SQLite

    pDestructor->nRef--;
    if( pDestructor->nRef==0 ){
      pDestructor->xDestroy(pDestructor->pUserData);
      sqlite3DbFree(db, pDestructor);
    }
  }
}

/*
** Disconnect all sqlite3_vtab objects that belong to database connection
** db. This is called when db is being closed.
*/
static void disconnectAllVtab(sqlite3 *db){
#ifndef SQLITE_OMIT_VIRTUALTABLE
  int i;
  sqlite3BtreeEnterAll(db);
  for(i=0; i<db->nDb; i++){
    Schema *pSchema = db->aDb[i].pSchema;
    if( db->aDb[i].pSchema ){
      HashElem *p;
      for(p=sqliteHashFirst(&pSchema->tblHash); p; p=sqliteHashNext(p)){
        Table *pTab = (Table *)sqliteHashData(p);
        if( IsVirtual(pTab) ) sqlite3VtabDisconnect(db, pTab);
      }
    }
  }
  sqlite3BtreeLeaveAll(db);
#else
  UNUSED_PARAMETER(db);
#endif
}

/*
** Close an existing SQLite database
*/
int sqlite3_close(sqlite3 *db){
  HashElem *i;                    /* Hash table iterator */
  int j;

  if( !db ){
    return SQLITE_OK;
  }
  if( !sqlite3SafetyCheckSickOrOk(db) ){
    return SQLITE_MISUSE_BKPT;
  }
  sqlite3_mutex_enter(db->mutex);

  /* Force xDestroy calls on all virtual tables */
  sqlite3ResetInternalSchema(db, -1);
  /* Force xDisconnect calls on all virtual tables */
  disconnectAllVtab(db);

  /* If a transaction is open, the ResetInternalSchema() call above
  /* If a transaction is open, the disconnectAllVtab() call above
  ** will not have called the xDisconnect() method on any virtual
  ** tables in the db->aVTrans[] array. The following sqlite3VtabRollback()
  ** call will do so. We need to do this before the check for active
  ** SQL statements below, as the v-table implementation may be storing
  ** some prepared statements internally.
  */
  sqlite3VtabRollback(db);

      sqlite3BtreeClose(pDb->pBt);
      pDb->pBt = 0;
      if( j!=1 ){
        pDb->pSchema = 0;
      }
    }
  }

  /* This call frees the schema associated with the temp database only (if
  ** any). It also frees the db->aDb array, if required.  */
  sqlite3ResetInternalSchema(db, -1);
  assert( db->nDb<=2 );
  assert( db->aDb==db->aDbStatic );

  /* Tell the code in notify.c that the connection no longer holds any
  ** locks and does not require any further unlock-notify callbacks.
  */
  sqlite3ConnectionClosed(db);

  assert( db->nDb<=2 );
  assert( db->aDb==db->aDbStatic );
  for(j=0; j<ArraySize(db->aFunc.a); j++){
    FuncDef *pNext, *pHash, *p;
    for(p=db->aFunc.a[j]; p; p=pHash){
      pHash = p->pHash;
      while( p ){
        functionDestroy(db, p);
        pNext = p->pNext;

#  define sqlite3VtabLock(X) 
#  define sqlite3VtabUnlock(X)
#  define sqlite3VtabUnlockList(X)
#  define sqlite3VtabSavepoint(X, Y, Z) SQLITE_OK
#  define sqlite3GetVTable(X,Y)  ((VTable*)0)
#else
   void sqlite3VtabClear(sqlite3 *db, Table*);
   void sqlite3VtabDisconnect(sqlite3 *db, Table *p);
   int sqlite3VtabSync(sqlite3 *db, char **);
   int sqlite3VtabRollback(sqlite3 *db);
   int sqlite3VtabCommit(sqlite3 *db);
   void sqlite3VtabLock(VTable *);
   void sqlite3VtabUnlock(VTable *);
   void sqlite3VtabUnlockList(sqlite3*);
   int sqlite3VtabSavepoint(sqlite3 *, int, int);

    }
    pVTable = pNext;
  }

  assert( !db || pRet );
  return pRet;
}

/*
** Table *p is a virtual table. This function removes the VTable object
** for table *p associated with database connection db from the linked
** list in p->pVTab. It also decrements the VTable ref count. This is
** used when closing database connection db to free all of its VTable
** objects without disturbing the rest of the Schema object (which may
** be being used by other shared-cache connections).
*/
void sqlite3VtabDisconnect(sqlite3 *db, Table *p){
  VTable **ppVTab;

  assert( IsVirtual(p) );
  assert( sqlite3BtreeHoldsAllMutexes(db) );
  assert( sqlite3_mutex_held(db->mutex) );

  for(ppVTab=&p->pVTable; *ppVTab; ppVTab=&(*ppVTab)->pNext){
    if( (*ppVTab)->db==db  ){
      VTable *pVTab = *ppVTab;
      *ppVTab = pVTab->pNext;
      sqlite3VtabUnlock(pVTab);
      break;
    }
  }
}


/*
** Disconnect all the virtual table objects in the sqlite3.pDisconnect list.
**
** This function may only be called when the mutexes associated with all
** shared b-tree databases opened using connection db are held by the 

  set STMT [sqlite3_prepare $DB $sql -1 TAIL]
  expr 0
} {0}
do_test capi3-6.1 {
  db cache flush
  sqlite3_close $DB
} {SQLITE_BUSY}

# 6.2 and 6.3 used to return SQLITE_ERROR and SQLITE_SCHEMA, respectively.
# But since attempting to close a connection no longer resets the internal
# schema and expires all statements, this is no longer the case.
do_test capi3-6.2 {
  sqlite3_step $STMT
} {SQLITE_ERROR}
} {SQLITE_ROW}
#check_data $STMT capi3-6.3 {INTEGER} {1} {1.0} {1}
do_test capi3-6.3 {
  sqlite3_finalize $STMT
} {SQLITE_SCHEMA}
} {SQLITE_OK}

do_test capi3-6.4-misuse {
  db cache flush
  sqlite3_close $DB
} {SQLITE_OK}
db close

# This procedure sets the value of the file-format in file 'test.db'

# 2012 May 15
#
# 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.
#
#***********************************************************************
#
# The tests in this file are intended to show that closing one database
# connection to a shared-cache while there exist other connections (a)
# does not cause the schema to be reloaded and (b) does not cause any
# other problems.
#

set testdir [file dirname $argv0]
source $testdir/tester.tcl
ifcapable !shared_cache { finish_test ; return }
set testprefix shared8

db close
set ::enable_shared_cache [sqlite3_enable_shared_cache 1]
do_test 0.0 { sqlite3_enable_shared_cache } {1}

proc roman {n} {
  array set R {1 i 2 ii 3 iii 4 iv 5 v 6 vi 7 vii 8 viii 9 ix 10 x}
  set R($n)
}

#-------------------------------------------------------------------------
# The following tests work as follows:
#
#    1.0: Open connection [db1] and populate the database.
#
#    1.1: Using "PRAGMA writable_schema", destroy the database schema on
#         disk. The schema is still in memory, so it is possible to keep
#         using it, but any attempt to reload it from disk will fail.
#
#    1.3-4: Open connection db2. Check that it can see the db schema. Then
#           close db1 and check that db2 still works. This shows that closing
#           db1 did not reset the in-memory schema.
#
#    1.5-7: Similar to 1.3-4.
#
#    1.8: Close all database connections (deleting the in-memory schema).
#         Then open a new connection and check that it cannot read the db.
#         
do_test 1.0 {
  sqlite3 db1 test.db
  db1 func roman roman
  execsql {
    CREATE TABLE t1(a, b);
    INSERT INTO t1 VALUES(1, 1);
    INSERT INTO t1 VALUES(2, 2);
    INSERT INTO t1 VALUES(3, 3);
    INSERT INTO t1 VALUES(4, 4);
    CREATE VIEW v1 AS SELECT a, roman(b) FROM t1;
    SELECT * FROM v1;
  } db1
} {1 i 2 ii 3 iii 4 iv}

do_test 1.1 {
  execsql { 
    PRAGMA writable_schema = 1;
    DELETE FROM sqlite_master WHERE 1;
    PRAGMA writable_schema = 0;
    SELECT * FROM sqlite_master;
  } db1
} {}

do_test 1.2 {
  execsql { SELECT * FROM v1 } db1
} {1 i 2 ii 3 iii 4 iv}

do_test 1.3 {
  sqlite3 db2 test.db
  db2 func roman roman
  execsql { SELECT * FROM v1 } db2
} {1 i 2 ii 3 iii 4 iv}

do_test 1.4 {
  db1 close
  execsql { SELECT * FROM v1 } db2
} {1 i 2 ii 3 iii 4 iv}

do_test 1.5 {
  sqlite3 db3 test.db
  db3 func roman roman
  execsql { SELECT * FROM v1 } db3
} {1 i 2 ii 3 iii 4 iv}

do_test 1.6 {
  execsql { SELECT * FROM v1 } db2
} {1 i 2 ii 3 iii 4 iv}

do_test 1.7 {
  db2 close
  execsql { SELECT * FROM v1 } db3
} {1 i 2 ii 3 iii 4 iv}

do_test 1.8 {
  db3 close
  sqlite3 db4 test.db
  catchsql { SELECT * FROM v1 } db4
} {1 {no such table: v1}}


foreach db {db1 db2 db3 db4} { catch { $db close } }
sqlite3_enable_shared_cache $::enable_shared_cache
finish_test