From ea3d5d7b9fb7be20287972b6d4e31dda6378e886 Mon Sep 17 00:00:00 2001
From: Abhishek Pandey <abhishek@alcion.ai>
Date: Fri, 6 Oct 2023 23:33:03 +0530
Subject: [PATCH] Add guage

---
 src/internal/events/adot_sdk_client.go        | 27 ++++++++++++++-----
 .../m365/graph/concurrency_middleware.go      | 19 +++++++++++--
 2 files changed, 37 insertions(+), 9 deletions(-)

diff --git a/src/internal/events/adot_sdk_client.go b/src/internal/events/adot_sdk_client.go
index ff4fcc215..2f926624a 100644
--- a/src/internal/events/adot_sdk_client.go
+++ b/src/internal/events/adot_sdk_client.go
@@ -19,6 +19,7 @@ import (
 
 var Ctr metric.Int64Counter
 var AsyncCtr metric.Int64ObservableCounter
+var RLGauge metric.Int64ObservableGauge
 var token int64
 
 type collector struct {
@@ -35,11 +36,13 @@ const (
 var metricKeys = []string{
 	APITokens,
 	GrowCounter,
-	RLTokens,
+	// RLTokens,
 }
 
 // Map of metricsCategory to metric.Int64Counter
-var data = map[string]metric.Int64Counter{}
+var counter = map[string]metric.Int64Counter{}
+
+//var guages = map[string]metric.Int64ObservableGauge{}
 
 func NewCollector(mp metric.MeterProvider) {
 	rmc := collector{}
@@ -47,12 +50,22 @@ func NewCollector(mp metric.MeterProvider) {
 	rmc.meter = mp.Meter("corso-meter")
 
 	for _, key := range metricKeys {
-		data[key], _ = rmc.meter.Int64Counter(key)
+		counter[key], _ = rmc.meter.Int64Counter(key)
 	}
 
-	// // Create a new guage
-	// g, _ := rmc.meter.Int64ObservableGauge(RLTokens)
+}
 
+func RegisterGauge(ctx context.Context, name string, cb func(_ context.Context, o metric.Observer) error) {
+	RLGauge, _ := otel.Meter("corso-meter").Int64ObservableGauge(name)
+
+	_, err := otel.Meter("corso-meter").RegisterCallback(
+		cb,
+		RLGauge,
+	)
+
+	if err != nil {
+		logger.CtxErr(ctx, err).Errorw("failed to register callback")
+	}
 }
 
 func NewMetrics(ctx context.Context, w io.Writer) (context.Context, func()) {
@@ -64,13 +77,13 @@ func NewMetrics(ctx context.Context, w io.Writer) (context.Context, func()) {
 
 // Inc increments the given category by 1.
 func Inc(ctx context.Context, cat string) {
-	ctr := data[cat]
+	ctr := counter[cat]
 	ctr.Add(ctx, 1)
 }
 
 // IncN increments the given category by N.
 func IncN(ctx context.Context, n int, cat string) {
-	ctr := data[cat]
+	ctr := counter[cat]
 	ctr.Add(ctx, int64(n))
 }
 
diff --git a/src/internal/m365/graph/concurrency_middleware.go b/src/internal/m365/graph/concurrency_middleware.go
index 5caa02a48..9a7787701 100644
--- a/src/internal/m365/graph/concurrency_middleware.go
+++ b/src/internal/m365/graph/concurrency_middleware.go
@@ -9,6 +9,7 @@ import (
 
 	"github.com/alcionai/clues"
 	khttp "github.com/microsoft/kiota-http-go"
+	"go.opentelemetry.io/otel/metric"
 	"golang.org/x/time/rate"
 
 	"github.com/alcionai/corso/src/internal/events"
@@ -159,6 +160,19 @@ const (
 	PermissionsLC = 5
 )
 
+var twonce sync.Once
+
+func RegisterRLMetrics(ctx context.Context) {
+	twonce.Do(func() {
+		cb := func(_ context.Context, o metric.Observer) error {
+			o.ObserveInt64(events.RLGauge, int64(ctxLimiter(ctx).Tokens()))
+			return nil
+		}
+
+		events.RegisterGauge(ctx, events.RLTokens, cb)
+	})
+}
+
 // ConsumeNTokens ensures any calls using this context will consume
 // n rate-limiter tokens.  Default is 1, and this value does not need
 // to be established in the context to consume the default tokens.
@@ -192,8 +206,7 @@ func QueueRequest(ctx context.Context) {
 		defaultConsumed = driveDefaultLC
 	}
 
-	t := limiter.Tokens()
-	events.IncN(ctx, int(t), events.RLTokens)
+	// events.IncN(ctx, int(t), events.RLTokens)
 
 	consume := ctxLimiterConsumption(ctx, defaultConsumed)
 
@@ -210,7 +223,9 @@ func (mw *RateLimiterMiddleware) Intercept(
 	middlewareIndex int,
 	req *http.Request,
 ) (*http.Response, error) {
+	RegisterRLMetrics(req.Context())
 	QueueRequest(req.Context())
+
 	return pipeline.Next(req, middlewareIndex)
 }