Update gomod and vendor

vendor/github.com/moby/buildkit/solver/result.go

@@ -0,0 +1,105 @@
+package solver
+
+import (
+	"context"
+	"sync"
+	"sync/atomic"
+
+	"github.com/pkg/errors"
+	"github.com/sirupsen/logrus"
+)
+
+// SharedResult is a result that can be cloned
+type SharedResult struct {
+	mu   sync.Mutex
+	main Result
+}
+
+func NewSharedResult(main Result) *SharedResult {
+	return &SharedResult{main: main}
+}
+
+func (r *SharedResult) Clone() Result {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+
+	r1, r2 := dup(r.main)
+	r.main = r1
+	return r2
+}
+
+func (r *SharedResult) Release(ctx context.Context) error {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+	return r.main.Release(ctx)
+}
+
+func dup(res Result) (Result, Result) {
+	sem := int64(0)
+	return &splitResult{Result: res, sem: &sem}, &splitResult{Result: res, sem: &sem}
+}
+
+type splitResult struct {
+	released int64
+	sem      *int64
+	Result
+}
+
+func (r *splitResult) Release(ctx context.Context) error {
+	if atomic.AddInt64(&r.released, 1) > 1 {
+		err := errors.Errorf("releasing already released reference")
+		logrus.Error(err)
+		return err
+	}
+	if atomic.AddInt64(r.sem, 1) == 2 {
+		return r.Result.Release(ctx)
+	}
+	return nil
+}
+
+// NewCachedResult combines a result and cache key into cached result
+func NewCachedResult(res Result, k []ExportableCacheKey) CachedResult {
+	return &cachedResult{res, k}
+}
+
+type cachedResult struct {
+	Result
+	k []ExportableCacheKey
+}
+
+func (cr *cachedResult) CacheKeys() []ExportableCacheKey {
+	return cr.k
+}
+
+func NewSharedCachedResult(res CachedResult) *SharedCachedResult {
+	return &SharedCachedResult{
+		SharedResult: NewSharedResult(res),
+		CachedResult: res,
+	}
+}
+
+func (r *SharedCachedResult) Clone() CachedResult {
+	return &clonedCachedResult{Result: r.SharedResult.Clone(), cr: r.CachedResult}
+}
+
+func (r *SharedCachedResult) Release(ctx context.Context) error {
+	return r.SharedResult.Release(ctx)
+}
+
+type clonedCachedResult struct {
+	Result
+	cr CachedResult
+}
+
+func (r *clonedCachedResult) ID() string {
+	return r.Result.ID()
+}
+
+func (cr *clonedCachedResult) CacheKeys() []ExportableCacheKey {
+	return cr.cr.CacheKeys()
+}
+
+type SharedCachedResult struct {
+	*SharedResult
+	CachedResult
+}