* ext/objspace/objspace.c: add ObjectSpace#reachable_objects_from.

  This method returns an array of objects referenced by given object.
  If given object is special objects such as true/false/nil/Fixnum etc
  then it returns nil. See rdoc for details.
  [ruby-core:39772]
* test/objspace/test_objspace.rb: add a test for this method.
* gc.c: add rb_objspace_reachable_objects_from().
  To make this function, add several member `mark_func_data'
  to rb_objspace_t.  If mark_func_data is not null, then
  gc_mark() calls mark_func_data::mark_func.
* gc.h: export rb_objspace_reachable_objects_from().



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@37094 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 111 insertions, 29 deletions

diff --git a/gc.c b/gc.c
index e87e029596..d34e70940b 100644
--- a/gc.c
+++ b/gc.c
@@ -273,6 +273,11 @@ typedef struct rb_objspace {
     struct gc_list *global_list;
     size_t count;
     int gc_stress;
+
+    struct mark_func_data_struct {
+	VALUE data;
+	void (*mark_func)(struct rb_objspace *objspace, VALUE v);
+    } *mark_func_data;
 } rb_objspace_t;
 
 #if defined(ENABLE_VM_OBJSPACE) && ENABLE_VM_OBJSPACE
@@ -1138,30 +1143,40 @@ struct os_each_struct {
 };
 
 static int
+internal_object_p(VALUE obj)
+{
+    RVALUE *p = (RVALUE *)obj;
+
+    if (p->as.basic.flags) {
+	switch (BUILTIN_TYPE(p)) {
+	  case T_NONE:
+	  case T_ICLASS:
+	  case T_NODE:
+	  case T_ZOMBIE:
+	    break;
+	  case T_CLASS:
+	    if (FL_TEST(p, FL_SINGLETON))
+	      break;
+	  default:
+	    if (!p->as.basic.klass) break;
+	    return 0;
+	}
+    }
+    return 1;
+}
+
+static int
 os_obj_of_i(void *vstart, void *vend, size_t stride, void *data)
 {
     struct os_each_struct *oes = (struct os_each_struct *)data;
     RVALUE *p = (RVALUE *)vstart, *pend = (RVALUE *)vend;
-    volatile VALUE v;
 
     for (; p != pend; p++) {
-	if (p->as.basic.flags) {
-	    switch (BUILTIN_TYPE(p)) {
-	      case T_NONE:
-	      case T_ICLASS:
-	      case T_NODE:
-	      case T_ZOMBIE:
-		continue;
-	      case T_CLASS:
-		if (FL_TEST(p, FL_SINGLETON))
-		    continue;
-	      default:
-		if (!p->as.basic.klass) continue;
-		v = (VALUE)p;
-		if (!oes->of || rb_obj_is_kind_of(v, oes->of)) {
-		    rb_yield(v);
-		    oes->num++;
-		}
+	volatile VALUE v = (VALUE)p;
+	if (!internal_object_p(v)) {
+	    if (!oes->of || rb_obj_is_kind_of(v, oes->of)) {
+		rb_yield(v);
+		oes->num++;
 	    }
 	}
     }
@@ -2521,17 +2536,31 @@ gc_mark_ptr(rb_objspace_t *objspace, VALUE ptr)
     return 1;
 }
 
+static int
+markable_object_p(rb_objspace_t *objspace, VALUE ptr)
+{
+    register RVALUE *obj = RANY(ptr);
+
+    if (rb_special_const_p(ptr)) return 0; /* special const not marked */
+    if (obj->as.basic.flags == 0) return 0 ;       /* free cell */
+
+    return 1;
+}
+
 static void
 gc_mark(rb_objspace_t *objspace, VALUE ptr)
 {
-    register RVALUE *obj;
-
-    obj = RANY(ptr);
-    if (rb_special_const_p(ptr)) return; /* special const not marked */
-    if (obj->as.basic.flags == 0) return;       /* free cell */
-    if (!gc_mark_ptr(objspace, ptr)) return;	/* already marked */
+    if (!markable_object_p(objspace, ptr)) {
+	return;
+    }
 
-    push_mark_stack(&objspace->mark_stack, ptr);
+    if (LIKELY(objspace->mark_func_data == 0)) {
+	if (!gc_mark_ptr(objspace, ptr)) return; /* already marked */
+	push_mark_stack(&objspace->mark_stack, ptr);
+    }
+    else {
+	objspace->mark_func_data->mark_func(objspace, ptr);
+    }
 }
 
 void
@@ -2548,10 +2577,16 @@ gc_mark_children(rb_objspace_t *objspace, VALUE ptr)
     goto marking;		/* skip */
 
   again:
-    obj = RANY(ptr);
-    if (rb_special_const_p(ptr)) return; /* special const not marked */
-    if (obj->as.basic.flags == 0) return;       /* free cell */
-    if (!gc_mark_ptr(objspace, ptr)) return;  /* already marked */
+    if (LIKELY(objspace->mark_func_data == 0)) {
+	obj = RANY(ptr);
+	if (rb_special_const_p(ptr)) return; /* special const not marked */
+	if (obj->as.basic.flags == 0) return;       /* free cell */
+	if (!gc_mark_ptr(objspace, ptr)) return;  /* already marked */
+    }
+    else {
+	gc_mark(objspace, ptr);
+	return;
+    }
 
   marking:
     if (FL_TEST(obj, FL_EXIVAR)) {
@@ -2953,6 +2988,8 @@ rb_gc_unregister_address(VALUE *addr)
 static int
 garbage_collect(rb_objspace_t *objspace)
 {
+    struct mark_func_data_struct *prev_mark_func_data;
+
     if (GC_NOTIFY) printf("start garbage_collect()\n");
 
     if (!heaps) {
@@ -2964,6 +3001,9 @@ garbage_collect(rb_objspace_t *objspace)
 
     gc_prof_timer_start(objspace);
 
+    prev_mark_func_data = objspace->mark_func_data;
+    objspace->mark_func_data = 0;
+
     rest_sweep(objspace);
 
     during_gc++;
@@ -2973,6 +3013,8 @@ garbage_collect(rb_objspace_t *objspace)
     gc_sweep(objspace);
     gc_prof_sweep_timer_stop(objspace);
 
+    objspace->mark_func_data = prev_mark_func_data;
+
     gc_prof_timer_stop(objspace, Qtrue);
     if (GC_NOTIFY) printf("end garbage_collect()\n");
     return TRUE;
@@ -3241,6 +3283,46 @@ rb_gc_set_params(void)
     }
 }
 
+static void
+collect_refs(rb_objspace_t *objspace, VALUE obj)
+{
+    if (markable_object_p(objspace, obj) && !internal_object_p(obj)) {
+	st_insert((st_table *)objspace->mark_func_data->data, obj, Qtrue);
+    }
+}
+
+static int
+collect_keys(st_data_t key, st_data_t value, st_data_t data)
+{
+    VALUE ary = (VALUE)data;
+    rb_ary_push(ary, (VALUE)key);
+    return ST_CONTINUE;
+}
+
+VALUE
+rb_objspace_reachable_objects_from(VALUE obj)
+{
+    rb_objspace_t *objspace = &rb_objspace;
+
+    if (markable_object_p(objspace, obj)) {
+	st_table *refs = st_init_numtable();
+	struct mark_func_data_struct mfd;
+	VALUE ret = rb_ary_new();
+	mfd.mark_func = collect_refs;
+	mfd.data = (VALUE)refs;
+	objspace->mark_func_data = &mfd;
+
+	gc_mark_children(objspace, obj);
+
+	objspace->mark_func_data = 0;
+	st_foreach(refs, collect_keys, (st_data_t)ret);
+	return ret;
+    }
+    else {
+	return Qnil;
+    }
+}
+
 /*
   ------------------------ Extended allocator ------------------------
 */