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Thu, 4 Nov 2021 17:50:49 -0400 (EDT) Date: Thu, 4 Nov 2021 16:50:47 -0500 From: Patrick Williams To: "Bills, Jason M" Subject: Re: [phosphor-logging] About the "Stop emitting Entry propChanged before ifacesAdded" change reason Message-ID: References: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="mCx/DXC54233AytT" Content-Disposition: inline In-Reply-To: X-BeenThere: openbmc@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Development list for OpenBMC List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: openbmc@lists.ozlabs.org Errors-To: openbmc-bounces+openbmc=archiver.kernel.org@lists.ozlabs.org Sender: "openbmc" --mCx/DXC54233AytT Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Nov 04, 2021 at 03:36:51PM -0600, Bills, Jason M wrote: > I'm not sure if it's what we're talking about here with the behavioral=20 > change, but in sdbusplus when a new interface is initialized, by default= =20 > it will also send a PropertiesChanged signal for newly added properties. >=20 > There is a 'skipPropertyChangedSignal' parameter that can be set to=20 > 'true' to skip the ProperitesChanged and only send InterfacesAdded: > bool initialize(const bool skipPropertyChangedSignal =3D false) >=20 > https://github.com/openbmc/sdbusplus/blob/master/include/sdbusplus/asio/o= bject_server.hpp#L740 >=20 > I think there are some components that depend on the default behavior=20 > and only watch for PropertiesChanged rather than InterfacesAdded. This behavior is only in the ASIO object_server implementation, which means= it only covers a subset of daemons. I really don't know why this was ever add= ed. There is nothing in the dbus spec to suggest that you should emit a flood of PropertyChanged signals when starting up. Maybe this is part of the cause = of some of the boot up performance issues. We should probably change the defaults to `true` on this and see what break= s. The commit[1] where this 'skipPropertyChangedSignal' argument was added gave this as the rationale: InterfacesAdded signal itself will send out all propety details and it's values during start-up of a D-Bus daemon service. Sending properties changed signal confuses the signal handler as it can't differentiate between service restart or real property change event. The original code that added the `initialize` method and the send-signals-for-all-properties behavior was the very first commit[2] James= made so it doesn't give us a whole lot of history or rationale. 1. https://github.com/openbmc/sdbusplus/commit/1ecde800380fbe9c9ce7c8a908aa= 55aeddb92c1d 2. https://github.com/openbmc/sdbusplus/commit/fce038ad5ac9f458b03d55b44125= 3a9c05dadc3e --=20 Patrick Williams --mCx/DXC54233AytT Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAABCAAdFiEEBGD9ii4LE9cNbqJBqwNHzC0AwRkFAmGEVbUACgkQqwNHzC0A wRkPhRAAi8qvbnh0k/ZOg5cYolS45sI79iDtHQjyGLsW1FqolkS5u0bTbqD3ylpm 8cow5myFDIC4cmRklHKkQYvAk0iFB9RZxT0txj2ve0kVa6kEPHq7cXdBh1kSrqVO hlGGbXpFNTeX5AI2DQ1PpMWTRl1ziLAK95U6H0b9i7TzLeublw6LouhtMZruszL4 lXpJ3yH8wMt9EMjOQnajFP0uXSbm0QZD/kcEJ1DBkU6Vn4sMS2mNT3e8Y3Xa9Zt5 op94MNkfGErF3zZFwqm3rTN68HVR7slI+T+0QV5zsmq0G6+rlt0NWMsRAwLEU0ra 2lC8WxadOPRuJUKlDFWOqFY7Qh6eRcJY3im89GSO70QKTudXv4qRbREoV5pu7UAE 4mTPuPEiq9YOswxqwaMgOary8Zxugg4hgOU95FWXP/3RZsZ8iPx0vCwxwz0jcKHt 9s/8YgW2hSJPyyD+5M7C1pjWo4NiIL706UMKlGNdiG7m2zeVEnETNoKH/BHvO8EY 2HIHyhq4ZcvuPz1xlyyVtZ0pq2nKjuGqvFhxKgx0NXGE6yMgL5L3ymlnRdmEaGQ9 6QL5bEtg7RfxoihtxaTWk3wFwbz2k3DuXNU7C2Tk/jO+olceuQ0A/c0QSDGFw/q1 /7z0HC1YLBEsI2xZvf6se4D0wAKUujvLCkOEmvZXdmGS1tRODeo= =+y9r -----END PGP SIGNATURE----- --mCx/DXC54233AytT--