Update gomod and vendor

vendor/github.com/moby/buildkit/worker/workercontroller.go

@@ -0,0 +1,77 @@
+package worker
+
+import (
+	"sync"
+
+	"github.com/containerd/containerd/filters"
+	"github.com/moby/buildkit/client"
+	"github.com/pkg/errors"
+)
+
+// Controller holds worker instances.
+// Currently, only local workers are supported.
+type Controller struct {
+	// TODO: define worker interface and support remote ones
+	workers   sync.Map
+	defaultID string
+}
+
+// Add adds a local worker
+func (c *Controller) Add(w Worker) error {
+	c.workers.Store(w.ID(), w)
+	if c.defaultID == "" {
+		c.defaultID = w.ID()
+	}
+	return nil
+}
+
+// List lists workers
+func (c *Controller) List(filterStrings ...string) ([]Worker, error) {
+	filter, err := filters.ParseAll(filterStrings...)
+	if err != nil {
+		return nil, err
+	}
+	var workers []Worker
+	c.workers.Range(func(k, v interface{}) bool {
+		w := v.(Worker)
+		if filter.Match(adaptWorker(w)) {
+			workers = append(workers, w)
+		}
+		return true
+	})
+	return workers, nil
+}
+
+// GetDefault returns the default local worker
+func (c *Controller) GetDefault() (Worker, error) {
+	if c.defaultID == "" {
+		return nil, errors.Errorf("no default worker")
+	}
+	return c.Get(c.defaultID)
+}
+
+func (c *Controller) Get(id string) (Worker, error) {
+	v, ok := c.workers.Load(id)
+	if !ok {
+		return nil, errors.Errorf("worker %s not found", id)
+	}
+	return v.(Worker), nil
+}
+
+// TODO: add Get(Constraint) (*Worker, error)
+
+func (c *Controller) WorkerInfos() []client.WorkerInfo {
+	workers, err := c.List()
+	if err != nil {
+		return nil
+	}
+	out := make([]client.WorkerInfo, 0, len(workers))
+	for _, w := range workers {
+		out = append(out, client.WorkerInfo{
+			ID:        w.ID(),
+			Labels:    w.Labels(),
+			Platforms: w.Platforms(true),
+		})
+	}
+	return out
+}