[PATCH] git: --no-lazy-fetch option

[PATCH] git: --no-lazy-fetch option

[Junio C Hamano]

Sometimes, especially during tests of low level machinery, it is
handy to have a way to disable lazy fetching of objects.  This
allows us to say, for example, "git cat-file -e <object-name>", to
see if the object is locally available.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 git.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/git.c b/git.c
index 7068a184b0..fd9b0e6a9e 100644
--- a/git.c
+++ b/git.c
@@ -4,6 +4,7 @@
 #include "exec-cmd.h"
 #include "gettext.h"
 #include "help.h"
+#include "object-file.h"
 #include "pager.h"
 #include "read-cache-ll.h"
 #include "run-command.h"
@@ -186,6 +187,8 @@ static int handle_options(const char ***argv, int *argc, int *envchanged)
 			use_pager = 0;
 			if (envchanged)
 				*envchanged = 1;
+		} else if (!strcmp(cmd, "--no-lazy-fetch")) {
+			fetch_if_missing = 0;
 		} else if (!strcmp(cmd, "--no-replace-objects")) {
 			disable_replace_refs();
 			setenv(NO_REPLACE_OBJECTS_ENVIRONMENT, "1", 1);
-- 
2.43.0-581-g5216f8f5c4

Re: [PATCH] git: --no-lazy-fetch option

[Linus Arver]

Junio C Hamano <gitster@pobox.com> writes:

> Sometimes, especially during tests of low level machinery, it is
> handy to have a way to disable lazy fetching of objects.  This
> allows us to say, for example, "git cat-file -e <object-name>", to
> see if the object is locally available.

Nit: perhaps s/locally/already locally/ is better?

Re: [PATCH] git: --no-lazy-fetch option

[Linus Arver]

Linus Arver <linusa@google.com> writes:

> Junio C Hamano <gitster@pobox.com> writes:
>
>> Sometimes, especially during tests of low level machinery, it is
>> handy to have a way to disable lazy fetching of objects.  This
>> allows us to say, for example, "git cat-file -e <object-name>", to
>> see if the object is locally available.
>
> Nit: perhaps s/locally/already locally/ is better?

I forgot to mention that the new flag is missing a documentation entry
in Documentation/git.txt. Perhaps something like

    --no-lazy-fetch::
        Do not fetch missing objects. Useful together with `git cat-file -e
        <object-name>`, for example, to see if the object is already
        locally available.

?

Re: [PATCH] git: --no-lazy-fetch option

[Junio C Hamano]

Linus Arver <linusa@google.com> writes:

> Linus Arver <linusa@google.com> writes:
>
>> Junio C Hamano <gitster@pobox.com> writes:
>>
>>> Sometimes, especially during tests of low level machinery, it is
>>> handy to have a way to disable lazy fetching of objects.  This
>>> allows us to say, for example, "git cat-file -e <object-name>", to
>>> see if the object is locally available.
>>
>> Nit: perhaps s/locally/already locally/ is better?
>
> I forgot to mention that the new flag is missing a documentation entry
> in Documentation/git.txt. Perhaps something like
>
>     --no-lazy-fetch::
>         Do not fetch missing objects. Useful together with `git cat-file -e
>         <object-name>`, for example, to see if the object is already
>         locally available.
>
> ?

Wonderful.  Thanks for an extra set of eyes.

Re: [PATCH] git: --no-lazy-fetch option

[Jeff King]

On Thu, Feb 08, 2024 at 03:17:31PM -0800, Junio C Hamano wrote:

> Sometimes, especially during tests of low level machinery, it is
> handy to have a way to disable lazy fetching of objects.  This
> allows us to say, for example, "git cat-file -e <object-name>", to
> see if the object is locally available.

That seems like a good feature, but...

> @@ -186,6 +187,8 @@ static int handle_options(const char ***argv, int *argc, int *envchanged)
>  			use_pager = 0;
>  			if (envchanged)
>  				*envchanged = 1;
> +		} else if (!strcmp(cmd, "--no-lazy-fetch")) {
> +			fetch_if_missing = 0;
>  		} else if (!strcmp(cmd, "--no-replace-objects")) {
>  			disable_replace_refs();
>  			setenv(NO_REPLACE_OBJECTS_ENVIRONMENT, "1", 1);

This will only help builtin commands, and even then only the top-level
one. If I run "git --no-lazy-fetch foo" and "foo" is a script or an
alias, I'd expect it to still take effect. Ditto for sub-commands kicked
off by a builtin (say, a "rev-list" connectivity check caused by a
fetch).

So this probably needs to be modeled after --no-replace-objects, etc,
where we set an environment variable that makes it to child processes.

-Peff

Re: [PATCH] git: --no-lazy-fetch option

[Junio C Hamano]

Jeff King <peff@peff.net> writes:

> On Thu, Feb 08, 2024 at 03:17:31PM -0800, Junio C Hamano wrote:
>
>> Sometimes, especially during tests of low level machinery, it is
>> handy to have a way to disable lazy fetching of objects.  This
>> allows us to say, for example, "git cat-file -e <object-name>", to
>> see if the object is locally available.
>
> That seems like a good feature, but...
>
>> @@ -186,6 +187,8 @@ static int handle_options(const char ***argv, int *argc, int *envchanged)
>>  			use_pager = 0;
>>  			if (envchanged)
>>  				*envchanged = 1;
>> +		} else if (!strcmp(cmd, "--no-lazy-fetch")) {
>> +			fetch_if_missing = 0;
>>  		} else if (!strcmp(cmd, "--no-replace-objects")) {
>>  			disable_replace_refs();
>>  			setenv(NO_REPLACE_OBJECTS_ENVIRONMENT, "1", 1);
>
> This will only help builtin commands, and even then only the top-level
> one. If I run "git --no-lazy-fetch foo" and "foo" is a script or an
> alias, I'd expect it to still take effect. Ditto for sub-commands kicked
> off by a builtin (say, a "rev-list" connectivity check caused by a
> fetch).
>
> So this probably needs to be modeled after --no-replace-objects, etc,
> where we set an environment variable that makes it to child processes.

Yuck, I was hoping that we can get away with the tiny change only
for builtins,but you're right.

Re: [PATCH] git: --no-lazy-fetch option

[Junio C Hamano]

Junio C Hamano <gitster@pobox.com> writes:

> Yuck, I was hoping that we can get away with the tiny change only
> for builtins,but you're right.

Here is a preliminary clean-up only for Documentation.  Will not be
queuing before the final, but just so that I won't forget.

------- >8 ------------- >8 ------------- >8 -------
Subject: [PATCH] git: document GIT_NO_REPLACE_OBJECTS environment variable

This variable is used as the primary way to disable the object
replacement mechanism, with the "--no-replace-objects" command line
option as an end-user visible way to set it, but has not been
documented.

The original reason why it was left undocumented might be because it
was meant as an internal implementation detail, but the thing is,
that our tests use the environment variable directly without the
command line option, and there certainly are folks who learned its
use from there, making it impossible to deprecate or change its
behaviour by now.

Add documentation and note that for this variable, unlike many
boolean-looking environment variables, only the presence matters,
not what value it is set to.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 Documentation/git.txt | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git c/Documentation/git.txt i/Documentation/git.txt
index 95f451b22b..2f1cb3ef4e 100644
--- c/Documentation/git.txt
+++ i/Documentation/git.txt
@@ -174,8 +174,10 @@ If you just want to run git as if it was started in `<path>` then use
 	directory.
 
 --no-replace-objects::
-	Do not use replacement refs to replace Git objects. See
-	linkgit:git-replace[1] for more information.
+	Do not use replacement refs to replace Git objects.
+	This is equivalent to exporting the `GIT_NO_REPLACE_OBJECTS`
+	environment variable with any value.
+	See linkgit:git-replace[1] for more information.
 
 --no-lazy-fetch::
 	Do not fetch missing objects from the promisor remote on

[PATCH] git: extend --no-lazy-fetch to work across subprocesses

[Junio C Hamano]

Modeling after how the `--no-replace-objects` option is made usable
across subprocess spawning (e.g., cURL based remote helpers are
spawned as a separate process while running "git fetch"), allow the
`--no-lazy-fetch` option to be passed across process boundary.

Do not model how the value of GIT_NO_REPLACE_OBJECTS environment
variable is ignored, though.  Just use the usual git_env_bool() to
allow "export GIT_NO_LAZY_FETCH=0" and "unset GIT_NO_LAZY_FETCH"
to be equivalents.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
---

 * And this comes on top of the original one plus the documentation
   update for GIT_NO_REPLACE_OBJECTS.

 Documentation/git.txt    | 2 ++
 environment.c            | 4 ++++
 environment.h            | 1 +
 git.c                    | 3 +++
 t/t0410-partial-clone.sh | 9 +++++++++
 5 files changed, 19 insertions(+)

diff --git a/Documentation/git.txt b/Documentation/git.txt
index 2f1cb3ef4e..be2829003d 100644
--- a/Documentation/git.txt
+++ b/Documentation/git.txt
@@ -183,6 +183,8 @@ If you just want to run git as if it was started in `<path>` then use
 	Do not fetch missing objects from the promisor remote on
 	demand.  Useful together with `git cat-file -e <object>` to
 	see if the object is locally available.
+	This is equivalent to setting the `GIT_NO_LAZY_FETCH`
+	environment variable to `1`.
 
 --literal-pathspecs::
 	Treat pathspecs literally (i.e. no globbing, no pathspec magic).
diff --git a/environment.c b/environment.c
index 9e37bf58c0..afad78a3f8 100644
--- a/environment.c
+++ b/environment.c
@@ -136,6 +136,7 @@ const char * const local_repo_env[] = {
 	GRAFT_ENVIRONMENT,
 	INDEX_ENVIRONMENT,
 	NO_REPLACE_OBJECTS_ENVIRONMENT,
+	NO_LAZY_FETCH_ENVIRONMENT,
 	GIT_REPLACE_REF_BASE_ENVIRONMENT,
 	GIT_PREFIX_ENVIRONMENT,
 	GIT_SHALLOW_FILE_ENVIRONMENT,
@@ -207,6 +208,9 @@ void setup_git_env(const char *git_dir)
 	shallow_file = getenv(GIT_SHALLOW_FILE_ENVIRONMENT);
 	if (shallow_file)
 		set_alternate_shallow_file(the_repository, shallow_file, 0);
+
+	if (git_env_bool(NO_LAZY_FETCH_ENVIRONMENT, 0))
+		fetch_if_missing = 0;
 }
 
 int is_bare_repository(void)
diff --git a/environment.h b/environment.h
index e5351c9dd9..74b3124f55 100644
--- a/environment.h
+++ b/environment.h
@@ -35,6 +35,7 @@ const char *getenv_safe(struct strvec *argv, const char *name);
 #define EXEC_PATH_ENVIRONMENT "GIT_EXEC_PATH"
 #define CEILING_DIRECTORIES_ENVIRONMENT "GIT_CEILING_DIRECTORIES"
 #define NO_REPLACE_OBJECTS_ENVIRONMENT "GIT_NO_REPLACE_OBJECTS"
+#define NO_LAZY_FETCH_ENVIRONMENT "GIT_NO_LAZY_FETCH"
 #define GIT_REPLACE_REF_BASE_ENVIRONMENT "GIT_REPLACE_REF_BASE"
 #define GITATTRIBUTES_FILE ".gitattributes"
 #define INFOATTRIBUTES_FILE "info/attributes"
diff --git a/git.c b/git.c
index 28e8bf7497..d11d4dc77b 100644
--- a/git.c
+++ b/git.c
@@ -189,6 +189,9 @@ static int handle_options(const char ***argv, int *argc, int *envchanged)
 				*envchanged = 1;
 		} else if (!strcmp(cmd, "--no-lazy-fetch")) {
 			fetch_if_missing = 0;
+			setenv(NO_LAZY_FETCH_ENVIRONMENT, "1", 1);
+			if (envchanged)
+				*envchanged = 1;
 		} else if (!strcmp(cmd, "--no-replace-objects")) {
 			disable_replace_refs();
 			setenv(NO_REPLACE_OBJECTS_ENVIRONMENT, "1", 1);
diff --git a/t/t0410-partial-clone.sh b/t/t0410-partial-clone.sh
index 5b7bee888d..59629cea1f 100755
--- a/t/t0410-partial-clone.sh
+++ b/t/t0410-partial-clone.sh
@@ -665,6 +665,15 @@ test_expect_success 'lazy-fetch when accessing object not in the_repository' '
 	git -C partial.git rev-list --objects --missing=print HEAD >out &&
 	grep "[?]$FILE_HASH" out &&
 
+	# The no-lazy-fetch mechanism prevents Git from fetching
+	test_must_fail env GIT_NO_LAZY_FETCH=1 \
+		git -C partial.git cat-file -e "$FILE_HASH" &&
+	test_must_fail git --no-lazy-fetch -C partial.git cat-file -e "$FILE_HASH" &&
+
+	# Sanity check that the file is still missing
+	git -C partial.git rev-list --objects --missing=print HEAD >out &&
+	grep "[?]$FILE_HASH" out &&
+
 	git -C full cat-file -s "$FILE_HASH" >expect &&
 	test-tool partial-clone object-info partial.git "$FILE_HASH" >actual &&
 	test_cmp expect actual &&
-- 
2.44.0-rc1-17-g3e0d3cd5c7

Re: [PATCH] git: extend --no-lazy-fetch to work across subprocesses

[Linus Arver]

FWIW, I see some typos. Otherwise this patch along with your "git:
document GIT_NO_REPLACE_OBJECTS environment variable" one both LGTM for
wording/readability. I must defer to Peff and others for "is this patch
actually doing the right thing?" ;).

Junio C Hamano <gitster@pobox.com> writes:

> Modeling after how the `--no-replace-objects` option is made usable
> across subprocess spawning (e.g., cURL based remote helpers are
> spawned as a separate process while running "git fetch"), allow the
> `--no-lazy-fetch` option to be passed across process boundary.

s/boundary/boundaries

> Do not model how the value of GIT_NO_REPLACE_OBJECTS environment
> variable is ignored, though.  Just use the usual git_env_bool() to
> allow "export GIT_NO_LAZY_FETCH=0" and "unset GIT_NO_LAZY_FETCH"
> to be equivalents.

s/equivalents/equivalent

Re: [PATCH] git: extend --no-lazy-fetch to work across subprocesses

[Junio C Hamano]

Linus Arver <linusa@google.com> writes:

> FWIW, I see some typos. Otherwise this patch along with your "git:
> document GIT_NO_REPLACE_OBJECTS environment variable" one both LGTM for
> wording/readability. I must defer to Peff and others for "is this patch
> actually doing the right thing?" ;).
>
> Junio C Hamano <gitster@pobox.com> writes:
>
>> Modeling after how the `--no-replace-objects` option is made usable
>> across subprocess spawning (e.g., cURL based remote helpers are
>> spawned as a separate process while running "git fetch"), allow the
>> `--no-lazy-fetch` option to be passed across process boundary.
>
> s/boundary/boundaries

Right; thanks.

>
>> Do not model how the value of GIT_NO_REPLACE_OBJECTS environment
>> variable is ignored, though.  Just use the usual git_env_bool() to
>> allow "export GIT_NO_LAZY_FETCH=0" and "unset GIT_NO_LAZY_FETCH"
>> to be equivalents.
>
> s/equivalents/equivalent

I meant to say that these two are "equivalents" (noun, plural).

I can rephrase to

	Just use git_env_bool() to make "export GIT_NO_LAZY_FETCH=0"
	an equivalent to "unset GIT_NO_LAZY_FETCH".

though, of course.

Re: [PATCH] git: extend --no-lazy-fetch to work across subprocesses

[Linus Arver]

Junio C Hamano <gitster@pobox.com> writes:

>>> Do not model how the value of GIT_NO_REPLACE_OBJECTS environment
>>> variable is ignored, though.  Just use the usual git_env_bool() to
>>> allow "export GIT_NO_LAZY_FETCH=0" and "unset GIT_NO_LAZY_FETCH"
>>> to be equivalents.
>>
>> s/equivalents/equivalent
>
> I meant to say that these two are "equivalents" (noun, plural).

Ah, I see.

> I can rephrase to
>
> 	Just use git_env_bool() to make "export GIT_NO_LAZY_FETCH=0"
> 	an equivalent to "unset GIT_NO_LAZY_FETCH".
>
> though, of course.

SGTM either way. Thanks.

Re: [PATCH] git: extend --no-lazy-fetch to work across subprocesses

[Jeff King]

On Fri, Feb 16, 2024 at 01:09:43PM -0800, Junio C Hamano wrote:

> Modeling after how the `--no-replace-objects` option is made usable
> across subprocess spawning (e.g., cURL based remote helpers are
> spawned as a separate process while running "git fetch"), allow the
> `--no-lazy-fetch` option to be passed across process boundary.
> 
> Do not model how the value of GIT_NO_REPLACE_OBJECTS environment
> variable is ignored, though.  Just use the usual git_env_bool() to
> allow "export GIT_NO_LAZY_FETCH=0" and "unset GIT_NO_LAZY_FETCH"
> to be equivalents.

Nice. I wondered if we would need to hide fetch_if_missing behind a
function that lazy-evaluates the environment variable, but it looks like
setup_git_env() is central enough to cover us here.

> diff --git a/Documentation/git.txt b/Documentation/git.txt
> index 2f1cb3ef4e..be2829003d 100644
> --- a/Documentation/git.txt
> +++ b/Documentation/git.txt
> @@ -183,6 +183,8 @@ If you just want to run git as if it was started in `<path>` then use
>  	Do not fetch missing objects from the promisor remote on
>  	demand.  Useful together with `git cat-file -e <object>` to
>  	see if the object is locally available.
> +	This is equivalent to setting the `GIT_NO_LAZY_FETCH`
> +	environment variable to `1`.

As with the other patch, I'd suggest adding an entry to the list of
environment variables later in the manpage.

> --- a/environment.h
> +++ b/environment.h
> @@ -35,6 +35,7 @@ const char *getenv_safe(struct strvec *argv, const char *name);
>  #define EXEC_PATH_ENVIRONMENT "GIT_EXEC_PATH"
>  #define CEILING_DIRECTORIES_ENVIRONMENT "GIT_CEILING_DIRECTORIES"
>  #define NO_REPLACE_OBJECTS_ENVIRONMENT "GIT_NO_REPLACE_OBJECTS"
> +#define NO_LAZY_FETCH_ENVIRONMENT "GIT_NO_LAZY_FETCH"
>  #define GIT_REPLACE_REF_BASE_ENVIRONMENT "GIT_REPLACE_REF_BASE"
>  #define GITATTRIBUTES_FILE ".gitattributes"
>  #define INFOATTRIBUTES_FILE "info/attributes"

A small nit, but maybe worth keeping the two replace-related variables
next to each other, rather than sticking the new one in the middle?

> diff --git a/git.c b/git.c
> index 28e8bf7497..d11d4dc77b 100644
> --- a/git.c
> +++ b/git.c
> @@ -189,6 +189,9 @@ static int handle_options(const char ***argv, int *argc, int *envchanged)
>  				*envchanged = 1;
>  		} else if (!strcmp(cmd, "--no-lazy-fetch")) {
>  			fetch_if_missing = 0;
> +			setenv(NO_LAZY_FETCH_ENVIRONMENT, "1", 1);
> +			if (envchanged)
> +				*envchanged = 1;
>  		} else if (!strcmp(cmd, "--no-replace-objects")) {
>  			disable_replace_refs();
>  			setenv(NO_REPLACE_OBJECTS_ENVIRONMENT, "1", 1);

I _suspect_ this makes the fetch_if_missing call redundant, since we
should be parsing these before doing any repo setup that would trigger
the code that reads the environment variable.

This should probably also be xsetenv(), though as you can see in the
context we are not very consistent about using it. :) But certainly if
we failed to set it I would prefer to see an error rather than
accidentally lazy-fetching.

> diff --git a/t/t0410-partial-clone.sh b/t/t0410-partial-clone.sh
> index 5b7bee888d..59629cea1f 100755
> --- a/t/t0410-partial-clone.sh
> +++ b/t/t0410-partial-clone.sh
> @@ -665,6 +665,15 @@ test_expect_success 'lazy-fetch when accessing object not in the_repository' '
>  	git -C partial.git rev-list --objects --missing=print HEAD >out &&
>  	grep "[?]$FILE_HASH" out &&
>  
> +	# The no-lazy-fetch mechanism prevents Git from fetching
> +	test_must_fail env GIT_NO_LAZY_FETCH=1 \
> +		git -C partial.git cat-file -e "$FILE_HASH" &&
> +	test_must_fail git --no-lazy-fetch -C partial.git cat-file -e "$FILE_HASH" &&
> +
> +	# Sanity check that the file is still missing
> +	git -C partial.git rev-list --objects --missing=print HEAD >out &&
> +	grep "[?]$FILE_HASH" out &&

OK, we exercise it by setting the variable directly. A more interesting
one might be:

  git -c alias.foo='!git cat-file' --no-lazy-fetch ...

which should fail without the patch.

I also wondered why we were testing the direct-builtin invocation here,
since we are building on top of the original --no-lazy-fetch patch, but
it looks like it is because that patch didn't add any tests at all). I
think they would make more sense as a single patch, but I guess the
original is already in 'next' (though I suppose it is about to be
rewound). I am OK with it either way.

-Peff

Re: [PATCH] git: extend --no-lazy-fetch to work across subprocesses

[Junio C Hamano]

Jeff King <peff@peff.net> writes:

>> diff --git a/Documentation/git.txt b/Documentation/git.txt
>> index 2f1cb3ef4e..be2829003d 100644
>> --- a/Documentation/git.txt
>> +++ b/Documentation/git.txt
>> @@ -183,6 +183,8 @@ If you just want to run git as if it was started in `<path>` then use
>>  	Do not fetch missing objects from the promisor remote on
>>  	demand.  Useful together with `git cat-file -e <object>` to
>>  	see if the object is locally available.
>> +	This is equivalent to setting the `GIT_NO_LAZY_FETCH`
>> +	environment variable to `1`.
>
> As with the other patch, I'd suggest adding an entry to the list of
> environment variables later in the manpage.

Thanks, done.

We'll have to make a separate patch to add GIT_NO_REPLACE_OBJECTS to
the list, by the way (#leftoverbits), which I used as a model to
find what needs to be updated.

>> --- a/environment.h
>> +++ b/environment.h
>> @@ -35,6 +35,7 @@ const char *getenv_safe(struct strvec *argv, const char *name);
>>  #define EXEC_PATH_ENVIRONMENT "GIT_EXEC_PATH"
>>  #define CEILING_DIRECTORIES_ENVIRONMENT "GIT_CEILING_DIRECTORIES"
>>  #define NO_REPLACE_OBJECTS_ENVIRONMENT "GIT_NO_REPLACE_OBJECTS"
>> +#define NO_LAZY_FETCH_ENVIRONMENT "GIT_NO_LAZY_FETCH"
>>  #define GIT_REPLACE_REF_BASE_ENVIRONMENT "GIT_REPLACE_REF_BASE"
>>  #define GITATTRIBUTES_FILE ".gitattributes"
>>  #define INFOATTRIBUTES_FILE "info/attributes"
>
> A small nit, but maybe worth keeping the two replace-related variables
> next to each other, rather than sticking the new one in the middle?

OK.

>> diff --git a/git.c b/git.c
>> index 28e8bf7497..d11d4dc77b 100644
>> --- a/git.c
>> +++ b/git.c
>> @@ -189,6 +189,9 @@ static int handle_options(const char ***argv, int *argc, int *envchanged)
>>  				*envchanged = 1;
>>  		} else if (!strcmp(cmd, "--no-lazy-fetch")) {
>>  			fetch_if_missing = 0;
>> +			setenv(NO_LAZY_FETCH_ENVIRONMENT, "1", 1);
>> +			if (envchanged)
>> +				*envchanged = 1;
>>  		} else if (!strcmp(cmd, "--no-replace-objects")) {
>>  			disable_replace_refs();
>>  			setenv(NO_REPLACE_OBJECTS_ENVIRONMENT, "1", 1);
>
> I _suspect_ this makes the fetch_if_missing call redundant, since we
> should be parsing these before doing any repo setup that would trigger
> the code that reads the environment variable.

True.  Again, we'd need to clean-up the NO_REPLACE_OBJECTS codepath
as well---the disable_replace_refs() call should also be redundant,
which I mimicked to add the no-lazy-fetch codepath (#leftoverbits).

> This should probably also be xsetenv(), though as you can see in the
> context we are not very consistent about using it. :) But certainly if
> we failed to set it I would prefer to see an error rather than
> accidentally lazy-fetching.

I'd probably leave it outside the scope of this series; as nobody
uses xsetenv() in git.c currently, it would be a clean-up topic on
its own (#leftoverbits).

>> diff --git a/t/t0410-partial-clone.sh b/t/t0410-partial-clone.sh
>> index 5b7bee888d..59629cea1f 100755
>> --- a/t/t0410-partial-clone.sh
>> +++ b/t/t0410-partial-clone.sh
>> @@ -665,6 +665,15 @@ test_expect_success 'lazy-fetch when accessing object not in the_repository' '
>>  	git -C partial.git rev-list --objects --missing=print HEAD >out &&
>>  	grep "[?]$FILE_HASH" out &&
>>  
>> +	# The no-lazy-fetch mechanism prevents Git from fetching
>> +	test_must_fail env GIT_NO_LAZY_FETCH=1 \
>> +		git -C partial.git cat-file -e "$FILE_HASH" &&
>> +	test_must_fail git --no-lazy-fetch -C partial.git cat-file -e "$FILE_HASH" &&
>> +
>> +	# Sanity check that the file is still missing
>> +	git -C partial.git rev-list --objects --missing=print HEAD >out &&
>> +	grep "[?]$FILE_HASH" out &&
>
> OK, we exercise it by setting the variable directly. A more interesting
> one might be:
>
>   git -c alias.foo='!git cat-file' --no-lazy-fetch ...
>
> which should fail without the patch.

True, again.  I'll test all three variants (i.e. environment,
command line option to "git", forced subprocess turning command line
option to "git" into environment).

Thanks.



----- >8 --------- >8 --------- >8 --------- >8 -----
Subject: [PATCH v2 3/3] git: extend --no-lazy-fetch to work across subprocesses

Modeling after how the `--no-replace-objects` option is made usable
across subprocess spawning (e.g., cURL based remote helpers are
spawned as a separate process while running "git fetch"), allow the
`--no-lazy-fetch` option to be passed across process boundaries.

Do not model how the value of GIT_NO_REPLACE_OBJECTS environment
variable is ignored, though.  Just use the usual git_env_bool() to
allow "export GIT_NO_LAZY_FETCH=0" and "unset GIT_NO_LAZY_FETCH"
to be equivalents.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
Range-diff:
1:  00e202b679 ! 1:  e0764f2e21 git: extend --no-lazy-fetch to work across subprocesses
    @@ Documentation/git.txt: If you just want to run git as if it was started in `<pat
      
      --literal-pathspecs::
      	Treat pathspecs literally (i.e. no globbing, no pathspec magic).
    +@@ Documentation/git.txt: for full details.
    + 	Setting this Boolean environment variable to true will cause Git to treat all
    + 	pathspecs as case-insensitive.
    + 
    ++`GIT_NO_LAZY_FETCH`::
    ++	Setting this Boolean environment variable to true tells Git
    ++	not to lazily fetch missing objects from the promisor remote
    ++	on demand.
    ++
    + `GIT_REFLOG_ACTION`::
    + 	When a ref is updated, reflog entries are created to keep
    + 	track of the reason why the ref was updated (which is
     
      ## environment.c ##
     @@ environment.c: const char * const local_repo_env[] = {
    @@ environment.c: void setup_git_env(const char *git_dir)
     
      ## environment.h ##
     @@ environment.h: const char *getenv_safe(struct strvec *argv, const char *name);
    - #define EXEC_PATH_ENVIRONMENT "GIT_EXEC_PATH"
      #define CEILING_DIRECTORIES_ENVIRONMENT "GIT_CEILING_DIRECTORIES"
      #define NO_REPLACE_OBJECTS_ENVIRONMENT "GIT_NO_REPLACE_OBJECTS"
    -+#define NO_LAZY_FETCH_ENVIRONMENT "GIT_NO_LAZY_FETCH"
      #define GIT_REPLACE_REF_BASE_ENVIRONMENT "GIT_REPLACE_REF_BASE"
    ++#define NO_LAZY_FETCH_ENVIRONMENT "GIT_NO_LAZY_FETCH"
      #define GITATTRIBUTES_FILE ".gitattributes"
      #define INFOATTRIBUTES_FILE "info/attributes"
    + #define ATTRIBUTE_MACRO_PREFIX "[attr]"
     
      ## git.c ##
     @@ git.c: static int handle_options(const char ***argv, int *argc, int *envchanged)
    @@ t/t0410-partial-clone.sh: test_expect_success 'lazy-fetch when accessing object
     +	# The no-lazy-fetch mechanism prevents Git from fetching
     +	test_must_fail env GIT_NO_LAZY_FETCH=1 \
     +		git -C partial.git cat-file -e "$FILE_HASH" &&
    ++
    ++	# The same with command line option to "git"
     +	test_must_fail git --no-lazy-fetch -C partial.git cat-file -e "$FILE_HASH" &&
     +
    ++	# The same, forcing a subprocess via an alias
    ++	test_must_fail git --no-lazy-fetch -C partial.git \
    ++		-c alias.foo="!git cat-file" foo -e "$FILE_HASH" &&
    ++
     +	# Sanity check that the file is still missing
     +	git -C partial.git rev-list --objects --missing=print HEAD >out &&
     +	grep "[?]$FILE_HASH" out &&

 Documentation/git.txt    |  7 +++++++
 environment.c            |  4 ++++
 environment.h            |  1 +
 git.c                    |  3 +++
 t/t0410-partial-clone.sh | 15 +++++++++++++++
 5 files changed, 30 insertions(+)

diff --git a/Documentation/git.txt b/Documentation/git.txt
index 2f1cb3ef4e..6fbaa9dd2b 100644
--- a/Documentation/git.txt
+++ b/Documentation/git.txt
@@ -183,6 +183,8 @@ If you just want to run git as if it was started in `<path>` then use
 	Do not fetch missing objects from the promisor remote on
 	demand.  Useful together with `git cat-file -e <object>` to
 	see if the object is locally available.
+	This is equivalent to setting the `GIT_NO_LAZY_FETCH`
+	environment variable to `1`.
 
 --literal-pathspecs::
 	Treat pathspecs literally (i.e. no globbing, no pathspec magic).
@@ -896,6 +898,11 @@ for full details.
 	Setting this Boolean environment variable to true will cause Git to treat all
 	pathspecs as case-insensitive.
 
+`GIT_NO_LAZY_FETCH`::
+	Setting this Boolean environment variable to true tells Git
+	not to lazily fetch missing objects from the promisor remote
+	on demand.
+
 `GIT_REFLOG_ACTION`::
 	When a ref is updated, reflog entries are created to keep
 	track of the reason why the ref was updated (which is
diff --git a/environment.c b/environment.c
index 9e37bf58c0..afad78a3f8 100644
--- a/environment.c
+++ b/environment.c
@@ -136,6 +136,7 @@ const char * const local_repo_env[] = {
 	GRAFT_ENVIRONMENT,
 	INDEX_ENVIRONMENT,
 	NO_REPLACE_OBJECTS_ENVIRONMENT,
+	NO_LAZY_FETCH_ENVIRONMENT,
 	GIT_REPLACE_REF_BASE_ENVIRONMENT,
 	GIT_PREFIX_ENVIRONMENT,
 	GIT_SHALLOW_FILE_ENVIRONMENT,
@@ -207,6 +208,9 @@ void setup_git_env(const char *git_dir)
 	shallow_file = getenv(GIT_SHALLOW_FILE_ENVIRONMENT);
 	if (shallow_file)
 		set_alternate_shallow_file(the_repository, shallow_file, 0);
+
+	if (git_env_bool(NO_LAZY_FETCH_ENVIRONMENT, 0))
+		fetch_if_missing = 0;
 }
 
 int is_bare_repository(void)
diff --git a/environment.h b/environment.h
index e5351c9dd9..5cec19cecc 100644
--- a/environment.h
+++ b/environment.h
@@ -36,6 +36,7 @@ const char *getenv_safe(struct strvec *argv, const char *name);
 #define CEILING_DIRECTORIES_ENVIRONMENT "GIT_CEILING_DIRECTORIES"
 #define NO_REPLACE_OBJECTS_ENVIRONMENT "GIT_NO_REPLACE_OBJECTS"
 #define GIT_REPLACE_REF_BASE_ENVIRONMENT "GIT_REPLACE_REF_BASE"
+#define NO_LAZY_FETCH_ENVIRONMENT "GIT_NO_LAZY_FETCH"
 #define GITATTRIBUTES_FILE ".gitattributes"
 #define INFOATTRIBUTES_FILE "info/attributes"
 #define ATTRIBUTE_MACRO_PREFIX "[attr]"
diff --git a/git.c b/git.c
index 28e8bf7497..d11d4dc77b 100644
--- a/git.c
+++ b/git.c
@@ -189,6 +189,9 @@ static int handle_options(const char ***argv, int *argc, int *envchanged)
 				*envchanged = 1;
 		} else if (!strcmp(cmd, "--no-lazy-fetch")) {
 			fetch_if_missing = 0;
+			setenv(NO_LAZY_FETCH_ENVIRONMENT, "1", 1);
+			if (envchanged)
+				*envchanged = 1;
 		} else if (!strcmp(cmd, "--no-replace-objects")) {
 			disable_replace_refs();
 			setenv(NO_REPLACE_OBJECTS_ENVIRONMENT, "1", 1);
diff --git a/t/t0410-partial-clone.sh b/t/t0410-partial-clone.sh
index 5b7bee888d..c282851af7 100755
--- a/t/t0410-partial-clone.sh
+++ b/t/t0410-partial-clone.sh
@@ -665,6 +665,21 @@ test_expect_success 'lazy-fetch when accessing object not in the_repository' '
 	git -C partial.git rev-list --objects --missing=print HEAD >out &&
 	grep "[?]$FILE_HASH" out &&
 
+	# The no-lazy-fetch mechanism prevents Git from fetching
+	test_must_fail env GIT_NO_LAZY_FETCH=1 \
+		git -C partial.git cat-file -e "$FILE_HASH" &&
+
+	# The same with command line option to "git"
+	test_must_fail git --no-lazy-fetch -C partial.git cat-file -e "$FILE_HASH" &&
+
+	# The same, forcing a subprocess via an alias
+	test_must_fail git --no-lazy-fetch -C partial.git \
+		-c alias.foo="!git cat-file" foo -e "$FILE_HASH" &&
+
+	# Sanity check that the file is still missing
+	git -C partial.git rev-list --objects --missing=print HEAD >out &&
+	grep "[?]$FILE_HASH" out &&
+
 	git -C full cat-file -s "$FILE_HASH" >expect &&
 	test-tool partial-clone object-info partial.git "$FILE_HASH" >actual &&
 	test_cmp expect actual &&
-- 
2.44.0-35-ga2082dbdd3

Re: [PATCH] git: extend --no-lazy-fetch to work across subprocesses

[Jeff King]

On Mon, Feb 26, 2024 at 10:04:54PM -0800, Junio C Hamano wrote:

> ----- >8 --------- >8 --------- >8 --------- >8 -----
> Subject: [PATCH v2 3/3] git: extend --no-lazy-fetch to work across subprocesses
> [...]

This looks pretty reasonable to me, and the lines you drew for
#leftoverbits all seemed liked good spots.

The only thing I noticed in the patch was this (which I think is not
even new in this round):

> diff --git a/environment.c b/environment.c
> index 9e37bf58c0..afad78a3f8 100644
> --- a/environment.c
> +++ b/environment.c
> @@ -136,6 +136,7 @@ const char * const local_repo_env[] = {
>  	GRAFT_ENVIRONMENT,
>  	INDEX_ENVIRONMENT,
>  	NO_REPLACE_OBJECTS_ENVIRONMENT,
> +	NO_LAZY_FETCH_ENVIRONMENT,
>  	GIT_REPLACE_REF_BASE_ENVIRONMENT,
>  	GIT_PREFIX_ENVIRONMENT,
>  	GIT_SHALLOW_FILE_ENVIRONMENT,

This will clear the environment variable when we move between
repositories. I can see an argument for it, and certainly that's how
GIT_NO_REPLACE_OBJECTS works.

But I can also see an argument that this is not a property of the
_repository_, but of the request. For example, if I run "git
--no-lazy-fetch log" and we cross into a submodule to do a diff, should
that submodule also avoid lazy-fetching? I'd think so, but I think your
patch would restore the defaults when we "enter" the submodule repo.

There's some prior art there, I think, in how GIT_CEILING_DIRECTORIES
works, or even something like "git --literal-pathspecs", neither of
which appear in local_repo_env.

-Peff

Re: [PATCH] git: extend --no-lazy-fetch to work across subprocesses

[Junio C Hamano]

Jeff King <peff@peff.net> writes:

> There's some prior art there, I think, in how GIT_CEILING_DIRECTORIES
> works, or even something like "git --literal-pathspecs", neither of
> which appear in local_repo_env.

Unlike GIT_CEILING_DIRECTORIES that is more or less permanent and a
part of configuring an everyday environment for real work, I view
this --no-lazy-fetch thing as solely a debugging aid.  A repository
with promisor wouldn't be able to "fill the gap" by forbidding
on-demand fetching of promised objects while running say "git fetch"
from elsewhere and it just will die with "some objects we are
supposed to have are missing from this repository".

So I do not have a strong opinion either way, if it is more
convenient to propagate the request out to other repositories when
we run processes in two or more repositories (e.g. "git clone
--local"), or if it is more convenient to make sure that the request
is limited to the target repository.  Here is a version without the
local_repo_env[] change.

----- >8 --------- >8 --------- >8 --------- >8 --------- >8 -----
Subject: [PATCH v3 3/3] git: extend --no-lazy-fetch to work across subprocesses

Modeling after how the `--no-replace-objects` option is made usable
across subprocess spawning (e.g., cURL based remote helpers are
spawned as a separate process while running "git fetch"), allow the
`--no-lazy-fetch` option to be passed across process boundaries.

Do not model how the value of GIT_NO_REPLACE_OBJECTS environment
variable is ignored, though.  Just use the usual git_env_bool() to
allow "export GIT_NO_LAZY_FETCH=0" and "unset GIT_NO_LAZY_FETCH"
to be equivalents.

Also do not model how the request is not propagated to subprocesses
we spawn (e.g. "git clone --local" that spawns a new process to work
in the origin repository, while the original one working in the
newly created one) by the "--no-replace-objects" option, as this "do
not lazily fetch from the promisor" is more about a per-request
debugging aid, not "this repository's promisor should not be relied
upon" property specific to a repository.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
Range-diff:
1:  5fa7ddbf68 ! 1:  ea40bb9a1d git: extend --no-lazy-fetch to work across subprocesses
    @@ Commit message
         allow "export GIT_NO_LAZY_FETCH=0" and "unset GIT_NO_LAZY_FETCH"
         to be equivalents.
     
    +    Also do not model how the request is not propagated to subprocesses
    +    we spawn (e.g. "git clone --local" that spawns a new process to work
    +    in the origin repository, while the original one working in the
    +    newly created one) by the "--no-replace-objects" option, as this "do
    +    not lazily fetch from the promisor" is more about a per-request
    +    debugging aid, not "this repository's promisor should not be relied
    +    upon" property specific to a repository.
    +
         Signed-off-by: Junio C Hamano <gitster@pobox.com>
     
      ## Documentation/git.txt ##
    @@ Documentation/git.txt: for full details.
      	track of the reason why the ref was updated (which is
     
      ## environment.c ##
    -@@ environment.c: const char * const local_repo_env[] = {
    - 	GRAFT_ENVIRONMENT,
    - 	INDEX_ENVIRONMENT,
    - 	NO_REPLACE_OBJECTS_ENVIRONMENT,
    -+	NO_LAZY_FETCH_ENVIRONMENT,
    - 	GIT_REPLACE_REF_BASE_ENVIRONMENT,
    - 	GIT_PREFIX_ENVIRONMENT,
    - 	GIT_SHALLOW_FILE_ENVIRONMENT,
     @@ environment.c: void setup_git_env(const char *git_dir)
      	shallow_file = getenv(GIT_SHALLOW_FILE_ENVIRONMENT);
      	if (shallow_file)

 Documentation/git.txt    |  7 +++++++
 environment.c            |  3 +++
 environment.h            |  1 +
 git.c                    |  3 +++
 t/t0410-partial-clone.sh | 15 +++++++++++++++
 5 files changed, 29 insertions(+)

diff --git a/Documentation/git.txt b/Documentation/git.txt
index b1f754e84b..a517d94a7a 100644
--- a/Documentation/git.txt
+++ b/Documentation/git.txt
@@ -183,6 +183,8 @@ If you just want to run git as if it was started in `<path>` then use
 	Do not fetch missing objects from the promisor remote on
 	demand.  Useful together with `git cat-file -e <object>` to
 	see if the object is locally available.
+	This is equivalent to setting the `GIT_NO_LAZY_FETCH`
+	environment variable to `1`.
 
 --literal-pathspecs::
 	Treat pathspecs literally (i.e. no globbing, no pathspec magic).
@@ -900,6 +902,11 @@ for full details.
 	Setting this Boolean environment variable to true will cause Git to treat all
 	pathspecs as case-insensitive.
 
+`GIT_NO_LAZY_FETCH`::
+	Setting this Boolean environment variable to true tells Git
+	not to lazily fetch missing objects from the promisor remote
+	on demand.
+
 `GIT_REFLOG_ACTION`::
 	When a ref is updated, reflog entries are created to keep
 	track of the reason why the ref was updated (which is
diff --git a/environment.c b/environment.c
index 9e37bf58c0..0ae5bbd4a1 100644
--- a/environment.c
+++ b/environment.c
@@ -207,6 +207,9 @@ void setup_git_env(const char *git_dir)
 	shallow_file = getenv(GIT_SHALLOW_FILE_ENVIRONMENT);
 	if (shallow_file)
 		set_alternate_shallow_file(the_repository, shallow_file, 0);
+
+	if (git_env_bool(NO_LAZY_FETCH_ENVIRONMENT, 0))
+		fetch_if_missing = 0;
 }
 
 int is_bare_repository(void)
diff --git a/environment.h b/environment.h
index e5351c9dd9..5cec19cecc 100644
--- a/environment.h
+++ b/environment.h
@@ -36,6 +36,7 @@ const char *getenv_safe(struct strvec *argv, const char *name);
 #define CEILING_DIRECTORIES_ENVIRONMENT "GIT_CEILING_DIRECTORIES"
 #define NO_REPLACE_OBJECTS_ENVIRONMENT "GIT_NO_REPLACE_OBJECTS"
 #define GIT_REPLACE_REF_BASE_ENVIRONMENT "GIT_REPLACE_REF_BASE"
+#define NO_LAZY_FETCH_ENVIRONMENT "GIT_NO_LAZY_FETCH"
 #define GITATTRIBUTES_FILE ".gitattributes"
 #define INFOATTRIBUTES_FILE "info/attributes"
 #define ATTRIBUTE_MACRO_PREFIX "[attr]"
diff --git a/git.c b/git.c
index 28e8bf7497..d11d4dc77b 100644
--- a/git.c
+++ b/git.c
@@ -189,6 +189,9 @@ static int handle_options(const char ***argv, int *argc, int *envchanged)
 				*envchanged = 1;
 		} else if (!strcmp(cmd, "--no-lazy-fetch")) {
 			fetch_if_missing = 0;
+			setenv(NO_LAZY_FETCH_ENVIRONMENT, "1", 1);
+			if (envchanged)
+				*envchanged = 1;
 		} else if (!strcmp(cmd, "--no-replace-objects")) {
 			disable_replace_refs();
 			setenv(NO_REPLACE_OBJECTS_ENVIRONMENT, "1", 1);
diff --git a/t/t0410-partial-clone.sh b/t/t0410-partial-clone.sh
index 5b7bee888d..c282851af7 100755
--- a/t/t0410-partial-clone.sh
+++ b/t/t0410-partial-clone.sh
@@ -665,6 +665,21 @@ test_expect_success 'lazy-fetch when accessing object not in the_repository' '
 	git -C partial.git rev-list --objects --missing=print HEAD >out &&
 	grep "[?]$FILE_HASH" out &&
 
+	# The no-lazy-fetch mechanism prevents Git from fetching
+	test_must_fail env GIT_NO_LAZY_FETCH=1 \
+		git -C partial.git cat-file -e "$FILE_HASH" &&
+
+	# The same with command line option to "git"
+	test_must_fail git --no-lazy-fetch -C partial.git cat-file -e "$FILE_HASH" &&
+
+	# The same, forcing a subprocess via an alias
+	test_must_fail git --no-lazy-fetch -C partial.git \
+		-c alias.foo="!git cat-file" foo -e "$FILE_HASH" &&
+
+	# Sanity check that the file is still missing
+	git -C partial.git rev-list --objects --missing=print HEAD >out &&
+	grep "[?]$FILE_HASH" out &&
+
 	git -C full cat-file -s "$FILE_HASH" >expect &&
 	test-tool partial-clone object-info partial.git "$FILE_HASH" >actual &&
 	test_cmp expect actual &&
-- 
2.44.0-35-ga2082dbdd3

Re: [PATCH] git: extend --no-lazy-fetch to work across subprocesses

[Jeff King]

On Tue, Feb 27, 2024 at 08:48:29AM -0800, Junio C Hamano wrote:

> Jeff King <peff@peff.net> writes:
> 
> > There's some prior art there, I think, in how GIT_CEILING_DIRECTORIES
> > works, or even something like "git --literal-pathspecs", neither of
> > which appear in local_repo_env.
> 
> Unlike GIT_CEILING_DIRECTORIES that is more or less permanent and a
> part of configuring an everyday environment for real work, I view
> this --no-lazy-fetch thing as solely a debugging aid.  A repository
> with promisor wouldn't be able to "fill the gap" by forbidding
> on-demand fetching of promised objects while running say "git fetch"
> from elsewhere and it just will die with "some objects we are
> supposed to have are missing from this repository".
> 
> So I do not have a strong opinion either way, if it is more
> convenient to propagate the request out to other repositories when
> we run processes in two or more repositories (e.g. "git clone
> --local"), or if it is more convenient to make sure that the request
> is limited to the target repository.  Here is a version without the
> local_repo_env[] change.

Yeah, GIT_CEILING_DIRECTORIES is maybe a bad example. But I do think
LITERAL_PATHSPECS is a better one, and the submodule-fetch example I
gave would be genuinely surprising if it behaved differently than the
superproject, I'd think.

I do agree this is probably going to mostly be a debugging aid, so it
might not matter much. But once in the wild these things tend to take on
a life of their own. ;)

> ----- >8 --------- >8 --------- >8 --------- >8 --------- >8 -----
> Subject: [PATCH v3 3/3] git: extend --no-lazy-fetch to work across subprocesses

So anyway, this version seems good to me.

-Peff

Re: [PATCH] git: extend --no-lazy-fetch to work across subprocesses

[Junio C Hamano]

Jeff King <peff@peff.net> writes:

>> So I do not have a strong opinion either way, if it is more
>> convenient to propagate the request out to other repositories when
>> we run processes in two or more repositories (e.g. "git clone
>> --local"), or if it is more convenient to make sure that the request
>> is limited to the target repository.  Here is a version without the
>> local_repo_env[] change.
>
> Yeah, GIT_CEILING_DIRECTORIES is maybe a bad example. But I do think
> LITERAL_PATHSPECS is a better one, and the submodule-fetch example I
> gave would be genuinely surprising if it behaved differently than the
> superproject, I'd think.
>
> I do agree this is probably going to mostly be a debugging aid, so it
> might not matter much. But once in the wild these things tend to take on
> a life of their own. ;)
>
>> ----- >8 --------- >8 --------- >8 --------- >8 --------- >8 -----
>> Subject: [PATCH v3 3/3] git: extend --no-lazy-fetch to work across subprocesses
>
> So anyway, this version seems good to me.

Thanks.

Re: [PATCH] git: --no-lazy-fetch option

[Jeff King]

On Fri, Feb 16, 2024 at 09:22:20AM -0800, Junio C Hamano wrote:

> Here is a preliminary clean-up only for Documentation.  Will not be
> queuing before the final, but just so that I won't forget.

I think this is an improvement, but two small comments...

> ------- >8 ------------- >8 ------------- >8 -------
> Subject: [PATCH] git: document GIT_NO_REPLACE_OBJECTS environment variable
> 
> This variable is used as the primary way to disable the object
> replacement mechanism, with the "--no-replace-objects" command line
> option as an end-user visible way to set it, but has not been
> documented.
> 
> The original reason why it was left undocumented might be because it
> was meant as an internal implementation detail, but the thing is,
> that our tests use the environment variable directly without the
> command line option, and there certainly are folks who learned its
> use from there, making it impossible to deprecate or change its
> behaviour by now.

I agree that we should document these sorts of variables; they really
are part of the public interface since it's so easy for users to see
them in their own scripts, aliases, etc, when we set them.

But in fact do document this environment variable in git-replace(1), and
have for a long time. So I don't think we need to even make claims about
its undocumented state. :)

>  --no-replace-objects::
> -	Do not use replacement refs to replace Git objects. See
> -	linkgit:git-replace[1] for more information.
> +	Do not use replacement refs to replace Git objects.
> +	This is equivalent to exporting the `GIT_NO_REPLACE_OBJECTS`
> +	environment variable with any value.
> +	See linkgit:git-replace[1] for more information.

The text both before and after your patch links to git-replace, which
covers the variable. So I think the "before" state is actually not that
bad. But I still think mentioning it explicitly is better still.

However, should it get an entry in the "ENVIRONMENT VARIABLES" section?
We cover stuff there like GIT_LITERAL_PATHSPECS, which is triggered in
the same way.

> Add documentation and note that for this variable, unlike many
> boolean-looking environment variables, only the presence matters,
> not what value it is set to.

Yuck. IMHO depending on GIT_NO_REPLACE_OBJECTS=0 is somewhat crazy, and
we could consider the current behavior a bug. It's probably not _that_
big a deal either way (because I would not expect anybody to set it that
way in the first place). But I wonder if being consistent across
variables trumps retaining weird historical compatibility for such a
far-fetched case. I dunno. I guess this is https://xkcd.com/1172/. :)

-Peff

Re: [PATCH] git: --no-lazy-fetch option

[Linus Arver]

Jeff King <peff@peff.net> writes:

> On Fri, Feb 16, 2024 at 09:22:20AM -0800, Junio C Hamano wrote:
>
> [...]
>> Add documentation and note that for this variable, unlike many
>> boolean-looking environment variables, only the presence matters,
>> not what value it is set to.
>
> Yuck. IMHO depending on GIT_NO_REPLACE_OBJECTS=0 is somewhat crazy, and
> we could consider the current behavior a bug. It's probably not _that_
> big a deal either way (because I would not expect anybody to set it that
> way in the first place). But I wonder if being consistent across
> variables trumps retaining weird historical compatibility for such a
> far-fetched case. I dunno. I guess this is https://xkcd.com/1172/. :)

I totally agree with your take on this. Would such cleanup patches
(e.g., changing the behavior of GIT_NO_REPLACE_OBJECTS=0 to be "false"
instead of "true") be acceptable as #leftoverbits?

Re: [PATCH] git: --no-lazy-fetch option

[Linus Arver]

Jeff King <peff@peff.net> writes:

> On Thu, Feb 08, 2024 at 03:17:31PM -0800, Junio C Hamano wrote:
>
>> Sometimes, especially during tests of low level machinery, it is
>> handy to have a way to disable lazy fetching of objects.  This
>> allows us to say, for example, "git cat-file -e <object-name>", to
>> see if the object is locally available.
>
> That seems like a good feature, but...
>
>> @@ -186,6 +187,8 @@ static int handle_options(const char ***argv, int *argc, int *envchanged)
>>  			use_pager = 0;
>>  			if (envchanged)
>>  				*envchanged = 1;
>> +		} else if (!strcmp(cmd, "--no-lazy-fetch")) {
>> +			fetch_if_missing = 0;
>>  		} else if (!strcmp(cmd, "--no-replace-objects")) {
>>  			disable_replace_refs();
>>  			setenv(NO_REPLACE_OBJECTS_ENVIRONMENT, "1", 1);
>
> This will only help builtin commands, and even then only the top-level
> one. If I run "git --no-lazy-fetch foo" and "foo" is a script or an
> alias, I'd expect it to still take effect. Ditto for sub-commands kicked
> off by a builtin (say, a "rev-list" connectivity check caused by a
> fetch).
>
> So this probably needs to be modeled after --no-replace-objects, etc,
> where we set an environment variable that makes it to child processes.

Thanks for the helpful explanation, very much appreciated.