perf(ext/fetch): consume body using ops (#16038)

This commit adds a fast path to `Request` and `Response` that
make consuming request bodies much faster when using `Body#text`,
`Body#arrayBuffer`, and `Body#blob`, if the body is a FastStream.
Because the response bodies for `fetch` are FastStream, this speeds up
consuming `fetch` response bodies significantly.

1 files changed, 6 insertions, 0 deletions

diff --git a/ext/fetch/lib.rs b/ext/fetch/lib.rs
index a7daaa63a..0adc32343 100644
--- a/ext/fetch/lib.rs
+++ b/ext/fetch/lib.rs
@@ -408,6 +408,7 @@ pub async fn op_fetch_send(
     .add(FetchResponseBodyResource {
       reader: AsyncRefCell::new(stream_reader),
       cancel: CancelHandle::default(),
+      size: content_length,
     });
 
   Ok(FetchResponse {
@@ -479,6 +480,7 @@ type BytesStream =
 struct FetchResponseBodyResource {
   reader: AsyncRefCell<StreamReader<BytesStream, bytes::Bytes>>,
   cancel: CancelHandle,
+  size: Option<u64>,
 }
 
 impl Resource for FetchResponseBodyResource {
@@ -498,6 +500,10 @@ impl Resource for FetchResponseBodyResource {
     })
   }
 
+  fn size_hint(&self) -> (u64, Option<u64>) {
+    (0, self.size)
+  }
+
   fn close(self: Rc<Self>) {
     self.cancel.cancel()
   }