region_cache: filter peers on tombstone or dropped stores (#24726) (#…

…25849)

go.mod

@@ -28,6 +28,7 @@ require (
 	github.com/grpc-ecosystem/go-grpc-middleware v1.1.0
 	github.com/grpc-ecosystem/grpc-gateway v1.14.3 // indirect
 	github.com/iancoleman/strcase v0.0.0-20191112232945-16388991a334
+	github.com/kisielk/errcheck v1.2.0 // indirect
 	github.com/klauspost/cpuid v1.2.1
 	github.com/kr/pretty v0.2.0 // indirect
 	github.com/mattn/go-colorable v0.1.7 // indirect

go.sum

@@ -271,6 +271,7 @@ github.com/juju/ratelimit v1.0.1 h1:+7AIFJVQ0EQgq/K9+0Krm7m530Du7tIz0METWzN0RgY=
 github.com/juju/ratelimit v1.0.1/go.mod h1:qapgC/Gy+xNh9UxzV13HGGl/6UXNN+ct+vwSgWNm/qk=
 github.com/julienschmidt/httprouter v1.2.0/go.mod h1:SYymIcj16QtmaHHD7aYtjjsJG7VTCxuUUipMqKk8s4w=
 github.com/kisielk/errcheck v1.1.0/go.mod h1:EZBBE59ingxPouuu3KfxchcWSUPOHkagtvWXihfKN4Q=
+github.com/kisielk/errcheck v1.2.0 h1:reN85Pxc5larApoH1keMBiu2GWtPqXQ1nc9gx+jOU+E=
 github.com/kisielk/errcheck v1.2.0/go.mod h1:/BMXB+zMLi60iA8Vv6Ksmxu/1UDYcXs4uQLJ+jE2L00=
 github.com/kisielk/gotool v1.0.0/go.mod h1:XhKaO+MFFWcvkIS/tQcRk01m1F5IRFswLeQ+oQHNcck=
 github.com/klauspost/cpuid v1.2.1 h1:vJi+O/nMdFt0vqm8NZBI6wzALWdA2X+egi0ogNyrC/w=

store/mockstore/mocktikv/pd.go

@@ -119,6 +119,7 @@ func (c *pdClient) GetStore(ctx context.Context, storeID uint64) (*metapb.Store,
 	default:
 	}
 	store := c.cluster.GetStore(storeID)
+	// It's same as PD's implementation.
 	if store == nil {
 		return nil, fmt.Errorf("invalid store ID %d, not found", storeID)
 	}