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Fix immediate slack re-apply issue #120

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Fix immediate slack re-apply issue #120

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2 changes: 1 addition & 1 deletion limiter_atomic_int64.go
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Original file line number Diff line number Diff line change
Expand Up @@ -69,7 +69,7 @@ func (t *atomicInt64Limiter) Take() time.Time {
case timeOfNextPermissionIssue == 0 || (t.maxSlack == 0 && now-timeOfNextPermissionIssue > int64(t.perRequest)):
// if this is our first call or t.maxSlack == 0 we need to shrink issue time to now
newTimeOfNextPermissionIssue = now
case t.maxSlack > 0 && now-timeOfNextPermissionIssue > int64(t.maxSlack):
case t.maxSlack > 0 && now-timeOfNextPermissionIssue > int64(t.maxSlack)+int64(t.perRequest):
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@VovkoO VovkoO Jan 25, 2024 •
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Wouldn't this solution make the withSlack and withoutSlack options work exactly the same.
Looks like without slack you condition looks like:
now - prev > period
and withSlack
now - (prev - slack) > slack + period
Which is the same thing

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We apply now - int64(t.maxSlack) only under condition and that makes the difference.

// a lot of nanoseconds passed since the last Take call
// we will limit max accumulated time to maxSlack
newTimeOfNextPermissionIssue = now - int64(t.maxSlack)
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15 changes: 15 additions & 0 deletions ratelimit_test.go
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Expand Up @@ -269,6 +269,21 @@ func TestInitial(t *testing.T) {
}
}

func TestImmediateSlackReapply(t *testing.T) {
t.Parallel()
rl := New(1, Per(time.Second), WithSlack(1))
rl.Take() // we take one immediately
time.Sleep(2 * time.Second) // waiting for slack to accumulate
start := time.Now()
for i := 0; i < 5; i++ {
rl.Take() // consume 2 immediately and then 1 every second after it
// sleep 1ns for now-timeOfNextPermissionIssue != int64(t.maxSlack)
time.Sleep(1 * time.Nanosecond)
}

assert.Condition(t, func() bool { return time.Since(start) > 3*time.Second }, "too fast consumption: %v", time.Since(start))
}

func TestSlack(t *testing.T) {
t.Parallel()
// To simulate slack, we combine two limiters.
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