Re: [Minios-devel] [UNIKRAFT PATCH 1/8] lib/ukdebug: trace.h - introduce UK_FOREACH and UK_NARGS macros

[Costin Lupu <costin.lup@xxxxxxxxx>]

H Yuri,

Please see my comments inline.

On 5/10/19 9:29 PM, Yuri Volchkov wrote:
> The UK_FOREACH is the central macro in the all macro hell needed to
> implement static tracepoints definitions. The UK_FOREACH takes up to 7
> parameters, and applies specified function to each of them, separating
> output with commas.
> 
> For example it can convert 'char, int, long' to 'sizeof(char),
> sizeof(int), sizeof(long)'
> 
> UK_NARGS calculates how many parameters it has received.
> 
> Signed-off-by: Yuri Volchkov <yuri.volchkov@xxxxxxxxx>
> ---
>  lib/ukdebug/include/uk/trace.h | 76 ++++++++++++++++++++++++++++++++++
>  1 file changed, 76 insertions(+)
>  create mode 100644 lib/ukdebug/include/uk/trace.h
> 
> diff --git a/lib/ukdebug/include/uk/trace.h b/lib/ukdebug/include/uk/trace.h
> new file mode 100644
> index 00000000..3e17b30e
> --- /dev/null
> +++ b/lib/ukdebug/include/uk/trace.h
> @@ -0,0 +1,76 @@
> +/* SPDX-License-Identifier: BSD-3-Clause */
> +/*
> + * Authors: Yuri Volchkov <yuri.volchkov@xxxxxxxxx>
> + *
> + * Copyright (c) 2019, NEC Laboratories Europe GmbH, NEC Corporation.
> + *
> + * Redistribution and use in source and binary forms, with or without
> + * modification, are permitted provided that the following conditions
> + * are met:
> + *
> + * 1. Redistributions of source code must retain the above copyright
> + *    notice, this list of conditions and the following disclaimer.
> + * 2. Redistributions in binary form must reproduce the above copyright
> + *    notice, this list of conditions and the following disclaimer in the
> + *    documentation and/or other materials provided with the distribution.
> + * 3. Neither the name of the copyright holder nor the names of its
> + *    contributors may be used to endorse or promote products derived from
> + *    this software without specific prior written permission.
> + *
> + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS 
> IS"
> + * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
> + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
> + * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
> + * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
> + * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
> + * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
> + * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
> + * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
> + * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
> + * POSSIBILITY OF SUCH DAMAGE.
> + *
> + * THIS HEADER MAY NOT BE EXTRACTED OR MODIFIED IN ANY WAY.
> + */
> +
> +#ifndef _UK_TRACE_H_
> +#define _UK_TRACE_H_
> +/* TODO: consider to move UK_CONCAT into public headers */
> +#define __UK_CONCAT_X(a, b) a##b
> +#define UK_CONCAT(a, b) __UK_CONCAT_X(a, b)
> +
> +#define __UK_NARGS_X(a, b, c, d, e, f, g, h, n, ...) n
> +#define UK_NARGS(...)  __UK_NARGS_X(, ##__VA_ARGS__, 7, 6, 5, 4, 3, 2, 1, 0)
> +
> +#define __UK_GET_ARG1(a1, ...) a1
> +#define __UK_GET_ARG2(a1, a2, ...) a2
> +#define __UK_GET_ARG3(a1, a2, a3, ...) a3
> +#define __UK_GET_ARG4(a1, a2, a3, a4, ...) a4
> +#define __UK_GET_ARG5(a1, a2, a3, a4, a5, ...) a5
> +#define __UK_GET_ARG6(a1, a2, a3, a4, a5, a6, ...) a6
> +#define __UK_GET_ARG7(a1, a2, a3, a4, a5, a6, a7) a7
> +/* Returns argument of a given number */
> +#define __UK_GET_ARG_N(n, ...)                               \
> +     UK_CONCAT(__UK_GET_ARG, n)(__VA_ARGS__)
> +
> +/* Calls given function with argument Nr n */
> +#define UK_1ARG_MAP(n, f, ...)               \
> +     f(n, __UK_GET_ARG_N(n, __VA_ARGS__))
> +#define UK_FOREACH0(f, ...)
> +#define UK_FOREACH1(f, ...) UK_1ARG_MAP(1, f, __VA_ARGS__)
> +#define UK_FOREACH2(f, ...) UK_FOREACH1(f, __VA_ARGS__), UK_1ARG_MAP(2, f, 
> __VA_ARGS__)
> +#define UK_FOREACH3(f, ...) UK_FOREACH2(f, __VA_ARGS__), UK_1ARG_MAP(3, f, 
> __VA_ARGS__)
> +#define UK_FOREACH4(f, ...) UK_FOREACH3(f, __VA_ARGS__), UK_1ARG_MAP(4, f, 
> __VA_ARGS__)
> +#define UK_FOREACH5(f, ...) UK_FOREACH4(f, __VA_ARGS__), UK_1ARG_MAP(5, f, 
> __VA_ARGS__)
> +#define UK_FOREACH6(f, ...) UK_FOREACH5(f, __VA_ARGS__), UK_1ARG_MAP(6, f, 
> __VA_ARGS__)
> +#define UK_FOREACH7(f, ...) UK_FOREACH6(f, __VA_ARGS__), UK_1ARG_MAP(7, f, 
> __VA_ARGS__)
> +
> +/* TODO: FOREACH could be useful for other Unikraft modules. Consider
> + * moving it to public headers */
> +
> +/* Apply function/macro f to every argument passed. Resulting
> + * arguments are separated with commas
> + */
> +#define UK_FOREACH(n, f, ...)                                        \
> +     UK_CONCAT(UK_FOREACH, n)(f, __VA_ARGS__)

You're right, UK_FOREACH is useful for other modules. For that reason,
we can get rid of the n parameter and simply define it like this:

+#define UK_FOREACH(f, ...)                                     \
+       UK_CONCAT(UK_FOREACH, UK_NARGS(__VA_ARGS__))(f, __VA_ARGS__)

> +
> +#endif /* _UK_TRACE_H_ */
> 

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