chore: import upstream snapshot with attribution

wrapper/monitoring/prometheus/wrapper.go

@@ -0,0 +1,89 @@
+package prometheus
+
+import (
+	"context"
+	"time"
+
+	"go-micro.dev/v6/client"
+	"go-micro.dev/v6/registry"
+	"go-micro.dev/v6/server"
+)
+
+// NewHandlerWrapper returns a server.HandlerWrapper that records Prometheus
+// metrics (request count and latency) for every incoming RPC handled by the
+// server.
+func NewHandlerWrapper(opts ...Option) server.HandlerWrapper {
+	m := getMetrics(newOptions(opts...))
+	return func(fn server.HandlerFunc) server.HandlerFunc {
+		return func(ctx context.Context, req server.Request, rsp interface{}) error {
+			start := time.Now()
+			err := fn(ctx, req, rsp)
+			observe(m, req.Service(), req.Endpoint(), err, start)
+			return err
+		}
+	}
+}
+
+// NewSubscriberWrapper returns a server.SubscriberWrapper that records
+// Prometheus metrics for every message delivered to a subscriber.
+func NewSubscriberWrapper(opts ...Option) server.SubscriberWrapper {
+	m := getMetrics(newOptions(opts...))
+	return func(fn server.SubscriberFunc) server.SubscriberFunc {
+		return func(ctx context.Context, msg server.Message) error {
+			start := time.Now()
+			err := fn(ctx, msg)
+			observe(m, "subscriber", msg.Topic(), err, start)
+			return err
+		}
+	}
+}
+
+// NewCallWrapper returns a client.CallWrapper that records Prometheus
+// metrics for every outgoing RPC issued by the client.
+func NewCallWrapper(opts ...Option) client.CallWrapper {
+	m := getMetrics(newOptions(opts...))
+	return func(fn client.CallFunc) client.CallFunc {
+		return func(ctx context.Context, node *registry.Node, req client.Request, rsp interface{}, opts client.CallOptions) error {
+			start := time.Now()
+			err := fn(ctx, node, req, rsp, opts)
+			observe(m, req.Service(), req.Endpoint(), err, start)
+			return err
+		}
+	}
+}
+
+// NewClientWrapper returns a client.Wrapper that records Prometheus metrics
+// for every Call and Publish issued on the wrapped client. Use it when you
+// need metrics for Publish as well as Call; NewCallWrapper only covers Call.
+func NewClientWrapper(opts ...Option) client.Wrapper {
+	m := getMetrics(newOptions(opts...))
+	return func(c client.Client) client.Client {
+		return &clientWrapper{Client: c, metrics: m}
+	}
+}
+
+type clientWrapper struct {
+	client.Client
+	metrics *metrics
+}
+
+func (w *clientWrapper) Call(ctx context.Context, req client.Request, rsp interface{}, opts ...client.CallOption) error {
+	start := time.Now()
+	err := w.Client.Call(ctx, req, rsp, opts...)
+	observe(w.metrics, req.Service(), req.Endpoint(), err, start)
+	return err
+}
+
+func (w *clientWrapper) Publish(ctx context.Context, p client.Message, opts ...client.PublishOption) error {
+	start := time.Now()
+	err := w.Client.Publish(ctx, p, opts...)
+	observe(w.metrics, "publisher", p.Topic(), err, start)
+	return err
+}
+
+// observe records a single request into the counter and histogram.
+func observe(m *metrics, service, endpoint string, err error, start time.Time) {
+	st := status(err)
+	m.requestTotal.WithLabelValues(service, endpoint, st).Inc()
+	m.requestDuration.WithLabelValues(service, endpoint, st).Observe(time.Since(start).Seconds())
+}