hrpc: Add CanBatch and GetPriority helpers

hrpc/call.go

@@ -90,6 +90,13 @@ func SkipBatch() func(Call) error {
 	}
 }
 
+// CanBatch returns true if this RPC can be included in a batch/multi
+// request.
+func CanBatch(c Call) bool {
+	b, ok := c.(Batchable)
+	return ok && !b.SkipBatch()
+}
+
 // hasQueryOptions is interface that needs to be implemented by calls
 // that allow to provide Families and Filters options.
 type hasQueryOptions interface {

hrpc/query.go

@@ -105,6 +105,16 @@ func (bq *baseQuery) Priority() uint32 {
 	return bq.priority
 }
 
+// GetPriority returns the priority of a Call. Returns 0 for calls
+// that don't have a priority set or don't support setting a priority.
+func GetPriority(c Call) uint32 {
+	p, ok := c.(interface{ Priority() uint32 })
+	if !ok {
+		return 0
+	}
+	return p.Priority()
+}
+
 // Families option adds families constraint to a Scan or Get request.
 func Families(f map[string][]string) func(Call) error {
 	return func(hc Call) error {

region/client.go

@@ -199,7 +199,7 @@ type client struct {
 
 // QueueRPC will add an rpc call to the queue for processing by the writer goroutine
 func (c *client) QueueRPC(rpc hrpc.Call) {
-	if b, ok := rpc.(hrpc.Batchable); ok && c.rpcQueueSize > 1 && !b.SkipBatch() {
+	if c.rpcQueueSize > 1 && hrpc.CanBatch(rpc) {
 		c.QueueBatch(rpc.Context(), []hrpc.Call{rpc})
 	} else {
 		select {
@@ -687,10 +687,8 @@ func marshalProto(rpc hrpc.Call, callID uint32, request proto.Message,
 	header.MethodName = proto.String(rpc.Name())
 	header.RequestParam = pbTrue
 	header.CallId = &callID
-	if p, ok := rpc.(interface{ Priority() uint32 }); ok {
-		if p := p.Priority(); p > 0 {
-			header.Priority = &p
-		}
+	if p := hrpc.GetPriority(rpc); p > 0 {
+		header.Priority = &p
 	}
 
 	if cellblocksLen > 0 {

rpc.go

@@ -240,7 +240,7 @@ func (c *client) SendBatch(ctx context.Context, batch []hrpc.Call) (
 			res[i].Error = fmt.Errorf("multiple tables in batch request: %q and %q",
 				string(table), string(rpc.Table()))
 			allOK = false
-		} else if b, batchable := rpc.(hrpc.Batchable); !batchable || b.SkipBatch() {
+		} else if !hrpc.CanBatch(rpc) {
 			res[i].Error = errors.New("non-batchable call passed to SendBatch")
 			allOK = false
 		}