3 files changed, 77 insertions, 0 deletions

diff --git a/core/bindings.rs b/core/bindings.rs
index 143ccda9b..d8337322d 100644
--- a/core/bindings.rs
+++ b/core/bindings.rs
@@ -22,7 +22,10 @@ use std::convert::TryInto;
 use std::option::Option;
 use std::rc::Rc;
 use url::Url;
+use v8::HandleScope;
+use v8::Local;
 use v8::MapFnTo;
+use v8::SharedArrayBuffer;
 
 lazy_static::lazy_static! {
   pub static ref EXTERNAL_REFERENCES: v8::ExternalReferences =
@@ -713,6 +716,22 @@ impl<'a> v8::ValueSerializerImpl for SerializeDeserialize<'a> {
     scope.throw_exception(error);
   }
 
+  fn get_shared_array_buffer_id<'s>(
+    &mut self,
+    scope: &mut HandleScope<'s>,
+    shared_array_buffer: Local<'s, SharedArrayBuffer>,
+  ) -> Option<u32> {
+    let state_rc = JsRuntime::state(scope);
+    let state = state_rc.borrow_mut();
+    if let Some(shared_array_buffer_store) = &state.shared_array_buffer_store {
+      let backing_store = shared_array_buffer.get_backing_store();
+      let id = shared_array_buffer_store.insert(backing_store);
+      Some(id)
+    } else {
+      None
+    }
+  }
+
   fn write_host_object<'s>(
     &mut self,
     scope: &mut v8::HandleScope<'s>,
@@ -735,6 +754,23 @@ impl<'a> v8::ValueSerializerImpl for SerializeDeserialize<'a> {
 }
 
 impl<'a> v8::ValueDeserializerImpl for SerializeDeserialize<'a> {
+  fn get_shared_array_buffer_from_id<'s>(
+    &mut self,
+    scope: &mut HandleScope<'s>,
+    transfer_id: u32,
+  ) -> Option<Local<'s, SharedArrayBuffer>> {
+    let state_rc = JsRuntime::state(scope);
+    let state = state_rc.borrow_mut();
+    if let Some(shared_array_buffer_store) = &state.shared_array_buffer_store {
+      let backing_store = shared_array_buffer_store.take(transfer_id)?;
+      let shared_array_buffer =
+        v8::SharedArrayBuffer::with_backing_store(scope, &backing_store);
+      Some(shared_array_buffer)
+    } else {
+      None
+    }
+  }
+
   fn read_host_object<'s>(
     &mut self,
     scope: &mut v8::HandleScope<'s>,
diff --git a/core/lib.rs b/core/lib.rs
index 4a9a213f4..8c8861c79 100644
--- a/core/lib.rs
+++ b/core/lib.rs
@@ -57,6 +57,7 @@ pub use crate::modules::ModuleLoader;
 pub use crate::modules::ModuleSource;
 pub use crate::modules::ModuleSourceFuture;
 pub use crate::modules::NoopModuleLoader;
+pub use crate::runtime::SharedArrayBufferStore;
 // TODO(bartlomieju): this struct should be implementation
 // detail nad not be public
 pub use crate::modules::RecursiveModuleLoad;
diff --git a/core/runtime.rs b/core/runtime.rs
index 48003c811..cf43c2adc 100644
--- a/core/runtime.rs
+++ b/core/runtime.rs
@@ -38,6 +38,8 @@ use std::mem::forget;
 use std::option::Option;
 use std::pin::Pin;
 use std::rc::Rc;
+use std::sync::Arc;
+use std::sync::Mutex;
 use std::sync::Once;
 use std::task::Context;
 use std::task::Poll;
@@ -97,6 +99,36 @@ struct ModEvaluate {
   sender: mpsc::Sender<Result<(), AnyError>>,
 }
 
+#[derive(Default, Clone)]
+pub struct SharedArrayBufferStore(Arc<Mutex<SharedArrayBufferStoreInner>>);
+
+#[derive(Default)]
+pub struct SharedArrayBufferStoreInner {
+  buffers: HashMap<u32, v8::SharedRef<v8::BackingStore>>,
+  last_id: u32,
+}
+
+impl SharedArrayBufferStore {
+  pub(crate) fn insert(
+    &self,
+    backing_store: v8::SharedRef<v8::BackingStore>,
+  ) -> u32 {
+    let mut buffers = self.0.lock().unwrap();
+    let last_id = buffers.last_id;
+    buffers.buffers.insert(last_id, backing_store);
+    buffers.last_id += 1;
+    last_id
+  }
+
+  pub(crate) fn take(
+    &self,
+    id: u32,
+  ) -> Option<v8::SharedRef<v8::BackingStore>> {
+    let mut buffers = self.0.lock().unwrap();
+    buffers.buffers.remove(&id)
+  }
+}
+
 /// Internal state for JsRuntime which is stored in one of v8::Isolate's
 /// embedder slots.
 pub(crate) struct JsRuntimeState {
@@ -116,6 +148,7 @@ pub(crate) struct JsRuntimeState {
   pub(crate) pending_unref_ops: FuturesUnordered<PendingOpFuture>,
   pub(crate) have_unpolled_ops: bool,
   pub(crate) op_state: Rc<RefCell<OpState>>,
+  pub(crate) shared_array_buffer_store: Option<SharedArrayBufferStore>,
   waker: AtomicWaker,
 }
 
@@ -204,6 +237,12 @@ pub struct RuntimeOptions {
   /// V8 platform instance to use. Used when Deno initializes V8
   /// (which it only does once), otherwise it's silenty dropped.
   pub v8_platform: Option<v8::SharedRef<v8::Platform>>,
+
+  /// The buffer to use for transferring SharedArrayBuffers between isolates.
+  /// If multiple isolates should have the possibility of sharing
+  /// SharedArrayBuffers, they should use the same SharedArrayBufferStore. If no
+  /// SharedArrayBufferStore is specified, SharedArrayBuffer can not be serialized.
+  pub shared_array_buffer_store: Option<SharedArrayBufferStore>,
 }
 
 impl JsRuntime {
@@ -294,6 +333,7 @@ impl JsRuntime {
       js_error_create_fn,
       pending_ops: FuturesUnordered::new(),
       pending_unref_ops: FuturesUnordered::new(),
+      shared_array_buffer_store: options.shared_array_buffer_store,
       op_state: op_state.clone(),
       have_unpolled_ops: false,
       waker: AtomicWaker::new(),