Add GC callbacks, and a mechanism to fix the threshold

quickjs.c

@@ -237,6 +237,9 @@ struct JSRuntime {
     struct list_head tmp_obj_list; /* used during GC */
     JSGCPhaseEnum gc_phase : 8;
     size_t malloc_gc_threshold;
+    BOOL fix_malloc_gc_threshold : 8;
+    BOOL (*gc_before_callback)(); /* Callback before the gc event takes place */
+    void (*gc_after_callback)(); /* Callback after the gc event takes place */
 #ifdef DUMP_LEAKS
     struct list_head string_list; /* list of JSString.link */
 #endif
@@ -1362,9 +1365,21 @@ static void js_trigger_gc(JSRuntime *rt, size_t size)
                    (uint64_t)rt->malloc_state.malloc_size);
         }
 #endif
-        JS_RunGC(rt);
-        rt->malloc_gc_threshold = rt->malloc_state.malloc_size +
-            (rt->malloc_state.malloc_size >> 1);
+        //To ensure JS_RunGC cannot be executed again within callbacks, disable and restore it after.
+        size_t tmp_threshold = rt->malloc_gc_threshold;
+        rt->malloc_gc_threshold=-1;
+
+        if((rt->gc_before_callback == NULL) || rt->gc_before_callback()){
+            JS_RunGC(rt);
+            if(rt->gc_after_callback != NULL)rt->gc_after_callback();
+        }
+
+        rt->malloc_gc_threshold=tmp_threshold;
+
+        if(rt->fix_malloc_gc_threshold == FALSE) {
+            rt->malloc_gc_threshold = rt->malloc_state.malloc_size +
+                (rt->malloc_state.malloc_size >> 1);
+        }
     }
 }
 
@@ -1631,6 +1646,10 @@ JSRuntime *JS_NewRuntime2(const JSMallocFunctions *mf, void *opaque)
     rt->malloc_state = ms;
     rt->malloc_gc_threshold = 256 * 1024;
 
+    rt->fix_malloc_gc_threshold = FALSE;
+    rt->gc_after_callback = NULL;
+    rt->gc_before_callback = NULL;
+
     bf_context_init(&rt->bf_ctx, js_bf_realloc, rt);
 
     init_list_head(&rt->context_list);
@@ -1777,6 +1796,22 @@ void JS_SetGCThreshold(JSRuntime *rt, size_t gc_threshold)
     rt->malloc_gc_threshold = gc_threshold;
 }
 
+void JS_SetGCThresholdFixed(JSRuntime *rt, BOOL fix)
+{
+    rt->fix_malloc_gc_threshold = fix;
+}
+
+
+void JS_SetGCBeforeCallback(JSRuntime *rt, BOOL(*fn)())
+{
+    rt->gc_before_callback = fn;
+}
+
+void JS_SetGCAfterCallback(JSRuntime *rt, void(*fn)())
+{
+    rt->gc_after_callback = fn;
+}
+
 #define malloc(s) malloc_is_forbidden(s)
 #define free(p) free_is_forbidden(p)
 #define realloc(p,s) realloc_is_forbidden(p,s)

quickjs.h

@@ -307,6 +307,9 @@ JS_EXTERN void JS_SetMemoryLimit(JSRuntime *rt, size_t limit);
 JS_EXTERN void JS_SetDumpFlags(JSRuntime *rt, uint64_t flags);
 JS_EXTERN size_t JS_GetGCThreshold(JSRuntime *rt);
 JS_EXTERN void JS_SetGCThreshold(JSRuntime *rt, size_t gc_threshold);
+JS_EXTERN void JS_SetGCThresholdFixed(JSRuntime *rt, JS_BOOL fixed);
+JS_EXTERN void JS_SetGCBeforeCallback(JSRuntime *rt, JS_BOOL(*cb)());
+JS_EXTERN void JS_SetGCAfterCallback(JSRuntime *rt, void(*cb)());
 /* use 0 to disable maximum stack size check */
 JS_EXTERN void JS_SetMaxStackSize(JSRuntime *rt, size_t stack_size);
 /* should be called when changing thread to update the stack top value