Implement AddToKeptObjects and add JS_ClearKeptObjects

api-test.c

@@ -473,6 +473,26 @@ static void promise_mark_as_handled(void)
     JS_FreeRuntime(rt);
 }
 
+static void clear_kept_objects(void)
+{
+    JSRuntime *rt = new_runtime();
+    JSContext *ctx = JS_NewContext(rt);
+
+    JSValue w = eval(ctx, "let o = {x:1}; const w = new WeakRef(o); o = null; w");
+    assert(JS_IsObject(w));
+    JSValue got = eval(ctx, "w.deref()");
+    assert(JS_IsObject(got));
+    JS_FreeValue(ctx, got);
+
+    JS_ClearKeptObjects(rt);
+    got = eval(ctx, "w.deref()");
+    assert(JS_IsUndefined(got));
+
+    JS_FreeValue(ctx, w);
+    JS_FreeContext(ctx);
+    JS_FreeRuntime(rt);
+}
+
 static void runtime_cstring_free(void)
 {
     JSRuntime *rt = new_runtime();
@@ -1294,6 +1314,7 @@ int main(void)
     module_serde();
     module_unhandled_rejection();
     promise_mark_as_handled();
+    clear_kept_objects();
     runtime_cstring_free();
     utf16_string();
     weak_map_gc_check();

quickjs.c

@@ -378,6 +378,9 @@ struct JSRuntime {
     // to js_promise_constructor
     JSValueLink *parent_promise;
 
+    // AddToKeptObjects list, dropped at job boundaries
+    JSValueLink *kept_objects;
+
     JSHostPromiseRejectionTracker *host_promise_rejection_tracker;
     void *host_promise_rejection_tracker_opaque;
 
@@ -2527,6 +2530,10 @@ int JS_ExecutePendingJob(JSRuntime *rt, JSContext **pctx)
     JSValue res;
     int i, ret;
 
+    /* job boundary: the host calling us means the previous script or job
+       finished */
+    JS_ClearKeptObjects(rt);
+
     if (list_empty(&rt->job_list)) {
         *pctx = NULL;
         return 0;
@@ -2641,6 +2648,7 @@ void JS_FreeRuntime(JSRuntime *rt)
 
     rt->in_free = true;
     JS_FreeValueRT(rt, rt->current_exception);
+    JS_ClearKeptObjects(rt);
 
     list_for_each_safe(el, el1, &rt->job_list) {
         JSJobEntry *e = list_entry(el, JSJobEntry, link);
@@ -62499,6 +62507,29 @@ typedef struct JSWeakRefData {
 
 static JSWeakRefData js_weakref_sentinel;
 
+static int js_add_to_kept_objects(JSContext *ctx, JSValueConst value)
+{
+    JSValueLink *link = js_malloc(ctx, sizeof(*link));
+    if (!link)
+        return -1;
+    link->value = js_dup(value);
+    link->next = ctx->rt->kept_objects;
+    ctx->rt->kept_objects = link;
+    return 0;
+}
+
+void JS_ClearKeptObjects(JSRuntime *rt)
+{
+    JSValueLink *link = rt->kept_objects;
+    rt->kept_objects = NULL;
+    while (link) {
+        JSValueLink *next = link->next;
+        JS_FreeValueRT(rt, unsafe_unconst(link->value));
+        js_free_rt(rt, link);
+        link = next;
+    }
+}
+
 static void js_weakref_finalizer(JSRuntime *rt, JSValueConst val)
 {
     JSWeakRefData *wrd = JS_GetOpaque(val, JS_CLASS_WEAK_REF);
@@ -62551,6 +62582,10 @@ static JSValue js_weakref_constructor(JSContext *ctx, JSValueConst new_target,
     insert_weakref_record(arg, wr);
 
     JS_SetOpaqueInternal(obj, wrd);
+    if (js_add_to_kept_objects(ctx, arg)) {
+        JS_FreeValue(ctx, obj);
+        return JS_EXCEPTION;
+    }
     return obj;
 }
 
@@ -62561,6 +62596,8 @@ static JSValue js_weakref_deref(JSContext *ctx, JSValueConst this_val, int argc,
         return JS_EXCEPTION;
     if (wrd == &js_weakref_sentinel)
         return JS_UNDEFINED;
+    if (js_add_to_kept_objects(ctx, wrd->target))
+        return JS_EXCEPTION;
     return js_dup(wrd->target);
 }
 

quickjs.h

@@ -557,6 +557,7 @@ JS_EXTERN int JS_AddIntrinsicTypedArrays(JSContext *ctx);
 JS_EXTERN int JS_AddIntrinsicPromise(JSContext *ctx);
 JS_EXTERN int JS_AddIntrinsicBigInt(JSContext *ctx);
 JS_EXTERN int JS_AddIntrinsicWeakRef(JSContext *ctx);
+JS_EXTERN void JS_ClearKeptObjects(JSRuntime *rt);
 JS_EXTERN int JS_AddPerformance(JSContext *ctx);
 JS_EXTERN int JS_AddIntrinsicDOMException(JSContext *ctx);
 JS_EXTERN int JS_AddIntrinsicAToB(JSContext *ctx);

tests/bug652.js

@@ -1,4 +1,4 @@
 import { assert } from "./assert.js"
 const ref = new WeakRef({})
 const val = ref.deref() // should not throw
-assert(val, undefined)
+assert(typeof val, "object") // kept alive until the end of the job

tests/weakref-kept-objects.js

@@ -0,0 +1,20 @@
+import { assert } from "./assert.js";
+
+/* the constructor keeps the target alive until the end of the job */
+{
+    let o = { x: 1 };
+    const w = new WeakRef(o);
+    o = null;
+    assert(typeof w.deref(), "object");
+}
+
+/* deref() keeps it too, and the kept set is cleared at job boundaries */
+{
+    let o = { x: 2 };
+    const w = new WeakRef(o);
+    assert(w.deref().x, 2);
+    o = null;
+    assert(typeof w.deref(), "object");
+    await Promise.resolve();
+    assert(w.deref(), undefined);
+}