refactor(api): streamline InfoResolver and SubscriptionTrackerService

- Removed unnecessary imports and parameters in InfoResolver for cleaner code.
- Updated CPU utilization method to directly use infoService for generating CPU load.
- Enhanced SubscriptionTrackerService to improve subscriber count management and added early return for idempotency in unsubscribe method.

api/src/unraid-api/graph/resolvers/info/info.resolver.ts

@@ -1,5 +1,5 @@
 import { OnModuleInit } from '@nestjs/common';
-import { Parent, Query, ResolveField, Resolver, Subscription } from '@nestjs/graphql';
+import { Query, ResolveField, Resolver, Subscription } from '@nestjs/graphql';
 
 import { Resource } from '@unraid/shared/graphql.model.js';
 import {
@@ -7,7 +7,6 @@ import {
     AuthPossession,
     UsePermissions,
 } from '@unraid/shared/use-permissions.directive.js';
-import { PubSub } from 'graphql-subscriptions';
 import { baseboard as getBaseboard, system as getSystem } from 'systeminformation';
 
 import { createSubscription, pubsub, PUBSUB_CHANNEL } from '@app/core/pubsub.js';
@@ -37,8 +36,7 @@ export class InfoResolver implements OnModuleInit {
     constructor(
         private readonly infoService: InfoService,
         private readonly displayService: DisplayService,
-        private readonly subscriptionTracker: SubscriptionTrackerService,
-        private readonly cpuDataService: CpuDataService
+        private readonly subscriptionTracker: SubscriptionTrackerService
     ) {}
 
     onModuleInit() {
@@ -148,12 +146,7 @@ export class InfoResolver implements OnModuleInit {
         possession: AuthPossession.ANY,
     })
     public async cpuUtilization(): Promise<CpuUtilization> {
-        const { currentLoad: load, cpus } = await this.cpuDataService.getCpuLoad();
-        return {
-            id: 'info/cpu-load',
-            load,
-            cpus,
-        };
+        return this.infoService.generateCpuLoad();
     }
 
     @Subscription(() => CpuUtilization, {
@@ -189,7 +182,7 @@ export class InfoCpuResolver {
         description: 'CPU utilization in percent',
         nullable: true,
     })
-    public async utilization(@Parent() cpu: InfoCpu): Promise<number> {
+    public async utilization(): Promise<number> {
         const { currentLoad } = await this.cpuDataService.getCpuLoad();
         return currentLoad;
     }

api/src/unraid-api/graph/services/subscription-tracker.service.ts

@@ -10,28 +10,39 @@ export class SubscriptionTrackerService {
     }
 
     public subscribe(topic: string): void {
-        const currentCount = this.subscriberCounts.get(topic) || 0;
+        const currentCount = this.subscriberCounts.get(topic) ?? 0;
         this.subscriberCounts.set(topic, currentCount + 1);
 
         if (currentCount === 0) {
             const handlers = this.topicHandlers.get(topic);
-            if (handlers) {
+            if (handlers?.onStart) {
                 handlers.onStart();
             }
         }
     }
 
     public unsubscribe(topic: string): void {
-        const currentCount = this.subscriberCounts.get(topic) || 1;
+        const currentCount = this.subscriberCounts.get(topic) ?? 0;
+
+        // Early return for idempotency - if already at 0, do nothing
+        if (currentCount === 0) {
+            return;
+        }
+
         const newCount = currentCount - 1;
 
-        this.subscriberCounts.set(topic, newCount);
-
         if (newCount === 0) {
+            // Delete the topic entry when reaching zero
+            this.subscriberCounts.delete(topic);
+
+            // Call onStop handler if it exists
             const handlers = this.topicHandlers.get(topic);
-            if (handlers) {
+            if (handlers?.onStop) {
                 handlers.onStop();
             }
+        } else {
+            // Only update the count if not zero
+            this.subscriberCounts.set(topic, newCount);
         }
     }
 }