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

     1  // The MIT License
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     5  // Copyright (c) 2020 Uber Technologies, Inc.
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    23  // THE SOFTWARE.
    24  
    25  package quotas
    26  
    27  import (
    28  	"context"
    29  	"sync/atomic"
    30  	"time"
    31  )
    32  
    33  // RequestRateLimiterDelegator is a request rate limiter that delegates to another rate limiter. The delegate can be
    34  // changed at runtime by calling SetRateLimiter. This rate limiter is useful for cases where you want to substitute one
    35  // rate limiter implementation for another at runtime. All methods of this type are thread-safe.
    36  type RequestRateLimiterDelegator struct {
    37  	// delegate is an atomic.Value so that it can be safely read from and written to concurrently. It stores the rate
    38  	// limiter that this rate limiter delegates to as a monomorphicRequestRateLimiter.
    39  	delegate atomic.Value
    40  }
    41  
    42  // monomorphicRequestRateLimiter is a workaround for the fact that the value stored in an atomic.Value must always be
    43  // the same type, but we want to allow the rate limiter delegate to be any type that implements the RequestRateLimiter
    44  // interface.
    45  type monomorphicRequestRateLimiter struct {
    46  	RequestRateLimiter
    47  }
    48  
    49  // SetRateLimiter sets the rate limiter to delegate to.
    50  func (d *RequestRateLimiterDelegator) SetRateLimiter(rl RequestRateLimiter) {
    51  	d.delegate.Store(monomorphicRequestRateLimiter{rl})
    52  }
    53  
    54  // loadDelegate returns the rate limiter that this rate limiter delegates to.
    55  func (d *RequestRateLimiterDelegator) loadDelegate() RequestRateLimiter {
    56  	return d.delegate.Load().(RequestRateLimiter)
    57  }
    58  
    59  // The following methods just delegate to the underlying rate limiter.
    60  
    61  func (d *RequestRateLimiterDelegator) Allow(now time.Time, request Request) bool {
    62  	return d.loadDelegate().Allow(now, request)
    63  }
    64  
    65  func (d *RequestRateLimiterDelegator) Reserve(now time.Time, request Request) Reservation {
    66  	return d.loadDelegate().Reserve(now, request)
    67  }
    68  
    69  func (d *RequestRateLimiterDelegator) Wait(ctx context.Context, request Request) error {
    70  	return d.loadDelegate().Wait(ctx, request)
    71  }