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.

1 files changed, 37 insertions, 25 deletions

diff --git a/ext/kv/lib.rs b/ext/kv/lib.rs
index 2763fcf50..db7c5c22e 100644
--- a/ext/kv/lib.rs
+++ b/ext/kv/lib.rs
@@ -19,10 +19,11 @@ use deno_core::op;
 use deno_core::serde_v8::AnyValue;
 use deno_core::serde_v8::BigInt;
 use deno_core::ByteString;
+use deno_core::JsBuffer;
 use deno_core::OpState;
 use deno_core::Resource;
 use deno_core::ResourceId;
-use deno_core::ZeroCopyBuf;
+use deno_core::ToJsBuffer;
 use serde::Deserialize;
 use serde::Serialize;
 
@@ -122,7 +123,8 @@ impl From<AnyValue> for KeyPart {
       AnyValue::Number(n) => KeyPart::Float(n),
       AnyValue::BigInt(n) => KeyPart::Int(n),
       AnyValue::String(s) => KeyPart::String(s),
-      AnyValue::Buffer(buf) => KeyPart::Bytes(buf.to_vec()),
+      AnyValue::V8Buffer(buf) => KeyPart::Bytes(buf.to_vec()),
+      AnyValue::RustBuffer(_) => unreachable!(),
     }
   }
 }
@@ -135,51 +137,61 @@ impl From<KeyPart> for AnyValue {
       KeyPart::Float(n) => AnyValue::Number(n),
       KeyPart::Int(n) => AnyValue::BigInt(n),
       KeyPart::String(s) => AnyValue::String(s),
-      KeyPart::Bytes(buf) => AnyValue::Buffer(buf.into()),
+      KeyPart::Bytes(buf) => AnyValue::RustBuffer(buf.into()),
     }
   }
 }
 
-#[derive(Debug, Deserialize, Serialize)]
+#[derive(Debug, Deserialize)]
 #[serde(tag = "kind", content = "value", rename_all = "snake_case")]
-enum V8Value {
-  V8(ZeroCopyBuf),
-  Bytes(ZeroCopyBuf),
+enum FromV8Value {
+  V8(JsBuffer),
+  Bytes(JsBuffer),
   U64(BigInt),
 }
 
-impl TryFrom<V8Value> for Value {
+#[derive(Debug, Serialize)]
+#[serde(tag = "kind", content = "value", rename_all = "snake_case")]
+enum ToV8Value {
+  V8(ToJsBuffer),
+  Bytes(ToJsBuffer),
+  U64(BigInt),
+}
+
+impl TryFrom<FromV8Value> for Value {
   type Error = AnyError;
-  fn try_from(value: V8Value) -> Result<Self, AnyError> {
+  fn try_from(value: FromV8Value) -> Result<Self, AnyError> {
     Ok(match value {
-      V8Value::V8(buf) => Value::V8(buf.to_vec()),
-      V8Value::Bytes(buf) => Value::Bytes(buf.to_vec()),
-      V8Value::U64(n) => Value::U64(num_bigint::BigInt::from(n).try_into()?),
+      FromV8Value::V8(buf) => Value::V8(buf.to_vec()),
+      FromV8Value::Bytes(buf) => Value::Bytes(buf.to_vec()),
+      FromV8Value::U64(n) => {
+        Value::U64(num_bigint::BigInt::from(n).try_into()?)
+      }
     })
   }
 }
 
-impl From<Value> for V8Value {
+impl From<Value> for ToV8Value {
   fn from(value: Value) -> Self {
     match value {
-      Value::V8(buf) => V8Value::V8(buf.into()),
-      Value::Bytes(buf) => V8Value::Bytes(buf.into()),
-      Value::U64(n) => V8Value::U64(num_bigint::BigInt::from(n).into()),
+      Value::V8(buf) => ToV8Value::V8(buf.into()),
+      Value::Bytes(buf) => ToV8Value::Bytes(buf.into()),
+      Value::U64(n) => ToV8Value::U64(num_bigint::BigInt::from(n).into()),
     }
   }
 }
 
-#[derive(Deserialize, Serialize)]
-struct V8KvEntry {
+#[derive(Serialize)]
+struct ToV8KvEntry {
   key: KvKey,
-  value: V8Value,
+  value: ToV8Value,
   versionstamp: ByteString,
 }
 
-impl TryFrom<KvEntry> for V8KvEntry {
+impl TryFrom<KvEntry> for ToV8KvEntry {
   type Error = AnyError;
   fn try_from(entry: KvEntry) -> Result<Self, AnyError> {
-    Ok(V8KvEntry {
+    Ok(ToV8KvEntry {
       key: decode_key(&entry.key)?
         .0
         .into_iter()
@@ -223,7 +235,7 @@ async fn op_kv_snapshot_read<DBH>(
   rid: ResourceId,
   ranges: Vec<SnapshotReadRange>,
   consistency: V8Consistency,
-) -> Result<Vec<Vec<V8KvEntry>>, AnyError>
+) -> Result<Vec<Vec<ToV8KvEntry>>, AnyError>
 where
   DBH: DatabaseHandler + 'static,
 {
@@ -301,7 +313,7 @@ impl<QMH: QueueMessageHandle + 'static> Resource for QueueMessageResource<QMH> {
 async fn op_kv_dequeue_next_message<DBH>(
   state: Rc<RefCell<OpState>>,
   rid: ResourceId,
-) -> Result<(ZeroCopyBuf, ResourceId), AnyError>
+) -> Result<(ToJsBuffer, ResourceId), AnyError>
 where
   DBH: DatabaseHandler + 'static,
 {
@@ -364,7 +376,7 @@ impl TryFrom<V8KvCheck> for KvCheck {
   }
 }
 
-type V8KvMutation = (KvKey, String, Option<V8Value>);
+type V8KvMutation = (KvKey, String, Option<FromV8Value>);
 
 impl TryFrom<V8KvMutation> for KvMutation {
   type Error = AnyError;
@@ -389,7 +401,7 @@ impl TryFrom<V8KvMutation> for KvMutation {
   }
 }
 
-type V8Enqueue = (ZeroCopyBuf, u64, Vec<KvKey>, Option<Vec<u32>>);
+type V8Enqueue = (JsBuffer, u64, Vec<KvKey>, Option<Vec<u32>>);
 
 impl TryFrom<V8Enqueue> for Enqueue {
   type Error = AnyError;