/
delayed_request_rate_limiter.go
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/
delayed_request_rate_limiter.go
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// The MIT License
//
// Copyright (c) 2020 Temporal Technologies Inc. All rights reserved.
//
// Copyright (c) 2020 Uber Technologies, Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
package quotas
import (
"errors"
"fmt"
"time"
"go.temporal.io/server/common/clock"
)
// DelayedRequestRateLimiter is a rate limiter that allows all requests without any delay for a given duration. After
// the delay expires, it delegates to another rate limiter. This rate limiter is useful for cases where you want to
// allow all requests for a given duration, e.g. during something volatile like a deployment, and then switch to another
// rate limiter after the duration expires.
type DelayedRequestRateLimiter struct {
// RequestRateLimiter is the delegate that we switch to after the delay expires.
RequestRateLimiter
// timer triggers the rate limiter to delegate to the underlying rate limiter. We hold a reference to it in order to
// cancel it prematurely if needed.
timer clock.Timer
}
var ErrNegativeDelay = errors.New("delay cannot be negative")
// NewDelayedRequestRateLimiter returns a DelayedRequestRateLimiter that delegates to the given rate limiter after a
// delay. The timeSource is used to create the timer that triggers the switch. It returns an error if the given delay
// is negative.
func NewDelayedRequestRateLimiter(
rl RequestRateLimiter,
delay time.Duration,
timeSource clock.TimeSource,
) (*DelayedRequestRateLimiter, error) {
if delay < 0 {
return nil, fmt.Errorf("%w: %v", ErrNegativeDelay, delay)
}
delegator := RequestRateLimiterDelegator{}
delegator.SetRateLimiter(NoopRequestRateLimiter)
timer := timeSource.AfterFunc(delay, func() {
delegator.SetRateLimiter(rl)
})
return &DelayedRequestRateLimiter{
RequestRateLimiter: &delegator,
timer: timer,
}, nil
}
// Cancel stops the timer that triggers the rate limiter to delegate to the underlying rate limiter. It returns true if
// the timer was stopped before it expired.
func (rl *DelayedRequestRateLimiter) Cancel() bool {
return rl.timer.Stop()
}