Merge pull request #121 from okekefrancis112/perf/issue-61-lru-cache-prices

perf: implement LRU cache for /api/v1/prices endpoint

Author: AlAfiz

package-lock.json

@@ -47,6 +47,7 @@
     "express-rate-limit": "^8.3.1",
     "ioredis": "^5.10.1",
     "jsonwebtoken": "^9.0.3",
+    "lru-cache": "^11.2.7",
     "node-cron": "^3.0.3",
     "pg": "^8.11.0",
     "prisma": "^5.19.1",

package.json

@@ -14,9 +14,10 @@ import { OgModule } from './og/og.module';
 import { RequireJwtMiddleware } from './common/middleware/require-jwt.middleware';
 import { ConfigModule } from './config/config.module';
 import { PoolsModule } from './pools/pools.module';
+import { PricesModule } from './prices/prices.module';
 
 @Module({
-  imports: [PrismaModule, HealthModule, RiskModule, AuthModule, AnalyticsModule, SwapModule, TokensModule, OgModule, ConfigModule, PoolsModule],
+  imports: [PrismaModule, HealthModule, RiskModule, AuthModule, AnalyticsModule, SwapModule, TokensModule, OgModule, ConfigModule, PoolsModule, PricesModule],
   controllers: [AppController],
   providers: [
     AppService,

src/app.module.ts

@@ -0,0 +1,22 @@
+import { Controller, Get } from '@nestjs/common';
+import { ApiOperation, ApiResponse, ApiTags } from '@nestjs/swagger';
+import { PricesService } from './prices.service';
+
+@ApiTags('prices')
+@Controller('api/v1/prices')
+export class PricesController {
+  constructor(private readonly pricesService: PricesService) {}
+
+  @Get()
+  @ApiOperation({ summary: 'Get current token prices' })
+  @ApiResponse({ status: 200, description: 'Token prices retrieved successfully' })
+  async getPrices() {
+    const { data, cached } = await this.pricesService.getPrices();
+    return {
+      success: true,
+      message: 'Prices retrieved successfully',
+      data,
+      meta: { count: data.length, cached },
+    };
+  }
+}

src/prices/prices.controller.ts

@@ -0,0 +1,9 @@
+import { Module } from '@nestjs/common';
+import { PricesController } from './prices.controller';
+import { PricesService } from './prices.service';
+
+@Module({
+  controllers: [PricesController],
+  providers: [PricesService],
+})
+export class PricesModule {}

src/prices/prices.module.ts

@@ -0,0 +1,47 @@
+import { Injectable, Logger } from '@nestjs/common';
+import axios from 'axios';
+
+const cache = require('../../../utils/cache');
+
+const CACHE_KEY = 'prices:all';
+
+const MOCK_PRICES = [
+  { symbol: 'USDC', price: 1.0 },
+  { symbol: 'XLM', price: 0.12 },
+];
+
+@Injectable()
+export class PricesService {
+  private readonly logger = new Logger(PricesService.name);
+
+  async getPrices(): Promise<{ data: { symbol: string; price: number }[]; cached: boolean }> {
+    const cached = cache.get(CACHE_KEY);
+
+    if (cached) {
+      this.logger.log('🎯 Cache HIT - Returning cached prices');
+      return { data: cached, cached: true };
+    }
+
+    this.logger.log('❌ Cache MISS - Fetching prices from external API');
+    const prices = await this.fetchPrices();
+    cache.set(CACHE_KEY, prices);
+
+    return { data: prices, cached: false };
+  }
+
+  private async fetchPrices(): Promise<{ symbol: string; price: number }[]> {
+    try {
+      const response = await axios.get(
+        'https://api.coingecko.com/api/v3/simple/price?ids=stellar,usd-coin&vs_currencies=usd',
+      );
+
+      return [
+        { symbol: 'USDC', price: response.data['usd-coin']?.usd ?? 1.0 },
+        { symbol: 'XLM', price: response.data['stellar']?.usd ?? 0.12 },
+      ];
+    } catch (error) {
+      this.logger.error('Failed to fetch prices from CoinGecko, using fallback data', error.message);
+      return MOCK_PRICES;
+    }
+  }
+}

src/prices/prices.service.ts

@@ -0,0 +1,8 @@
+const { LRUCache } = require('lru-cache');
+
+const cache = new LRUCache({
+  max: 500,
+  ttl: 60 * 1000, // 60 seconds in milliseconds
+});
+
+module.exports = cache;