[Libvir] PATCH 16/20: add a generic logging API

[Richard W.M. Jones]

Daniel P. Berrange wrote:
> This patch adds a generic API for drivers to log warning / debug / info 
> messages. The existing error APIs are not suitable for this purpose since
> each time you set an error, it clears the previous one. This adds a public
> API virSetLogFunc allowing applications to register a callback to receive
> log messages. If none is registered, they are sent to the big void. It
> adapts the QEMU driver to use this logging API instead of qemudLog and
> qemudDebug(). It makes the qemud/qemud.c file register a logging callback
> to receive the messages & send them onto syslog/stderr as needed.
> 
> There are other drivers (in particular src/xm_internal.c) where this
> logging API will be useful too. I've not attempted to make them use it
> yet though.

So to get this straight - this not intended to replace error messages, 
just informational messages?

You should allow more than one handler to be registered, and you should 
allow handlers to unregister themselves (give them a token which they 
can pass back to an unregister function).

Should the default be to print to stderr?  syslog? ...?

Rich.

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