Re: [RFC PATCH v2 4/4] fetch: do not list refs if fetching only hashes

[Jonathan Tan]

> > +   /*
> > +* We can avoid listing refs if all of them are exact
> > +* OIDs
> > +*/
> > +   must_list_refs = 0;
> > +   for (i = 0; i < rs->nr; i++) {
> > +   if (!rs->items[i].exact_sha1) {
> > +   must_list_refs = 1;
> > +   break;
> > +   }
> > +   }
> 
> This seems to be a repeat pattern, Is it worth it to encapsulate it
> as a function in transport or refs?
> 
>   int must_list_refs(struct ref **to_fetch)
>   {
> // body as the loop above
>   }

The repetition is unfortunate - I tried to think of a better way to do
it but couldn't. We can't do what you suggest because this one loops
over refspecs but the other one loops over refs.

Re: [RFC PATCH v2 4/4] fetch: do not list refs if fetching only hashes

[Stefan Beller]

On Thu, Sep 27, 2018 at 12:24 PM Jonathan Tan  wrote:
>
> If only hash literals are given on a "git fetch" command-line, tag
> following is not requested, and the fetch is done using protocol v2, a
> list of refs is not required from the remote. Therefore, optimize by
> invoking transport_get_remote_refs() only if we need the refs.
>

Makes sense

> +
> +   /*
> +* We can avoid listing refs if all of them are exact
> +* OIDs
> +*/
> +   must_list_refs = 0;
> +   for (i = 0; i < rs->nr; i++) {
> +   if (!rs->items[i].exact_sha1) {
> +   must_list_refs = 1;
> +   break;
> +   }
> +   }

This seems to be a repeat pattern, Is it worth it to encapsulate it
as a function in transport or refs?

  int must_list_refs(struct ref **to_fetch)
  {
// body as the loop above
  }

[RFC PATCH v2 4/4] fetch: do not list refs if fetching only hashes

[Jonathan Tan]

If only hash literals are given on a "git fetch" command-line, tag
following is not requested, and the fetch is done using protocol v2, a
list of refs is not required from the remote. Therefore, optimize by
invoking transport_get_remote_refs() only if we need the refs.

Signed-off-by: Jonathan Tan 
---
 builtin/fetch.c | 32 ++--
 t/t5551-http-fetch-smart.sh | 15 +++
 t/t5702-protocol-v2.sh  | 13 +
 3 files changed, 54 insertions(+), 6 deletions(-)

diff --git a/builtin/fetch.c b/builtin/fetch.c
index 0696abfc2a..4c4f8fa194 100644
--- a/builtin/fetch.c
+++ b/builtin/fetch.c
@@ -1175,6 +1175,7 @@ static int do_fetch(struct transport *transport,
int retcode = 0;
const struct ref *remote_refs;
struct argv_array ref_prefixes = ARGV_ARRAY_INIT;
+   int must_list_refs = 1;
 
if (tags == TAGS_DEFAULT) {
if (transport->remote->fetch_tags == 2)
@@ -1190,17 +1191,36 @@ static int do_fetch(struct transport *transport,
goto cleanup;
}
 
-   if (rs->nr)
+   if (rs->nr) {
+   int i;
+
refspec_ref_prefixes(rs, &ref_prefixes);
-   else if (transport->remote && transport->remote->fetch.nr)
+
+   /*
+* We can avoid listing refs if all of them are exact
+* OIDs
+*/
+   must_list_refs = 0;
+   for (i = 0; i < rs->nr; i++) {
+   if (!rs->items[i].exact_sha1) {
+   must_list_refs = 1;
+   break;
+   }
+   }
+   } else if (transport->remote && transport->remote->fetch.nr)
refspec_ref_prefixes(&transport->remote->fetch, &ref_prefixes);
 
-   if (ref_prefixes.argc &&
-   (tags == TAGS_SET || (tags == TAGS_DEFAULT))) {
-   argv_array_push(&ref_prefixes, "refs/tags/");
+   if (tags == TAGS_SET || tags == TAGS_DEFAULT) {
+   must_list_refs = 1;
+   if (ref_prefixes.argc)
+   argv_array_push(&ref_prefixes, "refs/tags/");
}
 
-   remote_refs = transport_get_remote_refs(transport, &ref_prefixes);
+   if (must_list_refs)
+   remote_refs = transport_get_remote_refs(transport, 
&ref_prefixes);
+   else
+   remote_refs = NULL;
+
argv_array_clear(&ref_prefixes);
 
ref_map = get_ref_map(transport->remote, remote_refs, rs,
diff --git a/t/t5551-http-fetch-smart.sh b/t/t5551-http-fetch-smart.sh
index 771f36f9ff..12b339d239 100755
--- a/t/t5551-http-fetch-smart.sh
+++ b/t/t5551-http-fetch-smart.sh
@@ -381,6 +381,21 @@ test_expect_success 'using fetch command in remote-curl 
updates refs' '
test_cmp expect actual
 '
 
+test_expect_success 'fetch by SHA-1 without tag following' '
+   SERVER="$HTTPD_DOCUMENT_ROOT_PATH/server" &&
+   rm -rf "$SERVER" client &&
+
+   git init "$SERVER" &&
+   test_commit -C "$SERVER" foo &&
+
+   git clone $HTTPD_URL/smart/server client &&
+
+   test_commit -C "$SERVER" bar &&
+   git -C "$SERVER" rev-parse bar >bar_hash &&
+   git -C client -c protocol.version=0 fetch \
+   --no-tags origin $(cat bar_hash)
+'
+
 test_expect_success 'GIT_REDACT_COOKIES redacts cookies' '
rm -rf clone &&
echo "Set-Cookie: Foo=1" >cookies &&
diff --git a/t/t5702-protocol-v2.sh b/t/t5702-protocol-v2.sh
index a316bb9bf4..1a97331648 100755
--- a/t/t5702-protocol-v2.sh
+++ b/t/t5702-protocol-v2.sh
@@ -79,6 +79,19 @@ test_expect_success 'fetch with git:// using protocol v2' '
grep "fetch< version 2" log
 '
 
+test_expect_success 'fetch by hash without tag following with protocol v2 does 
not list refs' '
+   test_when_finished "rm -f log" &&
+
+   test_commit -C "$daemon_parent" two_a &&
+   git -C "$daemon_parent" rev-parse two_a >two_a_hash &&
+
+   GIT_TRACE_PACKET="$(pwd)/log" git -C daemon_child -c protocol.version=2 
\
+   fetch --no-tags origin $(cat two_a_hash) &&
+
+   grep "fetch< version 2" log &&
+   ! grep "fetch> command=ls-refs" log
+'
+
 test_expect_success 'pull with git:// using protocol v2' '
test_when_finished "rm -f log" &&
 
-- 
2.19.0.605.g01d371f741-goog