** 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 1.669 2009/07/09 05:07:38 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"

................................................................................

#ifndef SQLITE_OMIT_SHARED_CACHE
/*
** Add a lock on the table with root-page iTable to the shared-btree used
** by Btree handle p. Parameter eLock must be either READ_LOCK or 
** WRITE_LOCK.
**









** SQLITE_OK is returned if the lock is added successfully. SQLITE_BUSY and
** SQLITE_NOMEM may also be returned.

*/
static int setSharedCacheTableLock(Btree *p, Pgno iTable, u8 eLock){
  BtShared *pBt = p->pBt;
  BtLock *pLock = 0;
  BtLock *pIter;

  assert( sqlite3BtreeHoldsMutex(p) );
................................................................................

  /* A connection with the read-uncommitted flag set will never try to
  ** obtain a read-lock using this function. The only read-lock obtained
  ** by a connection in read-uncommitted mode is on the sqlite_master 
  ** table, and that lock is obtained in BtreeBeginTrans().  */
  assert( 0==(p->db->flags&SQLITE_ReadUncommitted) || eLock==WRITE_LOCK );

  /* This is a no-op if the shared-cache is not enabled */

  if( !p->sharable ){
    return SQLITE_OK;
  }

  assert( SQLITE_OK==querySharedCacheTableLock(p, iTable, eLock) );

  /* First search the list for an existing lock on this table. */
  for(pIter=pBt->pLock; pIter; pIter=pIter->pNext){
    if( pIter->iTable==iTable && pIter->pBtree==p ){
      pLock = pIter;
      break;

** 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 1.670 2009/07/09 08:27:14 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"

................................................................................

#ifndef SQLITE_OMIT_SHARED_CACHE
/*
** Add a lock on the table with root-page iTable to the shared-btree used
** by Btree handle p. Parameter eLock must be either READ_LOCK or 
** WRITE_LOCK.
**
** This function assumes the following:
**
**   (a) The specified b-tree connection handle is connected to a sharable
**       b-tree database (one with the BtShared.sharable) flag set, and
**
**   (b) No other b-tree connection handle holds a lock that conflicts
**       with the requested lock (i.e. querySharedCacheTableLock() has
**       already been called and returned SQLITE_OK).
**
** SQLITE_OK is returned if the lock is added successfully. SQLITE_NOMEM 

** is returned if a malloc attempt fails.
*/
static int setSharedCacheTableLock(Btree *p, Pgno iTable, u8 eLock){
  BtShared *pBt = p->pBt;
  BtLock *pLock = 0;
  BtLock *pIter;

  assert( sqlite3BtreeHoldsMutex(p) );
................................................................................

  /* A connection with the read-uncommitted flag set will never try to
  ** obtain a read-lock using this function. The only read-lock obtained
  ** by a connection in read-uncommitted mode is on the sqlite_master 
  ** table, and that lock is obtained in BtreeBeginTrans().  */
  assert( 0==(p->db->flags&SQLITE_ReadUncommitted) || eLock==WRITE_LOCK );

  /* This function should only be called on a sharable b-tree after it 
  ** has been determined that no other b-tree holds a conflicting lock.  */
  assert( p->sharable );



  assert( SQLITE_OK==querySharedCacheTableLock(p, iTable, eLock) );

  /* First search the list for an existing lock on this table. */
  for(pIter=pBt->pLock; pIter; pIter=pIter->pNext){
    if( pIter->iTable==iTable && pIter->pBtree==p ){
      pLock = pIter;
      break;