How to implement a rate limiter using sync.Ticker and sync.Mutex in Golang?

To implement a rate limiter using sync.Ticker and sync.Mutex in Golang, follow these steps:

Import the required packages:

import (
	"sync"
	"time"
)

Create a struct to represent the rate limiter:

type RateLimiter struct {
	limiter  *sync.Ticker
	mutex    *sync.Mutex
	throttle <-chan time.Time
}

Create a NewRateLimiter function to initialize the rate limiter:

func NewRateLimiter(rps int) *RateLimiter {
	rl := &RateLimiter{
		limiter:  time.NewTicker(time.Second / time.Duration(rps)),
		mutex:    &sync.Mutex{},
		throttle: nil,
	}
	return rl
}

Create a Throttle method to limit the rate of execution:

func (rl *RateLimiter) Throttle() {
	<-rl.GetThrottle()
}

func (rl *RateLimiter) GetThrottle() <-chan time.Time {
	rl.mutex.Lock()
	defer rl.mutex.Unlock()
	if rl.throttle == nil {
		rl.throttle = rl.limiter.C
	}
	return rl.throttle
}

Use the rate limiter in your code:

func main() {
	rl := NewRateLimiter(10) // 10 requests per second

	for i := 0; i < 20; i++ {
		rl.Throttle()
		// Perform the desired operations
	}
}

In the example above, a rate limiter with a limit of 10 requests per second is created using NewRateLimiter(10). The Throttle function will limit the rate of execution to match the specified limit.

Note that the Throttle function uses the GetThrottle function to retrieve the throttle channel and wait for the appropriate time before proceeding. The GetThrottle function ensures that only one goroutine sets the throttle channel at a time using a mutex.

The rate limiter can be used in any section of the code that requires limiting the rate of execution by calling rl.Throttle() before executing the desired operations.