I noticed
[`set_response_body`](ce42f82b5a/ext/http/service.rs (L439-L443))
was unexpectedly hot in profiles, with most of the time being spent in
`memmove`.
It turns out that `ResponseBytesInner` was _massive_ (5624 bytes), so
every time we moved a `ResponseBytesInner` (for instance in
`set_response_body`) we were doing a >5kb memmove, which adds up pretty
quickly.
This PR boxes the two larger variants (the compression streams),
shrinking `ResponseBytesInner` to a reasonable 48 bytes.
---
Benchmarked with a simple hello world server:
```ts
// hello-server.ts
Deno.serve((_req) => {
return new Response("Hello world");
});
// run with `deno run -A hello-server.ts`
// in separate terminal `wrk -d 10s http://127.0.0.1:8000`
```
Main:
```
Running 10s test @ http://127.0.0.1:8000/
2 threads and 10 connections
Thread Stats Avg Stdev Max +/- Stdev
Latency 53.39us 9.53us 0.98ms 92.78%
Req/Sec 86.57k 3.56k 91.58k 91.09%
1739319 requests in 10.10s, 248.81MB read
Requests/sec: 172220.92
Transfer/sec: 24.64MB
```
This PR:
```
Running 10s test @ http://127.0.0.1:8000/
2 threads and 10 connections
Thread Stats Avg Stdev Max +/- Stdev
Latency 45.44us 8.49us 0.91ms 90.04%
Req/Sec 100.65k 2.26k 102.65k 96.53%
2022296 requests in 10.10s, 289.29MB read
Requests/sec: 200226.20
Transfer/sec: 28.64MB
```
So a nice ~15% bump. (With response body compression, the gain is ~10%
for gzip and neutral for brotli)
930ccf928a