feat: implement --parallelism flag for diff and sync commands

This controls the number of concurrent requests that are sent against
the Admin API of Kong.

Fix #85

cmd/diff.go

@@ -12,7 +12,10 @@ import (
 	"github.com/spf13/cobra"
 )
 
-var diffCmdKongStateFile string
+var (
+	diffCmdKongStateFile string
+	diffCmdParallelism   int
+)
 
 // diffCmd represents the diff command
 var diffCmd = &cobra.Command{
@@ -41,7 +44,7 @@ that will be created or updated or deleted.
 			return err
 		}
 		s, _ := diff.NewSyncer(currentState, targetState)
-		errs := solver.Solve(stopChannel, s, client, true)
+		errs := solver.Solve(stopChannel, s, client, diffCmdParallelism, true)
 		if errs != nil {
 			return utils.ErrArray{Errors: errs}
 		}
@@ -64,4 +67,6 @@ func init() {
 	diffCmd.Flags().BoolVar(&dumpConfig.SkipConsumers, "skip-consumers",
 		false, "do not diff consumers or "+
 			"any plugins associated with consumers")
+	diffCmd.Flags().IntVar(&diffCmdParallelism, "parallelism",
+		10, "Maximum number of concurrent operations")
 }

cmd/sync.go

@@ -12,7 +12,10 @@ import (
 	"github.com/spf13/cobra"
 )
 
-var syncCmdKongStateFile string
+var (
+	syncCmdKongStateFile string
+	syncCmdParallelism   int
+)
 
 // syncCmd represents the sync command
 var syncCmd = &cobra.Command{
@@ -38,7 +41,8 @@ to get Kong's state in sync with the input state.`,
 			return err
 		}
 		syncer, _ := diff.NewSyncer(currentState, targetState)
-		errs := solver.Solve(stopChannel, syncer, client, false)
+		errs := solver.Solve(stopChannel, syncer, client, syncCmdParallelism,
+			false)
 		if errs != nil {
 			return utils.ErrArray{Errors: errs}
 		}
@@ -61,4 +65,6 @@ func init() {
 	syncCmd.Flags().BoolVar(&dumpConfig.SkipConsumers, "skip-consumers",
 		false, "do not diff consumers or "+
 			"any plugins associated with consumers")
+	syncCmd.Flags().IntVar(&syncCmdParallelism, "parallelism",
+		10, "Maximum number of concurrent operations")
 }

dump/dump.go

@@ -286,6 +286,8 @@ func newOpt(tags []string) *kong.ListOpt {
 // all the entities in KongRawState.
 func Get(client *kong.Client, config Config) (*utils.KongRawState, error) {
 
+	// TODO make these requests concurrent
+
 	var state utils.KongRawState
 	services, err := GetAllServices(client, config.SelectorTags)
 	if err != nil {

reset/reset.go

@@ -8,10 +8,11 @@ import (
 
 // Reset deletes all entities in Kong.
 func Reset(state *utils.KongRawState, client *kong.Client) error {
-
 	if state == nil {
 		return errors.New("state cannot be empty")
 	}
+	// TODO parallelize these operations
+
 	// Delete routes before services
 	for _, r := range state.Routes {
 		err := client.Routes.Delete(nil, r.ID)

solver/solver.go

@@ -11,7 +11,7 @@ import (
 
 // Solve generates a diff and walks the graph.
 func Solve(doneCh chan struct{}, syncer *diff.Syncer,
-	client *kong.Client, dry bool) []error {
+	client *kong.Client, parallelism int, dry bool) []error {
 	var r *crud.Registry
 	var err error
 	if dry {
@@ -23,7 +23,7 @@ func Solve(doneCh chan struct{}, syncer *diff.Syncer,
 		return append([]error{}, errors.Wrapf(err, "cannot build registry"))
 	}
 
-	return syncer.Run(doneCh, 10, func(e diff.Event) (crud.Arg, error) {
+	return syncer.Run(doneCh, parallelism, func(e diff.Event) (crud.Arg, error) {
 		return r.Do(e.Kind, e.Op, e)
 	})
 }