refactor(core): Move optional callbacks from `JsRuntimeState` to `ContextState` (#17422)

The `JsRuntimeState` struct stores a number of JS callbacks that are
used either in the event loop or when interacting with V8. Some of these
callback fields are vectors of callbacks, and therefore could plausibly
store at least one callback per realm. However, some of those fields are
`Option<v8::Global<v8::Function>>`, which would make the callbacks set
by a realm override the one that might have been set by a different
realm.

As it turns out, all of the current such optional callbacks
(`js_promise_reject_cb`, `js_format_exception_cb` and
`js_wasm_streaming_cb`) are only used from inside a realm, and therefore
this change makes it so such callbacks can only be set from inside a
realm, and will only affect that realm.

This is a reland of #15599.

Towards #13239.

1 files changed, 23 insertions, 11 deletions

diff --git a/core/ops_builtin_v8.rs b/core/ops_builtin_v8.rs
index e1f497424..c9391a58f 100644
--- a/core/ops_builtin_v8.rs
+++ b/core/ops_builtin_v8.rs
@@ -114,8 +114,11 @@ fn op_set_promise_reject_callback<'a>(
   cb: serde_v8::Value,
 ) -> Result<Option<serde_v8::Value<'a>>, Error> {
   let cb = to_v8_fn(scope, cb)?;
-  let state_rc = JsRuntime::state(scope);
-  let old = state_rc.borrow_mut().js_promise_reject_cb.replace(cb);
+  let context_state_rc = JsRealm::state_from_scope(scope);
+  let old = context_state_rc
+    .borrow_mut()
+    .js_promise_reject_cb
+    .replace(cb);
   let old = old.map(|v| v8::Local::new(scope, v));
   Ok(old.map(|v| from_v8(scope, v.into()).unwrap()))
 }
@@ -682,22 +685,28 @@ fn op_set_wasm_streaming_callback(
   cb: serde_v8::Value,
 ) -> Result<(), Error> {
   let cb = to_v8_fn(scope, cb)?;
-  let state_rc = JsRuntime::state(scope);
-  let mut state = state_rc.borrow_mut();
+  let context_state_rc = JsRealm::state_from_scope(scope);
+  let mut context_state = context_state_rc.borrow_mut();
   // The callback to pass to the v8 API has to be a unit type, so it can't
   // borrow or move any local variables. Therefore, we're storing the JS
   // callback in a JsRuntimeState slot.
-  if state.js_wasm_streaming_cb.is_some() {
+  if context_state.js_wasm_streaming_cb.is_some() {
     return Err(type_error("op_set_wasm_streaming_callback already called"));
   }
-  state.js_wasm_streaming_cb = Some(cb);
+  context_state.js_wasm_streaming_cb = Some(cb);
 
   scope.set_wasm_streaming_callback(|scope, arg, wasm_streaming| {
     let (cb_handle, streaming_rid) = {
+      let context_state_rc = JsRealm::state_from_scope(scope);
+      let cb_handle = context_state_rc
+        .borrow()
+        .js_wasm_streaming_cb
+        .as_ref()
+        .unwrap()
+        .clone();
       let state_rc = JsRuntime::state(scope);
-      let state = state_rc.borrow();
-      let cb_handle = state.js_wasm_streaming_cb.as_ref().unwrap().clone();
-      let streaming_rid = state
+      let streaming_rid = state_rc
+        .borrow()
         .op_state
         .borrow_mut()
         .resource_table
@@ -835,8 +844,11 @@ fn op_set_format_exception_callback<'a>(
   cb: serde_v8::Value<'a>,
 ) -> Result<Option<serde_v8::Value<'a>>, Error> {
   let cb = to_v8_fn(scope, cb)?;
-  let state_rc = JsRuntime::state(scope);
-  let old = state_rc.borrow_mut().js_format_exception_cb.replace(cb);
+  let context_state_rc = JsRealm::state_from_scope(scope);
+  let old = context_state_rc
+    .borrow_mut()
+    .js_format_exception_cb
+    .replace(cb);
   let old = old.map(|v| v8::Local::new(scope, v));
   Ok(old.map(|v| from_v8(scope, v.into()).unwrap()))
 }