perf(ext/streams): fast path when consuming body of tee'd stream

[marcosc90]

Add a fast path for consuming the body of cloned Request/Response, which is very common specially when using cache API.

patch - deno_post_bin

Running 20s test @ http://127.0.0.1:4558/
  138683 requests in 20.10s, 19.05MB read
Requests/sec:   6899.70
Transfer/sec:      0.95MB

patch - deno_post_json

Running 20s test @ http://127.0.0.1:4558/
  312885 requests in 20.10s, 42.37MB read
Requests/sec:  15566.42
Transfer/sec:      2.11MB

main - deno_post_bin

Running 20s test @ http://127.0.0.1:4558/
  2 threads and 10 connections
  107811 requests in 20.00s, 14.81MB read
Requests/sec:   5389.68
Transfer/sec:    757.92KB

main - deno_post_json

Running 20s test @ http://127.0.0.1:4558/
  2 threads and 10 connections
  246295 requests in 20.00s, 33.35MB read
Requests/sec:  12313.82
Transfer/sec:      1.67MB

Modified the following for benching

deno/cli/bench/http/deno_post_json.js

Line 13 in 9df8d9d

const json = await request.json();

        // const json = await request.json();
        const clone = request.clone();
        const [json] = await Promise.all([
          request.json(),
          clone.json(),
        ]);

[lucacasonato]

I don't think this works. If the A side reads the stream, the B side gets nothing because the underlying resource has been read now.

[marcosc90]

I don't think this works. If the A side reads the stream, the B side gets nothing because the underlying resource has been read now.

To avoid that, I placed the fast path inside ReadableByteStreamController.pull, so controller.enqueue can be used so the read chunks are enqueued correctly to the other branch.

deno/ext/web/06_streams.js

Lines 684 to 696 in d65f4b3

	async pull(controller) {
	const v = controller.byobRequest.view;
	try {
	if (controller[_readAll] === true) {
	// fast path for tee'd streams consuming body
	const chunk = await core.readAll(rid);
	if (chunk.byteLength > 0) {
	controller.enqueue(chunk);
	}
	controller.close();
	tryClose();
	return;
	}

All the tests I've done work as expected so does all WPT.

[lucacasonato]

Sorry, I misunderstood what this does. LGTM, thanks.