Check if notes exist before requesting them

This is an optimisation for #714. We perform a single gitCommandExec to
get hashes for all commits with notes, place them into a map and use
them to query whether a commit has a note or not. This prevents
multiple calls to gitCommandExec just to see if there is a note
attached.

daemon/loop.go

@@ -167,6 +167,12 @@ func (d *Daemon) doSync(logger log.Logger) {
 		serviceIDs.Add(r.ServiceIDs(allResources))
 	}
 
+	notes, err := working.NoteRevList()
+	if err != nil {
+		logger.Log("err", errors.Wrap(err, "loading notes from repo"))
+		return
+	}
+
 	// Collect any events that come from notes attached to the commits
 	// we just synced. While we're doing this, keep track of what
 	// other things this sync includes e.g., releases and
@@ -178,6 +184,10 @@ func (d *Daemon) doSync(logger log.Logger) {
 
 		// Find notes in revisions.
 		for i := len(commits) - 1; i >= 0; i-- {
+			if ok := notes[commits[i].Revision]; !ok {
+				includes[history.NoneOfTheAbove] = true
+				continue
+			}
 			n, err := working.GetNote(commits[i].Revision)
 			if err != nil {
 				logger.Log("err", errors.Wrap(err, "loading notes from repo; possibly no notes"))

git/operations_test.go

@@ -2,13 +2,14 @@ package git
 
 import (
 	"fmt"
-	"github.com/weaveworks/flux/cluster/kubernetes/testfiles"
-	"github.com/weaveworks/flux/job"
-	"github.com/weaveworks/flux/update"
 	"io/ioutil"
 	"os/exec"
 	"path"
 	"testing"
+
+	"github.com/weaveworks/flux/cluster/kubernetes/testfiles"
+	"github.com/weaveworks/flux/job"
+	"github.com/weaveworks/flux/update"
 )
 
 const (
@@ -23,13 +24,19 @@ func TestListNotes_2Notes(t *testing.T) {
 	newDir, cleanup := testfiles.TempDir(t)
 	defer cleanup()
 
-	err := createRepo(newDir, "")
+	err := createRepo(newDir, "another")
 	if err != nil {
 		t.Fatal(err)
 	}
 
-	idHEAD_1 := testNote(newDir, "HEAD~1")
-	idHEAD := testNote(newDir, "HEAD")
+	idHEAD_1, err := testNote(newDir, "HEAD~1")
+	if err != nil {
+		t.Fatal(err)
+	}
+	idHEAD, err := testNote(newDir, "HEAD")
+	if err != nil {
+		t.Fatal(err)
+	}
 
 	notes, err := noteRevList(newDir, testNoteRef)
 	if err != nil {
@@ -58,7 +65,7 @@ func TestListNotes_0Notes(t *testing.T) {
 	newDir, cleanup := testfiles.TempDir(t)
 	defer cleanup()
 
-	err := createRepo(newDir, "")
+	err := createRepo(newDir, "another")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -73,10 +80,10 @@ func TestListNotes_0Notes(t *testing.T) {
 	}
 }
 
-func testNote(dir, rev string) job.ID {
+func testNote(dir, rev string) (job.ID, error) {
 	id := job.ID(fmt.Sprintf("%v", noteIdCounter))
 	noteIdCounter += 1
-	addNote(dir, rev, testNoteRef, &Note{
+	err := addNote(dir, rev, testNoteRef, &Note{
 		id,
 		update.Spec{
 			update.Auto,
@@ -88,7 +95,7 @@ func testNote(dir, rev string) job.ID {
 		},
 		update.Result{},
 	})
-	return id
+	return id, err
 }
 
 func TestChangedFiles_SlashPath(t *testing.T) {
@@ -148,28 +155,27 @@ func createRepo(dir string, nestedDir string) error {
 	if err = execCommand("git", "-C", dir, "init"); err != nil {
 		return err
 	}
-	if err := execCommand("mkdir", "-p", fullPath); err != nil {
-		return err
-	}
-	if err = testfiles.WriteTestFiles(fullPath); err != nil {
+
+	if err := execCommand("git", "-C", dir, "config", "user.name", "notes test"); err != nil {
 		return err
 	}
-	if err = execCommand("git", "-C", dir, "add", "--all"); err != nil {
+
+	if err := execCommand("git", "-C", dir, "config", "user.email", "example@example.com"); err != nil {
 		return err
 	}
-	if err = execCommand("git", "-C", dir, "commit", "-m", "'Initial revision'"); err != nil {
+	if err := execCommand("mkdir", "-p", fullPath); err != nil {
 		return err
 	}
-	if err := execCommand("mkdir", "-p", path.Join(fullPath, "another")); err != nil {
+	if err = testfiles.WriteTestFiles(fullPath); err != nil {
 		return err
 	}
-	if err = testfiles.WriteTestFiles(path.Join(fullPath, "another")); err != nil {
+	if err = execCommand("git", "-C", dir, "add", "--all"); err != nil {
 		return err
 	}
-	if err = execCommand("git", "-C", dir, "add", "--all"); err != nil {
+	if err = execCommand("git", "-C", dir, "commit", "-m", "'Initial revision'"); err != nil {
 		return err
 	}
-	if err = execCommand("git", "-C", dir, "commit", "-m", "'Second revision'"); err != nil {
+	if err = execCommand("git", "-C", dir, "commit", "--allow-empty", "-m", "'Second revision'"); err != nil {
 		return err
 	}
 	return nil

git/repo.go

@@ -233,3 +233,9 @@ func (c *Checkout) ChangedFiles(ref string) ([]string, error) {
 	}
 	return list, err
 }
+
+func (c *Checkout) NoteRevList() (map[string]bool, error) {
+	c.Lock()
+	defer c.Unlock()
+	return noteRevList(c.Dir, c.SyncTag)
+}