Imported github.com/ardanlabs/service as base example project

example-project/internal/mid/metrics.go

@@ -0,0 +1,58 @@
+package mid
+
+import (
+	"context"
+	"expvar"
+	"net/http"
+	"runtime"
+
+	"geeks-accelerator/oss/saas-starter-kit/example-project/internal/platform/web"
+	"go.opencensus.io/trace"
+)
+
+// m contains the global program counters for the application.
+var m = struct {
+	gr  *expvar.Int
+	req *expvar.Int
+	err *expvar.Int
+}{
+	gr:  expvar.NewInt("goroutines"),
+	req: expvar.NewInt("requests"),
+	err: expvar.NewInt("errors"),
+}
+
+// Metrics updates program counters.
+func Metrics() web.Middleware {
+
+	// This is the actual middleware function to be executed.
+	f := func(before web.Handler) web.Handler {
+
+		// Wrap this handler around the next one provided.
+		h := func(ctx context.Context, w http.ResponseWriter, r *http.Request, params map[string]string) error {
+			ctx, span := trace.StartSpan(ctx, "internal.mid.Metrics")
+			defer span.End()
+
+			err := before(ctx, w, r, params)
+
+			// Increment the request counter.
+			m.req.Add(1)
+
+			// Update the count for the number of active goroutines every 100 requests.
+			if m.req.Value()%100 == 0 {
+				m.gr.Set(int64(runtime.NumGoroutine()))
+			}
+
+			// Increment the errors counter if an error occurred on this request.
+			if err != nil {
+				m.err.Add(1)
+			}
+
+			// Return the error so it can be handled further up the chain.
+			return err
+		}
+
+		return h
+	}
+
+	return f
+}