From 703417dfe31a4298cb1c4062acb5ff7f581a3c5a Mon Sep 17 00:00:00 2001
From: Skylar <skylar.brown@kurtosistech.com>
Date: Fri, 27 Sep 2024 09:48:56 -0600
Subject: [PATCH] fix: fix gradual memory leak / perf issue with cytoscape
 (#56)

---
 kontrol-frontend/src/contexts/ApiContext.tsx  |  9 +--
 .../src/pages/TrafficConfiguration.tsx        | 68 +++++++++++--------
 2 files changed, 39 insertions(+), 38 deletions(-)

diff --git a/kontrol-frontend/src/contexts/ApiContext.tsx b/kontrol-frontend/src/contexts/ApiContext.tsx
index 09676b9..38a0e7c 100644
--- a/kontrol-frontend/src/contexts/ApiContext.tsx
+++ b/kontrol-frontend/src/contexts/ApiContext.tsx
@@ -31,7 +31,6 @@ export interface ApiContextType {
   getFlows: () => Promise<Flow[]>;
   getTemplates: () => Promise<void>;
   getTopology: () => Promise<components["schemas"]["ClusterTopology"]>;
-  loading: boolean;
   postFlowCreate: (
     b: RequestBody<"/tenant/{uuid}/flow/create", "post">,
   ) => Promise<Flow>;
@@ -50,7 +49,6 @@ const defaultContextValue: ApiContextType = {
   getTopology: async () => {
     return { nodes: [], edges: [] };
   },
-  loading: false,
   postFlowCreate: async () => ({
     "flow-id": "",
     "access-entry": [],
@@ -72,15 +70,13 @@ export const ApiContextProvider = ({ children }: PropsWithChildren) => {
   );
   const uuid = match?.params.uuid;
 
-  const [loading, setLoading] = useState(false);
   const [error, setError] = useState<string | null>(null);
   const [templates, setTemplates] = useState<Template[]>([]);
 
-  // boilerplate loading state, error handling for any API call
+  // boilerplate error handling for any API call
   const handleApiCall = useCallback(async function <T>(
     pendingRequest: Promise<{ data?: T }>, // Api fetch promise
   ): Promise<T> {
-    setLoading(true);
     try {
       const response = await pendingRequest;
       if (response.data == null) {
@@ -91,8 +87,6 @@ export const ApiContextProvider = ({ children }: PropsWithChildren) => {
       console.error("Failed to fetch route:", error);
       setError((error as Error).message);
       throw error;
-    } finally {
-      setLoading(false);
     }
   }, []);
 
@@ -198,7 +192,6 @@ export const ApiContextProvider = ({ children }: PropsWithChildren) => {
         getFlows,
         getTemplates,
         getTopology,
-        loading,
         postFlowCreate,
         postTemplateCreate,
         templates,
diff --git a/kontrol-frontend/src/pages/TrafficConfiguration.tsx b/kontrol-frontend/src/pages/TrafficConfiguration.tsx
index 2305a4a..09ad598 100644
--- a/kontrol-frontend/src/pages/TrafficConfiguration.tsx
+++ b/kontrol-frontend/src/pages/TrafficConfiguration.tsx
@@ -12,40 +12,48 @@ const Page = () => {
   const prevResponse = useRef<string>();
   const { getTopology } = useApi();
   const { refetchFlows, flowVisibility } = useFlowsContext();
+  const timerRef = useRef<NodeJS.Timeout | null>(null);
 
-  useEffect(() => {
-    const fetchElems = async () => {
-      const response = await getTopology();
-      const filtered = {
-        ...response,
-        nodes: response.nodes.map((node) => {
-          return {
-            ...node,
-            versions: node.versions?.filter((version) => {
-              return flowVisibility[version.flowId] === true;
-            }),
-          };
-        }),
-      };
-      const newElems = utils.normalizeData(filtered);
-
-      // dont update react state if the API response is identical to the previous one
-      // This avoids unnecessary re-renders
-      if (JSON.stringify(newElems) === prevResponse.current) {
-        return;
-      }
-      prevResponse.current = JSON.stringify(newElems);
-      setElems(newElems);
-      // re-fetch flows if topology changes
-      refetchFlows();
+  const fetchElems = async () => {
+    const response = await getTopology();
+    const filtered = {
+      ...response,
+      nodes: response.nodes.map((node) => {
+        return {
+          ...node,
+          versions: node.versions?.filter((version) => {
+            return flowVisibility[version.flowId] === true;
+          }),
+        };
+      }),
     };
+    const newElems = utils.normalizeData(filtered);
+
+    // dont update react state if the API response is identical to the previous one
+    // This avoids unnecessary re-renders
+    if (JSON.stringify(newElems) === prevResponse.current) {
+      return;
+    }
+    prevResponse.current = JSON.stringify(newElems);
+    setElems(newElems);
+    // re-fetch flows if topology changes
+    refetchFlows();
+  };
+
+  const startPolling = () => {
+    timerRef.current = setInterval(fetchElems, pollingIntervalSeconds * 1000);
+  };
 
-    // Continuously fetch elements
-    const intervalId = setInterval(fetchElems, pollingIntervalSeconds * 1000);
-    fetchElems();
-    return () => clearInterval(intervalId);
+  const stopPolling = () => {
+    clearInterval(timerRef.current!);
+    timerRef.current = null;
+  };
+
+  useEffect(() => {
+    startPolling();
+    return stopPolling;
     // eslint-disable-next-line react-hooks/exhaustive-deps
-  }, [flowVisibility]);
+  }, []);
 
   return (
     <Grid