cmd/restic, limiter: Move config knowledge to internal packages

The GlobalOptions struct now embeds a backend.TransportOptions, so it
doesn't need to construct one in open and create. The upload and
download limits are similarly now a struct in internal/limiter that is
embedded in GlobalOptions.

internal/limiter/limiter_backend_test.go

@@ -36,7 +36,7 @@ func TestLimitBackendSave(t *testing.T) {
 		}
 		return nil
 	}
-	limiter := NewStaticLimiter(42*1024, 42*1024)
+	limiter := NewStaticLimiter(Limits{42 * 1024, 42 * 1024})
 	limbe := LimitBackend(be, limiter)
 
 	rd := restic.NewByteReader(data, nil)
@@ -82,7 +82,7 @@ func TestLimitBackendLoad(t *testing.T) {
 			}
 			return newTracedReadCloser(src), nil
 		}
-		limiter := NewStaticLimiter(42*1024, 42*1024)
+		limiter := NewStaticLimiter(Limits{42 * 1024, 42 * 1024})
 		limbe := LimitBackend(be, limiter)
 
 		err := limbe.Load(context.TODO(), testHandle, 0, 0, func(rd io.Reader) error {

internal/limiter/static_limiter.go

@@ -12,20 +12,27 @@ type staticLimiter struct {
 	downstream *ratelimit.Bucket
 }
 
+// Limits represents static upload and download limits.
+// For both, zero means unlimited.
+type Limits struct {
+	UploadKb   int
+	DownloadKb int
+}
+
 // NewStaticLimiter constructs a Limiter with a fixed (static) upload and
 // download rate cap
-func NewStaticLimiter(uploadKb, downloadKb int) Limiter {
+func NewStaticLimiter(l Limits) Limiter {
 	var (
 		upstreamBucket   *ratelimit.Bucket
 		downstreamBucket *ratelimit.Bucket
 	)
 
-	if uploadKb > 0 {
-		upstreamBucket = ratelimit.NewBucketWithRate(toByteRate(uploadKb), int64(toByteRate(uploadKb)))
+	if l.UploadKb > 0 {
+		upstreamBucket = ratelimit.NewBucketWithRate(toByteRate(l.UploadKb), int64(toByteRate(l.UploadKb)))
 	}
 
-	if downloadKb > 0 {
-		downstreamBucket = ratelimit.NewBucketWithRate(toByteRate(downloadKb), int64(toByteRate(downloadKb)))
+	if l.DownloadKb > 0 {
+		downstreamBucket = ratelimit.NewBucketWithRate(toByteRate(l.DownloadKb), int64(toByteRate(l.DownloadKb)))
 	}
 
 	return staticLimiter{

internal/limiter/static_limiter_test.go

@@ -15,22 +15,19 @@ func TestLimiterWrapping(t *testing.T) {
 	reader := bytes.NewReader([]byte{})
 	writer := new(bytes.Buffer)
 
-	for _, limits := range []struct {
-		upstream   int
-		downstream int
-	}{
+	for _, limits := range []Limits{
 		{0, 0},
 		{42, 0},
 		{0, 42},
 		{42, 42},
 	} {
-		limiter := NewStaticLimiter(limits.upstream*1024, limits.downstream*1024)
+		limiter := NewStaticLimiter(limits)
 
-		mustWrapUpstream := limits.upstream > 0
+		mustWrapUpstream := limits.UploadKb > 0
 		test.Equals(t, limiter.Upstream(reader) != reader, mustWrapUpstream)
 		test.Equals(t, limiter.UpstreamWriter(writer) != writer, mustWrapUpstream)
 
-		mustWrapDownstream := limits.downstream > 0
+		mustWrapDownstream := limits.DownloadKb > 0
 		test.Equals(t, limiter.Downstream(reader) != reader, mustWrapDownstream)
 		test.Equals(t, limiter.DownstreamWriter(writer) != writer, mustWrapDownstream)
 	}
@@ -51,7 +48,7 @@ func (r *tracedReadCloser) Close() error {
 }
 
 func TestRoundTripperReader(t *testing.T) {
-	limiter := NewStaticLimiter(42*1024, 42*1024)
+	limiter := NewStaticLimiter(Limits{42 * 1024, 42 * 1024})
 	data := make([]byte, 1234)
 	_, err := io.ReadFull(rand.Reader, data)
 	test.OK(t, err)
@@ -89,7 +86,7 @@ func TestRoundTripperReader(t *testing.T) {
 }
 
 func TestRoundTripperCornerCases(t *testing.T) {
-	limiter := NewStaticLimiter(42*1024, 42*1024)
+	limiter := NewStaticLimiter(Limits{42 * 1024, 42 * 1024})
 
 	rt := limiter.Transport(roundTripper(func(req *http.Request) (*http.Response, error) {
 		return &http.Response{}, nil