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From: Phillip Wood <phillip.wood123@gmail.com>
To: Stefan Xenos via GitGitGadget <gitgitgadget@gmail.com>,
	git@vger.kernel.org
Cc: Christophe Poucet <christophe.poucet@gmail.com>,
	Stefan Xenos <sxenos@google.com>
Subject: Re: [PATCH 04/10] evolve: add support for parsing metacommits
Date: Mon, 26 Sep 2022 14:27:31 +0100	[thread overview]
Message-ID: <e7278794-428d-4aff-e91b-d2e6527f142d@gmail.com> (raw)
In-Reply-To: <2e9a4a9bd819785404e8a5343385f4fb2bc06109.1663959325.git.gitgitgadget@gmail.com>

Hi Chris

On 23/09/2022 19:55, Stefan Xenos via GitGitGadget wrote:
> From: Stefan Xenos <sxenos@google.com>
> 
> This patch adds the get_metacommit_content method, which can classify
> commits as either metacommits or normal commits, determine whether they
> are abandoned, and extract the content commit's object id from the
> metacommit.
> 
> Signed-off-by: Stefan Xenos <sxenos@google.com>
> Signed-off-by: Chris Poucet <poucet@google.com>
> ---
>   Makefile            |   1 +
>   metacommit-parser.c | 110 ++++++++++++++++++++++++++++++++++++++++++++
>   metacommit-parser.h |  19 ++++++++
>   3 files changed, 130 insertions(+)
>   create mode 100644 metacommit-parser.c
>   create mode 100644 metacommit-parser.h
> 
> diff --git a/Makefile b/Makefile
> index cac3452edb9..b2bcc00c289 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -999,6 +999,7 @@ LIB_OBJS += merge-ort.o
>   LIB_OBJS += merge-ort-wrappers.o
>   LIB_OBJS += merge-recursive.o
>   LIB_OBJS += merge.o
> +LIB_OBJS += metacommit-parser.o

There seems to be a problem with the indent here

>   LIB_OBJS += midx.o
>   LIB_OBJS += name-hash.o
>   LIB_OBJS += negotiator/default.o

 > diff --git a/metacommit-parser.h b/metacommit-parser.h
 > new file mode 100644
 > index 00000000000..1c74bd6d699
 > --- /dev/null
 > +++ b/metacommit-parser.h
 > @@ -0,0 +1,19 @@
 > +#ifndef METACOMMIT_PARSER_H
 > +#define METACOMMIT_PARSER_H
 > +
 > +#include "commit.h"
 > +#include "hash.h"
 > +
 > +/* Indicates a normal commit (non-metacommit) */
 > +#define METACOMMIT_TYPE_NONE 0
 > +/* Indicates a metacommit with normal content (non-abandoned) */
 > +#define METACOMMIT_TYPE_NORMAL 1
 > +/* Indicates a metacommit with abandoned content */
 > +#define METACOMMIT_TYPE_ABANDONED 2

Is it possible to define these as an enum? It would make the signature 
of get_meta_commit_content() nicer.

 > +struct commit;

What's this for? We're including commit.h above.

 > +extern int get_metacommit_content(
 > +	struct commit *commit, struct object_id *content);

> diff --git a/metacommit-parser.c b/metacommit-parser.c
> new file mode 100644
> index 00000000000..70c1428bfc6
> --- /dev/null
> +++ b/metacommit-parser.c
> @@ -0,0 +1,110 @@
> +#include "cache.h"
> +#include "metacommit-parser.h"
> +#include "commit.h"
> +
> +/*
> + * Search the commit buffer for a line starting with the given key. Unlike
> + * find_commit_header, this also searches the commit message body.
> + */

There is no explanation in the code or commit message as to why this 
function is needed. The documentation added in the first commit says 
that "parent-type" header is a commit header. I think the answer is that 
this series does not implement that header but uses the commit message 
instead. That's perfectly fine for a proof of concept but it is 
precisely the sort of detail that should be described it the commit 
message and probably flagged up in the cover letter.

> +static const char *find_key(const char *msg, const char *key, size_t *out_len)
> +{
> +	int key_len = strlen(key);
> +	const char *line = msg;
> +
> +	while (line) {
> +		const char *eol = strchrnul(line, '\n');
> +
> +		if (eol - line > key_len && !memcmp(line, key, key_len) &&
> +		    line[key_len] == ' ') {
> +			*out_len = eol - line - key_len - 1;
> +			return line + key_len + 1;
> +		}
> +		line = *eol ? eol + 1 : NULL;
> +	}
> +	return NULL;
> +}
> +
> +static struct commit *get_commit_by_index(struct commit_list *to_search, int index)
> +{
> +	while (to_search && index) {
> +		to_search = to_search->next;
> +		index--;
> +	}
> +
> +	if (!to_search)
> +		return NULL;
> +
> +	return to_search->item;
> +}

This function is a useful utility for struct commit_list and should live 
in commit.c. It could be used to simplify object-name.c:get_parent() for 
example.

> +/*
> + * Writes the index of the content parent to "result". Returns the metacommit
> + * type. See the METACOMMIT_TYPE_* constants.
> + */
> +static int index_of_content_commit(const char *buffer, int *result)

I found the signature confusing as it is returning an int but that is 
not the index. Switching to an enum for the metacommit types would 
clarify that.

> +{
> +	int index = 0;
> +	int ret = METACOMMIT_TYPE_NONE;
> +	size_t parent_types_size;
> +	const char *parent_types = find_key(buffer, "parent-type",
> +		&parent_types_size);
> +	const char *end;
> +	const char *enum_start = parent_types;
> +	int enum_length = 0;
> +
> +	if (!parent_types)
> +		return METACOMMIT_TYPE_NONE;
> +
> +	end = &parent_types[parent_types_size];
> +
> +	while (1) {
> +		char next = *parent_types;
> +		if (next == ' ' || parent_types >= end) {
> +			if (enum_length == 1) {

if enum_length != 1 then there is an error in the parent-type header and 
we should probably bail out.

> +				char first_char_in_enum = *enum_start;

It's not just the first character, it's the only character, do we really 
need such a long variable name? (how about just calling it "type")

I'll try and take at look at the next couple of patches later in the week.

Best Wishes

Phillip


  reply	other threads:[~2022-09-26 14:57 UTC|newest]

Thread overview: 66+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-09-23 18:55 [PATCH 00/10] Add the Git Change command Christophe Poucet via GitGitGadget
2022-09-23 18:55 ` [PATCH 01/10] technical doc: add a design doc for the evolve command Stefan Xenos via GitGitGadget
2022-09-23 19:59   ` Jerry Zhang
2022-09-28 21:26   ` Junio C Hamano
2022-09-28 22:20   ` Junio C Hamano
2022-09-29  9:17     ` Phillip Wood
2022-09-29 19:57   ` Jonathan Tan
2022-09-23 18:55 ` [PATCH 02/10] sha1-array: implement oid_array_readonly_contains Chris Poucet via GitGitGadget
2022-09-26 13:08   ` Phillip Wood
2022-09-23 18:55 ` [PATCH 03/10] ref-filter: add the metas namespace to ref-filter Chris Poucet via GitGitGadget
2022-09-26 13:13   ` Phillip Wood
2022-10-04  9:50     ` Chris P
2022-09-23 18:55 ` [PATCH 04/10] evolve: add support for parsing metacommits Stefan Xenos via GitGitGadget
2022-09-26 13:27   ` Phillip Wood [this message]
2022-10-04 11:21     ` Chris P
2022-10-04 14:10       ` Phillip Wood
2022-09-23 18:55 ` [PATCH 05/10] evolve: add the change-table structure Stefan Xenos via GitGitGadget
2022-09-27 13:27   ` Phillip Wood
2022-09-27 13:50     ` Ævar Arnfjörð Bjarmason
2022-09-27 14:13       ` Phillip Wood
2022-09-27 15:28         ` Ævar Arnfjörð Bjarmason
2022-09-28 14:33           ` Phillip Wood
2022-09-28 15:14             ` Ævar Arnfjörð Bjarmason
2022-09-28 15:59             ` Junio C Hamano
2022-09-27 14:18     ` Phillip Wood
2022-10-04 14:48     ` Chris P
2022-09-23 18:55 ` [PATCH 06/10] evolve: add support for writing metacommits Stefan Xenos via GitGitGadget
2022-09-28 14:27   ` Phillip Wood
2022-10-05  9:40     ` Chris P
2022-10-05 11:09       ` Phillip Wood
2022-09-23 18:55 ` [PATCH 07/10] evolve: implement the git change command Stefan Xenos via GitGitGadget
2022-09-25  9:10   ` Phillip Wood
2022-09-26  8:23     ` Ævar Arnfjörð Bjarmason
2022-09-26  8:25   ` Ævar Arnfjörð Bjarmason
2022-10-05 12:30     ` Chris P
2022-09-23 18:55 ` [PATCH 08/10] evolve: add the git change list command Stefan Xenos via GitGitGadget
2022-09-23 18:55 ` [PATCH 09/10] evolve: add delete command Chris Poucet via GitGitGadget
2022-09-26  8:38   ` Ævar Arnfjörð Bjarmason
2022-09-26  9:10     ` Chris Poucet
2022-09-23 18:55 ` [PATCH 10/10] evolve: add documentation for `git change` Chris Poucet via GitGitGadget
2022-09-25  8:41   ` Phillip Wood
2022-09-25  8:39 ` [PATCH 00/10] Add the Git Change command Phillip Wood
2022-10-04  9:33   ` Chris P
2022-10-04 14:24 ` Phillip Wood
2022-10-04 15:19   ` Chris P
2022-10-04 15:55     ` Chris P
2022-10-04 16:00       ` Phillip Wood
2022-10-04 15:57     ` Phillip Wood
2022-10-05 14:59 ` [PATCH v2 00/10] RFC: Git Evolve / Change Christophe Poucet via GitGitGadget
2022-10-05 14:59   ` [PATCH v2 01/10] technical doc: add a design doc for the evolve command Stefan Xenos via GitGitGadget
2022-10-05 15:16     ` Chris Poucet
2022-10-06 20:53       ` Glen Choo
2022-10-10 19:35     ` Victoria Dye
2022-10-11  8:59       ` Phillip Wood
2022-10-11 16:59         ` Victoria Dye
2022-10-12 19:19           ` Phillip Wood
2022-10-05 14:59   ` [PATCH v2 02/10] sha1-array: implement oid_array_readonly_contains Chris Poucet via GitGitGadget
2022-10-05 14:59   ` [PATCH v2 03/10] ref-filter: add the metas namespace to ref-filter Chris Poucet via GitGitGadget
2022-10-05 14:59   ` [PATCH v2 04/10] evolve: add support for parsing metacommits Stefan Xenos via GitGitGadget
2022-10-05 14:59   ` [PATCH v2 05/10] evolve: add the change-table structure Stefan Xenos via GitGitGadget
2022-10-05 14:59   ` [PATCH v2 06/10] evolve: add support for writing metacommits Stefan Xenos via GitGitGadget
2022-10-05 14:59   ` [PATCH v2 07/10] evolve: implement the git change command Stefan Xenos via GitGitGadget
2022-10-05 14:59   ` [PATCH v2 08/10] evolve: add delete command Chris Poucet via GitGitGadget
2022-10-05 14:59   ` [PATCH v2 09/10] evolve: add documentation for `git change` Chris Poucet via GitGitGadget
2022-10-05 14:59   ` [PATCH v2 10/10] evolve: add tests for the git-change command Chris Poucet via GitGitGadget
2022-10-10  9:23   ` [PATCH v2 00/10] RFC: Git Evolve / Change Phillip Wood

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