go.temporal.io/server@v1.23.0/common/quotas/delayed_request_rate_limiter.go (about)

     1  // The MIT License
     2  //
     3  // Copyright (c) 2020 Temporal Technologies Inc.  All rights reserved.
     4  //
     5  // Copyright (c) 2020 Uber Technologies, Inc.
     6  //
     7  // Permission is hereby granted, free of charge, to any person obtaining a copy
     8  // of this software and associated documentation files (the "Software"), to deal
     9  // in the Software without restriction, including without limitation the rights
    10  // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
    11  // copies of the Software, and to permit persons to whom the Software is
    12  // furnished to do so, subject to the following conditions:
    13  //
    14  // The above copyright notice and this permission notice shall be included in
    15  // all copies or substantial portions of the Software.
    16  //
    17  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    18  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    19  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
    20  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    21  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
    22  // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
    23  // THE SOFTWARE.
    24  
    25  package quotas
    26  
    27  import (
    28  	"errors"
    29  	"fmt"
    30  	"time"
    31  
    32  	"go.temporal.io/server/common/clock"
    33  )
    34  
    35  // DelayedRequestRateLimiter is a rate limiter that allows all requests without any delay for a given duration. After
    36  // the delay expires, it delegates to another rate limiter. This rate limiter is useful for cases where you want to
    37  // allow all requests for a given duration, e.g. during something volatile like a deployment, and then switch to another
    38  // rate limiter after the duration expires.
    39  type DelayedRequestRateLimiter struct {
    40  	// RequestRateLimiter is the delegate that we switch to after the delay expires.
    41  	RequestRateLimiter
    42  	// timer triggers the rate limiter to delegate to the underlying rate limiter. We hold a reference to it in order to
    43  	// cancel it prematurely if needed.
    44  	timer clock.Timer
    45  }
    46  
    47  var ErrNegativeDelay = errors.New("delay cannot be negative")
    48  
    49  // NewDelayedRequestRateLimiter returns a DelayedRequestRateLimiter that delegates to the given rate limiter after a
    50  // delay. The timeSource is used to create the timer that triggers the switch. It returns an error if the given delay
    51  // is negative.
    52  func NewDelayedRequestRateLimiter(
    53  	rl RequestRateLimiter,
    54  	delay time.Duration,
    55  	timeSource clock.TimeSource,
    56  ) (*DelayedRequestRateLimiter, error) {
    57  	if delay < 0 {
    58  		return nil, fmt.Errorf("%w: %v", ErrNegativeDelay, delay)
    59  	}
    60  
    61  	delegator := RequestRateLimiterDelegator{}
    62  	delegator.SetRateLimiter(NoopRequestRateLimiter)
    63  
    64  	timer := timeSource.AfterFunc(delay, func() {
    65  		delegator.SetRateLimiter(rl)
    66  	})
    67  
    68  	return &DelayedRequestRateLimiter{
    69  		RequestRateLimiter: &delegator,
    70  		timer:              timer,
    71  	}, nil
    72  }
    73  
    74  // Cancel stops the timer that triggers the rate limiter to delegate to the underlying rate limiter. It returns true if
    75  // the timer was stopped before it expired.
    76  func (rl *DelayedRequestRateLimiter) Cancel() bool {
    77  	return rl.timer.Stop()
    78  }