Squashed commit of the following:

commit ce33557832515d541b9d2b505c53225885fd61c7
Author: Sergey Yakubov <sergey.yakubov@desy.de>
Date:   Wed Feb 19 13:41:28 2020 +0100

    update producer side

commit 0bed6f6ecf3d83ca2f958b6574ad63664f1bfc8c
Author: Sergey Yakubov <sergey.yakubov@desy.de>
Date:   Wed Feb 19 11:55:56 2020 +0100

    receiver sends warnings for duplicated requests

commit fedf16d3eec9f9a7a1582c8b9f1b8028815a31eb
Author: Sergey Yakubov <sergey.yakubov@desy.de>
Date:   Wed Feb 19 11:29:18 2020 +0100

    db handler deals with duplicate record

commit d9d242e72b522b15a894c23732f261a584574cb5
Author: Sergey Yakubov <sergey.yakubov@desy.de>
Date:   Wed Feb 19 10:31:11 2020 +0100

    fix memory error in tests

commit a6c382c2a13dd31520a4bf4561bab1c5ca7e9adf
Author: Sergey Yakubov <sergey.yakubov@desy.de>
Date:   Tue Feb 18 17:40:48 2020 +0100

    fix mongodb bug

commit 79eaa0107c4550b36c9d3d82259a05c39508b7cc
Author: Sergey Yakubov <sergey.yakubov@desy.de>
Date:   Tue Feb 18 16:47:01 2020 +0100

    refactor write/receive file handlers, check record in db

commit 20b4dc0533128ec192134d0ffc2899351d933e5b
Author: Sergey Yakubov <sergey.yakubov@desy.de>
Date:   Mon Feb 17 16:39:49 2020 +0100

    add overwrite flag to IO routines

commit cf23ea3ca5387ed7c7d52726806bae0e3f6ff1d6
Author: Sergey Yakubov <sergey.yakubov@desy.de>
Date:   Mon Feb 17 14:50:14 2020 +0100

    introduce timeout for producer

commit 943cf3c837f151708e538813cf8480bf82e50a53
Author: Sergey Yakubov <sergey.yakubov@desy.de>
Date:   Fri Feb 14 13:47:39 2020 +0100

    implement GetById for c mongo client

commit 0153e0d1e662584b18c3f55a64093dd343176ac2
Author: Sergey Yakubov <sergey.yakubov@desy.de>
Date:   Fri Feb 14 12:08:03 2020 +0100

    refactor

commit 631ca34a8be489ba3261a697d5ca889a666d78f2
Author: Sergey Yakubov <sergey.yakubov@desy.de>
Date:   Thu Feb 13 18:16:42 2020 +0100

    receiver request handler to check db