Re: SQL_ATTR_LOGIN_TIMEOUT behaviour

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Please note we are using
unixODBC version : 2.3.1
mysql odbc driver version : 5.3.4

On Tue, Mar 22, 2016 at 12:34 AM, Satheesh Subramanian <
[email protected]> wrote:

> Hi,
>  We ran into a problem where connection to mysql database is not timing
> out within specified SQL_ATTR_LOGIN_TIMEOUT value even when the database is
> not reachable.
>
>  We use UNixODBC driver manager and mysql odbc driver to connect to the
> mysql database. In order to make a connection to the database we do the
> following
> 1) Allocate Handle
> 2) Set SQL_ATTR_LOGIN_TIMEOUT to 5 seconds by calling SQLSetConnectAttr
> 3) Call SQLDriverConnect to make the connection.
>
> To debug the issue, I first enabled the trace logs and then started to
> look at the source code of unix odbc driver manager.
>
> By looking at the SQLDriverConnectW.c code, looks like the
> attribute SQL_ATTR_LOGIN_TIMEOUT is only saved to an internal variable as
> long as the connection state is C2.
>
> And SQLDriverConnectW.c is trying to load the driver as part pf
> "part_one_connection" and then trying to make SQLDriverConnectW call to the
> mysql odbc driver. So, looks like SQL_ATTR_LOGIN_TIMEOUT is being ignored
> and will never be passed on to mysql driver unless the connection state is
> something other than C2. Looking at the code connection state would be
> moved out of S2 state only after a successful connect request to the driver
>
> I believe this is the reason why login timeout is not getting honoured.
>
> So, to confirm that, I made a change in SQLDriverConnectW to call the
> mysql driver to set the login timeout(which was saved to internal variable
> in  an earlier call) after loading the driver but before making the actual
> connection. Afer this change, value set for SQL_ATTR_LOGIN_TIMEOUT started
> to work.
>
> I am not convinced driver manager would ignore the timeout and I suspect I
> am doing something wrong. I could not find the reason after going through
> the code multiple times over last few days.
>
> Can someone please point me to the right direction? How does the driver
> manager set the connection timeout to mysql driver? Any help is much
> appreciated!.
>
> Thanks in advance
>

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<div dir=3D"ltr">Please note we are using=C2=A0<div>unixODBC version : 2.3.=
1</div><div>mysql odbc driver version : 5.3.4</div></div><div class=3D"gmai=
l_extra"><br><div class=3D"gmail_quote">On Tue, Mar 22, 2016 at 12:34 AM, S=
atheesh Subramanian <span dir=3D"ltr">&lt;<a href=3D"mailto:satheesh101@gma=
il.com" target=3D"_blank">[email protected]</a>&gt;</span> wrote:<br><b=
lockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1px =
#ccc solid;padding-left:1ex"><div dir=3D"ltr">Hi,<div>=C2=A0We ran into a p=
roblem where connection to mysql=C2=A0database is not timing out within spe=
cified SQL_ATTR_LOGIN_TIMEOUT value even when the database is not reachable=
.</div><div><br></div><div>=C2=A0We use UNixODBC driver manager and mysql o=
dbc=C2=A0driver to connect to the mysql database. In order to make a connec=
tion to the database we do the following</div><div>1) Allocate Handle</div>=
<div>2) Set=C2=A0SQL_ATTR_LOGIN_TIMEOUT to 5 seconds by calling SQLSetConne=
ctAttr</div><div>3) Call SQLDriverConnect to make the connection.</div><div=
><br></div><div>To debug the issue, I first enabled the trace logs and then=
 started to look at the source code of unix odbc driver manager.</div><div>=
<br></div><div>By looking at the=C2=A0SQLDriverConnectW.c code, looks like =
the attribute=C2=A0SQL_ATTR_LOGIN_TIMEOUT=C2=A0is only saved to=C2=A0an int=
ernal variable as long as the connection state is C2.=C2=A0</div><div><br><=
/div><div>And SQLDriverConnectW.c is trying to load the driver as part pf &=
quot;part_one_connection&quot; and then trying to make=C2=A0SQLDriverConnec=
tW call to the mysql=C2=A0odbc driver. So, looks like SQL_ATTR_LOGIN_TIMEOU=
T is being ignored and will never be passed on to mysql driver unless the c=
onnection state is something other than C2. Looking at the code connection =
state would be moved out of S2 state only after a successful connect reques=
t to the driver</div><div><br></div><div>I believe this is the reason why l=
ogin timeout is not getting honoured.=C2=A0</div><div><br></div><div>So, to=
 confirm that, I made=C2=A0a change in SQLDriverConnectW to call the mysql =
driver to set the login timeout(which was saved to internal variable in =C2=
=A0an earlier call) after loading the driver but before making the actual c=
onnection. Afer this change, value set for SQL_ATTR_LOGIN_TIMEOUT=C2=A0star=
ted to work.</div><div><br></div><div>I am not convinced driver manager wou=
ld ignore the timeout and I suspect I am doing something wrong. I could not=
 find the reason after going through the code multiple times over last few =
days.</div><div><br></div><div>Can someone please point me to the right dir=
ection?=C2=A0How does the driver manager set the connection timeout to mysq=
l=C2=A0driver? Any help is much appreciated!.=C2=A0</div><div><br></div><di=
v>Thanks in advance=C2=A0</div></div>
</blockquote></div><br></div>

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