// New returns an AddService backed by a gRPC client connection. It is the
// responsibility of the caller to dial, and later close, the connection.
func New(conn *grpc.ClientConn, tracer stdopentracing.Tracer, logger log.Logger) addsvc.Service {
// We construct a single ratelimiter middleware, to limit the total outgoing
// QPS from this client to all methods on the remote instance. We also
// construct per-endpoint circuitbreaker middlewares to demonstrate how
// that's done, although they could easily be combined into a single breaker
// for the entire remote instance, too.
limiter := ratelimit.NewTokenBucketLimiter(jujuratelimit.NewBucketWithRate(100, 100))
var sumEndpoint endpoint.Endpoint
{
sumEndpoint = grpctransport.NewClient(
conn,
"Add",
"Sum",
addsvc.EncodeGRPCSumRequest,
addsvc.DecodeGRPCSumResponse,
pb.SumReply{},
grpctransport.SetClientBefore(opentracing.FromGRPCRequest(tracer, "Sum", logger)),
).Endpoint()
sumEndpoint = opentracing.TraceClient(tracer, "Sum")(sumEndpoint)
sumEndpoint = limiter(sumEndpoint)
sumEndpoint = circuitbreaker.Gobreaker(gobreaker.NewCircuitBreaker(gobreaker.Settings{
Name: "Sum",
Timeout: 30 * time.Second,
}))(sumEndpoint)
}
var concatEndpoint endpoint.Endpoint
{
concatEndpoint = grpctransport.NewClient(
conn,
"Add",
"Concat",
addsvc.EncodeGRPCConcatRequest,
addsvc.DecodeGRPCConcatResponse,
pb.ConcatReply{},
grpctransport.SetClientBefore(opentracing.FromGRPCRequest(tracer, "Concat", logger)),
).Endpoint()
concatEndpoint = opentracing.TraceClient(tracer, "Concat")(concatEndpoint)
concatEndpoint = limiter(concatEndpoint)
sumEndpoint = circuitbreaker.Gobreaker(gobreaker.NewCircuitBreaker(gobreaker.Settings{
Name: "Concat",
Timeout: 30 * time.Second,
}))(sumEndpoint)
}
return addsvc.Endpoints{
SumEndpoint: sumEndpoint,
ConcatEndpoint: concatEndpoint,
}
}
// MakeConcatEndpointFactory returns a loadbalancer.Factory that transforms
// GRPC host:port strings into Endpoints that call the Concat method on a GRPC
// server at that address.
func MakeConcatEndpointFactory(tracer opentracing.Tracer, tracingLogger log.Logger) loadbalancer.Factory {
return func(instance string) (endpoint.Endpoint, io.Closer, error) {
cc, err := grpc.Dial(instance, grpc.WithInsecure())
return grpctransport.NewClient(
cc,
"Add",
"Concat",
encodeConcatRequest,
decodeConcatResponse,
pb.ConcatReply{},
grpctransport.SetClientBefore(kitot.ToGRPCRequest(tracer, tracingLogger)),
).Endpoint(), cc, err
}
}