Move to vendor

Signed-off-by: Olivier Gambier <olivier@docker.com>

vendor/github.com/docker/goamz/aws/retry.go

@@ -0,0 +1,136 @@
+package aws
+
+import (
+	"math/rand"
+	"net"
+	"net/http"
+	"time"
+)
+
+const (
+	maxDelay             = 20 * time.Second
+	defaultScale         = 300 * time.Millisecond
+	throttlingScale      = 500 * time.Millisecond
+	throttlingScaleRange = throttlingScale / 4
+	defaultMaxRetries    = 3
+	dynamoDBScale        = 25 * time.Millisecond
+	dynamoDBMaxRetries   = 10
+)
+
+// A RetryPolicy encapsulates a strategy for implementing client retries.
+//
+// Default implementations are provided which match the AWS SDKs.
+type RetryPolicy interface {
+	// ShouldRetry returns whether a client should retry a failed request.
+	ShouldRetry(target string, r *http.Response, err error, numRetries int) bool
+
+	// Delay returns the time a client should wait before issuing a retry.
+	Delay(target string, r *http.Response, err error, numRetries int) time.Duration
+}
+
+// DefaultRetryPolicy implements the AWS SDK default retry policy.
+//
+// It will retry up to 3 times, and uses an exponential backoff with a scale
+// factor of 300ms (300ms, 600ms, 1200ms). If the retry is because of
+// throttling, the delay will also include some randomness.
+//
+// See https://github.com/aws/aws-sdk-java/blob/master/aws-java-sdk-core/src/main/java/com/amazonaws/retry/PredefinedRetryPolicies.java#L90.
+type DefaultRetryPolicy struct {
+}
+
+// ShouldRetry implements the RetryPolicy ShouldRetry method.
+func (policy DefaultRetryPolicy) ShouldRetry(target string, r *http.Response, err error, numRetries int) bool {
+	return shouldRetry(r, err, numRetries, defaultMaxRetries)
+}
+
+// Delay implements the RetryPolicy Delay method.
+func (policy DefaultRetryPolicy) Delay(target string, r *http.Response, err error, numRetries int) time.Duration {
+	scale := defaultScale
+	if err, ok := err.(*Error); ok && isThrottlingException(err) {
+		scale = throttlingScale + time.Duration(rand.Int63n(int64(throttlingScaleRange)))
+	}
+	return exponentialBackoff(numRetries, scale)
+}
+
+// DynamoDBRetryPolicy implements the AWS SDK DynamoDB retry policy.
+//
+// It will retry up to 10 times, and uses an exponential backoff with a scale
+// factor of 25ms (25ms, 50ms, 100ms, ...).
+//
+// See https://github.com/aws/aws-sdk-java/blob/master/aws-java-sdk-core/src/main/java/com/amazonaws/retry/PredefinedRetryPolicies.java#L103.
+type DynamoDBRetryPolicy struct {
+}
+
+// ShouldRetry implements the RetryPolicy ShouldRetry method.
+func (policy DynamoDBRetryPolicy) ShouldRetry(target string, r *http.Response, err error, numRetries int) bool {
+	return shouldRetry(r, err, numRetries, dynamoDBMaxRetries)
+}
+
+// Delay implements the RetryPolicy Delay method.
+func (policy DynamoDBRetryPolicy) Delay(target string, r *http.Response, err error, numRetries int) time.Duration {
+	return exponentialBackoff(numRetries, dynamoDBScale)
+}
+
+// NeverRetryPolicy never retries requests and returns immediately on failure.
+type NeverRetryPolicy struct {
+}
+
+// ShouldRetry implements the RetryPolicy ShouldRetry method.
+func (policy NeverRetryPolicy) ShouldRetry(target string, r *http.Response, err error, numRetries int) bool {
+	return false
+}
+
+// Delay implements the RetryPolicy Delay method.
+func (policy NeverRetryPolicy) Delay(target string, r *http.Response, err error, numRetries int) time.Duration {
+	return time.Duration(0)
+}
+
+// shouldRetry determines if we should retry the request.
+//
+// See http://docs.aws.amazon.com/general/latest/gr/api-retries.html.
+func shouldRetry(r *http.Response, err error, numRetries int, maxRetries int) bool {
+	// Once we've exceeded the max retry attempts, game over.
+	if numRetries >= maxRetries {
+		return false
+	}
+
+	// Always retry temporary network errors.
+	if err, ok := err.(net.Error); ok && err.Temporary() {
+		return true
+	}
+
+	// Always retry 5xx responses.
+	if r != nil && r.StatusCode >= 500 {
+		return true
+	}
+
+	// Always retry throttling exceptions.
+	if err, ok := err.(ServiceError); ok && isThrottlingException(err) {
+		return true
+	}
+
+	// Other classes of failures indicate a problem with the request. Retrying
+	// won't help.
+	return false
+}
+
+func exponentialBackoff(numRetries int, scale time.Duration) time.Duration {
+	if numRetries < 0 {
+		return time.Duration(0)
+	}
+
+	delay := (1 << uint(numRetries)) * scale
+	if delay > maxDelay {
+		return maxDelay
+	}
+	return delay
+}
+
+func isThrottlingException(err ServiceError) bool {
+	switch err.ErrorCode() {
+	case "Throttling", "ThrottlingException", "ProvisionedThroughputExceededException":
+		return true
+	default:
+		return false
+	}
+}