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Overview
Comment:Allow database writes from within virtual table module xSync() callbacks. (CVS 3334)
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Timelines: family | ancestors | descendants | both | trunk
Files: files | file ages | folders
SHA1: d5a608d0a412e13dfced6a3827574a2cff802f25
User & Date: danielk1977 2006-07-25 15:14:53
Context
2006-07-26
01:39
Initial attempt at making sqlite3_interrupt() work even when called from a separate thread. (CVS 3335) check-in: 35fd67d7 user: drh tags: trunk
2006-07-25
15:14
Allow database writes from within virtual table module xSync() callbacks. (CVS 3334) check-in: d5a608d0 user: danielk1977 tags: trunk
2006-07-17
00:19
Fix lemon so that it does not crash on a empty reduce action. Ticket #1892. (CVS 3333) check-in: 4207ebc4 user: drh tags: trunk
Changes
Hide Diffs Unified Diffs Ignore Whitespace Patch

Changes to src/vdbeaux.c.

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    sqlite3BtreeClose(pCx->pBt);
  }
#ifndef SQLITE_OMIT_VIRTUALTABLE
  if( pCx->pVtabCursor ){
    sqlite3_vtab_cursor *pVtabCursor = pCx->pVtabCursor;
    const sqlite3_module *pModule = pCx->pModule;
    p->inVtabMethod = 1;

    pModule->xClose(pVtabCursor);

    p->inVtabMethod = 0;
  }
#endif
  sqliteFree(pCx->pData);
  sqliteFree(pCx->aType);
  sqliteFree(pCx);
}
................................................................................
*/
static int vdbeCommit(sqlite3 *db){
  int i;
  int nTrans = 0;  /* Number of databases with an active write-transaction */
  int rc = SQLITE_OK;
  int needXcommit = 0;


















  for(i=0; i<db->nDb; i++){ 
    Btree *pBt = db->aDb[i].pBt;
    if( pBt && sqlite3BtreeIsInTrans(pBt) ){
      needXcommit = 1;
      if( i!=1 ) nTrans++;
    }
  }
................................................................................
  if( 0==strlen(sqlite3BtreeGetFilename(db->aDb[0].pBt)) || nTrans<=1 ){
    for(i=0; rc==SQLITE_OK && i<db->nDb; i++){ 
      Btree *pBt = db->aDb[i].pBt;
      if( pBt ){
        rc = sqlite3BtreeSync(pBt, 0);
      }
    }
    rc = sqlite3VtabSync(db, rc);

    /* Do the commit only if all databases successfully synced */
    if( rc==SQLITE_OK ){
      for(i=0; i<db->nDb; i++){
        Btree *pBt = db->aDb[i].pBt;
        if( pBt ){
          sqlite3BtreeCommit(pBt);
................................................................................
    **
    ** If the error occurs during the first call to sqlite3BtreeSync(),
    ** then there is a chance that the master journal file will be
    ** orphaned. But we cannot delete it, in case the master journal
    ** file name was written into the journal file before the failure
    ** occured.
    */
    for(i=0; i<db->nDb; i++){ 
      Btree *pBt = db->aDb[i].pBt;
      if( pBt && sqlite3BtreeIsInTrans(pBt) ){
        rc = sqlite3BtreeSync(pBt, zMaster);
        if( rc!=SQLITE_OK ){


          sqlite3OsClose(&master);

          sqliteFree(zMaster);
          return rc;
        }
      }
    }
    rc = sqlite3VtabSync(db, SQLITE_OK);
    if( rc!=SQLITE_OK ) return rc;
    sqlite3OsClose(&master);

    /* Delete the master journal file. This commits the transaction. After
    ** doing this the directory is synced again before any individual
    ** transaction files are deleted.
    */
    rc = sqlite3OsDelete(zMaster);
    assert( rc==SQLITE_OK );
................................................................................
    return SQLITE_MISUSE;
  }

  /* If the VM did not run to completion or if it encountered an
  ** error, then it might not have been halted properly.  So halt
  ** it now.
  */

  sqlite3VdbeHalt(p);


  /* If the VDBE has be run even partially, then transfer the error code
  ** and error message from the VDBE into the main database structure.  But
  ** if the VDBE has just been set to run but has not actually executed any
  ** instructions yet, leave the main database error information unchanged.
  */
  if( p->pc>=0 ){
................................................................................
 
/*
** Clean up and delete a VDBE after execution.  Return an integer which is
** the result code.  Write any error message text into *pzErrMsg.
*/
int sqlite3VdbeFinalize(Vdbe *p){
  int rc = SQLITE_OK;

  if( p->magic==VDBE_MAGIC_RUN || p->magic==VDBE_MAGIC_HALT ){
    rc = sqlite3VdbeReset(p);
  }else if( p->magic!=VDBE_MAGIC_INIT ){
    return SQLITE_MISUSE;
  }
  sqlite3VdbeDelete(p);
  return rc;







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    sqlite3BtreeClose(pCx->pBt);
  }
#ifndef SQLITE_OMIT_VIRTUALTABLE
  if( pCx->pVtabCursor ){
    sqlite3_vtab_cursor *pVtabCursor = pCx->pVtabCursor;
    const sqlite3_module *pModule = pCx->pModule;
    p->inVtabMethod = 1;
    sqlite3SafetyOff(p->db);
    pModule->xClose(pVtabCursor);
    sqlite3SafetyOn(p->db);
    p->inVtabMethod = 0;
  }
#endif
  sqliteFree(pCx->pData);
  sqliteFree(pCx->aType);
  sqliteFree(pCx);
}
................................................................................
*/
static int vdbeCommit(sqlite3 *db){
  int i;
  int nTrans = 0;  /* Number of databases with an active write-transaction */
  int rc = SQLITE_OK;
  int needXcommit = 0;

  /* Before doing anything else, call the xSync() callback for any
  ** virtual module tables written in this transaction. This has to
  ** be done before determining whether a master journal file is 
  ** required, as an xSync() callback may add an attached database
  ** to the transaction.
  */
  rc = sqlite3VtabSync(db, rc);
  if( rc!=SQLITE_OK ){
    return rc;
  }

  /* This loop determines (a) if the commit hook should be invoked and
  ** (b) how many database files have open write transactions, not 
  ** including the temp database. (b) is important because if more than 
  ** one database file has an open write transaction, a master journal
  ** file is required for an atomic commit.
  */ 
  for(i=0; i<db->nDb; i++){ 
    Btree *pBt = db->aDb[i].pBt;
    if( pBt && sqlite3BtreeIsInTrans(pBt) ){
      needXcommit = 1;
      if( i!=1 ) nTrans++;
    }
  }
................................................................................
  if( 0==strlen(sqlite3BtreeGetFilename(db->aDb[0].pBt)) || nTrans<=1 ){
    for(i=0; rc==SQLITE_OK && i<db->nDb; i++){ 
      Btree *pBt = db->aDb[i].pBt;
      if( pBt ){
        rc = sqlite3BtreeSync(pBt, 0);
      }
    }


    /* Do the commit only if all databases successfully synced */
    if( rc==SQLITE_OK ){
      for(i=0; i<db->nDb; i++){
        Btree *pBt = db->aDb[i].pBt;
        if( pBt ){
          sqlite3BtreeCommit(pBt);
................................................................................
    **
    ** If the error occurs during the first call to sqlite3BtreeSync(),
    ** then there is a chance that the master journal file will be
    ** orphaned. But we cannot delete it, in case the master journal
    ** file name was written into the journal file before the failure
    ** occured.
    */
    for(i=0; rc==SQLITE_OK && i<db->nDb; i++){ 
      Btree *pBt = db->aDb[i].pBt;
      if( pBt && sqlite3BtreeIsInTrans(pBt) ){
        rc = sqlite3BtreeSync(pBt, zMaster);

      }
    }
    sqlite3OsClose(&master);
    if( rc!=SQLITE_OK ){
      sqliteFree(zMaster);
      return rc;
    }






    /* Delete the master journal file. This commits the transaction. After
    ** doing this the directory is synced again before any individual
    ** transaction files are deleted.
    */
    rc = sqlite3OsDelete(zMaster);
    assert( rc==SQLITE_OK );
................................................................................
    return SQLITE_MISUSE;
  }

  /* If the VM did not run to completion or if it encountered an
  ** error, then it might not have been halted properly.  So halt
  ** it now.
  */
  sqlite3SafetyOn(p->db);
  sqlite3VdbeHalt(p);
  sqlite3SafetyOff(p->db);

  /* If the VDBE has be run even partially, then transfer the error code
  ** and error message from the VDBE into the main database structure.  But
  ** if the VDBE has just been set to run but has not actually executed any
  ** instructions yet, leave the main database error information unchanged.
  */
  if( p->pc>=0 ){
................................................................................
 
/*
** Clean up and delete a VDBE after execution.  Return an integer which is
** the result code.  Write any error message text into *pzErrMsg.
*/
int sqlite3VdbeFinalize(Vdbe *p){
  int rc = SQLITE_OK;

  if( p->magic==VDBE_MAGIC_RUN || p->magic==VDBE_MAGIC_HALT ){
    rc = sqlite3VdbeReset(p);
  }else if( p->magic!=VDBE_MAGIC_INIT ){
    return SQLITE_MISUSE;
  }
  sqlite3VdbeDelete(p);
  return rc;

Changes to src/vtab.c.

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**    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 contains code used to help implement virtual tables.
**
** $Id: vtab.c,v 1.27 2006/07/08 18:09:15 drh Exp $
*/
#ifndef SQLITE_OMIT_VIRTUALTABLE
#include "sqliteInt.h"

/*
** External API function used to create a new virtual-table module.
*/
................................................................................
  }
  sqliteFree(db->aVTrans);
  db->nVTrans = 0;
  db->aVTrans = 0;
}

/*
** If argument rc is not SQLITE_OK, then return it and do nothing. 
** Otherwise, invoke the xSync method of all virtual tables in the 
** sqlite3.aVTrans array. Return the error code for the first error 
** that occurs, or SQLITE_OK if all xSync operations are successful.
*/
int sqlite3VtabSync(sqlite3 *db, int rc2){
  int i;
  int rc = SQLITE_OK;

  if( rc2!=SQLITE_OK ) return rc2;

  for(i=0; rc==SQLITE_OK && i<db->nVTrans && db->aVTrans[i]; i++){
    sqlite3_vtab *pVtab = db->aVTrans[i];
    int (*x)(sqlite3_vtab *);
    x = pVtab->pModule->xSync;
    if( x ){
      rc = x(pVtab);
    }




  }
  return rc;
}

/*
** Invoke the xRollback method of all virtual tables in the 
** sqlite3.aVTrans array. Then clear the array itself.
................................................................................
  Expr *pExpr     /* First argument to the function */
){
  Table *pTab;
  sqlite3_vtab *pVtab;
  sqlite3_module *pMod;
  void (*xFunc)(sqlite3_context*,int,sqlite3_value**);
  void *pArg;
  int rc;
  FuncDef *pNew;

  /* Check to see the left operand is a column in a virtual table */
  if( pExpr==0 ) return pDef;
  if( pExpr->op!=TK_COLUMN ) return pDef;
  pTab = pExpr->pTab;
  if( pTab==0 ) return pDef;
  if( !pTab->isVirtual ) return pDef;
  pVtab = pTab->pVtab;
  assert( pVtab!=0 );
  assert( pVtab->pModule!=0 );
  pMod = pVtab->pModule;
  if( pMod->xFindFunction==0 ) return pDef;
 
  /* Call the xFuncFunction method on the virtual table implementation
  ** to see if the implementation wants to overload this function */
  if( pMod->xFindFunction(pVtab, nArg, pDef->zName, &xFunc, &pArg)==0 ){
    return pDef;
  }







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**    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 contains code used to help implement virtual tables.
**
** $Id: vtab.c,v 1.28 2006/07/25 15:14:53 danielk1977 Exp $
*/
#ifndef SQLITE_OMIT_VIRTUALTABLE
#include "sqliteInt.h"

/*
** External API function used to create a new virtual-table module.
*/
................................................................................
  }
  sqliteFree(db->aVTrans);
  db->nVTrans = 0;
  db->aVTrans = 0;
}

/*
** If argument rc2 is not SQLITE_OK, then return it and do nothing. 
** Otherwise, invoke the xSync method of all virtual tables in the 
** sqlite3.aVTrans array. Return the error code for the first error 
** that occurs, or SQLITE_OK if all xSync operations are successful.
*/
int sqlite3VtabSync(sqlite3 *db, int rc2){
  int i;
  int rc = SQLITE_OK;
  int rcsafety;
  if( rc2!=SQLITE_OK ) return rc2;
  rc = sqlite3SafetyOff(db);
  for(i=0; rc==SQLITE_OK && i<db->nVTrans && db->aVTrans[i]; i++){
    sqlite3_vtab *pVtab = db->aVTrans[i];
    int (*x)(sqlite3_vtab *);
    x = pVtab->pModule->xSync;
    if( x ){
      rc = x(pVtab);
    }
  }
  rcsafety = sqlite3SafetyOn(db);
  if( rc==SQLITE_OK ){
    rc = rcsafety;
  }
  return rc;
}

/*
** Invoke the xRollback method of all virtual tables in the 
** sqlite3.aVTrans array. Then clear the array itself.
................................................................................
  Expr *pExpr     /* First argument to the function */
){
  Table *pTab;
  sqlite3_vtab *pVtab;
  sqlite3_module *pMod;
  void (*xFunc)(sqlite3_context*,int,sqlite3_value**);
  void *pArg;

  FuncDef *pNew;

  /* Check to see the left operand is a column in a virtual table */
  if( pExpr==0 ) return pDef;
  if( pExpr->op!=TK_COLUMN ) return pDef;
  pTab = pExpr->pTab;
  if( pTab==0 ) return pDef;
  if( !pTab->isVirtual ) return pDef;
  pVtab = pTab->pVtab;
  assert( pVtab!=0 );
  assert( pVtab->pModule!=0 );
  pMod = (sqlite3_module *)pVtab->pModule;
  if( pMod->xFindFunction==0 ) return pDef;
 
  /* Call the xFuncFunction method on the virtual table implementation
  ** to see if the implementation wants to overload this function */
  if( pMod->xFindFunction(pVtab, nArg, pDef->zName, &xFunc, &pArg)==0 ){
    return pDef;
  }

Added test/vtab7.test.







































































































































































































































































































































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# 2006 July 25
#
# 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. The focus
# of this test is reading and writing to the database from within a
# virtual table xSync() callback.
#
# $Id: vtab7.test,v 1.1 2006/07/25 15:14:53 danielk1977 Exp $

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

ifcapable !vtab {
  finish_test
  return
}

# Register the echo module. Code inside the echo module appends elements
# to the global tcl list variable ::echo_module whenever SQLite invokes
# certain module callbacks. This includes the xSync(), xCommit() and 
# xRollback() callbacks. For each of these callback, two elements are
# appended to ::echo_module, as follows:
#
#     Module method        Elements appended to ::echo_module
#     -------------------------------------------------------
#     xSync()              xSync echo($tablename)
#     xCommit()            xCommit echo($tablename)
#     xRollback()          xRollback echo($tablename)
#     -------------------------------------------------------
#
# In each case, $tablename is replaced by the name of the real table (not
# the echo table). By setting up a tcl trace on the ::echo_module variable,
# code in this file arranges for a Tcl script to be executed from within
# the echo module xSync() callback.
#
register_echo_module [sqlite3_connection_pointer db]
trace add variable ::echo_module write echo_module_trace

# This Tcl proc is invoked whenever the ::echo_module variable is written.
#
proc echo_module_trace {args} {
  # Filter out writes to ::echo_module that are not xSync, xCommit or 
  # xRollback callbacks.
  if {[llength $::echo_module] < 2} return
  set x [lindex $::echo_module end-1]
  if {$x ne "xSync" && $x ne "xCommit" && $x ne "xRollback"} return

  regexp {^echo.(.*).$} [lindex $::echo_module end] dummy tablename
  # puts "Ladies and gentlemen, an $x on $tablename!"

  if {[info exists ::callbacks($x,$tablename)]} {
    eval $::callbacks($x,$tablename)
  }
}

# The following tests, vtab7-1.*, test that the trace callback on 
# ::echo_module is providing the expected tcl callbacks.
do_test vtab7-1.1 {
  execsql {
    CREATE TABLE abc(a, b, c);
    CREATE VIRTUAL TABLE abc2 USING echo(abc);
  }
} {}

do_test vtab7-1.2 {
  set ::callbacks(xSync,abc) {incr ::counter}
  set ::counter 0
  execsql {
    INSERT INTO abc2 VALUES(1, 2, 3);
  }
  set ::counter
} {1}

# Write to an existing database table from within an xSync callback.
do_test vtab7-2.1 {
  set ::callbacks(xSync,abc) {
    execsql {INSERT INTO log VALUES('xSync');}
  }
  execsql {
    CREATE TABLE log(msg);
    INSERT INTO abc2 VALUES(4, 5, 6);
    SELECT * FROM log;
  }
} {xSync}
do_test vtab7-2.3 {
  execsql {
    INSERT INTO abc2 VALUES(4, 5, 6);
    SELECT * FROM log;
  }
} {xSync xSync}
do_test vtab7-2.4 {
  execsql {
    INSERT INTO abc2 VALUES(4, 5, 6);
    SELECT * FROM log;
  }
} {xSync xSync xSync}

# Create a database table from within xSync callback.
do_test vtab7-2.5 {
  set ::callbacks(xSync,abc) {
    execsql { CREATE TABLE newtab(d, e, f); }
  }
  execsql {
    INSERT INTO abc2 VALUES(1, 2, 3);
    SELECT name FROM sqlite_master ORDER BY name;
  }
} {abc abc2 log newtab}

# Drop a database table from within xSync callback.
do_test vtab7-2.6 {
  set ::callbacks(xSync,abc) {
    execsql { DROP TABLE newtab }
  }
  execsql {
    INSERT INTO abc2 VALUES(1, 2, 3);
    SELECT name FROM sqlite_master ORDER BY name;
  }
} {abc abc2 log}

# Write to an attached database from xSync().
do_test vtab7-3.1 {
  file delete -force test2.db
  file delete -force test2.db-journal
  execsql {
    ATTACH 'test2.db' AS db2;
    CREATE TABLE db2.stuff(description, shape, color);
  }
  set ::callbacks(xSync,abc) {
    execsql { INSERT INTO db2.stuff VALUES('abc', 'square', 'green'); }
  }
  execsql {
    INSERT INTO abc2 VALUES(1, 2, 3);
    SELECT * from stuff;
  }
} {abc square green}

# UPDATE: The next test passes, but leaks memory. So leave it out.
#
# The following tests test that writing to the database from within
# the xCommit callback causes a misuse error.
# do_test vtab7-4.1 {
#   unset -nocomplain ::callbacks(xSync,abc)
#   set ::callbacks(xCommit,abc) {
#     execsql { INSERT INTO log VALUES('hello') }
#   }
#   catchsql {
#     INSERT INTO abc2 VALUES(1, 2, 3);
#   }
# } {1 {library routine called out of sequence}}


trace remove variable ::echo_module write echo_module_trace
unset -nocomplain ::callbacks

finish_test