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.

6 files changed, 31 insertions, 28 deletions

diff --git a/core/examples/http_bench_json_ops/main.rs b/core/examples/http_bench_json_ops/main.rs
index 36c0996c3..a4d6afe31 100644
--- a/core/examples/http_bench_json_ops/main.rs
+++ b/core/examples/http_bench_json_ops/main.rs
@@ -3,11 +3,11 @@ use deno_core::anyhow::Error;
 use deno_core::op;
 use deno_core::AsyncRefCell;
 use deno_core::AsyncResult;
+use deno_core::JsBuffer;
 use deno_core::JsRuntimeForSnapshot;
 use deno_core::OpState;
 use deno_core::Resource;
 use deno_core::ResourceId;
-use deno_core::ZeroCopyBuf;
 use std::cell::RefCell;
 use std::env;
 use std::net::SocketAddr;
@@ -116,7 +116,7 @@ fn create_js_runtime() -> JsRuntimeForSnapshot {
 async fn op_read_socket(
   state: Rc<RefCell<OpState>>,
   rid: ResourceId,
-  mut data: ZeroCopyBuf,
+  mut data: JsBuffer,
 ) -> Result<u32, Error> {
   let resource = state.borrow_mut().resource_table.get::<TcpStream>(rid)?;
   let nread = resource.read(&mut data).await?;
diff --git a/core/io.rs b/core/io.rs
index 567d50bd4..a02b4b492 100644
--- a/core/io.rs
+++ b/core/io.rs
@@ -4,7 +4,7 @@ use std::ops::Deref;
 use std::ops::DerefMut;
 
 use bytes::Buf;
-use serde_v8::ZeroCopyBuf;
+use serde_v8::JsBuffer;
 
 /// BufView is a wrapper around an underlying contiguous chunk  of bytes. It can
 /// be created from a [ZeroCopyBuf], [bytes::Bytes], or [Vec<u8>] and implements
@@ -22,7 +22,7 @@ pub struct BufView {
 enum BufViewInner {
   Empty,
   Bytes(bytes::Bytes),
-  ZeroCopy(ZeroCopyBuf),
+  ZeroCopy(JsBuffer),
   Vec(Vec<u8>),
 }
 
@@ -100,8 +100,8 @@ impl AsRef<[u8]> for BufView {
   }
 }
 
-impl From<ZeroCopyBuf> for BufView {
-  fn from(buf: ZeroCopyBuf) -> Self {
+impl From<JsBuffer> for BufView {
+  fn from(buf: JsBuffer) -> Self {
     Self::from_inner(BufViewInner::ZeroCopy(buf))
   }
 }
@@ -145,7 +145,7 @@ pub struct BufMutView {
 }
 
 enum BufMutViewInner {
-  ZeroCopy(ZeroCopyBuf),
+  ZeroCopy(JsBuffer),
   Vec(Vec<u8>),
 }
 
@@ -273,8 +273,8 @@ impl AsMut<[u8]> for BufMutView {
   }
 }
 
-impl From<ZeroCopyBuf> for BufMutView {
-  fn from(buf: ZeroCopyBuf) -> Self {
+impl From<JsBuffer> for BufMutView {
+  fn from(buf: JsBuffer) -> Self {
     Self::from_inner(BufMutViewInner::ZeroCopy(buf))
   }
 }
diff --git a/core/lib.rs b/core/lib.rs
index ddc4d6d91..1f069e661 100644
--- a/core/lib.rs
+++ b/core/lib.rs
@@ -32,9 +32,10 @@ pub use serde_json;
 pub use serde_v8;
 pub use serde_v8::ByteString;
 pub use serde_v8::DetachedBuffer;
+pub use serde_v8::JsBuffer;
 pub use serde_v8::StringOrBuffer;
+pub use serde_v8::ToJsBuffer;
 pub use serde_v8::U16String;
-pub use serde_v8::ZeroCopyBuf;
 pub use sourcemap;
 pub use url;
 pub use v8;
diff --git a/core/ops_builtin.rs b/core/ops_builtin.rs
index 70f478acd..2334c6918 100644
--- a/core/ops_builtin.rs
+++ b/core/ops_builtin.rs
@@ -6,11 +6,12 @@ use crate::io::BufView;
 use crate::ops_builtin_v8;
 use crate::ops_metrics::OpMetrics;
 use crate::resources::ResourceId;
+use crate::JsBuffer;
 use crate::OpState;
 use crate::Resource;
-use crate::ZeroCopyBuf;
 use anyhow::Error;
 use deno_ops::op;
+use serde_v8::ToJsBuffer;
 use std::cell::RefCell;
 use std::io::stderr;
 use std::io::stdout;
@@ -218,7 +219,7 @@ pub fn op_wasm_streaming_set_url(
 async fn op_read(
   state: Rc<RefCell<OpState>>,
   rid: ResourceId,
-  buf: ZeroCopyBuf,
+  buf: JsBuffer,
 ) -> Result<u32, Error> {
   let resource = state.borrow().resource_table.get_any(rid)?;
   let view = BufMutView::from(buf);
@@ -229,7 +230,7 @@ async fn op_read(
 async fn op_read_all(
   state: Rc<RefCell<OpState>>,
   rid: ResourceId,
-) -> Result<ZeroCopyBuf, Error> {
+) -> Result<ToJsBuffer, Error> {
   let resource = state.borrow().resource_table.get_any(rid)?;
 
   // The number of bytes we attempt to grow the buffer by each time it fills
@@ -291,14 +292,14 @@ async fn op_read_all(
     vec.truncate(nread);
   }
 
-  Ok(ZeroCopyBuf::from(vec))
+  Ok(ToJsBuffer::from(vec))
 }
 
 #[op]
 async fn op_write(
   state: Rc<RefCell<OpState>>,
   rid: ResourceId,
-  buf: ZeroCopyBuf,
+  buf: JsBuffer,
 ) -> Result<u32, Error> {
   let resource = state.borrow().resource_table.get_any(rid)?;
   let view = BufView::from(buf);
@@ -331,7 +332,7 @@ fn op_write_sync(
 async fn op_write_all(
   state: Rc<RefCell<OpState>>,
   rid: ResourceId,
-  buf: ZeroCopyBuf,
+  buf: JsBuffer,
 ) -> Result<(), Error> {
   let resource = state.borrow().resource_table.get_any(rid)?;
   let view = BufView::from(buf);
diff --git a/core/ops_builtin_v8.rs b/core/ops_builtin_v8.rs
index 9fd906291..034a3810d 100644
--- a/core/ops_builtin_v8.rs
+++ b/core/ops_builtin_v8.rs
@@ -9,9 +9,10 @@ use crate::resolve_url;
 use crate::runtime::script_origin;
 use crate::serde_v8::from_v8;
 use crate::source_map::apply_source_map;
+use crate::JsBuffer;
 use crate::JsRealm;
 use crate::JsRuntime;
-use crate::ZeroCopyBuf;
+use crate::ToJsBuffer;
 use anyhow::Error;
 use deno_ops::op;
 use serde::Deserialize;
@@ -375,7 +376,7 @@ fn op_serialize(
   value: serde_v8::Value,
   options: Option<SerializeDeserializeOptions>,
   error_callback: Option<serde_v8::Value>,
-) -> Result<ZeroCopyBuf, Error> {
+) -> Result<ToJsBuffer, Error> {
   let options = options.unwrap_or_default();
   let error_callback = match error_callback {
     Some(cb) => Some(
@@ -448,7 +449,7 @@ fn op_serialize(
   if scope.has_caught() || scope.has_terminated() {
     scope.rethrow();
     // Dummy value, this result will be discarded because an error was thrown.
-    Ok(ZeroCopyBuf::empty())
+    Ok(ToJsBuffer::empty())
   } else if let Some(true) = ret {
     let vector = value_serializer.release();
     Ok(vector.into())
@@ -460,7 +461,7 @@ fn op_serialize(
 #[op(v8)]
 fn op_deserialize<'a>(
   scope: &mut v8::HandleScope<'a>,
-  zero_copy: ZeroCopyBuf,
+  zero_copy: JsBuffer,
   options: Option<SerializeDeserializeOptions>,
 ) -> Result<serde_v8::Value<'a>, Error> {
   let options = options.unwrap_or_default();
diff --git a/core/runtime/tests.rs b/core/runtime/tests.rs
index 857290b80..d2283365e 100644
--- a/core/runtime/tests.rs
+++ b/core/runtime/tests.rs
@@ -18,7 +18,7 @@ use crate::modules::ModuleType;
 use crate::modules::ResolutionKind;
 use crate::modules::SymbolicModule;
 use crate::Extension;
-use crate::ZeroCopyBuf;
+use crate::JsBuffer;
 use crate::*;
 use anyhow::Error;
 use deno_ops::op;
@@ -55,7 +55,7 @@ struct TestState {
 async fn op_test(
   rc_op_state: Rc<RefCell<OpState>>,
   control: u8,
-  buf: Option<ZeroCopyBuf>,
+  buf: Option<JsBuffer>,
 ) -> Result<u8, AnyError> {
   #![allow(clippy::await_holding_refcell_ref)] // False positive.
   let op_state_ = rc_op_state.borrow();
@@ -1977,15 +1977,15 @@ fn js_realm_init_snapshot() {
 
 #[test]
 fn js_realm_sync_ops() {
-  // Test that returning a ZeroCopyBuf and throwing an exception from a sync
+  // Test that returning a RustToV8Buf and throwing an exception from a sync
   // op result in objects with prototypes from the right realm. Note that we
   // don't test the result of returning structs, because they will be
   // serialized to objects with null prototype.
 
   #[op]
-  fn op_test(fail: bool) -> Result<ZeroCopyBuf, Error> {
+  fn op_test(fail: bool) -> Result<ToJsBuffer, Error> {
     if !fail {
-      Ok(ZeroCopyBuf::empty())
+      Ok(ToJsBuffer::empty())
     } else {
       Err(crate::error::type_error("Test"))
     }
@@ -2025,15 +2025,15 @@ fn js_realm_sync_ops() {
 
 #[tokio::test]
 async fn js_realm_async_ops() {
-  // Test that returning a ZeroCopyBuf and throwing an exception from a async
+  // Test that returning a RustToV8Buf and throwing an exception from a async
   // op result in objects with prototypes from the right realm. Note that we
   // don't test the result of returning structs, because they will be
   // serialized to objects with null prototype.
 
   #[op]
-  async fn op_test(fail: bool) -> Result<ZeroCopyBuf, Error> {
+  async fn op_test(fail: bool) -> Result<ToJsBuffer, Error> {
     if !fail {
-      Ok(ZeroCopyBuf::empty())
+      Ok(ToJsBuffer::empty())
     } else {
       Err(crate::error::type_error("Test"))
     }