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feat: add dynamic backoff #54

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feat: add dynamic backoff #54

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2 changes: 1 addition & 1 deletion retrier/classifier_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -34,7 +34,7 @@ type wrappedErr struct {
}

func (w wrappedErr) Error() string {
return "there's an error happening during X: " + w.Error()
return "there's an error happening during X: " + w.error.Error()
}

func (w wrappedErr) Unwrap() error {
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19 changes: 19 additions & 0 deletions retrier/errors.go
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Original file line number Diff line number Diff line change
@@ -0,0 +1,19 @@
package retrier

import "time"

type errWithBackoff struct {
err error
backoff time.Duration
}

func ErrWithBackoff(err error, backoff time.Duration) error {
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@eapache eapache Jan 18, 2025

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Please add godocs for any new public types/methods/etc.

return &errWithBackoff{
err: err,
backoff: backoff,
}
}

func (e *errWithBackoff) Error() string {
return e.err.Error()
}
11 changes: 10 additions & 1 deletion retrier/retrier.go
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@ package retrier

import (
"context"
"errors"
"math/rand"
"sync"
"time"
Expand Down Expand Up @@ -89,7 +90,15 @@ func (r *Retrier) RunFn(ctx context.Context, work func(ctx context.Context, retr
return ret
}

timer := time.NewTimer(r.calcSleep(retries))
var err *errWithBackoff
var backoff time.Duration
if errors.As(ret, &err) {
backoff = err.backoff
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@eapache eapache Jan 21, 2025

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If the response gives us a backoff value, does it still make sense to add some jitter to that? I'm not honestly sure...

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@tukeJonny tukeJonny Feb 23, 2025

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I agree with eapache's point.
I don't think Jitter should be unnecessarily considered by the client when given by Retry-After.
The client should add the Jitter because it is the same program or could be executed at the same time, and the Retry-After reverses the timing decision.

} else {
backoff = r.calcSleep(retries)
}

timer := time.NewTimer(backoff)
if err := r.sleep(ctx, timer); err != nil {
if r.surfaceWorkErrors {
return ret
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18 changes: 18 additions & 0 deletions retrier/retrier_test.go
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Expand Up @@ -153,6 +153,24 @@ func TestRetrierRunFnWithInfinite(t *testing.T) {
}
}

func TestRetrierWithDynamicBackoff(t *testing.T) {
r := New([]time.Duration{0, 10 * time.Millisecond}, nil)
st := time.Now()

err := r.Run(genWork([]error{ErrWithBackoff(errFoo, 500*time.Millisecond)}))
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@eapache eapache Jan 18, 2025

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Prefer to swap these times (so the retrier defaults to 500ms and the error overrides it to 10ms), so the test runs that much faster.

if err != nil {
t.Error(err)
}
if i != 2 {
t.Error("run wrong number of times")
}

if time.Since(st) < 500*time.Millisecond {
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@eapache eapache Jan 18, 2025

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I have tried to avoid doing time-based assertions in the test suite, they tend to be quite flaky.

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@OrangeFlag OrangeFlag Jan 20, 2025

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Yes, the test results may be flaky, but I couldn't think of any other way to check 🤔

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@eapache eapache Jan 21, 2025

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Currently, I don't assert on how long it actually sleeps (I trust go's timer to work) and I simply unit-test the return value of calcSleep (and then the bigger tests just assert on the number of times that the method gets retried, which should be deterministic).

Perhaps for this PR you could pass err into calcSleep and move the logic into that method, so you can test that logic in a unit test of that method without any time-based assertions?

t.Error("not wait dynamic backoff")
}

}

func TestRetrierRunFnWithSurfaceWorkErrors(t *testing.T) {
ctx, cancel := context.WithCancel(context.Background())
defer cancel()
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