Circuit Breaker

Circuit breaker middleware for providing client-side breaker functionality, with sre breaker algorithm implemented by default。

Configuration

WithGroup

breaker depends on container/group to implement the use of mutually independent breaker for different Operation. use WithGroup to configure a costom Breaker to replace the default breaker algorithm：

  1. // WithGroup with circuit breaker group.
  2. // NOTE: implements generics circuitbreaker.CircuitBreaker
  3. func WithGroup(g *group.Group) Option {
  4.     return func(o *options) {
  5.         o.group = g
  6.     }
  7. }

The default configuration generates separate breakers for different Operation(s).

  1. opt := &options{
  2.     group: group.NewGroup(func() interface{} {
  3.         return sre.NewBreaker()
  4.     }),
  5. }

group.Group is a lazy load container . The instance of group.Group should be implement the CircuitBreaker interface in aegis/circuitbreaker

  1. // CircuitBreaker is a circuit breaker.
  2. type CircuitBreaker interface {
  3.     Allow() error // it means rejected when return error
  4.   MarkSuccess() 
  5.     MarkFailed() 
  6. }

Usage

Use circuit breaker in client

  1. // http
  2. conn, err := http.NewClient(
  3.     context.Background(),
  4.     http.WithMiddleware(
  5.         circuitbreaker.Client(),
  6.     ),
  7.     http.WithEndpoint("127.0.0.1:8000"),
  8. )
  9. // grpc 
  10. conn,err := transgrpc.Dial(
  11.   context.Background(), 
  12.     grpc.WithMiddleware(
  13.         circuitbreaker.Client(),
  14.     ),
  15.   grpc.WithEndpoint("127.0.0.1:9000"),
  16. )

Trigger circuit breaker

When the breaker is triggered, the client call for this Operation fails quickly for a period of time and returns the error ErrNotAllowed immediately，which defined as follows：

  1. // ErrNotAllowed is request failed due to circuit breaker triggered.
  2. var ErrNotAllowed = errors.New(503, "CIRCUITBREAKER", "request failed due to circuit breaker triggered")