From f2b3605e1a3b1d33baf5ebdd2e2ab953d70cd58f Mon Sep 17 00:00:00 2001
From: Abhimanyu Singh Gaur
 <12651351+abhimanyusinghgaur@users.noreply.github.com>
Date: Thu, 10 Dec 2020 16:27:23 +0530
Subject: [PATCH] fix(GraphQL): don't update cacheMb if not specified by user
 (GRAPHQL-888) (#7103)

Fixes GRAPHQL-888.
Previously, if you ran this request:
```
$ curl -H "Content-Type: application/json" http://localhost:8080/admin -d '{"query": "mutation {config(input: {logRequest: false}){response {code message}}}"}'
```
Alpha logs would also print this:
```
I1205 22:22:51.684693 2681396 middlewares.go:178] GraphQL admin mutation. Name =  config
I1205 22:22:51.684724 2681396 config.go:38] Got config update through GraphQL admin API
I1205 22:22:51.684810 2681396 worker.go:138] Updating cacheMb to 0
```
Indicating that cacheMb was also updated, even it wasn't specified in the request.

This PR fixes this issue.

(cherry picked from commit c03c32766f460d20a219e97711bb7ea84e54d965)

# Conflicts:
#	graphql/admin/config.go
---
 graphql/admin/config.go | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/graphql/admin/config.go b/graphql/admin/config.go
index d570f98cb4d..e72abbe6a5b 100644
--- a/graphql/admin/config.go
+++ b/graphql/admin/config.go
@@ -28,7 +28,7 @@ import (
 )
 
 type configInput struct {
-	LruMB float64
+	LruMB *float64
 	// LogRequest is used to update WorkerOptions.LogRequest. true value of LogRequest enables
 	// logging of all requests coming to alphas. LogRequest type has been kept as *bool instead of
 	// bool to avoid updating WorkerOptions.LogRequest when it has default value of false.
@@ -43,8 +43,9 @@ func resolveUpdateConfig(ctx context.Context, m schema.Mutation) (*resolve.Resol
 		return resolve.EmptyResult(m, err), false
 	}
 
-	if input.LruMB > 0 {
-		if err = worker.UpdateLruMb(input.LruMB); err != nil {
+	// update LruMB only when it is specified by user
+	if input.LruMB != nil {
+		if err = worker.UpdateLruMb(*input.LruMB); err != nil {
 			return resolve.EmptyResult(m, err), false
 		}
 	}