submatview: remove notifyUpdateLocked from reset

This call appears to only be necessary because reset() was called from
NewMaterializer.

This commit has the constructor set a default value for updateCh, and
removes both the call to reset() from New(), and the call to
notifyUpdateLocked() from reset().

This should ensure that we do not notify the Fetch() call before we have new
values to report.

agent/submatview/materializer.go

@@ -78,8 +78,8 @@ func NewMaterializer(deps Deps) *Materializer {
 		deps:        deps,
 		view:        deps.View,
 		retryWaiter: deps.Waiter,
+		updateCh:    make(chan struct{}),
 	}
-	v.reset()
 	return v
 }
 
@@ -112,8 +112,8 @@ func (m *Materializer) Run(ctx context.Context) {
 	}
 }
 
-// isNonTemporaryOrConsecutiveFailure returns true if the error is a temporary error
-// or if the failures > 0.
+// isNonTemporaryOrConsecutiveFailure returns true if the error is not a
+// temporary error or if failures > 0.
 func isNonTemporaryOrConsecutiveFailure(err error, failures int) bool {
 	// temporary is an interface used by net and other std lib packages to
 	// show error types represent temporary/recoverable errors.
@@ -181,7 +181,6 @@ func (m *Materializer) reset() {
 
 	m.view.Reset()
 	m.index = 0
-	m.notifyUpdateLocked(nil)
 	m.retryWaiter.Reset()
 }
 
@@ -202,9 +201,7 @@ func (m *Materializer) updateView(events []*pbsubscribe.Event, index uint64) err
 // one. It must be called while holding the s.lock lock.
 func (m *Materializer) notifyUpdateLocked(err error) {
 	m.err = err
-	if m.updateCh != nil {
-		close(m.updateCh)
-	}
+	close(m.updateCh)
 	m.updateCh = make(chan struct{})
 }