Re: [Qemu-devel] [PATCH 1/2] qapi: add visitor for parsing int[KMGT] input string

[mdroth <mdroth@linux.vnet.ibm.com>]

On Mon, Dec 10, 2012 at 05:01:38PM +0100, Igor Mammedov wrote:
> On Fri, 07 Dec 2012 19:57:35 +0100
> Andreas Färber <afaerber@suse.de> wrote:
> 
> > Am 06.12.2012 22:12, schrieb Igor Mammedov:
> > > Caller of visit_type_unit_suffixed_int() will have to specify
> > > value of 'K' suffix via unit argument.
> > > For Kbytes it's 1024, for Khz it's 1000.
> > > 
> > > Signed-off-by: Igor Mammedov <imammedo@redhat.com>
> > > ---
> > >  v2:
> > >   - convert type_freq to type_unit_suffixed_int.
> > >   - provide qapi_dealloc_type_unit_suffixed_int() impl.
> > > ---
> > >  qapi/qapi-dealloc-visitor.c |  7 +++++++
> > >  qapi/qapi-visit-core.c      | 13 +++++++++++++
> > >  qapi/qapi-visit-core.h      |  8 ++++++++
> > >  qapi/string-input-visitor.c | 22 ++++++++++++++++++++++
> > >  4 files changed, 50 insertions(+)
> > > 
> > > diff --git a/qapi/qapi-dealloc-visitor.c b/qapi/qapi-dealloc-visitor.c
> > > index 75214e7..57e662c 100644
> > > --- a/qapi/qapi-dealloc-visitor.c
> > > +++ b/qapi/qapi-dealloc-visitor.c
> > > @@ -143,6 +143,12 @@ static void qapi_dealloc_type_enum(Visitor *v, int
> > > *obj, const char *strings[], {
> > >  }
> > >  
> > > +static void qapi_dealloc_type_unit_suffixed_int(Visitor *v, int64_t *obj,
> > > +                                                const char *name,
> > > +                                                const int unit, Error
> > > **errp) +{
> > > +}
> > > +
> > >  Visitor *qapi_dealloc_get_visitor(QapiDeallocVisitor *v)
> > >  {
> > >      return &v->visitor;
> > > @@ -170,6 +176,7 @@ QapiDeallocVisitor *qapi_dealloc_visitor_new(void)
> > >      v->visitor.type_str = qapi_dealloc_type_str;
> > >      v->visitor.type_number = qapi_dealloc_type_number;
> > >      v->visitor.type_size = qapi_dealloc_type_size;
> > > +    v->visitor.type_unit_suffixed_int =
> > > qapi_dealloc_type_unit_suffixed_int; 
> > >      QTAILQ_INIT(&v->stack);
> > >  
> > > diff --git a/qapi/qapi-visit-core.c b/qapi/qapi-visit-core.c
> > > index 7a82b63..dcbc1a9 100644
> > > --- a/qapi/qapi-visit-core.c
> > > +++ b/qapi/qapi-visit-core.c
> > > @@ -311,3 +311,16 @@ void input_type_enum(Visitor *v, int *obj, const
> > > char *strings[], g_free(enum_str);
> > >      *obj = value;
> > >  }
> > > +
> > > +void visit_type_unit_suffixed_int(Visitor *v, int64_t *obj, const char
> > > *name,
> > > +                                  const int unit, Error **errp)
> > > +{
> > > +    if (!error_is_set(errp)) {
> > 
> > if (error_is_set(errp)) {
> Thanks, I'll fix it.
> 
> > > +        return;
> > > +    }
> > > +    if (v->type_unit_suffixed_int) {
> > > +        v->type_unit_suffixed_int(v, obj, name, unit, errp);
> > > +    } else {
> > > +        visit_type_int64(v, obj, name, errp);
> > > +    }
> > > +}
> > > diff --git a/qapi/qapi-visit-core.h b/qapi/qapi-visit-core.h
> > > index 60aceda..04e690a 100644
> > > --- a/qapi/qapi-visit-core.h
> > > +++ b/qapi/qapi-visit-core.h
> > > @@ -62,6 +62,12 @@ struct Visitor
> > >      void (*type_int64)(Visitor *v, int64_t *obj, const char *name, Error
> > > **errp); /* visit_type_size() falls back to (*type_uint64)() if type_size
> > > is unset */ void (*type_size)(Visitor *v, uint64_t *obj, const char
> > > *name, Error **errp);
> > > +    /*
> > > +     * visit_unit_suffixed_int() falls back to (*type_int64)()
> > > +     * if type_unit_suffixed_int is unset
> > > +    */
> > 
> > Indentation is one off.
> ditto
> 
> > 
> > > +    void (*type_unit_suffixed_int)(Visitor *v, int64_t *obj, const char
> > > *name,
> > > +                                   const int unit, Error **errp);
> > 
> > Are we expecting differently suffixed ints? Otherwise we could
> > optionally shorten to type_suffixed_int (but that probably still doesn't
> > fit within one comment line ;)).
> Not with current implementation. I'll shorten it as you've suggested.
> 
> > 
> > >  };
> > >  
> > >  void visit_start_handle(Visitor *v, void **obj, const char *kind,
> > > @@ -91,5 +97,7 @@ void visit_type_size(Visitor *v, uint64_t *obj, const
> > > char *name, Error **errp); void visit_type_bool(Visitor *v, bool *obj,
> > > const char *name, Error **errp); void visit_type_str(Visitor *v, char
> > > **obj, const char *name, Error **errp); void visit_type_number(Visitor
> > > *v, double *obj, const char *name, Error **errp); +void
> > > visit_type_unit_suffixed_int(Visitor *v, int64_t *obj, const char *name,
> > > +                                  const int unit, Error **errp);
> > >  
> > >  #endif
> > > diff --git a/qapi/string-input-visitor.c b/qapi/string-input-visitor.c
> > > index 497eb9a..d2bd154 100644
> > > --- a/qapi/string-input-visitor.c
> > > +++ b/qapi/string-input-visitor.c
> > > @@ -110,6 +110,27 @@ static void parse_start_optional(Visitor *v, bool
> > > *present, *present = true;
> > >  }
> > >  
> > > +static void parse_type_unit_suffixed_int(Visitor *v, int64_t *obj,
> > > +                                         const char *name, const int
> > > unit,
> > > +                                         Error **errp)
> > > +{
> > > +    StringInputVisitor *siv = DO_UPCAST(StringInputVisitor, visitor, v);
> > > +    char *endp = (char *) siv->string;
> > > +    long long val = 0;
> > > +
> > > +    if (siv->string) {
> > > +        val = strtosz_suffix_unit(siv->string, &endp,
> > > +                             STRTOSZ_DEFSUFFIX_B, unit);
> > > +    }
> > > +    if (!siv->string || val == -1 || *endp) {
> > > +        error_set(errp, QERR_INVALID_PARAMETER_VALUE, name,
> > > +              "a value representable as a non-negative int64");
> > 
> > Weird indentation remaining, looks as if we could align with errp within
> > 80 chars.
> Thanks, I'll fix it.
> 
> > 
> > However, I wonder if "unit" is the (physically etc.) correct term here?
> > Isn't the "unit" Hz / byte / ... and 1000 more of a conversion factor or
> > something? At least that's the way I've seen unit used in the API of
> > another project, passing an enum of Hertz, gram, meter/second, etc.
> If we are to generalize it to integer than units might not make much sense,
> they could be anything. Perhaps 'suffix_factor' would be descriptive enough
> + adding documentation comment to the visitor.

The real distinction I think is base=2 vs. base=10, but that might cause
confusion WRT to how the numberical value should be intepreted (10==2
vs. 10==10), so maybe suffix_base==2|10, or suffix_factor==1000/1024 as you
suggested. I think I'd prefer the former but either works for me.

> 
> > 
> > Andreas
> > 
> > > +        return;
> > > +    }
> > > +
> > > +    *obj = val;
> > > +}
> > > +
> > >  Visitor *string_input_get_visitor(StringInputVisitor *v)
> > >  {
> > >      return &v->visitor;
> > > @@ -132,6 +153,7 @@ StringInputVisitor *string_input_visitor_new(const
> > > char *str) v->visitor.type_str = parse_type_str;
> > >      v->visitor.type_number = parse_type_number;
> > >      v->visitor.start_optional = parse_start_optional;
> > > +    v->visitor.type_unit_suffixed_int = parse_type_unit_suffixed_int;
> > >  
> > >      v->string = str;
> > >      return v;
> > > 
> > 
> > 
>