feat: common .RetryAfter() interface for errors (#60)

caboose.go

@@ -104,25 +104,31 @@ var ErrSaturnTimeout error = errors.New("saturn backend timed out")
 
 type ErrSaturnTooManyRequests struct {
 	Node       string
-	RetryAfter time.Duration // TODO: DRY refactor after https://github.com/ipfs/go-libipfs/issues/188
+	retryAfter time.Duration
 }
 
-func (e ErrSaturnTooManyRequests) Error() string {
-	return fmt.Sprintf("saturn node %s returned Too Many Requests error, please retry after %s", e.Node, humanRetry(e.RetryAfter))
+func (e *ErrSaturnTooManyRequests) Error() string {
+	return fmt.Sprintf("saturn node %s returned Too Many Requests error, please retry after %s", e.Node, humanRetry(e.retryAfter))
+}
+
+func (e *ErrSaturnTooManyRequests) RetryAfter() time.Duration {
+	return e.retryAfter
 }
 
 type ErrCoolDown struct {
 	Cid        cid.Cid
 	Path       string
-	RetryAfter time.Duration // TODO: DRY refactor after https://github.com/ipfs/go-libipfs/issues/188
+	retryAfter time.Duration
 }
 
 func (e *ErrCoolDown) Error() string {
-	return fmt.Sprintf("multiple saturn retrieval failures seen for CID %s/Path %s, please retry after %s", e.Cid, e.Path, humanRetry(e.RetryAfter))
+	return fmt.Sprintf("multiple saturn retrieval failures seen for CID %s/Path %s, please retry after %s", e.Cid, e.Path, humanRetry(e.retryAfter))
+}
+
+func (e *ErrCoolDown) RetryAfter() time.Duration {
+	return e.retryAfter
 }
 
-// TODO: move this to upstream error interface in https://github.com/ipfs/go-libipfs/issues/188
-// and refactor ErrCoolDown and ErrSaturnTooManyRequests to inherit from that instead
 func humanRetry(d time.Duration) string {
 	return d.Truncate(time.Second).String()
 }

failure_test.go

@@ -2,15 +2,16 @@ package caboose_test
 
 import (
 	"context"
+	"errors"
 	"net/http"
 	"net/http/httptest"
 	"sync"
 	"testing"
 	"time"
 
+	"github.com/filecoin-saturn/caboose"
 	"github.com/stretchr/testify/require"
 
-	"github.com/filecoin-saturn/caboose"
 	"github.com/ipfs/go-cid"
 	"github.com/multiformats/go-multicodec"
 )
@@ -30,8 +31,10 @@ func TestHttp429(t *testing.T) {
 	_, err := ch.c.Get(ctx, testCid)
 	require.Error(t, err)
 
-	ferr := err.(*caboose.ErrSaturnTooManyRequests)
-	require.EqualValues(t, expRetryAfter, ferr.RetryAfter)
+	var ferr *caboose.ErrSaturnTooManyRequests
+	ok := errors.As(err, &ferr)
+	require.True(t, ok)
+	require.EqualValues(t, expRetryAfter, ferr.RetryAfter())
 }
 
 func TestCabooseTransientFailures(t *testing.T) {
@@ -163,10 +166,12 @@ func (ch *CabooseHarness) runFetchesForRandCids(n int) {
 func (ch *CabooseHarness) fetchAndAssertCoolDownError(t *testing.T, ctx context.Context, cid cid.Cid) {
 	_, err := ch.c.Get(ctx, cid)
 	require.Error(t, err)
-	coolDownErr, ok := err.(*caboose.ErrCoolDown)
+
+	var coolDownErr *caboose.ErrCoolDown
+	ok := errors.As(err, &coolDownErr)
 	require.True(t, ok)
 	require.EqualValues(t, cid, coolDownErr.Cid)
-	require.NotZero(t, coolDownErr.RetryAfter)
+	require.NotZero(t, coolDownErr.RetryAfter())
 }
 
 func (ch *CabooseHarness) fetchAndAssertFailure(t *testing.T, ctx context.Context, testCid cid.Cid, contains string) {

fetcher.go

@@ -188,7 +188,7 @@ func (p *pool) fetchResource(ctx context.Context, from string, resource string,
 				retryAfter = p.config.SaturnNodeCoolOff
 			}
 
-			return fmt.Errorf("http error from strn: %d, err=%w", resp.StatusCode, ErrSaturnTooManyRequests{RetryAfter: retryAfter, Node: from})
+			return fmt.Errorf("http error from strn: %d, err=%w", resp.StatusCode, &ErrSaturnTooManyRequests{retryAfter: retryAfter, Node: from})
 		}
 
 		// empty body so it can be re-used.

pool.go

@@ -286,7 +286,7 @@ func (p *pool) fetchBlockWith(ctx context.Context, c cid.Cid, with string) (blk
 		expireAt := at.(time.Time)
 		return nil, &ErrCoolDown{
 			Cid:        c,
-			RetryAfter: time.Until(expireAt),
+			retryAfter: time.Until(expireAt),
 		}
 	}
 	p.fetchKeyLk.RUnlock()
@@ -426,7 +426,7 @@ func (p *pool) fetchResourceWith(ctx context.Context, path string, cb DataCallba
 		expireAt := at.(time.Time)
 		return &ErrCoolDown{
 			Path:       path,
-			RetryAfter: time.Until(expireAt),
+			retryAfter: time.Until(expireAt),
 		}
 	}
 	p.fetchKeyLk.RUnlock()
@@ -517,14 +517,8 @@ func (p *pool) commonUpdate(node string, err error) (ferr error) {
 		}
 	}
 
-	var errTooManyRequests ErrSaturnTooManyRequests
-	if errors.As(err, &errTooManyRequests) {
-
-		ferr = &ErrSaturnTooManyRequests{
-			Node:       errTooManyRequests.Node,
-			RetryAfter: errTooManyRequests.RetryAfter,
-		}
-
+	if errors.Is(err, &ErrSaturnTooManyRequests{}) {
+		ferr = err
 		if ok := p.isCoolOffLocked(node); ok {
 			return
 		}