Manage object reference count in JS runtime

Author: kateinoigakukun

Runtime/src/index.ts

@@ -50,22 +50,29 @@ class SwiftRuntimeHeap {
     allocHeap(value: any) {
         const isObject = typeof value == "object"
         if (isObject && value.swjs_heap_id) {
+            value.swjs_heap_rc++;
             return value.swjs_heap_id
         }
         const id = this._heapNextKey++;
         this._heapValues.set(id, value)
-        if (isObject)
+        if (isObject) {
             Reflect.set(value, "swjs_heap_id", id);
+            Reflect.set(value, "swjs_heap_rc", 1);
+        }
         return id
     }
 
     freeHeap(ref: ref) {
         const value = this._heapValues.get(ref);
         const isObject = typeof value == "object"
-        if (isObject && value.swjs_heap_id) {
+        if (isObject) {
+            const rc = --value.swjs_heap_rc;
+            if (rc != 0) return;
             delete value.swjs_heap_id;
+            this._heapValues.delete(ref)
+        } else {
+            this._heapValues.delete(ref)
         }
-        this._heapValues.delete(ref)
     }
 
     referenceHeap(ref: ref) {

Sources/JavaScriptKit/JSObject.swift

@@ -1,28 +1,12 @@
 import _CJavaScriptKit
 
-private struct Weak<T: AnyObject> {
-  weak var ref: T?
-}
-
-private var cache = [UInt32: Weak<JSObjectRef>]()
-
 @dynamicMemberLookup
 public class JSObjectRef: Equatable {
     internal var id: UInt32
     init(id: UInt32) {
         self.id = id
     }
 
-    static func retrieve(id: UInt32) -> JSObjectRef {
-        if id != 0, let ref = cache[id]?.ref {
-            return ref
-        } else {
-            let ref = JSObjectRef(id: id)
-            cache[id] = Weak(ref: ref)
-            return ref
-        }
-    }
-
     @_disfavoredOverload
     public subscript(dynamicMember name: String) -> ((JSValueConvertible...) -> JSValue)? {
         get {
@@ -62,10 +46,7 @@ public class JSObjectRef: Equatable {
     static let _JS_Predef_Value_Global: UInt32 = 0
     public static let global = JSObjectRef(id: _JS_Predef_Value_Global)
 
-    deinit {
-        cache[id] = nil
-        _destroy_ref(id)
-    }
+    deinit { _destroy_ref(id) }
 
     public static func == (lhs: JSObjectRef, rhs: JSObjectRef) -> Bool {
         return lhs.id == rhs.id

Sources/JavaScriptKit/JSValueConvertible.swift

@@ -111,7 +111,7 @@ extension RawJSValue: JSValueConvertible {
             let string = String(decodingCString: UnsafePointer(buffer), as: UTF8.self)
             return .string(string)
         case JavaScriptValueKind_Object:
-            return .object(JSObjectRef.retrieve(id: UInt32(payload1)))
+            return .object(JSObjectRef(id: UInt32(payload1)))
         case JavaScriptValueKind_Null:
             return .null
         case JavaScriptValueKind_Undefined: