & BTCF_WriteFlag)==0 ){
        if( p->eState==CURSOR_VALID ){
          int rc = saveCursorPosition(p);
          if( rc!=SQLITE_OK ){
            (void)sqlite3BtreeTripAllCursors(pBtree, rc, 0);
            break;
          }
        }
      }else{
        sqlite3BtreeClearCursor(p);
        p->eState = CURSOR_FAULT;
        p->skipNext = errCode;
      }
      for(i=0; i<=p->iPage; i++){
        releasePage(p->apPage[i]);
        p->apPage[i] = 0;
      }
    }
    sqlite3BtreeLeave(pBtree);
  }
  return rc;
}

/*
** Rollback the transaction in progress.
**
** If tripCode is not SQLITE_OK then cursors will be invalidated (tripped).
** Only write cursors are tripped if writeOnly is true but all cursors are

  if( tripCode==SQLITE_OK ){
    rc = tripCode = saveAllCursors(pBt, 0, 0);
    if( rc ) writeOnly = 0;
  }else{
    rc = SQLITE_OK;
  }
  if( tripCode ){
    int rc2 = sqlite3BtreeTripAllCursors(p, tripCode, writeOnly);
    assert( rc==SQLITE_OK || (writeOnly==0 && rc2==SQLITE_OK) );
    if( rc2!=SQLITE_OK ) rc = rc2;
  }
  btreeIntegrity(p);

  if( p->inTrans==TRANS_WRITE ){
    int rc2;

    assert( TRANS_WRITE==pBt->inTransaction );

*/
#define BTREE_INTKEY     1    /* Table has only 64-bit signed integer keys */
#define BTREE_BLOBKEY    2    /* Table has keys only - no data */

int sqlite3BtreeDropTable(Btree*, int, int*);
int sqlite3BtreeClearTable(Btree*, int, int*);
int sqlite3BtreeClearTableOfCursor(BtCursor*);
int sqlite3BtreeTripAllCursors(Btree*, int, int);

void sqlite3BtreeGetMeta(Btree *pBtree, int idx, u32 *pValue);
int sqlite3BtreeUpdateMeta(Btree*, int idx, u32 value);

int sqlite3BtreeNewDb(Btree *p);

/*

        rc = p->rc;
      }else{
        int isSchemaChange;
        iSavepoint = db->nSavepoint - iSavepoint - 1;
        if( p1==SAVEPOINT_ROLLBACK ){
          isSchemaChange = (db->flags & SQLITE_InternChanges)!=0;
          for(ii=0; ii<db->nDb; ii++){
            rc = sqlite3BtreeTripAllCursors(db->aDb[ii].pBt, SQLITE_ABORT,
                                       isSchemaChange==0);
            if( rc!=SQLITE_OK ) goto abort_due_to_error;
          }
        }else{
          isSchemaChange = 0;
        }
        for(ii=0; ii<db->nDb; ii++){
          rc = sqlite3BtreeSavepoint(db->aDb[ii].pBt, p1, iSavepoint);
          if( rc!=SQLITE_OK ){

# 2014 November 12
#
# 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.
#
#***********************************************************************
#

set testdir [file dirname $argv0]
source $testdir/tester.tcl
set ::testprefix rollback2

proc int2hex {i} { format %.2X $i }
db func int2hex int2hex

do_execsql_test 1.0 {
  SELECT int2hex(0), int2hex(100), int2hex(255)
} {00 64 FF}
do_execsql_test 1.1 {
  CREATE TABLE t1(i, h);
  CREATE INDEX i1 ON t1(h);
  WITH data(a, b) AS (
    SELECT 1, int2hex(1)
      UNION ALL
    SELECT a+1, int2hex(a+1) FROM data WHERE a<40
  )
  INSERT INTO t1 SELECT * FROM data;
} {}


proc do_rollback_test {tn args} {
  set A(-setup)    ""
  set A(-select)   ""
  set A(-result)   ""
  set A(-rollback) ROLLBACK

  array set O $args
  foreach k [array names O] {
    if {[info exists A($k)]==0} { error "unknown option: $k" }
    set A($k) $O($k)
  }

  for {set iRollback 0} 1 {incr iRollback} {
    catch { db eval ROLLBACK }
    set res [list]
    db eval $A(-setup)

    set i 0
    db eval $A(-select) x {
      if {$i==$iRollback} { db eval $A(-rollback) }
      foreach k $x(*) { lappend res $x($k) }
      incr i
    }

    do_test $tn.$iRollback [list set {} $res] [list {*}$A(-result)]
    if {$i < $iRollback} break
  }
}

do_rollback_test 2 -setup {
  BEGIN;
    DELETE FROM t1 WHERE (i%2)==1;
} -select {
  SELECT i FROM t1 WHERE (i%2)==0
} -result {
  2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40
}

finish_test