shared frozen constant for empty JSON bodies

[aryan55254]

Fixes [#34]

Overview

This PR introduces a module-level constant EMPTY_FROZEN_OBJECT defined once at module load time, eliminating redundant object allocations for empty request bodies.

Implementation

/**
 * This is a single shared constant used inside the request class.
 * The object is created and frozen exactly once when the file is first loaded. 
 * Subsequent requests just point to this same memory address.
 */
const EMPTY_FROZEN_OBJECT = Object.freeze({});
 
// Later, inside the json() method:
this.cachedJson = EMPTY_FROZEN_OBJECT as T; // zero allocation

Why This Matters

Metric	Inline Object.freeze({})	Module-level Constant
Allocations	1 per qualifying request	1 total (at module load)
GC Pressure	Proportional to request rate	Zero
Referential Equality (===)	❌ Each call returns a different object	✅ Always the same object

Performance & Validation

Memory Footprint

• Local benchmark with --logHeapUsage showed 6 MB reduction in peak heap size
  • Before: 48 MB
  • After: 42 MB

Identity Verification

• Added regression test in request.spec.ts using .toBe() assertion
• Ensures multiple distinct requests share the exact same memory reference for empty bodies
• ✅ Test passes with this optimization (previously failed on main)

Checklist

• Read relevant documentation at uwest.js.org/docs
• Linter passes locally with no errors or warnings
• Written tests for changes (Identity/Referential equality check)
• All existing and new tests pass (95 total)
• Branch rebased on latest main
• Commits squashed into clean, logical units

Summary by CodeRabbit

• Tests

  • Added test coverage for request body parsing caching behavior.

• Refactor

  • Optimized empty request body handling by reusing cached frozen objects instead of creating new instances for GET, HEAD, and DELETE requests.

[coderabbitai]

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[coderabbitai]

Agent ran but didn't generate any test files. Tests may already exist or changes don't require additional tests.

[aryan55254]

Hey @VikramAditya33 have a look at the pr , all the checks have passed
I dunno what coderabbit is generating unit tests for tho

[coderabbitai]

❌ Failed to create PR with unit tests: AGENT_CHAT: Failed to open pull request

[VikramAditya33]

Hey @VikramAditya33 have a look at the pr , all the checks have passed
I dunno what coderabbit is generating unit tests for tho

I'm wondering the same thing too I just triggered a review lol although everything LGTM. Probably just wait for a while, meanwhile let's just watch what coderabbit comes up with 😆

[aryan55254]

@VikramAditya33 coderabbit doesn't seem to do anything lol , ig this can be merged ??

[coderabbitai]

🧹 Nitpick comments (1)

src/http/core/request.spec.ts (1)

445-461: Test passes incidentally — two lines are misleading no-ops.

Two issues that don't break the assertion today but obscure intent and are fragile:

1. Line 449: mockUwsReq.getMethod.mockReturnValue('GET') runs after the UwsRequest constructors at lines 446–447. The constructor synchronously caches this.method from uwsReq.getMethod() (request.ts line 182), so this mock change has no effect on req1/req2. The test only passes because the default beforeEach mock already returns 'get' (uppercased to 'GET').

2. Line 453: With no setHeaders([...]) call, neither content-length nor transfer-encoding is set, so _initBodyParser returns early at request.ts line 874–877 and never registers onData. The onDataCallback reference here still points to whatever the previous test installed (or the initial throwing stub if this test ran in isolation). The call therefore doesn't feed an empty body into req1/req2 — they already have doneReadingData = true, which is what actually drives json() down the empty-body branch.

Tightening the test makes the optimization being verified unambiguous and removes cross-test coupling on onDataCallback:

♻️ Suggested cleanup

       it('should optimize empty bodies by using the exact same memory reference', async () => {
+        // No content-length / transfer-encoding => _initBodyParser short-circuits,
+        // doneReadingData stays true, and json() takes the empty-body GET branch.
+        mockUwsReq.getMethod.mockReturnValue('get');
         const req1 = new UwsRequest(mockUwsReq, mockUwsRes);
         const req2 = new UwsRequest(mockUwsReq, mockUwsRes);
 
-        mockUwsReq.getMethod.mockReturnValue('GET');
         req1._initBodyParser(1024);
         req2._initBodyParser(1024);
 
-        onDataCallback(toArrayBuffer(Buffer.from('')), true);
-
         const res1 = await req1.json();
         const res2 = await req2.json();
 
         // Referential equality proves zero new objects were allocated
         expect(res1).toBe(res2);
         expect(Object.isFrozen(res1)).toBe(true);
       });

Optionally also assert expect(res1).toEqual({}) to pin the shape, and add a sibling test for HEAD/DELETE and one negative test that POST with empty body still throws — that would lock in the full contract documented at request.ts lines 1066–1073.

🤖 Prompt for AI Agents

Verify each finding against the current code and only fix it if needed.

In `@src/http/core/request.spec.ts` around lines 445 - 461, The test relies on
incidental state and should explicitly configure method and headers so the body
parser is actually wired: construct UwsRequest instances after mocking
mockUwsReq.getMethod to the intended verb (e.g., 'GET' or 'HEAD'), call
setHeaders(...) to set either content-length: '0' or transfer-encoding to ensure
_initBodyParser registers onData (so onDataCallback is the one used by these
instances), then call _initBodyParser(1024) and invoke onDataCallback with an
empty buffer before calling json(); reference UwsRequest, _initBodyParser,
onDataCallback, json, setHeaders, and the header names
content-length/transfer-encoding when making these changes.

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Nitpick comments:
In `@src/http/core/request.spec.ts`:
- Around line 445-461: The test relies on incidental state and should explicitly
configure method and headers so the body parser is actually wired: construct
UwsRequest instances after mocking mockUwsReq.getMethod to the intended verb
(e.g., 'GET' or 'HEAD'), call setHeaders(...) to set either content-length: '0'
or transfer-encoding to ensure _initBodyParser registers onData (so
onDataCallback is the one used by these instances), then call
_initBodyParser(1024) and invoke onDataCallback with an empty buffer before
calling json(); reference UwsRequest, _initBodyParser, onDataCallback, json,
setHeaders, and the header names content-length/transfer-encoding when making
these changes.

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📥 Commits

Reviewing files that changed from the base of the PR and between 7468f48 and 528c197.

📒 Files selected for processing (2)

• src/http/core/request.spec.ts
• src/http/core/request.ts

[VikramAditya33]

@aryan55254 does the nitpick regarding cleanup makes sense to you? Seems like a cleanup if you feel like it's okay otherwise I'm satisfied with the current implementation

[aryan55254]

yeah I am satisified with it as well , i don't fully understand what the nitpick is saying tbh , it kinda seems to say the test is only passing because both req are empty but we were optimizing for when the requests are empty anyways so , and the memory reference matches so its solid from my side

[VikramAditya33]

Alright it's a nitpick after all we can completely ignore it. LGTM, Thank you.

[aryan55254]

cool