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[PATCH/RFC 5/6] fetch: pass refspec to http server

From
David Turner <dturner@twopensource.com>
Date
Apr 15, 2016, 19:19 UTC
Message-ID
<1460747949-3514-6-git-send-email-dturner@twopensource.com>
In-Reply-To
<1460747949-3514-1-git-send-email-dturner@twopensource.com>

When fetching over http, send the requested refspec to the server. The server will then only send refs matching that refspec. It is permitted for old servers to ignore that parameter, and the client will automatically handle this.

When the server has many refs, and the client only wants a few, this can save bandwidth and reduce fetch latency.

Signed-off-by: David Turner <dturner@twopensource.com>
---
 Documentation/technical/protocol-capabilities.txt | 23 +++++++++++++
 builtin/fetch.c                                   | 20 ++++++++++-
 remote-curl.c                                     |  7 ++++
 t/t5552-http-fetch-branch.sh                      | 42 +++++++++++++++++++++++
 transport-helper.c                                |  8 ++++-
 5 files changed, 98 insertions(+), 2 deletions(-)
 create mode 100755 t/t5552-http-fetch-branch.sh
diff --git a/Documentation/technical/protocol-capabilities.txt b/Documentation/technical/protocol-capabilities.txt
index eaab6b4..8c4a0b9 100644
--- a/Documentation/technical/protocol-capabilities.txt
+++ b/Documentation/technical/protocol-capabilities.txt
@@ -275,3 +275,26 @@ to accept a signed push certificate, and asks the <nonce> to be
 included in the push certificate.  A send-pack client MUST NOT
 send a push-cert packet unless the receive-pack server advertises
 this capability.
+
+interesting-refs
+----------------
+
+For HTTP(S) servers only:
+
+Whether or not the upload-pack server advertises this capability,
+fetch-pack may send a "refspec" parameter in the query string of a
+fetch request.  This capability indicates that such a parameter will
+be respected, in case the client cares.
+
+Whenever the receive-pack server gets that parameter, it will not
+advertise all refs and will instead only advertise refs that match
+those listed in the header. The parameter is a space-separated list of
+refs.  A ref may optionally contain up to one wildcard.
+Advertisements will still respect hideRefs.
+
+The presence or absence of the "refspec" parameter does not affect
+what refs a client is permitted to fetch; this is still controlled in
+the normal fashion.
+
+This saves time in the presence of a large number of refs, because the
+client need not wait for the server to send the complete list of refs.
diff --git a/builtin/fetch.c b/builtin/fetch.c
index cafab37..c22a92f 100644
--- a/builtin/fetch.c
+++ b/builtin/fetch.c
@@ -302,9 +302,27 @@ static struct ref *get_ref_map(struct transport *transport,
 
 	/* opportunistically-updated references: */
 	struct ref *orefs = NULL, **oref_tail = &orefs;
+	struct refspec *qualified_refspecs;
 	const struct ref *remote_refs;
 
-	remote_refs = transport_get_remote_refs(transport, NULL, 0);
+	qualified_refspecs = xcalloc(refspec_count, sizeof(*qualified_refspecs));
+	for (i = 0; i < refspec_count; i++) {
+		if (starts_with(refspecs[i].src, "refs/")) {
+			qualified_refspecs[i].src = xstrdup(refspecs[i].src);
+		} else {
+			struct strbuf buf = STRBUF_INIT;
+			strbuf_addf(&buf, "refs/heads/%s", refspecs[i].src);
+			qualified_refspecs[i].src = strbuf_detach(&buf, NULL);
+		}
+	}
+
+	remote_refs = transport_get_remote_refs(transport, qualified_refspecs,
+						refspec_count);
+
+	for (i = 0; i < refspec_count; i++) {
+		free(qualified_refspecs[i].src);
+	}
+	free(qualified_refspecs);
 
 	if (refspec_count) {
 		struct refspec *fetch_refspec;
diff --git a/remote-curl.c b/remote-curl.c
index b9b6a90..e914d3f 100644
--- a/remote-curl.c
+++ b/remote-curl.c
@@ -20,6 +20,7 @@ static struct strbuf url = STRBUF_INIT;
 struct options {
 	int verbosity;
 	unsigned long depth;
+	char *refspec;
 	unsigned progress : 1,
 		check_self_contained_and_connected : 1,
 		cloning : 1,
@@ -43,6 +44,10 @@ static int set_option(const char *name, const char *value)
 		options.verbosity = v;
 		return 0;
 	}
+	else if (!strcmp(name, "refspec")) {
+		options.refspec = xstrdup(value);
+		return 0;
+	}
 	else if (!strcmp(name, "progress")) {
 		if (!strcmp(value, "true"))
 			options.progress = 1;
@@ -269,6 +274,8 @@ static struct discovery *discover_refs(const char *service, int for_push)
 		else
 			strbuf_addch(&refs_url, '&');
 		strbuf_addf(&refs_url, "service=%s", service);
+		if (options.refspec)
+			strbuf_addf(&refs_url, "&refspec=%s", options.refspec);
 	}
 
 	memset(&get_options, 0, sizeof(get_options));
diff --git a/t/t5552-http-fetch-branch.sh b/t/t5552-http-fetch-branch.sh
new file mode 100755
index 0000000..0e905d9
--- /dev/null
+++ b/t/t5552-http-fetch-branch.sh
@@ -0,0 +1,42 @@
+#!/bin/sh
+
+test_description='fetch just one branch'
+
+. ./test-lib.sh
+. "$TEST_DIRECTORY"/lib-httpd.sh
+start_httpd
+
+test_expect_success 'setup repo' '
+	git init "$HTTPD_DOCUMENT_ROOT_PATH/repo.git" &&
+	(
+		cd "$HTTPD_DOCUMENT_ROOT_PATH/repo.git" &&
+		test_commit 1
+	)
+'
+
+test_expect_success 'clone http repository' '
+	git clone $HTTPD_URL/smart/repo.git clone
+'
+
+test_expect_success 'make some more commits' '
+	(
+		cd "$HTTPD_DOCUMENT_ROOT_PATH/repo.git" &&
+		test_commit 2 &&
+		git checkout -b another_branch &&
+		test_commit 3
+		git checkout -b a_third_branch &&
+		test_commit 4
+	)
+'
+
+test_expect_success 'fetch with refspec only fetches requested branch' '
+	test_when_finished "rm trace" &&
+	(
+		cd clone &&
+		GIT_TRACE_PACKET="$TRASH_DIRECTORY/trace" git fetch origin another_branch &&
+		! grep "refs/heads/master" ../trace
+	)
+'
+
+stop_httpd
+test_done
diff --git a/transport-helper.c b/transport-helper.c
index b5c91d2..7d75d64 100644
--- a/transport-helper.c
+++ b/transport-helper.c
@@ -40,6 +40,9 @@ struct helper_data {
 	struct git_transport_options transport_options;
 };
 
+static int set_helper_option(struct transport *transport,
+			     const char *name, const char *value);
+
 static void sendline(struct helper_data *helper, struct strbuf *buffer)
 {
 	if (debug)
@@ -109,6 +112,7 @@ static struct child_process *get_helper(struct transport *transport, const struc
 	int refspec_alloc = 0;
 	int duped;
 	int code;
+	int i;
 
 	if (data->helper)
 		return data->helper;
@@ -202,7 +206,6 @@ static struct child_process *get_helper(struct transport *transport, const struc
 		}
 	}
 	if (refspecs) {
-		int i;
 		data->refspec_nr = refspec_nr;
 		data->refspecs = parse_fetch_refspec(refspec_nr, refspecs);
 		for (i = 0; i < refspec_nr; i++)
@@ -214,6 +217,9 @@ static struct child_process *get_helper(struct transport *transport, const struc
 	strbuf_release(&buf);
 	if (debug)
 		fprintf(stderr, "Debug: Capabilities complete.\n");
+
+	for (i = 0; i < req_refspec_nr; i++)
+		set_helper_option(transport, "refspec", req_refspecs[i].src);
 	standard_options(transport);
 	return data->helper;
 }

-- 
2.4.2.767.g62658d5-twtrsrc
Previous: David TurnerNext: Eric Sunshine
Message 30 of 36 in “fetch with refspec”
  1. 0/6 fetch with refspecDavid Turner, Apr 15, 2016
  2. 1/6 http-backend: use argv_array functionsDavid Turner, Apr 15, 2016
  3. Junio C HamanoApr 18, 2016
  4. David TurnerApr 19, 2016
  5. 2/6 remote-curl.c: fix variable shadowingDavid Turner, Apr 15, 2016
  6. Junio C HamanoApr 18, 2016
  7. David TurnerApr 19, 2016
  8. 3/6 http-backend: handle refspec argumentDavid Turner, Apr 15, 2016
  9. Eric SunshineApr 17, 2016
  10. David TurnerApr 19, 2016
  11. 4/6 transport: add refspec list parameters to functionsDavid Turner, Apr 15, 2016
  12. Junio C HamanoApr 18, 2016
  13. Jeff KingApr 19, 2016
  14. Stefan BellerApr 19, 2016
  15. Junio C HamanoApr 19, 2016
  16. David TurnerApr 19, 2016
  17. Jeff KingApr 19, 2016
  18. David TurnerApr 19, 2016
  19. Jeff KingApr 20, 2016
  20. David TurnerApr 20, 2016
  21. Jeff KingApr 20, 2016
  22. David TurnerApr 25, 2016
  23. Stefan BellerApr 25, 2016
  24. Stefan BellerApr 27, 2016
  25. Jeff KingApr 27, 2016
  26. Junio C HamanoApr 27, 2016
  27. David TurnerApr 29, 2016
  28. Stefan BellerApr 29, 2016
  29. David TurnerApr 19, 2016
  30. 5/6 fetch: pass refspec to http serverDavid Turner, Apr 15, 2016
  31. Eric SunshineApr 17, 2016
  32. David TurnerApr 19, 2016
  33. 6/6 clone: send refspec for single-branch clonesDavid Turner, Apr 15, 2016
  34. Eric SunshineApr 17, 2016
  35. David TurnerApr 19, 2016
  36. Stefan BellerApr 15, 2016

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