submatview: more test cases for Store.Get

And simplify the return value by using a Result type.

agent/submatview/materializer.go

@@ -215,17 +215,17 @@ func (m *Materializer) notifyUpdateLocked(err error) {
 	m.updateCh = make(chan struct{})
 }
 
-type viewResult struct {
+type Result struct {
 	Index uint64
 	Value interface{}
 }
 
 // getFromView blocks until the index of the View is greater than opts.MinIndex,
 //or the context is cancelled.
-func (m *Materializer) getFromView(ctx context.Context, minIndex uint64) (viewResult, error) {
+func (m *Materializer) getFromView(ctx context.Context, minIndex uint64) (Result, error) {
 	m.lock.Lock()
 
-	result := viewResult{
+	result := Result{
 		Index: m.index,
 		Value: m.view.Result(m.index),
 	}

agent/submatview/store.go

@@ -25,7 +25,6 @@ type entry struct {
 	requests int
 }
 
-// TODO: start expiration loop
 func NewStore() *Store {
 	return &Store{
 		byKey:      make(map[string]entry),
@@ -77,11 +76,7 @@ type Request interface {
 // Get a value from the store, blocking if the store has not yet seen the
 // req.Index value.
 // See agent/cache.Cache.Get for complete documentation.
-func (s *Store) Get(
-	ctx context.Context,
-	req Request,
-	// TODO: only the Index field of ResultMeta is relevant, return a result struct instead.
-) (interface{}, cache.ResultMeta, error) {
+func (s *Store) Get(ctx context.Context, req Request) (Result, error) {
 	info := req.CacheInfo()
 	key, e := s.getEntry(req)
 	defer s.releaseEntry(key)
@@ -94,7 +89,7 @@ func (s *Store) Get(
 	// TODO: does context.DeadlineExceeded need to be translated into a nil error
 	// to match the old interface?
 
-	return result.Value, cache.ResultMeta{Index: result.Index}, err
+	return result, err
 }
 
 // Notify the updateCh when there are updates to the entry identified by req.

agent/submatview/store_test.go

@@ -15,7 +15,7 @@ import (
 	"github.com/hashicorp/consul/proto/pbsubscribe"
 )
 
-func TestStore_Get_Fresh(t *testing.T) {
+func TestStore_Get(t *testing.T) {
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
 
@@ -30,25 +30,102 @@ func TestStore_Get_Fresh(t *testing.T) {
 		newEventServiceHealthRegister(10, 1, "srv1"),
 		newEventServiceHealthRegister(22, 2, "srv1"))
 
-	result, md, err := store.Get(ctx, req)
-	require.NoError(t, err)
-	require.Equal(t, uint64(22), md.Index)
+	runStep(t, "from empty store, starts materializer", func(t *testing.T) {
+		result, err := store.Get(ctx, req)
+		require.NoError(t, err)
+		require.Equal(t, uint64(22), result.Index)
 
-	r, ok := result.(fakeResult)
-	require.True(t, ok)
-	require.Len(t, r.srvs, 2)
-	require.Equal(t, uint64(22), r.index)
+		r, ok := result.Value.(fakeResult)
+		require.True(t, ok)
+		require.Len(t, r.srvs, 2)
+		require.Equal(t, uint64(22), r.index)
 
-	store.lock.Lock()
-	require.Len(t, store.byKey, 1)
-	e := store.byKey[makeEntryKey(req.Type(), req.CacheInfo())]
-	require.Equal(t, 0, e.expiry.Index())
+		store.lock.Lock()
+		defer store.lock.Unlock()
+		require.Len(t, store.byKey, 1)
+		e := store.byKey[makeEntryKey(req.Type(), req.CacheInfo())]
+		require.Equal(t, 0, e.expiry.Index())
+		require.Equal(t, 0, e.requests)
 
-	defer store.lock.Unlock()
-	require.Equal(t, store.expiryHeap.Next().Entry, e.expiry)
+		require.Equal(t, store.expiryHeap.Next().Entry, e.expiry)
+	})
+
+	runStep(t, "with an index that already exists in the view", func(t *testing.T) {
+		req.index = 21
+		result, err := store.Get(ctx, req)
+		require.NoError(t, err)
+		require.Equal(t, uint64(22), result.Index)
+
+		r, ok := result.Value.(fakeResult)
+		require.True(t, ok)
+		require.Len(t, r.srvs, 2)
+		require.Equal(t, uint64(22), r.index)
+
+		store.lock.Lock()
+		defer store.lock.Unlock()
+		require.Len(t, store.byKey, 1)
+		e := store.byKey[makeEntryKey(req.Type(), req.CacheInfo())]
+		require.Equal(t, 0, e.expiry.Index())
+		require.Equal(t, 0, e.requests)
+
+		require.Equal(t, store.expiryHeap.Next().Entry, e.expiry)
+	})
+
+	runStep(t, "blocks with an index that is not yet in the view", func(t *testing.T) {
+		req.index = 23
+
+		chResult := make(chan resultOrError, 1)
+		go func() {
+			result, err := store.Get(ctx, req)
+			chResult <- resultOrError{Result: result, Err: err}
+		}()
+
+		select {
+		case <-chResult:
+			t.Fatalf("expected Get to block")
+		case <-time.After(50 * time.Millisecond):
+		}
+
+		store.lock.Lock()
+		e := store.byKey[makeEntryKey(req.Type(), req.CacheInfo())]
+		store.lock.Unlock()
+		require.Equal(t, 1, e.requests)
+
+		req.client.QueueEvents(newEventServiceHealthRegister(24, 1, "srv1"))
+
+		var getResult resultOrError
+		select {
+		case getResult = <-chResult:
+		case <-time.After(100 * time.Millisecond):
+			t.Fatalf("expected Get to unblock when new events are received")
+		}
+
+		require.NoError(t, getResult.Err)
+		require.Equal(t, uint64(24), getResult.Result.Index)
+
+		r, ok := getResult.Result.Value.(fakeResult)
+		require.True(t, ok)
+		require.Len(t, r.srvs, 2)
+		require.Equal(t, uint64(24), r.index)
+
+		store.lock.Lock()
+		defer store.lock.Unlock()
+		require.Len(t, store.byKey, 1)
+		e = store.byKey[makeEntryKey(req.Type(), req.CacheInfo())]
+		require.Equal(t, 0, e.expiry.Index())
+		require.Equal(t, 0, e.requests)
+
+		require.Equal(t, store.expiryHeap.Next().Entry, e.expiry)
+	})
+}
+
+type resultOrError struct {
+	Result Result
+	Err    error
 }
 
 type fakeRequest struct {
+	index  uint64
 	client *TestStreamingClient
 }
 
@@ -58,6 +135,7 @@ func (r *fakeRequest) CacheInfo() cache.RequestInfo {
 		Token:      "abcd",
 		Datacenter: "dc1",
 		Timeout:    4 * time.Second,
+		MinIndex:   r.index,
 	}
 }
 
@@ -125,8 +203,7 @@ func (f *fakeView) Reset() {
 	f.srvs = make(map[string]*pbservice.CheckServiceNode)
 }
 
-// TODO: Get with an entry that already has index
-// TODO: Get with an entry that is not yet at index
+// TODO: Get with Notify
 
 func TestStore_Notify(t *testing.T) {
 	// TODO: Notify with no existing entry
@@ -134,3 +211,10 @@ func TestStore_Notify(t *testing.T) {
 	// TODO: Notify multiple times same key
 	// TODO: Notify no update if index is not past MinIndex.
 }
+
+func runStep(t *testing.T, name string, fn func(t *testing.T)) {
+	t.Helper()
+	if !t.Run(name, fn) {
+		t.FailNow()
+	}
+}