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Add support for RFC1123 Date/Time in Retry-After header.
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palczyn committed Sep 20, 2021
1 parent 02c1586 commit 8ebfaae
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Showing 2 changed files with 59 additions and 35 deletions.
14 changes: 8 additions & 6 deletions client.go
Original file line number Diff line number Diff line change
Expand Up @@ -470,12 +470,14 @@ func baseRetryPolicy(resp *http.Response, err error) (bool, error) {
// (HTTP Code 429) is found in the resp parameter. Hence it will return the number of
// seconds the server states it may be ready to process more requests from this client.
func DefaultBackoff(min, max time.Duration, attemptNum int, resp *http.Response) time.Duration {
if resp != nil {
if resp.StatusCode == http.StatusTooManyRequests || resp.StatusCode == http.StatusServiceUnavailable {
if s, ok := resp.Header["Retry-After"]; ok {
if sleep, err := strconv.ParseInt(s[0], 10, 64); err == nil {
return time.Second * time.Duration(sleep)
}
if resp != nil && resp.StatusCode == http.StatusTooManyRequests {
if s, ok := resp.Header["Retry-After"]; ok {
if sleep, err := strconv.ParseInt(s[0], 10, 64); err == nil {
return time.Second * time.Duration(sleep)
}

if after, err := time.Parse(time.RFC1123, s[0]); err == nil {
return after.Sub(time.Now())
}
}
}
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80 changes: 51 additions & 29 deletions client_test.go
Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,7 @@ import (
"fmt"
"io"
"io/ioutil"
"math"
"net"
"net/http"
"net/http/httptest"
Expand Down Expand Up @@ -524,38 +525,59 @@ func TestClient_CheckRetry(t *testing.T) {
}

func TestClient_DefaultBackoff(t *testing.T) {
for _, code := range []int{http.StatusTooManyRequests, http.StatusServiceUnavailable} {
t.Run(fmt.Sprintf("http_%d", code), func(t *testing.T) {
ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
w.Header().Set("Retry-After", "2")
http.Error(w, fmt.Sprintf("test_%d_body", code), code)
}))
defer ts.Close()

client := NewClient()

var retryAfter time.Duration
retryable := false

client.CheckRetry = func(_ context.Context, resp *http.Response, err error) (bool, error) {
retryable, _ = DefaultRetryPolicy(context.Background(), resp, err)
retryAfter = DefaultBackoff(client.RetryWaitMin, client.RetryWaitMax, 1, resp)
return false, nil
}
type tcase struct {
name string
header string
}

_, err := client.Get(ts.URL)
if err != nil {
t.Fatalf("expected no errors since retryable")
}
cases := []tcase{
{
name: "RFC1123_datetime",
header: time.Now().Add(2 * time.Second).Format(time.RFC1123),
},
{
name: "numeric_duration",
header: "2",
},
}

if !retryable {
t.Fatal("Since the error is recoverable, the default policy shall return true")
}
var header string

if retryAfter != 2*time.Second {
t.Fatalf("The header Retry-After specified 2 seconds, and shall not be %d seconds", retryAfter/time.Second)
}
})
for _, code := range []int{http.StatusTooManyRequests, http.StatusServiceUnavailable} {
for _, tt := range cases {
t.Run(fmt.Sprintf("http_%d", code), func(t *testing.T) {
ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
w.Header().Set("Retry-After", header)
http.Error(w, fmt.Sprintf("test_%d_body", code), code)
}))
defer ts.Close()

client := NewClient()

var retryAfter time.Duration
retryable := false
client.CheckRetry = func(_ context.Context, resp *http.Response, err error) (bool, error) {
retryable, _ = DefaultRetryPolicy(context.Background(), resp, err)
retryAfter = DefaultBackoff(client.RetryWaitMin, client.RetryWaitMax, 1, resp)
return false, nil
}

header = tt.header

_, err := client.Get(ts.URL)
if err != nil {
t.Fatalf("expected no errors since retryable")
}

if !retryable {
t.Fatal("Since the error is recoverable, the default policy shall return true")
}

if math.Ceil(retryAfter.Seconds()) != 2 {
t.Fatalf("The header Retry-After specified 2 seconds, and shall not be %.0f seconds", math.Ceil(retryAfter.Seconds()))
}
})
}
}
}

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