[Libvir] [PATCH] Remote 4/8: Server-side call dispatch

As with the client side, the server side dispatch consists mainly of a long and rather tedious list of calls which deal with deserialising the args, calling the appropriate function, and serialising the result back to the client. In remote.c we enter from the QEMU daemon at remoteDispatchClientRequest with a full request which has been read in but not decoded yet. This function deserialises the request header (remote_message_header defined in remote_protocol.x) and dispatches the request to the correct remoteDispatch* function. This function is arranged so that the remoteDispatch* functions need to do as little as possible -- in particular error handling is handled transparently as far as they are concerned. The function then serialises the reply (or error) and returns it up to the QEMU daemon to be sent out. You may notice in remoteDispatchClientRequest that parts are generated automatically, eg. the dispatch switch statement: switch (req.proc) { #include "remote_dispatch_proc_switch.h" default: remoteDispatchError (client, &req, "unknown procedure: %d", req.proc); xdr_destroy (&xdr); return; } This is to remove the need to write this tedious and error-prone code by hand. Each remoteDispatch* function can be as small as possible and deals only with deserialising the remote_foo_args (parameters), calling the appropriate libvirt function, then serialising the remote_foo_ret (return value). Error cases are handled entirely by remoteDispatchClientRequest in order to remove duplicated code. The remoteDispatch* functions may return one of the following values: 0 = OK -1 = The libvirt function returned an error (remoteDispatchClientRequest will pick up and serialise the error) -2 = There was an error in the dispatch function itself, something to do with the mechanics of RPC. In this case the function has already set up an error buffer using remoteDispatchError directly. The four other attached files are the script used to generate the automatically generated code for remoteDispatchClientRequest, and the 3 files of generated code that it creates, which I suggest we put in EXTRA_DIST. Rich. -- Emerging Technologies, Red Hat http://et.redhat.com/~rjones/ 64 Baker Street, London, W1U 7DF Mobile: +44 7866 314 421 Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SL4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 Directors: Michael Cunningham (USA), Charlie Peters (USA) and David Owens (Ireland)