pre-push: find named remote for URL if possible

Some users use tools like JGit, which use URLs instead of named remotes
when invoking the pre-push hook.  This is problematic because we use
remote-tracking branches to optimize our ref walk and when a user is
using a URL, we can't apply that optimization since we don't know which
named remote is being used.

However, if we have a named remote with only one URL, we can apply this
optimization by looking up the remote name and using that as our remote
instead.  We do this only in the pre-push hook, since this is the major
time that we need to walk the history.

Add some unit and integration tests for this and also update one of the
existing integration tests which was relying on the previous behavior by
switching it to use an equivalent URL instead of the actual remote URL.

commands/command_pre_push.go

@@ -47,7 +47,8 @@ func prePushCommand(cmd *cobra.Command, args []string) {
 	requireGitVersion()
 
 	// Remote is first arg
-	if err := cfg.SetValidPushRemote(args[0]); err != nil {
+	remote, _ := git.MapRemoteURL(args[0], true)
+	if err := cfg.SetValidPushRemote(remote); err != nil {
 		Exit("Invalid remote name %q: %s", args[0], err)
 	}
 

git/git.go

@@ -353,6 +353,54 @@ func RemoteList() ([]string, error) {
 	return ret, nil
 }
 
+func RemoteURLs(push bool) (map[string][]string, error) {
+	cmd := gitNoLFS("remote", "-v")
+
+	outp, err := cmd.StdoutPipe()
+	if err != nil {
+		return nil, fmt.Errorf("failed to call git remote -v: %v", err)
+	}
+	cmd.Start()
+	defer cmd.Wait()
+
+	scanner := bufio.NewScanner(outp)
+
+	text := "(fetch)"
+	if push {
+		text = "(push)"
+	}
+	ret := make(map[string][]string)
+	for scanner.Scan() {
+		// [remote, urlpair-text]
+		pair := strings.Split(strings.TrimSpace(scanner.Text()), "\t")
+		if len(pair) != 2 {
+			continue
+		}
+		// [url, "(fetch)" | "(push)"]
+		urlpair := strings.Split(pair[1], " ")
+		if len(urlpair) != 2 || urlpair[1] != text {
+			continue
+		}
+		ret[pair[0]] = append(ret[pair[0]], urlpair[0])
+	}
+
+	return ret, nil
+}
+
+func MapRemoteURL(url string, push bool) (string, bool) {
+	urls, err := RemoteURLs(push)
+	if err != nil {
+		return url, false
+	}
+
+	for name, remotes := range urls {
+		if len(remotes) == 1 && url == remotes[0] {
+			return name, true
+		}
+	}
+	return url, false
+}
+
 // Refs returns all of the local and remote branches and tags for the current
 // repository. Other refs (HEAD, refs/stash, git notes) are ignored.
 func LocalRefs() ([]*Ref, error) {

git/git_test.go

@@ -702,3 +702,90 @@ func TestRefTypeKnownPrefixes(t *testing.T) {
 		assert.Equal(t, expected.Ok, ok)
 	}
 }
+
+func TestRemoteURLs(t *testing.T) {
+	repo := test.NewRepo(t)
+	repo.Pushd()
+	defer func() {
+		repo.Popd()
+		repo.Cleanup()
+	}()
+	cfg := repo.GitConfig()
+	cfg.SetLocal("remote.foo.url", "https://github.com/git-lfs/git-lfs.git")
+	cfg.SetLocal("remote.bar.url", "https://github.com/git-lfs/wildmatch.git")
+	cfg.SetLocal("remote.bar.pushurl", "https://github.com/git-lfs/pktline.git")
+
+	expected := make(map[string][]string)
+	expected["foo"] = []string{"https://github.com/git-lfs/git-lfs.git"}
+	expected["bar"] = []string{"https://github.com/git-lfs/wildmatch.git"}
+	actual, err := RemoteURLs(false)
+	assert.Nil(t, err)
+	assert.Equal(t, expected, actual)
+
+	expected["bar"] = []string{"https://github.com/git-lfs/pktline.git"}
+	actual, err = RemoteURLs(true)
+	assert.Nil(t, err)
+	assert.Equal(t, expected, actual)
+}
+
+func TestMapRemoteURL(t *testing.T) {
+	repo := test.NewRepo(t)
+	repo.Pushd()
+	defer func() {
+		repo.Popd()
+		repo.Cleanup()
+	}()
+	cfg := repo.GitConfig()
+	cfg.SetLocal("remote.foo.url", "https://github.com/git-lfs/git-lfs.git")
+	cfg.SetLocal("remote.bar.url", "https://github.com/git-lfs/wildmatch.git")
+	cfg.SetLocal("remote.bar.pushurl", "https://github.com/git-lfs/pktline.git")
+
+	tests := []struct {
+		url   string
+		push  bool
+		match bool
+		val   string
+	}{
+		{
+			"https://github.com/git-lfs/git-lfs.git",
+			false,
+			true,
+			"foo",
+		},
+		{
+			"https://github.com/git-lfs/git-lfs.git",
+			true,
+			true,
+			"foo",
+		},
+		{
+			"https://github.com/git-lfs/wildmatch.git",
+			false,
+			true,
+			"bar",
+		},
+		{
+			"https://github.com/git-lfs/pktline.git",
+			true,
+			true,
+			"bar",
+		},
+		{
+			"https://github.com/git-lfs/pktline.git",
+			false,
+			false,
+			"https://github.com/git-lfs/pktline.git",
+		},
+		{
+			"https://github.com/git/git.git",
+			true,
+			false,
+			"https://github.com/git/git.git",
+		},
+	}
+	for _, test := range tests {
+		val, ok := MapRemoteURL(test.url, test.push)
+		assert.Equal(t, ok, test.match)
+		assert.Equal(t, val, test.val)
+	}
+}

t/t-pre-push.sh

@@ -1181,6 +1181,28 @@ begin_test "pre-push with pushDefault and explicit remote"
 )
 end_test
 
+begin_test "pre-push uses optimization if remote URL matches"
+(
+  set -e
+  reponame="pre-push-remote-url-optimization"
+  setup_remote_repo "$reponame"
+  clone_repo "$reponame" "$reponame"
+
+  endpoint=$(git config remote.origin.url)
+  contents_oid=$(calc_oid 'hi\n')
+  git config "lfs.$endpoint.locksverify" false
+  git lfs track "*.dat"
+  echo "hi" > a.dat
+  git add .gitattributes a.dat
+  git commit -m "add a.dat"
+
+  refute_server_object "$reponame" $contents_oid "refs/heads/master"
+
+  GIT_TRACE=1 GIT_TRANSFER_TRACE=1 git push "$endpoint" master 2>&1 | tee push.log
+  grep 'rev-list.*--not --remotes=origin' push.log
+)
+end_test
+
 begin_test "pre-push does not traverse Git objects server has"
 (
   set -e
@@ -1198,10 +1220,10 @@ begin_test "pre-push does not traverse Git objects server has"
 
   refute_server_object "$reponame" $contents_oid "refs/heads/master"
 
-  # We use a URL instead of a named remote so that we can't make use of the
-  # optimization that ignores objects we already have in remote tracking
-  # branches.
-  GIT_TRACE=1 GIT_TRANSFER_TRACE=1 git push "$endpoint" master 2>&1 | tee push.log
+  # We use a different URL instead of a named remote or the remote URL so that
+  # we can't make use of the optimization that ignores objects we already have
+  # in remote tracking branches.
+  GIT_TRACE=1 GIT_TRANSFER_TRACE=1 git push "$endpoint.git" master 2>&1 | tee push.log
 
   assert_server_object "$reponame" $contents_oid "refs/heads/master"
 
@@ -1212,7 +1234,7 @@ begin_test "pre-push does not traverse Git objects server has"
 
   refute_server_object "$reponame" $contents2_oid "refs/heads/master"
 
-  GIT_TRACE=1 GIT_TRANSFER_TRACE=1 git push "$endpoint" master 2>&1 | tee push.log
+  GIT_TRACE=1 GIT_TRANSFER_TRACE=1 git push "$endpoint.git" master 2>&1 | tee push.log
 
   assert_server_object "$reponame" $contents2_oid "refs/heads/master"