Rename matcherCache to matcherIndex (#4703)

* Rename matcherCache to matcherIndex

The matcherCache is in fact not a cache.
We never used to evict from it, and now we need to update it when we
update the state, as such call it a name that identifies its purpose.

Signed-off-by: Guido Trotter <[email protected]>

* Update silence/silence.go

Co-authored-by: Ben Kochie <[email protected]>
Signed-off-by: Guido Trotter <[email protected]>

---------

Signed-off-by: Guido Trotter <[email protected]>
Signed-off-by: Guido Trotter <[email protected]>
Co-authored-by: Guido Trotter <[email protected]>
Co-authored-by: Ben Kochie <[email protected]>

Author: 3 people

silence/silence.go

@@ -50,10 +50,10 @@ var ErrNotFound = errors.New("silence not found")
 // ErrInvalidState is returned if the state isn't valid.
 var ErrInvalidState = errors.New("invalid state")
 
-type matcherCache map[string]labels.Matchers
+type matcherIndex map[string]labels.Matchers
 
 // get retrieves the matchers for a given silence.
-func (c matcherCache) get(s *pb.Silence) (labels.Matchers, error) {
+func (c matcherIndex) get(s *pb.Silence) (labels.Matchers, error) {
 	if m, ok := c[s.Id]; ok {
 		return m, nil
 	}
@@ -62,7 +62,7 @@ func (c matcherCache) get(s *pb.Silence) (labels.Matchers, error) {
 
 // add compiles a silences' matchers and adds them to the cache.
 // It returns the compiled matchers.
-func (c matcherCache) add(s *pb.Silence) (labels.Matchers, error) {
+func (c matcherIndex) add(s *pb.Silence) (labels.Matchers, error) {
 	ms := make(labels.Matchers, len(s.Matchers))
 
 	for i, m := range s.Matchers {
@@ -198,7 +198,7 @@ type Silences struct {
 	st        state
 	version   int // Increments whenever silences are added.
 	broadcast func([]byte)
-	mc        matcherCache
+	mi        matcherIndex
 }
 
 // Limits contains the limits for silences.
@@ -228,7 +228,7 @@ type metrics struct {
 	propagatedMessagesTotal               prometheus.Counter
 	maintenanceTotal                      prometheus.Counter
 	maintenanceErrorsTotal                prometheus.Counter
-	matcherCompileCacheSilenceErrorsTotal prometheus.Counter
+	matcherCompileIndexSilenceErrorsTotal prometheus.Counter
 	matcherCompileLoadSnapshotErrorsTotal prometheus.Counter
 }
 
@@ -281,7 +281,7 @@ func newMetrics(r prometheus.Registerer, s *Silences) *metrics {
 		},
 		[]string{"stage"},
 	)
-	m.matcherCompileCacheSilenceErrorsTotal = matcherCompileErrorsTotal.WithLabelValues("cache_silence")
+	m.matcherCompileIndexSilenceErrorsTotal = matcherCompileErrorsTotal.WithLabelValues("index")
 	m.matcherCompileLoadSnapshotErrorsTotal = matcherCompileErrorsTotal.WithLabelValues("load_snapshot")
 	m.queriesTotal = promauto.With(r).NewCounter(prometheus.CounterOpts{
 		Name: "alertmanager_silences_queries_total",
@@ -345,7 +345,7 @@ func New(o Options) (*Silences, error) {
 
 	s := &Silences{
 		clock:     quartz.NewReal(),
-		mc:        matcherCache{},
+		mi:        matcherIndex{},
 		logger:    promslog.NewNopLogger(),
 		retention: o.Retention,
 		limits:    o.Limits,
@@ -477,7 +477,7 @@ func (s *Silences) GC() (int, error) {
 		}
 		if !sil.ExpiresAt.After(now) {
 			delete(s.st, id)
-			delete(s.mc, sil.Silence.Id)
+			delete(s.mi, sil.Silence.Id)
 			n++
 		}
 	}
@@ -559,11 +559,11 @@ func (s *Silences) checkSizeLimits(msil *pb.MeshSilence) error {
 	return nil
 }
 
-func (s *Silences) cacheSilence(sil *pb.Silence) {
+func (s *Silences) indexSilence(sil *pb.Silence) {
 	s.version++
-	_, err := s.mc.add(sil)
+	_, err := s.mi.add(sil)
 	if err != nil {
-		s.metrics.matcherCompileCacheSilenceErrorsTotal.Inc()
+		s.metrics.matcherCompileIndexSilenceErrorsTotal.Inc()
 		s.logger.Error("Failed to compile silence matchers", "silence_id", sil.Id, "err", err)
 	}
 }
@@ -590,7 +590,7 @@ func (s *Silences) setSilence(msil *pb.MeshSilence, now time.Time) error {
 	}
 	_, added := s.st.merge(msil, now)
 	if added {
-		s.cacheSilence(msil.Silence)
+		s.indexSilence(msil.Silence)
 	}
 	s.broadcast(b)
 	return nil
@@ -744,7 +744,7 @@ func QIDs(ids ...string) QueryParam {
 func QMatches(set model.LabelSet) QueryParam {
 	return func(q *query) error {
 		f := func(sil *pb.Silence, s *Silences, _ time.Time) (bool, error) {
-			m, err := s.mc.get(sil)
+			m, err := s.mi.get(sil)
 			if err != nil {
 				return true, err
 			}
@@ -889,8 +889,8 @@ func (s *Silences) loadSnapshot(r io.Reader) error {
 			e.Silence.CreatedBy = e.Silence.Comments[0].Author
 			e.Silence.Comments = nil
 		}
-		// Add to matcher cache, and only if successful, to the new state.
-		if _, err := s.mc.add(e.Silence); err != nil {
+		// Add to matcher index, and only if successful, to the new state.
+		if _, err := s.mi.add(e.Silence); err != nil {
 			s.metrics.matcherCompileLoadSnapshotErrorsTotal.Inc()
 			s.logger.Error("Failed to compile silence matchers during snapshot load", "silence_id", e.Silence.Id, "err", err)
 		} else {
@@ -945,7 +945,7 @@ func (s *Silences) Merge(b []byte) error {
 		merged, added := s.st.merge(e, now)
 		if merged {
 			if added {
-				s.cacheSilence(e.Silence)
+				s.indexSilence(e.Silence)
 			}
 			if !cluster.OversizedMessage(b) {
 				// If this is the first we've seen the message and it's

silence/silence_test.go

@@ -100,7 +100,7 @@ func TestSilenceGCOverTime(t *testing.T) {
 		}
 		for _, sil := range initialState {
 			s.st[sil.Silence.Id] = sil
-			s.cacheSilence(sil.Silence)
+			s.indexSilence(sil.Silence)
 		}
 		want := state{
 			"3": &pb.MeshSilence{Silence: &pb.Silence{Id: "3"}, ExpiresAt: now.Add(time.Second)},
@@ -127,15 +127,15 @@ func TestSilenceGCOverTime(t *testing.T) {
 		}
 		require.NoError(t, s.Set(sil1))
 		require.Len(t, s.st, 1)
-		require.Len(t, s.mc, 1)
+		require.Len(t, s.mi, 1)
 		// Move time forward and both silence and cache entry should be garbage
 		// collected.
 		clock.Advance(time.Minute)
 		n, err := s.GC()
 		require.NoError(t, err)
 		require.Equal(t, 1, n)
 		require.Empty(t, s.st)
-		require.Empty(t, s.mc)
+		require.Empty(t, s.mi)
 	})
 
 	t.Run("replacing a silences does not leak cache entries", func(t *testing.T) {
@@ -154,7 +154,7 @@ func TestSilenceGCOverTime(t *testing.T) {
 		}
 		require.NoError(t, s.Set(sil1))
 		require.Len(t, s.st, 1)
-		require.Len(t, s.mc, 1)
+		require.Len(t, s.mi, 1)
 		// must clone sil1 before replacing it.
 		sil2 := cloneSilence(sil1)
 		sil2.Matchers = []*pb.Matcher{{
@@ -164,15 +164,15 @@ func TestSilenceGCOverTime(t *testing.T) {
 		}}
 		require.NoError(t, s.Set(sil2))
 		require.Len(t, s.st, 2)
-		require.Len(t, s.mc, 2)
+		require.Len(t, s.mi, 2)
 		// Move time forward and both silence and cache entry should be garbage
 		// collected.
 		clock.Advance(time.Minute)
 		n, err := s.GC()
 		require.NoError(t, err)
 		require.Equal(t, 2, n)
 		require.Empty(t, s.st)
-		require.Empty(t, s.mc)
+		require.Empty(t, s.mi)
 	})
 
 	// This test checks for a memory leak that occurred in the matcher cache when
@@ -193,8 +193,8 @@ func TestSilenceGCOverTime(t *testing.T) {
 			EndsAt:   clock.Now().Add(time.Minute),
 		}
 		s.st["1"] = &pb.MeshSilence{Silence: sil1, ExpiresAt: clock.Now().Add(time.Minute)}
-		s.cacheSilence(sil1)
-		require.Len(t, s.mc, 1)
+		s.indexSilence(sil1)
+		require.Len(t, s.mi, 1)
 		// must clone sil1 before updating it.
 		sil2 := cloneSilence(sil1)
 		require.NoError(t, s.Set(sil2))
@@ -203,15 +203,15 @@ func TestSilenceGCOverTime(t *testing.T) {
 		// This check asserts that this no longer happens.
 		s.Query(QMatches(model.LabelSet{"foo": "bar"}))
 		require.Len(t, s.st, 1)
-		require.Len(t, s.mc, 1)
+		require.Len(t, s.mi, 1)
 		// Move time forward and both silence and cache entry should be garbage
 		// collected.
 		clock.Advance(time.Minute)
 		n, err := s.GC()
 		require.NoError(t, err)
 		require.Equal(t, 1, n)
 		require.Empty(t, s.st)
-		require.Empty(t, s.mc)
+		require.Empty(t, s.mi)
 	})
 }
 
@@ -284,7 +284,7 @@ func TestSilencesSnapshot(t *testing.T) {
 		require.NoError(t, err, "opening snapshot file failed")
 
 		// Check again against new nlog instance.
-		s2 := &Silences{mc: matcherCache{}, st: state{}}
+		s2 := &Silences{mi: matcherIndex{}, st: state{}}
 		err = s2.loadSnapshot(f)
 		require.NoError(t, err, "error loading snapshot")
 		require.Equal(t, s1.st, s2.st, "state after loading snapshot did not match snapshotted state")
@@ -947,8 +947,8 @@ func TestQMatches(t *testing.T) {
 		},
 	}
 	for _, c := range cases {
-		silences := &Silences{mc: matcherCache{}, st: state{}}
-		silences.mc.add(c.sil)
+		silences := &Silences{mi: matcherIndex{}, st: state{}}
+		silences.mi.add(c.sil)
 		drop, err := f(c.sil, silences, time.Time{})
 		require.NoError(t, err)
 		require.Equal(t, c.drop, drop, "unexpected filter result")