snapshot of https://github.com/ThreeDotsLabs/watermill.git (master, 2026-09-15; blobs > 131072B omitted)

message/router/middleware/circuit_breaker.go

@@ -0,0 +1,37 @@
+package middleware
+
+import (
+	"github.com/ThreeDotsLabs/watermill/message"
+	"github.com/sony/gobreaker"
+)
+
+// CircuitBreaker is a middleware that wraps the handler in a circuit breaker.
+// Based on the configuration, the circuit breaker will fail fast if the handler keeps returning errors.
+// This is useful for preventing cascading failures.
+type CircuitBreaker struct {
+	cb *gobreaker.CircuitBreaker
+}
+
+// NewCircuitBreaker returns a new CircuitBreaker middleware.
+// Refer to the gobreaker documentation for the available settings.
+func NewCircuitBreaker(settings gobreaker.Settings) CircuitBreaker {
+	return CircuitBreaker{
+		cb: gobreaker.NewCircuitBreaker(settings),
+	}
+}
+
+// Middleware returns the CircuitBreaker middleware.
+func (c CircuitBreaker) Middleware(h message.HandlerFunc) message.HandlerFunc {
+	return func(msg *message.Message) ([]*message.Message, error) {
+		out, err := c.cb.Execute(func() (interface{}, error) {
+			return h(msg)
+		})
+
+		var result []*message.Message
+		if out != nil {
+			result = out.([]*message.Message)
+		}
+
+		return result, err
+	}
+}