fixup! fixup! fixup! Patch v8 to support promise cross-context resolu…

…tion

src/workerd/io/io-context.c++

@@ -121,7 +121,7 @@ IoContext::IoContext(ThreadContext& thread,
       actor(actorParam),
       limitEnforcer(kj::mv(limitEnforcerParam)),
       threadId(getThreadId()),
-      deleteQueue(kj::atomicRefcounted<DeleteQueue>()),
+      deleteQueue(kj::atomicRefcounted<DeleteQueue>(), *this),
       cachePutSerializer(kj::READY_NOW),
       waitUntilTasks(*this),
       timeoutManager(kj::heap<TimeoutManagerImpl>()),

src/workerd/io/io-own.c++

@@ -59,6 +59,29 @@ void DeleteQueue::scheduleAction(jsg::Lock& js, kj::Function<void(jsg::Lock&)>&&
   }
 }
 
+DeleteQueuePtr::~DeleteQueuePtr() noexcept(false) {
+  auto ptr = get();
+  if (ptr != nullptr) {
+    auto lock = ptr->crossThreadDeleteQueue.lockExclusive();
+    // If there are actions still pending in the DeleteQueue, those will end up being
+    // silently dropped on the floor. This might cause some confusion for users who
+    // might expect promise continuations to still run. Let's log a warning in that
+    // case to help users understand what is happening.
+    KJ_IF_SOME(state, *lock) {
+      if (state.actions.size() > 0) {
+        context.logWarning(
+            "A promise was resolved or rejected from a different request context than "
+            "the one it was created in. However, the creating context is being destroyed "
+            "with continuations for that request still pending that can no longer be run "
+            "safely. This is usally because of the request being canceled or detected as "
+            "being hung.");
+        // TODO(soon): Add documentation link to this warning.
+      }
+    }
+    *lock = kj::none;
+  }
+}
+
 void DeleteQueue::checkFarGet(const DeleteQueue* deleteQueue, const std::type_info& type) {
   IoContext::current().checkFarGet(deleteQueue, type);
 }

src/workerd/io/io-own.h

@@ -222,18 +222,18 @@ inline ReverseIoOwn<T> DeleteQueue::addObjectReverse(
 
 // When the IoContext is destroyed, we need to null out the DeleteQueue. Complicating
 // matters a bit, we need to cancel all tasks (destroy the TaskSet) before this happens, so
-// we can't just do it in IoContext's destrucrtor. As a hack, we customize our pointer
+// we can't just do it in IoContext's destructor. As a hack, we customize our pointer
 // to the delete queue to get the tear-down order right.
 class DeleteQueuePtr: public kj::Own<DeleteQueue> {
 public:
-  DeleteQueuePtr(kj::Own<DeleteQueue> value): kj::Own<DeleteQueue>(kj::mv(value)) {}
+  DeleteQueuePtr(kj::Own<DeleteQueue> value, IoContext& context)
+      : kj::Own<DeleteQueue>(kj::mv(value)),
+        context(context) {}
   KJ_DISALLOW_COPY_AND_MOVE(DeleteQueuePtr);
-  ~DeleteQueuePtr() noexcept(false) {
-    auto ptr = get();
-    if (ptr != nullptr) {
-      *ptr->crossThreadDeleteQueue.lockExclusive() = kj::none;
-    }
-  }
+  ~DeleteQueuePtr() noexcept(false);
+
+private:
+  IoContext& context;
 };
 
 // Owned pointer held by a V8 heap object, pointing to a KJ event loop object. Cannot be