[sr-dev] [patch] invalid type (3) or nul (0) version columns for trusted (kamailio 3.1 with db_postgres latest from git)

[Robert Verspuy]

  I found the cause of my issue.

In the source lib/srdb1/* some kind of pooling is used.
When kamailio needs a database connection, the cmp_db_id function checks 
to see if there is already a database connection with the exact same 
params (username, database, server etc..).

According to the PQ library every proces / thread should have it's own 
database connection.
The db_postgres is setup to use asynchronous I/O with the PQ library.
So when two threads are using the same database connection it is 
possible that,
the resultset from a query of thread A is returned to thread B.
The cmp_db_id function in lib/srdb1/db_id.c does _not_ check the PID.

I've created a small patch to fix the problems mentioned above.

The changes are made in lib/srdb1/* files
So if you apply them, it will be active for _every_ database module.
Maybe it's not needed for the mysql database,
but I *assume* it will not break when used on a mysql database. (not tested)
Maybe you will get a bit more database connections, but that depends on 
which modules you're using.

What did I do:

    * Added pid to the db_id struct.
    * During initialization the pid is saved into the db_id struct.
    * In cmp_db_id the pid is also checked when searching for a database
      connection to be reused.

With kind Regards,
Robert Verspuy

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