Fixes retry support to not fail due to body not being rewound between…

… retry attempts.

Merged #196 and #204 together along with other changes to make sure rewind works in all cases,
Made sure the ordering of handler's setting Request.Retryable vs the Service.ShouldRetry are consitent.
A Request Handler setting Request.Retryable will prevent RetryHandler calling Service.ShouldRetry. The Service's
delay value wills still be applied though.

aws/handler_functions.go

@@ -54,25 +54,27 @@ func ValidateResponseHandler(r *Request) {
 		// this may be replaced by an UnmarshalError handler
 		r.Error = &APIError{
 			StatusCode: r.HTTPResponse.StatusCode,
-			Message:    r.HTTPResponse.Status,
+			Code:       "UnknownError",
+			Message:    "unknown error",
 		}
 	}
 }
 
 func RetryHandler(r *Request) {
-	r.Retryable = r.Service.ShouldRetry(r)
-	r.RetryDelay = r.Service.RetryRules(r)
-	if r.Retryable {
-		r.ResetReaderBody()
+	// If one of the other handlers already set the retry state
+	// we don't want to override it based on the service's state
+	if !r.Retryable.IsSet() {
+		r.Retryable.Set(r.Service.ShouldRetry(r))
 	}
+
+	r.RetryDelay = r.Service.RetryRules(r)
 }
 
 func AfterRetryHandler(r *Request) {
 	if r.WillRetry() {
 		sleepDelay(r.RetryDelay)
 
 		r.RetryCount++
-		r.Retryable = false
 		r.Error = nil
 	}
 }

aws/request.go

@@ -26,7 +26,7 @@ type Request struct {
 	Data         interface{}
 	RequestID    string
 	RetryCount   uint
-	Retryable    bool
+	Retryable    SettableBool
 	RetryDelay   time.Duration
 
 	built bool
@@ -69,7 +69,7 @@ func NewRequest(service *Service, operation *Operation, params interface{}, data
 }
 
 func (r *Request) WillRetry() bool {
-	return r.Error != nil && r.Retryable && r.RetryCount < r.Service.MaxRetries()
+	return r.Error != nil && r.Retryable.Get() && r.RetryCount < r.Service.MaxRetries()
 }
 
 func (r *Request) ParamsFilled() bool {
@@ -93,11 +93,6 @@ func (r *Request) SetReaderBody(reader io.ReadSeeker) {
 	r.Body = reader
 }
 
-func (r *Request) ResetReaderBody() {
-	r.Body.Seek(r.bodyStart, 0)
-	r.HTTPRequest.Body = ioutil.NopCloser(r.Body)
-}
-
 func (r *Request) Presign(expireTime time.Duration) (string, error) {
 	r.ExpireTime = expireTime
 	r.Sign()
@@ -139,6 +134,13 @@ func (r *Request) Send() error {
 	}
 
 	for {
+		if r.Retryable.Get() {
+			// Re-seek the body back to the original point in for a retry so that
+			// send will send the body's contents again in the upcoming request.
+			r.Body.Seek(r.bodyStart, 0)
+		}
+		r.Retryable.Reset()
+
 		r.Handlers.Send.Run(r)
 		if r.Error != nil {
 			return r.Error

aws/types.go

@@ -1,6 +1,7 @@
 package aws
 
 import (
+	"fmt"
 	"io"
 	"time"
 )
@@ -61,3 +62,52 @@ func (r ReaderSeekerCloser) Close() error {
 	}
 	return nil
 }
+
+// A SettableBool provides a boolean value which includes the state if
+// the value was set or unset.  The set state is in addition to the value's
+// value(true|false)
+type SettableBool struct {
+	value bool
+	set   bool
+}
+
+// SetBool returns a SettableBool with a value set
+func SetBool(value bool) SettableBool {
+	return SettableBool{value: value, set: true}
+}
+
+// Get returns the value. Will always be false if the SettableBool was not set.
+func (b *SettableBool) Get() bool {
+	if !b.set {
+		return false
+	}
+	return b.value
+}
+
+// Set sets the value and updates the state that the value has been set.
+func (b *SettableBool) Set(value bool) {
+	b.value = value
+	b.set = true
+}
+
+// IsSet returns if the value has been set
+func (b *SettableBool) IsSet() bool {
+	return b.set
+}
+
+// Reset resets the state and value of the SettableBool to its initial default
+// state of not set and zero value.
+func (b *SettableBool) Reset() {
+	b.value = false
+	b.set = false
+}
+
+// String returns the string representation of the value if set. Zero if not set.
+func (b *SettableBool) String() string {
+	return fmt.Sprintf("%t", b.Get())
+}
+
+// GoString returns the string representation of the SettableBool value and state
+func (b *SettableBool) GoString() string {
+	return fmt.Sprintf("Bool{value:%t, set:%t}", b.value, b.set)
+}

service/dynamodb/customizations.go

@@ -74,7 +74,7 @@ func validateCRC32(r *aws.Request) {
 
 	if crc != uint32(expected) {
 		// CRC does not match, set a retryable error
-		r.Retryable = true
+		r.Retryable.Set(true)
 		r.Error = &aws.APIError{
 			Code:    "CRC32CheckFailed",
 			Message: "CRC32 integrity check failed",

service/sqs/checksums.go

@@ -98,7 +98,7 @@ func checksumsMatch(body, expectedMD5 *string) error {
 }
 
 func setChecksumError(r *aws.Request, format string, args ...interface{}) {
-	r.Retryable = true
+	r.Retryable.Set(true)
 	r.Error = &aws.APIError{
 		StatusCode: r.HTTPResponse.StatusCode,
 		Code:       "InvalidChecksum",