feat: implemented memory logger and a new endpoint

src/app.ts

@@ -5,7 +5,8 @@ import helmet from "helmet";
 import { getPublicKey, blindEvaluate } from "./voprf/routes";
 import { gateRouter } from "./interface/gate";
 import { expressErrorHandler } from "./infra/error-handler";
-
+import { getMemoryStats } from "./infra/memory";
+import { memoryLogger } from "./infra/memoryLogger";
 // Express App
 const app = express();
 
@@ -15,6 +16,7 @@ app.use(express.urlencoded({ extended: false }));
 // parse application/json
 app.use(express.json());
 
+app.use(memoryLogger);
 // Use default logger for now
 
 app.use(
@@ -34,6 +36,7 @@ app.use("/ping", function (req: Request, res: Response) {
   res.json({ reply: "pong" });
   res.end();
 });
+app.get("/internal/memory", getMemoryStats);
 
 // VOPRF endpoints
 app.get("/voprf/public-key", getPublicKey);

src/domain/gate/proof-verification.ts

@@ -123,5 +123,6 @@ export const assertProofValid = async (proof: SemaphoreProofShape): Promise<void
     logger.warn("gate: verifyProof threw (mapping to invalid-proof 403)", error);
     valid = false;
   }
+
   if (!valid) throwError({ code: 403, message: GateErrorCode.INVALID_PROOF });
 };

src/infra/memory.ts

@@ -0,0 +1,33 @@
+import { Request, Response } from "express";
+
+export interface MemorySnapshot {
+  bn128EngineCached: boolean;
+
+  rssMb: number;
+  heapUsedMb: number;
+  heapTotalMb: number;
+  externalMb: number;
+  arrayBuffersMb: number;
+}
+
+const bytesToMb = (bytes: number): number =>
+  Number((bytes / 1024 / 1024).toFixed(2));
+
+export const collectMemoryStats = (): MemorySnapshot => {
+  const memory = process.memoryUsage();
+  const bn128Engine = (globalThis as any).curve_bn128;
+  return {
+
+    bn128EngineCached: !!bn128Engine,
+
+    rssMb: bytesToMb(memory.rss),
+    heapUsedMb: bytesToMb(memory.heapUsed),
+    heapTotalMb: bytesToMb(memory.heapTotal),
+    externalMb: bytesToMb(memory.external),
+    arrayBuffersMb: bytesToMb(memory.arrayBuffers),
+  };
+};
+
+export const getMemoryStats = (_req: Request, res: Response): void => {
+  res.json(collectMemoryStats());
+};

src/infra/memoryLogger.ts

@@ -0,0 +1,39 @@
+import { NextFunction, Request, Response } from "express";
+import { collectMemoryStats } from "./memory";
+import { logger } from "../logger";
+
+export const memoryLogger = (
+  req: Request,
+  res: Response,
+  next: NextFunction
+): void => {
+  if (req.originalUrl === "/internal/memory") {
+    return next();
+  }
+
+  const before = collectMemoryStats();
+  const start = Date.now();
+
+  res.on("finish", () => {
+    const after = collectMemoryStats();
+
+    logger.info({
+      method: req.method,
+      path: req.originalUrl,
+      statusCode: res.statusCode,
+      durationMs: Date.now() - start,
+
+      mem_before_rssMb: before.rssMb,
+      mem_before_heapUsedMb: before.heapUsedMb,
+      mem_before_externalMb: before.externalMb,
+
+      mem_after_rssMb: after.rssMb,
+      mem_after_heapUsedMb: after.heapUsedMb,
+      mem_after_externalMb: after.externalMb,
+
+      bn128Cached: after.bn128EngineCached
+    });
+  });
+
+  next();
+};