Marcus try something like this pseudo code:
local_Exec( exec_Str) {
*pStmt = NULL;
rc = prepare_v2 (exec_Str)
if (rc != SQLITE_OK) goto exec_err
rc = step ( );
if (rc != SQLITE_OK or SQLITE_DONE ) goto exec_err
rc = finalize( )
if rc != SQLITE_OK ) goto exec_err
return SQLITE_OK;
:exec_err
if (pStmt) sqlite_finalize;
return rc ;
}
==============================
code to lock:
do
{
rc = local_exec(db, "BEGIN EXCLUSIVE TRANSACTION;", -1, 0);
if( (rc == SQLITE_BUSY) || (rc == SQLITE_LOCKED) )
{
n++;
Sleep(SQLTM_TIME);
}
}while( (n < SQLTM_COUNT) && ((rc == SQLITE_BUSY)
|| (rc == SQLITE_LOCKED)));
==============================================================
--- On Wed, 12/3/08, Marcus Grimm <[EMAIL PROTECTED]> wrote:
> From: Marcus Grimm <[EMAIL PROTECTED]>
> Subject: [sqlite] Transaction Timeout and crash
> To: "General Discussion of SQLite Database" <sqlite-users@sqlite.org>
> Date: Wednesday, December 3, 2008, 4:15 AM
> Hi all,
>
> while doing a stress test on my embedded server application
> I'm noting a crash in sqlite3_finalize that I don't
> understand,
> and I'm wondering if I'm doing the right error
> handling.
>
> Background: In order to encapsulate writings to the tables
> I'm using
> BEGIN EXCLUSIVE TRANSACTION to block all other threads from
> reading and writing. Of course this requires a timeout and
> busy
> handling when trying to acquire the exclusive lock.
>
> So the code looks like:
>
> ---------------------------------------
> /** Obtain exclusive lock **/
> n = 0;
> do
> {
> rc = sqlite3_prepare_v2(db, "BEGIN EXCLUSIVE
> TRANSACTION;", -1, &stmt, 0);
>
> if( (rc == SQLITE_BUSY) || (rc == SQLITE_LOCKED) )
> {
> n++;
> Sleep(SQLTM_TIME);
> }
> }while( (n < SQLTM_COUNT) && ((rc ==
> SQLITE_BUSY) || (rc == SQLITE_LOCKED)));
>
> if( n == SQLTM_COUNT )
> return(TIMEOUT_ERROR); /** --> Timeout during
> prepare, never happends so far **/
>
> n = 0;
> do
> {
> rc = sqlite3_step(stmt);
> if( (rc == SQLITE_BUSY) || (rc == SQLITE_LOCKED) )
> {
> Sleep(SQLTM_TIME);
> n++;
> }
> }while( (n < SQLTM_COUNT) && ((rc ==
> SQLITE_BUSY) || (rc == SQLITE_LOCKED)));
>
> /** we are done **/
> sqlite3_finalize(stmt); /** <<- crash if timeout
> occurs **/
>
> if( n == SQLTM_COUNT )
> return(TIMEOUT_ERROR);
>
> ------------------------
>
> The problem is that it crashes in the sqlite3_finalize
> function in case the
> sqlite3_step doesn't actually did something and the
> timeout condition
> becames true.
> My feeling is that it occurs only when trying to get the
> exclusive transaction;
> A simple "SELECT *" that runs into a timeout
> doesn't crash when using sqlite3_finalize.
>
> Before starting to deeper debugging this, I would like to
> ask if there
> is an advice or known issue concerning the sqlite3_finalize
> when a
> step was not successful due to busy or locking state.
> It is not allowed to call this function in this case ?
> But then: How to free the statement, succesfully created by
> sqlite3_prepare_v2 ?
>
> I'm using sqlite 3.6.6.2, compiled using MSVS 2008, and
> of course threadsafe.
> I'm not using any timeout callback or timeout value
> settings since I'm handling
> this by my selve like in the code above.
>
> Thank you in advance.
>
> Marcus
>
>
>
> _______________________________________________
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> sqlite-users@sqlite.org
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