Fix self conn deadlock

When a node goes to sleep and manages to send
a request to itself the request gets queued. Once
it wakes up from the sleep it will try to process
that request synchronous to own event loop and locks
itself. Queued messages should be handled async to the
event loop.

Author: omerfirmak

source/geod24/LocalRest.d

@@ -770,12 +770,14 @@ public final class RemoteAPI (API, alias S = VibeJSONSerializer!()) : API
 
                     auto sel_ret = C.select(read_list, write_list, 10.msecs);
 
-                    if (!control.isSleeping())
+                    if (await_msgs.length > 0 && !control.isSleeping())
                     {
-                        foreach (ref await_msg; await_msgs)
-                            handleCommand(await_msg.var.cmd, node, control.filter, await_msg.conn.resp_chn);
+                        scheduler.spawn({
+                            auto prev_await_msgs = await_msgs;
+                            foreach (ref await_msg; prev_await_msgs)
+                                handleCommand(await_msg.var.cmd, node, control.filter, await_msg.conn.resp_chn);
+                        });
                         await_msgs.length = 0;
-                        assumeSafeAppend(await_msgs);
                     }
 
                     if (!sel_ret.success)
@@ -2544,3 +2546,47 @@ unittest
     assert(test.pubkey() == 42);
     assert(called);
 }
+
+// Self connection deadlock scenario
+// without the proper fix, this test should hang
+unittest
+{
+    import core.atomic;
+
+    static interface API
+    {
+        @safe:
+        public void call0 ();
+        public int get44 ();
+    }
+
+    __gshared Listener!API node1Addr;
+
+    static class Node : API
+    {
+        private RemoteAPI!API self;
+
+        @trusted:
+        public override void call0 ()
+        {
+            this.self = new RemoteAPI!API(atomicLoad(node1Addr));
+            this.self.ctrl.sleep(1.seconds);
+            assert(this.self.get44() == 44);
+        }
+
+        public override int get44 ()
+        {
+            return 44;
+        }
+    }
+
+    auto node1 = RemoteAPI!API.spawn!Node();
+    scope (exit)
+    {
+        node1.ctrl.shutdown();
+        thread_joinAll();
+    }
+
+    atomicStore(node1Addr, node1.ctrl.listener());
+    node1.call0();
+}