Re: RM2815: Relogin to pgAdmin from sqleditor/datadrid if session exprires

On Mon, Jan 8, 2018 at 5:15 PM, Dave Page <dpage(at)pgadmin(dot)org> wrote:

> HI
>
> On Mon, Jan 8, 2018 at 11:41 AM, Harshal Dhumal <
> harshal(dot)dhumal(at)enterprisedb(dot)com> wrote:
>
>> On Mon, Jan 8, 2018 at 4:34 PM, Dave Page <dpage(at)pgadmin(dot)org> wrote:
>>
>>> Hi
>>>
>>> On Fri, Jan 5, 2018 at 7:50 AM, Harshal Dhumal <
>>> harshal(dot)dhumal(at)enterprisedb(dot)com> wrote:
>>>
>>>> Further details:
>>>>
>>>> 1. If session is expired and user performs any action from sqleditor
>>>> that makes ajax call
>>>> then in ajax error call back user can check and handle login related
>>>> error using code snippet.
>>>>
>>>> if (pgAdmin.Browser.UserManagement.is_pga_login_required(xhr)) {
>>>> return pgAdmin.Browser.UserManagement.pga_login();
>>>> }
>>>>
>>>> Where is xhr is standard xhr or jqxhr object.
>>>>
>>>> 2. Similarly for connection lost (only maintenance db connection as we
>>>> can recover or reconnect other
>>>> connections if maintenance db connection is alive). It will attempt to
>>>> create/reconnect connection without
>>>> asking password (to handle passwordless connection, or saveed password
>>>> or password from pgpass file)
>>>> If connection to database still fails then it'll prompt for password.
>>>>
>>>> Code snippet:
>>>> SqlEditorController.handle_connection_lost();
>>>> once connection lost is detected one can call handle_connection_lost()
>>>> to reconnect.
>>>>
>>>> 3. We maintain some additional data in session to maintain affinity
>>>> between
>>>> each sqleditor/datagrid instance to backend database connection.
>>>> However if session expires and user
>>>> re-loggins then we need to first restore affinity between sqleditor to
>>>> backend database before we can start
>>>> using query tool.
>>>>
>>>> Code snippet:
>>>>
>>>> if(is_new_transaction_required(xhr)) {
>>>> SqlEditorController.init_transaction();
>>>> }
>>>>
>>>> (note: I haven't looked at the code yet)
>>>
>>> How does this handle re-establishment of the connection mid-transaction,
>>> or, if the user has modified any session variables?
>>>
>>> ServeManager and Connection Manager are written in a such way that if
>> any connection is lost except maintenance db connection
>> then we can re-connect or create new connection without prompting for
>> database password and if maintenance db connection is lost
>> then It prompts for password.
>>
>
> Right.
>
>
>>
>> Regarding session variables as long as flask session is not expired we
>> uses same session variables. But in case of user logout (due to
>> flask session expire) we create new transaction id and sets new session
>> variables for that particular Sql editor /datagrid instance.
>>
>
> I mean DB session variables (and related things). For example, if the user
> executed queries such as the following, then they absolutely need to know
> if the session got reset:
>

Ok.
Then in this case can we notify user about the same. That we're unable to
restore old database connection and created new one and therefore
any DB session variables were set/modified (like SET CLIENT_ENCODING...,
SET DATESTYLE...) are lost (or similar message).

> CREATE TEMPORARY TABLE ....
> SET ROLE ...
> SET [various other options]
>
> If the user has done any of those things (or similar things that I haven't
> thought of), then we cannot just blindly reset the database connection.
>

We only create new connection if flask session was expired as we lost
transaction id associated with Sql editor/datagrid and therefore unique
connection id
given to connection which was associated to Sql editor/datagrid. In this
case we can notify about same (as stated above).

--
> Dave Page
> Blog: http://pgsnake.blogspot.com
> Twitter: @pgsnake
>
> EnterpriseDB UK: http://www.enterprisedb.com
> The Enterprise PostgreSQL Company
>