share the deferred_wait thread at process level

Author: Jacob Lacouture

ccan/list/list.h

@@ -200,6 +200,26 @@ static inline void ccan_list_add_tail_(struct ccan_list_head *h,
 	ccan_list_add_before_(h, &h->n, n, abortstr);
 }
 
+/**
+ * ccan_node_linked - is a node embedded in any list?
+ * @n: the ccan_list_node
+ *
+ * Returns false if the node belongs to any list.
+ * We tolerate two "unlinked" states. One created by ccan_list_node_init
+ * and one where the pointers are set to NULL, as by ccan_list_del when
+ * CCAN_LIST_DEBUG is enabled.
+ *
+ * Example:
+ *  ccan_list_del(&child->list);
+ *	assert(!ccan_node_linked(&child->list));
+ */
+#define ccan_node_linked(n) ccan_node_linked_(n, CCAN_LIST_LOC)
+static inline int ccan_node_linked_(const struct ccan_list_node *n, const char* abortstr)
+{
+	(void)ccan_list_debug_node(n, abortstr);
+	return n != n->next && n->next;
+}
+
 /**
  * ccan_list_empty - is a list empty?
  * @h: the ccan_list_head

eval.c

@@ -262,6 +262,7 @@ rb_ec_cleanup(rb_execution_context_t *ec, enum ruby_tag_type ex)
     EC_POP_TAG();
     th = th0;
     rb_thread_stop_timer_thread();
+    rb_thread_stop_deferred_wait_thread(false);
     ruby_vm_destruct(th->vm);
     // For YJIT, call this after ruby_vm_destruct() frees jit_cont for the root fiber.
     rb_jit_cont_finish();

process.c

@@ -1522,6 +1522,7 @@ before_exec_non_async_signal_safe(void)
      * Nowadays, we always stop the timer thread completely to allow redirects.
      */
     rb_thread_stop_timer_thread();
+    rb_thread_stop_deferred_wait_thread(false);
 }
 
 #define WRITE_CONST(fd, str) (void)(write((fd),(str),sizeof(str)-1)<0)
@@ -1569,6 +1570,7 @@ after_exec(void)
 {
     rb_thread_reset_timer_thread();
     rb_thread_start_timer_thread();
+    rb_thread_start_deferred_wait_thread(false);
 }
 
 #if defined HAVE_WORKING_FORK || defined HAVE_DAEMON

thread.c

@@ -5761,6 +5761,7 @@ Init_Thread(void)
     }
 
     rb_thread_create_timer_thread();
+    rb_thread_start_deferred_wait_thread(true);
 
     Init_thread_sync();
 

thread_none.c

@@ -47,6 +47,16 @@ thread_sched_blocking_region_exit(struct rb_thread_sched *sched, rb_thread_t *th
 {
 }
 
+void
+rb_thread_start_deferred_wait_thread(bool init)
+{
+}
+
+void
+rb_thread_stop_deferred_wait_thread(bool destroy)
+{
+}
+
 void
 rb_thread_sched_init(struct rb_thread_sched *sched, bool atfork)
 {