client-go/rest: backoff with context support

The BackoffManager interface sleeps without considering the caller's context,
i.e. cancellation is not supported. This alone is reason enough to deprecate it
and to replace it with an interface that supports a context parameter.

The other reason is that contextual logging needs that parameter.

Kubernetes-commit: b15a1943d51adfb8c5e0185d58d25e038c3d6ade

rest/urlbackoff.go

@@ -17,6 +17,8 @@ limitations under the License.
 package rest
 
 import (
+	"context"
+	"fmt"
 	"net/url"
 	"time"
 
@@ -32,12 +34,24 @@ import (
 var serverIsOverloadedSet = sets.NewInt(429)
 var maxResponseCode = 499
 
+//go:generate mockery
+
+// Deprecated: BackoffManager.Sleep ignores the caller's context. Use BackoffManagerWithContext instead.
 type BackoffManager interface {
-	UpdateBackoff(actualUrl *url.URL, err error, responseCode int)
-	CalculateBackoff(actualUrl *url.URL) time.Duration
+	UpdateBackoff(actualURL *url.URL, err error, responseCode int)
+	CalculateBackoff(actualURL *url.URL) time.Duration
 	Sleep(d time.Duration)
 }
 
+type BackoffManagerWithContext interface {
+	UpdateBackoffWithContext(ctx context.Context, actualURL *url.URL, err error, responseCode int)
+	CalculateBackoffWithContext(ctx context.Context, actualURL *url.URL) time.Duration
+	SleepWithContext(ctx context.Context, d time.Duration)
+}
+
+var _ BackoffManager = &URLBackoff{}
+var _ BackoffManagerWithContext = &URLBackoff{}
+
 // URLBackoff struct implements the semantics on top of Backoff which
 // we need for URL specific exponential backoff.
 type URLBackoff struct {
@@ -49,11 +63,19 @@ type URLBackoff struct {
 type NoBackoff struct {
 }
 
-func (n *NoBackoff) UpdateBackoff(actualUrl *url.URL, err error, responseCode int) {
+func (n *NoBackoff) UpdateBackoff(actualURL *url.URL, err error, responseCode int) {
 	// do nothing.
 }
 
-func (n *NoBackoff) CalculateBackoff(actualUrl *url.URL) time.Duration {
+func (n *NoBackoff) UpdateBackoffWithContext(ctx context.Context, actualURL *url.URL, err error, responseCode int) {
+	// do nothing.
+}
+
+func (n *NoBackoff) CalculateBackoff(actualURL *url.URL) time.Duration {
+	return 0 * time.Second
+}
+
+func (n *NoBackoff) CalculateBackoffWithContext(ctx context.Context, actualURL *url.URL) time.Duration {
 	return 0 * time.Second
 }
 
@@ -61,10 +83,21 @@ func (n *NoBackoff) Sleep(d time.Duration) {
 	time.Sleep(d)
 }
 
+func (n *NoBackoff) SleepWithContext(ctx context.Context, d time.Duration) {
+	if d == 0 {
+		return
+	}
+	t := time.NewTimer(d)
+	defer t.Stop()
+	select {
+	case <-ctx.Done():
+	case <-t.C:
+	}
+}
+
 // Disable makes the backoff trivial, i.e., sets it to zero.  This might be used
 // by tests which want to run 1000s of mock requests without slowing down.
 func (b *URLBackoff) Disable() {
-	klog.V(4).Infof("Disabling backoff strategy")
 	b.Backoff = flowcontrol.NewBackOff(0*time.Second, 0*time.Second)
 }
 
@@ -76,32 +109,74 @@ func (b *URLBackoff) baseUrlKey(rawurl *url.URL) string {
 	// in the future.
 	host, err := url.Parse(rawurl.String())
 	if err != nil {
-		klog.V(4).Infof("Error extracting url: %v", rawurl)
-		panic("bad url!")
+		panic(fmt.Sprintf("Error parsing bad URL %q: %v", rawurl, err))
 	}
 	return host.Host
 }
 
 // UpdateBackoff updates backoff metadata
-func (b *URLBackoff) UpdateBackoff(actualUrl *url.URL, err error, responseCode int) {
+func (b *URLBackoff) UpdateBackoff(actualURL *url.URL, err error, responseCode int) {
+	b.UpdateBackoffWithContext(context.Background(), actualURL, err, responseCode)
+}
+
+// UpdateBackoffWithContext updates backoff metadata
+func (b *URLBackoff) UpdateBackoffWithContext(ctx context.Context, actualURL *url.URL, err error, responseCode int) {
 	// range for retry counts that we store is [0,13]
 	if responseCode > maxResponseCode || serverIsOverloadedSet.Has(responseCode) {
-		b.Backoff.Next(b.baseUrlKey(actualUrl), b.Backoff.Clock.Now())
+		b.Backoff.Next(b.baseUrlKey(actualURL), b.Backoff.Clock.Now())
 		return
 	} else if responseCode >= 300 || err != nil {
-		klog.V(4).Infof("Client is returning errors: code %v, error %v", responseCode, err)
+		klog.FromContext(ctx).V(4).Info("Client is returning errors", "code", responseCode, "err", err)
 	}
 
 	//If we got this far, there is no backoff required for this URL anymore.
-	b.Backoff.Reset(b.baseUrlKey(actualUrl))
+	b.Backoff.Reset(b.baseUrlKey(actualURL))
 }
 
 // CalculateBackoff takes a url and back's off exponentially,
 // based on its knowledge of existing failures.
-func (b *URLBackoff) CalculateBackoff(actualUrl *url.URL) time.Duration {
-	return b.Backoff.Get(b.baseUrlKey(actualUrl))
+func (b *URLBackoff) CalculateBackoff(actualURL *url.URL) time.Duration {
+	return b.Backoff.Get(b.baseUrlKey(actualURL))
+}
+
+// CalculateBackoffWithContext takes a url and back's off exponentially,
+// based on its knowledge of existing failures.
+func (b *URLBackoff) CalculateBackoffWithContext(ctx context.Context, actualURL *url.URL) time.Duration {
+	return b.Backoff.Get(b.baseUrlKey(actualURL))
 }
 
 func (b *URLBackoff) Sleep(d time.Duration) {
 	b.Backoff.Clock.Sleep(d)
 }
+
+func (b *URLBackoff) SleepWithContext(ctx context.Context, d time.Duration) {
+	if d == 0 {
+		return
+	}
+	t := b.Backoff.Clock.NewTimer(d)
+	defer t.Stop()
+	select {
+	case <-ctx.Done():
+	case <-t.C():
+	}
+}
+
+// backoffManagerNopContext wraps a BackoffManager and adds the *WithContext methods.
+type backoffManagerNopContext struct {
+	BackoffManager
+}
+
+var _ BackoffManager = &backoffManagerNopContext{}
+var _ BackoffManagerWithContext = &backoffManagerNopContext{}
+
+func (b *backoffManagerNopContext) UpdateBackoffWithContext(ctx context.Context, actualURL *url.URL, err error, responseCode int) {
+	b.UpdateBackoff(actualURL, err, responseCode)
+}
+
+func (b *backoffManagerNopContext) CalculateBackoffWithContext(ctx context.Context, actualURL *url.URL) time.Duration {
+	return b.CalculateBackoff(actualURL)
+}
+
+func (b *backoffManagerNopContext) SleepWithContext(ctx context.Context, d time.Duration) {
+	b.Sleep(d)
+}