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, 21 insertions, 0 deletions

diff --git a/core/ops_builtin.rs b/core/ops_builtin.rs
index 6ca2a132c..7393d4b69 100644
--- a/core/ops_builtin.rs
+++ b/core/ops_builtin.rs
@@ -34,6 +34,7 @@ pub(crate) fn init_builtins() -> Extension {
       op_add::decl(),
       // // TODO(@AaronO): track IO metrics for builtin streams
       op_read::decl(),
+      op_read_all::decl(),
       op_write::decl(),
       op_shutdown::decl(),
       op_metrics::decl(),
@@ -169,6 +170,26 @@ async fn op_read(
 }
 
 #[op]
+async fn op_read_all(
+  state: Rc<RefCell<OpState>>,
+  rid: ResourceId,
+) -> Result<ZeroCopyBuf, Error> {
+  let resource = state.borrow().resource_table.get_any(rid)?;
+  let (min, maximum) = resource.size_hint();
+  let size = maximum.unwrap_or(min) as usize;
+
+  let mut buffer = Vec::with_capacity(size);
+  loop {
+    let tmp = ZeroCopyBuf::new_temp(vec![0u8; 64 * 1024]);
+    let (nread, tmp) = resource.clone().read_return(tmp).await?;
+    if nread == 0 {
+      return Ok(buffer.into());
+    }
+    buffer.extend_from_slice(&tmp[..nread]);
+  }
+}
+
+#[op]
 async fn op_write(
   state: Rc<RefCell<OpState>>,
   rid: ResourceId,