agent: move the SnapshotReplyFn out of the way

When splitting up the consul package into server and client
the SnapshotReplyFn needs to be in a separate package to avoid
a circular dependency.

agent/agent.go

@@ -68,7 +68,7 @@ type delegate interface {
 	JoinLAN(addrs []string) (n int, err error)
 	RemoveFailedNode(node string) error
 	RPC(method string, args interface{}, reply interface{}) error
-	SnapshotRPC(args *structs.SnapshotRequest, in io.Reader, out io.Writer, replyFn consul.SnapshotReplyFn) error
+	SnapshotRPC(args *structs.SnapshotRequest, in io.Reader, out io.Writer, replyFn structs.SnapshotReplyFn) error
 	Shutdown() error
 	Stats() map[string]map[string]string
 }
@@ -1080,7 +1080,7 @@ func (a *Agent) RPC(method string, args interface{}, reply interface{}) error {
 // payload, and the response message will determine the error status, and any
 // return payload will be written to out.
 func (a *Agent) SnapshotRPC(args *structs.SnapshotRequest, in io.Reader, out io.Writer,
-	replyFn consul.SnapshotReplyFn) error {
+	replyFn structs.SnapshotReplyFn) error {
 	return a.delegate.SnapshotRPC(args, in, out, replyFn)
 }
 

agent/consul/client.go

@@ -341,15 +341,11 @@ func (c *Client) RPC(method string, args interface{}, reply interface{}) error {
 	return nil
 }
 
-// SnapshotReplyFn gets a peek at the reply before the snapshot streams, which
-// is useful for setting headers.
-type SnapshotReplyFn func(reply *structs.SnapshotResponse) error
-
 // SnapshotRPC sends the snapshot request to one of the servers, reading from
 // the streaming input and writing to the streaming output depending on the
 // operation.
 func (c *Client) SnapshotRPC(args *structs.SnapshotRequest, in io.Reader, out io.Writer,
-	replyFn SnapshotReplyFn) error {
+	replyFn structs.SnapshotReplyFn) error {
 
 	// Locate a server to make the request to.
 	server := c.servers.FindServer()

agent/consul/server.go

@@ -937,7 +937,7 @@ func (s *Server) RPC(method string, args interface{}, reply interface{}) error {
 // SnapshotRPC dispatches the given snapshot request, reading from the streaming
 // input and writing to the streaming output depending on the operation.
 func (s *Server) SnapshotRPC(args *structs.SnapshotRequest, in io.Reader, out io.Writer,
-	replyFn SnapshotReplyFn) error {
+	replyFn structs.SnapshotReplyFn) error {
 
 	// Perform the operation.
 	var reply structs.SnapshotResponse

agent/consul/structs/snapshot.go

@@ -7,6 +7,10 @@ const (
 	SnapshotRestore
 )
 
+// SnapshotReplyFn gets a peek at the reply before the snapshot streams, which
+// is useful for setting headers.
+type SnapshotReplyFn func(reply *SnapshotResponse) error
+
 // SnapshotRequest is used as a header for a snapshot RPC request. This will
 // precede any streaming data that's part of the request and is JSON-encoded on
 // the wire.