Re: [PATCH 24.03 1/4] arg_parser: new library for command line parsing

[Bruce Richardson <bruce.richardson@intel.com>]

On Wed, Nov 22, 2023 at 04:45:47PM +0000, Euan Bourke wrote:
> Add a new library to make it easier for eal and other libraries to parse
> command line arguments.
> 
> The first function in this library is one to parse a corelist string into an
> array of individual core ids. The function will then return the total number
> of cores described in the corelist
> 
> Signed-off-by: Euan Bourke <euan.bourke@intel.com>

Thanks for the patchset. Some comments inline below.

/Bruce

> ---
>  .mailmap                        |   1 +
>  MAINTAINERS                     |   5 ++
>  doc/api/doxy-api-index.md       |   3 +-
>  doc/api/doxy-api.conf.in        |   1 +
>  lib/arg_parser/arg_parser.c     | 113 ++++++++++++++++++++++++++++++++
>  lib/arg_parser/meson.build      |   7 ++
>  lib/arg_parser/rte_arg_parser.h |  66 +++++++++++++++++++
>  lib/arg_parser/version.map      |  10 +++
>  lib/meson.build                 |   1 +
>  9 files changed, 206 insertions(+), 1 deletion(-)
>  create mode 100644 lib/arg_parser/arg_parser.c
>  create mode 100644 lib/arg_parser/meson.build
>  create mode 100644 lib/arg_parser/rte_arg_parser.h
>  create mode 100644 lib/arg_parser/version.map
> 
> diff --git a/.mailmap b/.mailmap
> index 72b216df9c..c1a4bf85f6 100644
> --- a/.mailmap
> +++ b/.mailmap
> @@ -379,6 +379,7 @@ Eric Zhang <eric.zhang@windriver.com>
>  Erik Gabriel Carrillo <erik.g.carrillo@intel.com>
>  Erik Ziegenbalg <eziegenb@brocade.com>
>  Erlu Chen <erlu.chen@intel.com>
> +Euan Bourke <euan.bourke@intel.com>
>  Eugenio Pérez <eperezma@redhat.com>
>  Eugeny Parshutin <eugeny.parshutin@linux.intel.com>
>  Evan Swanson <evan.swanson@intel.com>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index cf2af0d3a4..ce81877ce0 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -1753,6 +1753,11 @@ M: Nithin Dabilpuram <ndabilpuram@marvell.com>
>  M: Pavan Nikhilesh <pbhagavatula@marvell.com>
>  F: lib/node/
>  
> +Argument parsing
> +M: Bruce Richardson <bruce.richardson@intel.com>
> +M: Euan Bourke <euan.bourke@intel.com>
> +F: lib/arg_parser/
> +
>  
>  Test Applications
>  -----------------
> diff --git a/doc/api/doxy-api-index.md b/doc/api/doxy-api-index.md
> index a6a768bd7c..f711010140 100644
> --- a/doc/api/doxy-api-index.md
> +++ b/doc/api/doxy-api-index.md
> @@ -221,7 +221,8 @@ The public API headers are grouped by topics:
>    [config file](@ref rte_cfgfile.h),
>    [key/value args](@ref rte_kvargs.h),
>    [string](@ref rte_string_fns.h),
> -  [thread](@ref rte_thread.h)
> +  [thread](@ref rte_thread.h),
> +  [argument parsing](@ref rte_arg_parser.h)
>  
>  - **debug**:
>    [jobstats](@ref rte_jobstats.h),
> diff --git a/doc/api/doxy-api.conf.in b/doc/api/doxy-api.conf.in
> index e94c9e4e46..05718ba6ed 100644
> --- a/doc/api/doxy-api.conf.in
> +++ b/doc/api/doxy-api.conf.in
> @@ -28,6 +28,7 @@ INPUT                   = @TOPDIR@/doc/api/doxy-api-index.md \
>                            @TOPDIR@/lib/eal/include \
>                            @TOPDIR@/lib/eal/include/generic \
>                            @TOPDIR@/lib/acl \
> +                          @TOPDIR@/lib/arg_parser \
>                            @TOPDIR@/lib/bbdev \
>                            @TOPDIR@/lib/bitratestats \
>                            @TOPDIR@/lib/bpf \
> diff --git a/lib/arg_parser/arg_parser.c b/lib/arg_parser/arg_parser.c
> new file mode 100644
> index 0000000000..45acaf5631
> --- /dev/null
> +++ b/lib/arg_parser/arg_parser.c
> @@ -0,0 +1,113 @@
> +/* SPDX-License-Identifier: BSD-3-Clause
> + * Copyright(c) 2023 Intel Corporation
> + */
> +
> +#include "errno.h"
> +#include "stdlib.h"
> +#include "ctype.h"
> +#include "string.h"
> +#include "stdbool.h"
> +
> +#include <rte_arg_parser.h>
> +#include <rte_common.h>
> +
> +
> +struct core_bits {
> +	uint8_t bits[(UINT16_MAX + 1)/CHAR_BIT];
> +	uint16_t max_bit_set;
> +	uint16_t min_bit_set;
> +	uint32_t total_bits_set;
> +};
> +
> +static inline bool
> +get_core_bit(struct core_bits *mask, uint16_t idx)
> +{
> +	return !!(mask->bits[idx/8] & (1 << (idx % 8)));

Very minor nit, whitespace around the "/" in idx/8.

> +}
> +
> +static inline void
> +set_core_bit(struct core_bits *mask, uint16_t idx)
> +{
> +	if (get_core_bit(mask, idx) == 0) {

The function would be simpler flipping the comparison, since we do nothing
if the bit is already set.

	if (get_core_bit(mask, idx))
	    return;

Thereafter you can unconditionally set the bit, and increment
total_bits_set, before branching for total_bits_set == 1, and the min/max
comparison in the else leg of that.

> +		mask->total_bits_set++;
> +
> +		/* If its the first bit, assign min and max that value */
> +		if (mask->total_bits_set == 1) {
> +			mask->min_bit_set = idx;
> +			mask->max_bit_set = idx;
> +		}
> +	}
> +
> +	mask->bits[idx/8] |= 1 << (idx % 8);
> +
> +	if (idx > mask->max_bit_set)
> +		mask->max_bit_set = idx;
> +
> +	if (idx < mask->min_bit_set)
> +		mask->min_bit_set = idx;
> +}
> +
> +static inline void
> +corebits_to_array(struct core_bits *mask, uint16_t *cores, size_t max_cores)
> +{
> +	uint32_t count = 0;
> +	for (uint32_t i = mask->min_bit_set; i <= mask->max_bit_set && count < max_cores; i++) {
> +		if (get_core_bit(mask, i))
> +			cores[count++] = i;
> +	}
> +}
> +
> +
> +int
> +rte_parse_corelist(const char *corelist, uint16_t *cores, uint32_t cores_len)
> +{
> +	int32_t min = -1;
> +	char *end = NULL;
> +
> +	struct core_bits *mask = malloc(sizeof(struct core_bits));
> +	memset(mask, 0, sizeof(struct core_bits));
> +
> +	min = -1;
> +	do {
> +		uint32_t idx;
> +		int32_t max;
> +
> +		while (isblank(*corelist))
> +			corelist++;
> +		if (!isdigit(*corelist))
> +			return -1;

a blank line here wouldn't hurt to break up the block.

> +		errno = 0;
> +		idx = strtol(corelist, &end, 10);
> +		if (errno || end == NULL)
> +			return -1;
> +		if (idx > UINT16_MAX)
> +			return -1;

Can shorten code by merging these two conditions since both just return -1.

> +		while (isblank(*end))
> +			end++;
> +		if (*end == '-')
> +			min = idx;
> +
> +		else if (*end == ',' || *end == '\0') {
> +			max = idx;
> +			if (min == -1)
> +				min = idx;
> +
> +			/* Swap min and max if min is larger than max */
> +			if (min > max)
> +				RTE_SWAP(min, max);
> +
> +			for (; min <= max; min++)
> +				set_core_bit(mask, min);
> +
> +			min = -1;
> +		} else
> +			return -1;
> +		corelist = end + 1;
> +	} while (*end != '\0');
> +
> +	corebits_to_array(mask, cores, cores_len);
> +	uint32_t total_count = mask->total_bits_set;

corebits_to_array() should return total_bits_set, save accessing the
structure directly.

> +	free(mask);
> +
> +	return total_count;
> +}
> diff --git a/lib/arg_parser/meson.build b/lib/arg_parser/meson.build
> new file mode 100644
> index 0000000000..6ee228bd69
> --- /dev/null
> +++ b/lib/arg_parser/meson.build
> @@ -0,0 +1,7 @@
> +# SPDX-License-Identifier: BSD-3-Clause
> +# Copyright(c) 2023 Intel Corporation
> +
> +sources = files('arg_parser.c')
> +headers = files('rte_arg_parser.h')
> +
> +includes += global_inc
> diff --git a/lib/arg_parser/rte_arg_parser.h b/lib/arg_parser/rte_arg_parser.h
> new file mode 100644
> index 0000000000..1b12bf451f
> --- /dev/null
> +++ b/lib/arg_parser/rte_arg_parser.h
> @@ -0,0 +1,66 @@
> +/* SPDX-License-Identifier: BSD-3-Clause
> + * Copyright(c) 2023 Intel Corporation
> + */
> +
> +#ifndef _RTE_ARG_PARSER_H_
> +#define _RTE_ARG_PARSER_H_
> +
> +/**
> + * @file
> + *
> + * RTE Argument Parsing API
> + *
> + * The argument parsing API is a collection of functions to help parse
> + * command line arguments. The API takes a string input and will return
> + * it to the user in a more usable format.
> + * 
> + */
> +
> +#ifdef __cplusplus
> +extern "C" {
> +#endif
> +
> +#include <stdint.h>
> +
> +#include <rte_compat.h>
> +
> +
> +/**
> + * Convert a string describing a list of core ids into an array of core ids.
> + *
> + * On success, the passed array is filled with the core ids present in the
> + * list up to the "cores_len", and the length of the array is returned.
> + * For example, passing a 1-3,6 "corelist" results in an array of [1, 2, 3, 6]
> + * and would return 4.
> + * 
> + * Like the snprintf function for strings, if the length of the input array is
> + * insufficient to hold the number of cores in the "corelist", the input array is
> + * filled to capacity and the return value is the number of elements which would
> + * be returned if the array had been big enough.
> + * Function can also be called with a NULL array and 0 "cores_len" to find out
> + * the "cores_len" required.
> + *
> + * @param corelist
> + *   Input string describing a list of core ids.
> + * @param cores
> + *   An array where to store the core ids.
> + *   Array can be NULL if "cores_len" is 0.
> + * @param cores_len
> + *   The length of the "cores" array.
> + *   If the size is smaller than that needed to hold all cores from "corelist",
> + *   only "cores_len" elements will be written to the array.
> + * @return
> + *   n: the number of unique cores present in "corelist".
> + *   -1 if the string was invalid.
> + *   NOTE: if n > "cores_len", then only "cores_len" elements in the "cores" array are valid.
> + */
> +__rte_experimental
> +int
> +rte_parse_corelist(const char *corelist, uint16_t *cores, uint32_t cores_len);
> +
> +
> +#ifdef __cplusplus
> +}
> +#endif
> +
> +#endif /* _RTE_ARG_PARSER_H_ */
> diff --git a/lib/arg_parser/version.map b/lib/arg_parser/version.map
> new file mode 100644
> index 0000000000..f11699a306
> --- /dev/null
> +++ b/lib/arg_parser/version.map
> @@ -0,0 +1,10 @@
> +DPDK_24 {
> +    local: *;
> +};
> +
> +EXPERIMENTAL {
> +    global:
> +
> +    # added in 24.03
> +    rte_parse_corelist;
> +};
> diff --git a/lib/meson.build b/lib/meson.build
> index 6c143ce5a6..1b068fc61f 100644
> --- a/lib/meson.build
> +++ b/lib/meson.build
> @@ -11,6 +11,7 @@
>  libraries = [
>          'log',
>          'kvargs', # eal depends on kvargs
> +        'arg_parser',
>          'telemetry', # basic info querying
>          'eal', # everything depends on eal
>          'ring',

The new lib needs to be added to the list for windows builds too.

> -- 
> 2.34.1
>