breaker

README

circuit-breaker

The circuit-breaker resiliency pattern for golang.

Creating a breaker takes three parameters:

• error threshold (for opening the breaker)
• success threshold (for closing the breaker)
• timeout (how long to keep the breaker open)

b := breaker.New(3, 1, 5*time.Second)

for {
	result := b.Run(func() error {
		// communicate with some external service and
		// return an error if the communication failed
		return nil
	})

	switch result {
	case nil:
		// success!
	case breaker.ErrBreakerOpen:
		// our function wasn't run because the breaker was open
	default:
		// some other error
	}
}

Documentation

Overview

Package breaker implements the circuit-breaker resiliency pattern for Go.

Index

• Variables
• type Breaker
  • func New(errorThreshold, successThreshold int, timeout time.Duration) *Breaker
  • func (b *Breaker) Go(work func() error) error
  • func (b *Breaker) Run(work func() error) error

Examples

• Breaker

Variables

var ErrBreakerOpen = errors.New("circuit breaker is open")

ErrBreakerOpen is the error returned from Run() when the function is not executed because the breaker is currently open.

Types

type Breaker

type Breaker struct {
	// contains filtered or unexported fields
}

Breaker implements the circuit-breaker resiliency pattern

Example

breaker := New(3, 1, 5*time.Second)

for {
	result := breaker.Run(func() error {
		// communicate with some external service and
		// return an error if the communication failed
		return nil
	})

	switch result {
	case nil:
		// success!
	case ErrBreakerOpen:
		// our function wasn't run because the breaker was open
	default:
		// some other error
	}
}

func New

func New(errorThreshold, successThreshold int, timeout time.Duration) *Breaker

New constructs a new circuit-breaker that starts closed. From closed, the breaker opens if "errorThreshold" errors are seen without an error-free period of at least "timeout". From open, the breaker half-closes after "timeout". From half-open, the breaker closes after "successThreshold" consecutive successes, or opens on a single error.

func (*Breaker) Go

func (b *Breaker) Go(work func() error) error

Go will either return ErrBreakerOpen immediately if the circuit-breaker is already open, or it will run the given function in a separate goroutine. If the function is run, Go will return nil immediately, and will *not* return the return value of the function. It is safe to call Go concurrently on the same Breaker.

func (*Breaker) Run

func (b *Breaker) Run(work func() error) error

Run will either return ErrBreakerOpen immediately if the circuit-breaker is already open, or it will run the given function and pass along its return value. It is safe to call Run concurrently on the same Breaker.