Re: [PATCH v3 6/6] [RFC] [INCOMPLETE] libxc/restore: Remus

[Yang Hongyang <yanghy@cn.fujitsu.com>]

I will try to implement the restore side as you proposed. The save side
was a single do{}while loop already. I use ctx.save.live to differentiate
the two phases.

On 05/12/2015 05:35 PM, Andrew Cooper wrote:
> Some basic infrastructure.
>
> CC: Yang Hongyang <yanghy@cn.fujitsu.com>
>
> ---
>
> I started attempting to explain this in text, but concluded that pseudocode
> would be easier.
>
> My design for the restore side handling was always based around a single "do {
> } while ( not end )" loop, and specifically not to split into two phases.
>
> If I have interpreted your restore patch correctly, then this should be
> plausible way to avoid splitting into two phases.  Please feel free to modify
> to suit.
>
> If at all possible, I would like to see about simiarly not splitting the save
> side into multiple phases, but that is proving far harder, and it is probably
> worth waiting for another iteration with current improvements integrated.
> ---
>   tools/libxc/xc_sr_common.h  |    6 ++++++
>   tools/libxc/xc_sr_restore.c |   34 ++++++++++++++++++++++++++++++++++
>   2 files changed, 40 insertions(+)
>
> diff --git a/tools/libxc/xc_sr_common.h b/tools/libxc/xc_sr_common.h
> index c0f90d4..116c89b 100644
> --- a/tools/libxc/xc_sr_common.h
> +++ b/tools/libxc/xc_sr_common.h
> @@ -219,6 +219,12 @@ struct xc_sr_context
>
>               /* Sender has invoked verify mode on the stream. */
>               bool verify;
> +
> +            /* Expecting a checkpointed stream? */
> +            bool checkpointed;
> +
> +            /* Currently buffering records between a checkpoints? */
> +            bool buffer_all_records;
>           } restore;
>       };
>
> diff --git a/tools/libxc/xc_sr_restore.c b/tools/libxc/xc_sr_restore.c
> index 53bd674..7a124bd 100644
> --- a/tools/libxc/xc_sr_restore.c
> +++ b/tools/libxc/xc_sr_restore.c
> @@ -468,11 +468,40 @@ static int handle_page_data(struct xc_sr_context *ctx, struct xc_sr_record *rec)
>       return rc;
>   }
>
> +static int handle_checkpoint(struct xc_sr_context *ctx)
> +{
> +    xc_interface *xch = ctx->xch;
> +    int rc = 0;
> +
> +    if ( !ctx->restore.checkpointed )
> +    {
> +        ERROR("Found checkpoint in non-checkpointed stream\n");
> +        return -1;
> +    }
> +
> +    if ( ctx->restore.buffer_all_records )
> +    {
> +        /* TODO drain buffer */
> +    }
> +    else
> +        ctx->restore.buffer_all_records = 1;
> +
> +    return rc;
> +}
> +
>   static int process_record(struct xc_sr_context *ctx, struct xc_sr_record *rec)
>   {
>       xc_interface *xch = ctx->xch;
>       int rc = 0;
>
> +    if ( ctx->restore.buffer_all_records &&
> +         rec->type != REC_TYPE_END &&
> +         rec->type != REC_TYPE_CHECKPOINT )
> +    {
> +        /* TODO: copy into buffer */
> +        return 0;
> +    }
> +
>       switch ( rec->type )
>       {
>       case REC_TYPE_END:
> @@ -487,6 +516,10 @@ static int process_record(struct xc_sr_context *ctx, struct xc_sr_record *rec)
>           ctx->restore.verify = true;
>           break;
>
> +    case REC_TYPE_CHECKPOINT:
> +        rc = handle_checkpoint(ctx);
> +        break;
> +
>       default:
>           rc = ctx->restore.ops.process_record(ctx, rec);
>           break;
> @@ -592,6 +625,7 @@ int xc_domain_restore2(xc_interface *xch, int io_fd, uint32_t dom,
>       ctx.restore.console_domid = console_domid;
>       ctx.restore.xenstore_evtchn = store_evtchn;
>       ctx.restore.xenstore_domid = store_domid;
> +    ctx.restore.checkpointed = checkpointed_stream;
>       ctx.restore.callbacks = callbacks;
>
>       IPRINTF("In experimental %s", __func__);
>

-- 
Thanks,
Yang.