ovsdb: implement Client echo RPC

Author: mdlayher

ovsdb/client_integration_test.go

@@ -28,6 +28,9 @@ func TestClientIntegration(t *testing.T) {
 	c := dialOVSDB(t)
 	defer c.Close()
 
+	t.Run("echo", func(t *testing.T) {
+		testClientEcho(t, c)
+	})
 	t.Run("databases", func(t *testing.T) {
 		testClientDatabases(t, c)
 	})
@@ -85,6 +88,12 @@ func testClientDatabases(t *testing.T, c *ovsdb.Client) {
 	}
 }
 
+func testClientEcho(t *testing.T, c *ovsdb.Client) {
+	if err := c.Echo(context.Background()); err != nil {
+		t.Fatalf("failed to echo: %v", err)
+	}
+}
+
 func dialOVSDB(t *testing.T) *ovsdb.Client {
 	t.Helper()
 

ovsdb/rpc.go

@@ -14,7 +14,10 @@
 
 package ovsdb
 
-import "context"
+import (
+	"context"
+	"fmt"
+)
 
 // ListDatabases returns the name of all databases known to the OVSDB server.
 func (c *Client) ListDatabases(ctx context.Context) ([]string, error) {
@@ -25,3 +28,20 @@ func (c *Client) ListDatabases(ctx context.Context) ([]string, error) {
 
 	return dbs, nil
 }
+
+// Echo verifies that the OVSDB connection is alive, and can be used to keep
+// the connection alive.
+func (c *Client) Echo(ctx context.Context) error {
+	const req = "github.com/digitalocean/go-openvswitch/ovsdb"
+
+	var res [1]string
+	if err := c.rpc(ctx, "echo", &res, req); err != nil {
+		return err
+	}
+
+	if res[0] != req {
+		return fmt.Errorf("invalid echo response: %q", res[0])
+	}
+
+	return nil
+}

ovsdb/rpc_test.go

@@ -50,3 +50,41 @@ func TestClientListDatabases(t *testing.T) {
 		t.Fatalf("unexpected databases (-want +got):\n%s", diff)
 	}
 }
+
+func TestClientEchoError(t *testing.T) {
+	c, _, done := testClient(t, func(req jsonrpc.Request) jsonrpc.Response {
+		return jsonrpc.Response{
+			ID:     intPtr(1),
+			Result: mustMarshalJSON(t, []string{"foo"}),
+		}
+	})
+	defer done()
+
+	if err := c.Echo(context.Background()); err == nil {
+		t.Fatal("expected an error, but none occurred")
+	}
+}
+
+func TestClientEchoOK(t *testing.T) {
+	const echo = "github.com/digitalocean/go-openvswitch/ovsdb"
+
+	c, _, done := testClient(t, func(req jsonrpc.Request) jsonrpc.Response {
+		if diff := cmp.Diff("echo", req.Method); diff != "" {
+			panicf("unexpected RPC method (-want +got):\n%s", diff)
+		}
+
+		if diff := cmp.Diff([]interface{}{echo}, req.Params); diff != "" {
+			panicf("unexpected RPC parameters (-want +got):\n%s", diff)
+		}
+
+		return jsonrpc.Response{
+			ID:     intPtr(1),
+			Result: mustMarshalJSON(t, []string{echo}),
+		}
+	})
+	defer done()
+
+	if err := c.Echo(context.Background()); err != nil {
+		t.Fatalf("failed to echo: %v", err)
+	}
+}