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：

// WithGroup with circuit breaker group.
// NOTE: implements generics circuitbreaker.CircuitBreaker
func WithGroup(g *group.Group) Option {
  return func(o *options) {
    o.group = g
  }
}

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

opt := &options{
  group: group.NewGroup(func() interface{} {
    return sre.NewBreaker()
  }),
}

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

// CircuitBreaker is a circuit breaker.
type CircuitBreaker interface {
  Allow() error // it means rejected when return error
  MarkSuccess()
  MarkFailed()
}

Usage

Use circuit breaker in client

// http
conn, err := http.NewClient(
  context.Background(),
  http.WithMiddleware(
    circuitbreaker.Client(),
  ),
  http.WithEndpoint("127.0.0.1:8000"),
)
// grpc
conn,err := transgrpc.Dial(
  context.Background(),
  grpc.WithMiddleware(
    circuitbreaker.Client(),
  ),
  grpc.WithEndpoint("127.0.0.1:9000"),
)

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：

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