refactor(serde_v8): split ZeroCopyBuf into JsBuffer and ToJsBuffer (#19566)

`ZeroCopyBuf` was convenient to use, but sometimes it did hide details
that some copies were necessary in certain cases. Also it made it way to easy
for the caller to pass around and convert into different values. This commit
splits `ZeroCopyBuf` into `JsBuffer` (an array buffer coming from V8) and
`ToJsBuffer` (a Rust buffer that will be converted into a V8 array buffer).

As a result some magical conversions were removed (they were never used)
limiting the API surface and preparing for changes in #19534.

3 files changed, 10 insertions, 9 deletions

diff --git a/ext/web/blob.rs b/ext/web/blob.rs
index 7796c18af..9c5f5a09c 100644
--- a/ext/web/blob.rs
+++ b/ext/web/blob.rs
@@ -12,8 +12,9 @@ use deno_core::error::AnyError;
 use deno_core::op;
 use deno_core::parking_lot::Mutex;
 use deno_core::url::Url;
+use deno_core::JsBuffer;
 use deno_core::OpState;
-use deno_core::ZeroCopyBuf;
+use deno_core::ToJsBuffer;
 use serde::Deserialize;
 use serde::Serialize;
 use uuid::Uuid;
@@ -160,7 +161,7 @@ impl BlobPart for SlicedBlobPart {
 }
 
 #[op]
-pub fn op_blob_create_part(state: &mut OpState, data: ZeroCopyBuf) -> Uuid {
+pub fn op_blob_create_part(state: &mut OpState, data: JsBuffer) -> Uuid {
   let blob_store = state.borrow::<BlobStore>();
   let part = InMemoryBlobPart(data.to_vec());
   blob_store.insert_part(Arc::new(part))
@@ -203,7 +204,7 @@ pub fn op_blob_slice_part(
 pub async fn op_blob_read_part(
   state: Rc<RefCell<OpState>>,
   id: Uuid,
-) -> Result<ZeroCopyBuf, AnyError> {
+) -> Result<ToJsBuffer, AnyError> {
   let part = {
     let state = state.borrow();
     let blob_store = state.borrow::<BlobStore>();
@@ -211,7 +212,7 @@ pub async fn op_blob_read_part(
   }
   .ok_or_else(|| type_error("Blob part not found"))?;
   let buf = part.read().await?;
-  Ok(ZeroCopyBuf::from(buf.to_vec()))
+  Ok(ToJsBuffer::from(buf.to_vec()))
 }
 
 #[op]
diff --git a/ext/web/compression.rs b/ext/web/compression.rs
index 11ea9196a..557bff6ba 100644
--- a/ext/web/compression.rs
+++ b/ext/web/compression.rs
@@ -5,7 +5,7 @@ use deno_core::op;
 use deno_core::OpState;
 use deno_core::Resource;
 use deno_core::ResourceId;
-use deno_core::ZeroCopyBuf;
+use deno_core::ToJsBuffer;
 use flate2::write::DeflateDecoder;
 use flate2::write::DeflateEncoder;
 use flate2::write::GzDecoder;
@@ -69,7 +69,7 @@ pub fn op_compression_write(
   state: &mut OpState,
   rid: ResourceId,
   input: &[u8],
-) -> Result<ZeroCopyBuf, AnyError> {
+) -> Result<ToJsBuffer, AnyError> {
   let resource = state.resource_table.get::<CompressionResource>(rid)?;
   let mut inner = resource.0.borrow_mut();
   let out: Vec<u8> = match &mut *inner {
@@ -112,7 +112,7 @@ pub fn op_compression_write(
 pub fn op_compression_finish(
   state: &mut OpState,
   rid: ResourceId,
-) -> Result<ZeroCopyBuf, AnyError> {
+) -> Result<ToJsBuffer, AnyError> {
   let resource = state.resource_table.take::<CompressionResource>(rid)?;
   let resource = Rc::try_unwrap(resource).unwrap();
   let inner = resource.0.into_inner();
diff --git a/ext/web/lib.rs b/ext/web/lib.rs
index b1e0dd5d8..af213b5be 100644
--- a/ext/web/lib.rs
+++ b/ext/web/lib.rs
@@ -18,8 +18,8 @@ use deno_core::CancelHandle;
 use deno_core::OpState;
 use deno_core::Resource;
 use deno_core::ResourceId;
+use deno_core::ToJsBuffer;
 use deno_core::U16String;
-use deno_core::ZeroCopyBuf;
 
 use encoding_rs::CoderResult;
 use encoding_rs::Decoder;
@@ -123,7 +123,7 @@ deno_core::extension!(deno_web,
 );
 
 #[op]
-fn op_base64_decode(input: String) -> Result<ZeroCopyBuf, AnyError> {
+fn op_base64_decode(input: String) -> Result<ToJsBuffer, AnyError> {
   let mut s = input.into_bytes();
   let decoded_len = forgiving_base64_decode_inplace(&mut s)?;
   s.truncate(decoded_len);