On Thu, Aug 04, 2016 at 02:58:38PM -0700, Joe Stringer wrote:
> To assist debugging pipelines when resubmit resource checks fail, print
> the base_flow from the translation context. This base flow can then be
> used from ofproto/trace to figure out which parts of the pipeline lead
> to this translation error.
>
> As far as I can see, the "## __VA_ARGS__" trick is a GCC thing rather
> than part of the C standard, but it successfully compiles on GCC 6.1.1,
> Clang 3.8.1, and the compiler that Appveyor CI uses so it seems like it
> is widely supported.
>
> Signed-off-by: Joe Stringer <j...@ovn.org>
It's a little extra-tricky. Any change you'd instead be willing to use
ds_put_format() on the local 'ds' instead? Something like this:
struct ds ds = DS_EMPTY_INITIALIZER;
flow_format(&ds, &ctx->base_flow);
ds_put_cstr(&ds, ": ");
ds_put_format(&ds, __VA_LIST__);
It might be slightly slower but this is not a fast path.
> ofproto/ofproto-dpif-xlate.c | 21 ++++++++++++++-------
> 1 file changed, 14 insertions(+), 7 deletions(-)
>
> diff --git a/ofproto/ofproto-dpif-xlate.c b/ofproto/ofproto-dpif-xlate.c
> index 393854e4bfc7..73ab3e558f9d 100644
> --- a/ofproto/ofproto-dpif-xlate.c
> +++ b/ofproto/ofproto-dpif-xlate.c
> @@ -627,13 +627,20 @@ xlate_report(struct xlate_ctx *ctx, const char *format,
> ...)
>
> static struct vlog_rate_limit error_report_rl = VLOG_RATE_LIMIT_INIT(1, 5);
>
> -#define XLATE_REPORT_ERROR(CTX, ...) \
> - do { \
> - if (OVS_UNLIKELY((CTX)->xin->report_hook)) { \
> - xlate_report(CTX, __VA_ARGS__); \
> - } else { \
> - VLOG_ERR_RL(&error_report_rl, __VA_ARGS__); \
> - } \
> +#define XLATE_REORDER(LAST, DUMMY, ...) __VA_ARGS__, LAST
> +#define XLATE_REPORT_ERROR(CTX, FMT, ...) \
> + do { \
> + if (OVS_UNLIKELY((CTX)->xin->report_hook)) { \
> + xlate_report(CTX, FMT, ## __VA_ARGS__); \
> + } else { \
> + struct ds ds = DS_EMPTY_INITIALIZER; \
> + \
> + flow_format(&ds, &ctx->base_flow); \
> + VLOG_ERR_RL(&error_report_rl, \
> + XLATE_REORDER(ds_cstr(&ds), dummy, \
> + FMT": %s", ## __VA_ARGS__)); \
> + ds_destroy(&ds); \
> + } \
> } while (0)
>
> static inline void
> --
> 2.9.2
>
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