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

On Mon, Jan 8, 2018 at 6:11 PM, Dave Page <dpage@pgadmin.org> wrote:

On Mon, Jan 8, 2018 at 12:37 PM, Harshal Dhumal <harshal.dhumal@enterprisedb.com> wrote:

On Mon, Jan 8, 2018 at 5:15 PM, Dave Page <dpage@pgadmin.org> wrote:

HI

On Mon, Jan 8, 2018 at 11:41 AM, Harshal Dhumal <harshal.dhumal@enterprisedb.com> wrote:

On Mon, Jan 8, 2018 at 4:34 PM, Dave Page <dpage@pgadmin.org> wrote:

Hi

On Fri, Jan 5, 2018 at 7:50 AM, Harshal Dhumal <harshal.dhumal@enterprisedb.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).

If it's only the flask session we're resetting, not the database connection, we won't need to warn the user will we?

The problem here is that if flask session is reset then we lose the information about which connection was associate with which query tool/datagrid.

lets say If user have opened 3 query tools with same database therefore we'll have 3 separate connections

(each will have unique connection id). Now this information that which connection is associate with which query

tool is lost and also unique connection id. So there is no way that we can get that connection

from connection manager ( manager.connection(did=<some did>, conn_id=<unique connection id>) ).

So even database connection was not lost and only flask session was reset we need to create new connection. So I think we'll need to warn user.

Also If we save connection id to client side (in browser in JS) still we won't be able to get same connection

even though we know connection id in case of flask session reset. As for each logged in user (pgAdmin user)

but for same database server we create separate ServerManager (and therefore separate connection pool)

and flask session reset is same as if same user is logged in from another browser.

 

But... what if the database connection has also been lost in the meantime. Would we handle that?

We create new connection irrespective of old connection state if flask session was reset as explained above.