Add flag to check if currently doing GC

include/refcount/refcount.h

@@ -66,6 +66,9 @@ typedef struct RefcountContext {
 #ifdef REFCOUNT_HAS_THREADS
     mtx_t so_mtx; //<! Mutex protecting static_objects.
     mtx_t gr_mtx; //<! Mutex protecting gc_roots.
+    _Atomic bool doing_gc;
+#else
+    bool doing_gc;
 #endif
 } RefcountContext;
 
@@ -195,6 +198,20 @@ static inline void refcount_context_unref_as_callback(void *obj, void *ctx) {
 
 ptrdiff_t refcount_context_garbage_collect(RefcountContext *ctx);
 
+/**
+ * Test weather a give context is currently performing a GC operation.
+ * @param ctx The #RefcountContext
+ * @return True if the context is currently doing a GC operation, false
+ * otherwise
+ */
+static bool refcount_context_is_doing_gc(const RefcountContext *ctx) {
+#ifdef REFCOUNT_HAS_THREADS
+    return atomic_load_explicit(&ctx->doing_gc, memory_order_relaxed);
+#else
+    return ctx->doing_gc;
+#endif
+}
+
 RefcountWeakref *refcount_context_make_weakref(const RefcountContext *ctx,
                                                void *obj);
 
@@ -320,7 +337,7 @@ static inline void refcount_unref_as_callback(void *obj) {
 }
 
 /**
- * Same as #refcount_context_garbage_collect, but only operates on the globa
+ * Same as #refcount_context_garbage_collect, but only operates on the global
  * context.
  * @return The number of object's freed, or -1 if an error occurred
  */
@@ -328,6 +345,16 @@ static inline ptrdiff_t refcount_garbage_collect(void) {
     return refcount_context_garbage_collect(refcount_default_context);
 }
 
+/**
+ * Same as #refcount_context_is_doing_gc, but only operates on the global
+ * context.
+ * @return True if the context is currently doing a GC operation, false
+ * otherwise
+ */
+static inline bool refcount_is_doing_gc(void) {
+    return refcount_context_is_doing_gc(refcount_default_context);
+}
+
 /**
  * Same as #refcount_context_make_weakref, but operates on the global context.
  * @param obj The object to reference