From c3b244cd11978062b90d8aba4853df4dcacbdcc1 Mon Sep 17 00:00:00 2001
From: Anshul <malikanshul29@gmail.com>
Date: Sun, 7 Apr 2024 16:15:25 +0400
Subject: [PATCH 1/2] fix: concurrently fetch metrics

---
 internal/insight/insight.go | 39 ++++++++++++++++++++++++++++---------
 1 file changed, 30 insertions(+), 9 deletions(-)

diff --git a/internal/insight/insight.go b/internal/insight/insight.go
index 92c8069..d0edd2c 100644
--- a/internal/insight/insight.go
+++ b/internal/insight/insight.go
@@ -10,6 +10,7 @@ package insight
 
 import (
 	"context"
+	"sync"
 	"time"
 
 	"github.com/aws/aws-sdk-go-v2/aws"
@@ -65,17 +66,37 @@ func (in *Insight) Fetch(ctx context.Context, dbiResourceId string, dur time.Dur
 		chunks = append(chunks, metrics[i:end])
 	}
 
-	// TODO: concurrent
+	childContext, cancel := context.WithCancel(ctx)
+	defer cancel()
+
 	samples := map[string]Samples{}
-	for _, chunk := range chunks {
-		set, err := in.fetch(ctx, dbiResourceId, dur, chunk...)
-		if err != nil {
-			return nil, err
-		}
+	var wg sync.WaitGroup
+	var err error
 
-		for k, v := range set {
-			samples[k] = v
-		}
+	for _, chunk := range chunks {
+		chunk := chunk
+		wg.Add(1)
+
+		go func() {
+			defer wg.Done()
+
+			set, e := in.fetch(childContext, dbiResourceId, dur, chunk...)
+			if e != nil {
+				if e != context.Canceled {
+					cancel()
+					err = e
+				}
+				return
+			}
+
+			for k, v := range set {
+				samples[k] = v
+			}
+		}()
+	}
+	wg.Wait()
+	if err != nil {
+		return nil, err
 	}
 
 	return samples, nil

From 4bb8c8e3fa6c6c69b12e992e4975406dbf1d0bdc Mon Sep 17 00:00:00 2001
From: Anshul <malikanshul29@gmail.com>
Date: Sun, 7 Apr 2024 22:49:54 +0400
Subject: [PATCH 2/2] chore: review comments

---
 internal/insight/insight.go | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/internal/insight/insight.go b/internal/insight/insight.go
index d0edd2c..5dd3873 100644
--- a/internal/insight/insight.go
+++ b/internal/insight/insight.go
@@ -72,6 +72,7 @@ func (in *Insight) Fetch(ctx context.Context, dbiResourceId string, dur time.Dur
 	samples := map[string]Samples{}
 	var wg sync.WaitGroup
 	var err error
+	var mu sync.Mutex
 
 	for _, chunk := range chunks {
 		chunk := chunk
@@ -81,8 +82,12 @@ func (in *Insight) Fetch(ctx context.Context, dbiResourceId string, dur time.Dur
 			defer wg.Done()
 
 			set, e := in.fetch(childContext, dbiResourceId, dur, chunk...)
+
+			mu.Lock()
+			defer mu.Unlock()
+
 			if e != nil {
-				if e != context.Canceled {
+				if err == nil {
 					cancel()
 					err = e
 				}