From 57f7e07c13a1a692602022af4fc32c6ac352bb72 Mon Sep 17 00:00:00 2001
From: Divy Srivastava <dj.srivastava23@gmail.com>
Date: Fri, 22 Apr 2022 16:19:08 +0530
Subject: Reland "perf(http): optimize ReadableStreams backed by a resource"
 (#14346)

---
 serde_v8/magic/buffer.rs | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

(limited to 'serde_v8/magic/buffer.rs')

diff --git a/serde_v8/magic/buffer.rs b/serde_v8/magic/buffer.rs
index 484984ac5..3a8c9499b 100644
--- a/serde_v8/magic/buffer.rs
+++ b/serde_v8/magic/buffer.rs
@@ -14,19 +14,36 @@ use crate::magic::transl8::impl_magic;
 pub enum MagicBuffer {
   FromV8(ZeroCopyBuf),
   ToV8(Mutex<Option<Box<[u8]>>>),
+  // Variant of the MagicBuffer than is never exposed to the JS.
+  // Generally used to pass Vec<u8> backed buffers to resource methods.
+  Temp(Vec<u8>),
 }
+
 impl_magic!(MagicBuffer);
 
 impl MagicBuffer {
   pub fn empty() -> Self {
     MagicBuffer::ToV8(Mutex::new(Some(vec![0_u8; 0].into_boxed_slice())))
   }
+
+  pub fn new_temp(vec: Vec<u8>) -> Self {
+    MagicBuffer::Temp(vec)
+  }
+
+  // TODO(@littledivy): Temporary, this needs a refactor.
+  pub fn to_temp(self) -> Vec<u8> {
+    match self {
+      MagicBuffer::Temp(vec) => vec,
+      _ => unreachable!(),
+    }
+  }
 }
 
 impl Clone for MagicBuffer {
   fn clone(&self) -> Self {
     match self {
       Self::FromV8(zbuf) => Self::FromV8(zbuf.clone()),
+      Self::Temp(vec) => Self::Temp(vec.clone()),
       Self::ToV8(_) => panic!("Don't Clone a MagicBuffer sent to v8"),
     }
   }
@@ -49,6 +66,7 @@ impl Deref for MagicBuffer {
   fn deref(&self) -> &[u8] {
     match self {
       Self::FromV8(buf) => &*buf,
+      Self::Temp(vec) => &*vec,
       Self::ToV8(_) => panic!("Don't Deref a MagicBuffer sent to v8"),
     }
   }
@@ -58,6 +76,7 @@ impl DerefMut for MagicBuffer {
   fn deref_mut(&mut self) -> &mut [u8] {
     match self {
       Self::FromV8(buf) => &mut *buf,
+      Self::Temp(vec) => &mut *vec,
       Self::ToV8(_) => panic!("Don't Deref a MagicBuffer sent to v8"),
     }
   }
@@ -85,6 +104,7 @@ impl ToV8 for MagicBuffer {
         let value: &[u8] = buf;
         value.into()
       }
+      Self::Temp(_) => unreachable!(),
       Self::ToV8(x) => x.lock().unwrap().take().expect("MagicBuffer was empty"),
     };
 
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