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import { Request, Response } from "express";
import { QueryResult } from "pg";
import db from "../database/postgres.js";
import redisClient from "../database/redis.js";
import { ErrorResponse } from "../types/error.js";
import { Robot, RobotsResponse } from "../types/robot.js";
const CACHE_TTL = 10;
const ROBOTS_CACHE_KEY = "allMyRobots";
async function getRobots(_req: Request, res: Response) {
try {
// Check if Redis has cached data to send to frontend
const cachedData = await redisClient.get(ROBOTS_CACHE_KEY);
if (cachedData) {
console.log("Data served from Redis cache.");
const robots: Robot[] = JSON.parse(cachedData);
const simulationRunning = robots?.every(
(robot) => robot.status === "moving"
);
const response: RobotsResponse = {
source: "cache",
robots,
simulationRunning,
};
return res.status(200).json(response);
}
// Else query database, then save in Redis cache and send to frontend
const robotsQuery: QueryResult<Robot> = await db.query(
"SELECT * FROM robots ORDER BY id;"
);
const robots = robotsQuery.rows;
const simulationRunning = robots?.every(
(robot) => robot.status === "moving"
);
await redisClient.set(ROBOTS_CACHE_KEY, JSON.stringify(robots), {
EX: CACHE_TTL,
});
console.log("Cache miss: data queried from PostgreSQL.");
const response: RobotsResponse = {
source: "database",
robots,
simulationRunning,
};
return res.status(200).json(response);
} catch (error) {
console.error("Failed to load the robots: ", error);
const errorResponse: ErrorResponse = {
message: "Internal server error while loading the robots.",
error,
};
return res.status(500).json(errorResponse);
}
}
export default getRobots;
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