Merge branch 'jt/push-negotiation'

"git push" learns to discover common ancestor with the receiving
end over protocol v2.

* jt/push-negotiation:
  send-pack: support push negotiation
  fetch: teach independent negotiation (no packfile)
  fetch-pack: refactor command and capability write
  fetch-pack: refactor add_haves()
  fetch-pack: refactor process_acks()

3 files changed, 125 insertions, 1 deletions

diff --git a/t/t5516-fetch-push.sh b/t/t5516-fetch-push.sh
index f11742ed59..0916f76302 100755
--- a/t/t5516-fetch-push.sh
+++ b/t/t5516-fetch-push.sh
@@ -191,6 +191,41 @@ test_expect_success 'fetch with pushInsteadOf (should not rewrite)' '
 	)
 '
 
+grep_wrote () {
+	object_count=$1
+	file_name=$2
+	grep 'write_pack_file/wrote.*"value":"'$1'"' $2
+}
+
+test_expect_success 'push with negotiation' '
+	# Without negotiation
+	mk_empty testrepo &&
+	git push testrepo $the_first_commit:refs/remotes/origin/first_commit &&
+	git -C testrepo config receive.hideRefs refs/remotes/origin/first_commit &&
+	echo now pushing without negotiation &&
+	GIT_TRACE2_EVENT="$(pwd)/event" git -c protocol.version=2 push testrepo refs/heads/main:refs/remotes/origin/main &&
+	grep_wrote 5 event && # 2 commits, 2 trees, 1 blob
+
+	# Same commands, but with negotiation
+	rm event &&
+	mk_empty testrepo &&
+	git push testrepo $the_first_commit:refs/remotes/origin/first_commit &&
+	git -C testrepo config receive.hideRefs refs/remotes/origin/first_commit &&
+	GIT_TRACE2_EVENT="$(pwd)/event" git -c protocol.version=2 -c push.negotiate=1 push testrepo refs/heads/main:refs/remotes/origin/main &&
+	grep_wrote 2 event # 1 commit, 1 tree
+'
+
+test_expect_success 'push with negotiation proceeds anyway even if negotiation fails' '
+	rm event &&
+	mk_empty testrepo &&
+	git push testrepo $the_first_commit:refs/remotes/origin/first_commit &&
+	git -C testrepo config receive.hideRefs refs/remotes/origin/first_commit &&
+	GIT_TEST_PROTOCOL_VERSION=0 GIT_TRACE2_EVENT="$(pwd)/event" \
+		git -c push.negotiate=1 push testrepo refs/heads/main:refs/remotes/origin/main 2>err &&
+	grep_wrote 5 event && # 2 commits, 2 trees, 1 blob
+	test_i18ngrep "push negotiation failed" err
+'
+
 test_expect_success 'push without wildcard' '
 	mk_empty testrepo &&
 
diff --git a/t/t5701-git-serve.sh b/t/t5701-git-serve.sh
index 73e74a9c54..930721f053 100755
--- a/t/t5701-git-serve.sh
+++ b/t/t5701-git-serve.sh
@@ -16,7 +16,7 @@ test_expect_success 'test capability advertisement' '
 	version 2
 	agent=git/$(git version | cut -d" " -f3)
 	ls-refs=unborn
-	fetch=shallow
+	fetch=shallow wait-for-done
 	server-option
 	object-format=$(test_oid algo)
 	object-info
diff --git a/t/t5702-protocol-v2.sh b/t/t5702-protocol-v2.sh
index 2e1243ca40..66af411057 100755
--- a/t/t5702-protocol-v2.sh
+++ b/t/t5702-protocol-v2.sh
@@ -585,6 +585,49 @@ test_expect_success 'deepen-relative' '
 	test_cmp expected actual
 '
 
+setup_negotiate_only () {
+	SERVER="$1"
+	URI="$2"
+
+	rm -rf "$SERVER" client
+
+	git init "$SERVER"
+	test_commit -C "$SERVER" one
+	test_commit -C "$SERVER" two
+
+	git clone "$URI" client
+	test_commit -C client three
+}
+
+test_expect_success 'file:// --negotiate-only' '
+	SERVER="server" &&
+	URI="file://$(pwd)/server" &&
+
+	setup_negotiate_only "$SERVER" "$URI" &&
+
+	git -c protocol.version=2 -C client fetch \
+		--no-tags \
+		--negotiate-only \
+		--negotiation-tip=$(git -C client rev-parse HEAD) \
+		origin >out &&
+	COMMON=$(git -C "$SERVER" rev-parse two) &&
+	grep "$COMMON" out
+'
+
+test_expect_success 'file:// --negotiate-only with protocol v0' '
+	SERVER="server" &&
+	URI="file://$(pwd)/server" &&
+
+	setup_negotiate_only "$SERVER" "$URI" &&
+
+	test_must_fail git -c protocol.version=0 -C client fetch \
+		--no-tags \
+		--negotiate-only \
+		--negotiation-tip=$(git -C client rev-parse HEAD) \
+		origin 2>err &&
+	test_i18ngrep "negotiate-only requires protocol v2" err
+'
+
 # Test protocol v2 with 'http://' transport
 #
 . "$TEST_DIRECTORY"/lib-httpd.sh
@@ -1035,6 +1078,52 @@ test_expect_success 'packfile-uri with transfer.fsckobjects fails when .gitmodul
 	test_i18ngrep "disallowed submodule name" err
 '
 
+test_expect_success 'http:// --negotiate-only' '
+	SERVER="$HTTPD_DOCUMENT_ROOT_PATH/server" &&
+	URI="$HTTPD_URL/smart/server" &&
+
+	setup_negotiate_only "$SERVER" "$URI" &&
+
+	git -c protocol.version=2 -C client fetch \
+		--no-tags \
+		--negotiate-only \
+		--negotiation-tip=$(git -C client rev-parse HEAD) \
+		origin >out &&
+	COMMON=$(git -C "$SERVER" rev-parse two) &&
+	grep "$COMMON" out
+'
+
+test_expect_success 'http:// --negotiate-only without wait-for-done support' '
+	SERVER="server" &&
+	URI="$HTTPD_URL/one_time_perl/server" &&
+
+	setup_negotiate_only "$SERVER" "$URI" &&
+
+	echo "s/ wait-for-done/ xxxx-xxx-xxxx/" \
+		>"$HTTPD_ROOT_PATH/one-time-perl" &&
+
+	test_must_fail git -c protocol.version=2 -C client fetch \
+		--no-tags \
+		--negotiate-only \
+		--negotiation-tip=$(git -C client rev-parse HEAD) \
+		origin 2>err &&
+	test_i18ngrep "server does not support wait-for-done" err
+'
+
+test_expect_success 'http:// --negotiate-only with protocol v0' '
+	SERVER="$HTTPD_DOCUMENT_ROOT_PATH/server" &&
+	URI="$HTTPD_URL/smart/server" &&
+
+	setup_negotiate_only "$SERVER" "$URI" &&
+
+	test_must_fail git -c protocol.version=0 -C client fetch \
+		--no-tags \
+		--negotiate-only \
+		--negotiation-tip=$(git -C client rev-parse HEAD) \
+		origin 2>err &&
+	test_i18ngrep "negotiate-only requires protocol v2" err
+'
+
 # DO NOT add non-httpd-specific tests here, because the last part of this
 # test script is only executed when httpd is available and enabled.