[Qemu-devel] Re: [RFC][PATCH v5 03/21] virtagent: common code for managing client/server rpc jobs

[Jes Sorensen <Jes.Sorensen@redhat.com>]

On 12/03/10 19:03, Michael Roth wrote:
> This implements a simple state machine to manage client/server rpc
> jobs being multiplexed over a single channel.
> 
> A client job consists of sending an rpc request, reading an
> rpc response, then making the appropriate callbacks. We allow one
> client job to be processed at a time, which will make the following
> state transitions:
> 
> VA_CLIENT_IDLE -> VA_CLIENT_SEND (job queued, send channel open)
> VA_CLIENT_SEND -> VA_CLIENT_WAIT (request sent, awaiting response)
> VA_CLIENT_WAIT -> VA_CLIENT_IDLE (response recieved, callbacks made)
> 
> A server job consists of recieving an rpc request, generating a
> response, then sending the response. We expect to receive one server
> request at a time due to the 1 at a time restriction for client jobs.
> Server jobs make the following transitions:
> 
> VA_SERVER_IDLE -> VA_SERVER_WAIT (recieved/executed request, send
> channel busy, response deferred)
> VA_SERVER_IDLE -> VA_SERVER_SEND (recieved/executed request, send
> channel open, sending response)
> VA_SERVER_WAIT -> VA_SERVER_SEND (send channel now open, sending
> response)
> VA_SERVER_SEND -> VA_SERVER_IDLE (response sent)
> 
> Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>

As mentioned before, I really don't understand why this is part of QEMU,
the guest agent really should be able to run totally outside of QEMU.

> +
> +#define DEBUG_VA
> +
> +#ifdef DEBUG_VA
> +#define TRACE(msg, ...) do { \
> +    fprintf(stderr, "%s:%s():L%d: " msg "\n", \
> +            __FILE__, __FUNCTION__, __LINE__, ## __VA_ARGS__); \
> +} while(0)
> +#else
> +#define TRACE(msg, ...) \
> +    do { } while (0)
> +#endif
> +
> +#define LOG(msg, ...) do { \
> +    fprintf(stderr, "%s:%s(): " msg "\n", \
> +            __FILE__, __FUNCTION__, ## __VA_ARGS__); \
> +} while(0)

This must be like the 217th copy of these functions, could you please
use some of the code that is already in the tree, and make it generic if
needed.

> +
> +#define VERSION "1.0"
> +#define EOL "\r\n"
> +
> +#define VA_HDR_LEN_MAX 4096 /* http header limit */
> +#define VA_CONTENT_LEN_MAX 2*1024*1024 /* rpc/http send limit */
> +#define VA_CLIENT_JOBS_MAX 5 /* max client rpcs we can queue */
> +#define VA_SERVER_JOBS_MAX 1 /* max server rpcs we can queue */

As mentioned last time, please make this stuff configurable and not hard
coded.

Cheers,
Jes