From 96f357c5d698dcbb8edbf53b9d0c9d99f888d432 Mon Sep 17 00:00:00 2001
From: Maria Matejka <mq@ucw.cz>
Date: Tue, 10 Sep 2024 11:25:59 +0200
Subject: [PATCH] Minimalist mainloop implementation

---
 lib/io-loop.h         |  2 ++
 sysdep/unix/io-loop.c | 38 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 40 insertions(+)

diff --git a/lib/io-loop.h b/lib/io-loop.h
index cd4e2132..c043d1a0 100644
--- a/lib/io-loop.h
+++ b/lib/io-loop.h
@@ -82,5 +82,7 @@ struct thread_config {
 
 void bird_thread_commit(struct thread_config *new);
 
+/* Minimalist main */
+void birdloop_minimalist_main(void) NORET;
 
 #endif /* _BIRD_IO_LOOP_H_ */
diff --git a/sysdep/unix/io-loop.c b/sysdep/unix/io-loop.c
index 9d2aa83f..afe60621 100644
--- a/sysdep/unix/io-loop.c
+++ b/sysdep/unix/io-loop.c
@@ -1594,3 +1594,41 @@ ev_send_defer(event *e)
   else
     ev_send(&this_birdloop->defer_list, e);
 }
+
+/*
+ * Minimalist mainloop with no sockets
+ */
+
+void
+birdloop_minimalist_main(void)
+{
+  while (1)
+  {
+    times_update();
+    ev_run_list(&global_event_list);
+    ev_run_list(&global_work_list);
+    ev_run_list(&main_birdloop.event_list);
+    timers_fire(&main_birdloop.time);
+
+    bool events =
+      !ev_list_empty(&global_event_list) ||
+      !ev_list_empty(&global_work_list) ||
+      !ev_list_empty(&main_birdloop.event_list);
+
+    int poll_tout = (events ? 0 : 3000); /* Time in milliseconds */
+    timer *t;
+    if (t = timers_first(&main_birdloop.time))
+    {
+      times_update();
+      int timeout = (tm_remains(t) TO_MS) + 1;
+      poll_tout = MIN(poll_tout, timeout);
+    }
+
+    struct pollfd pfd = {
+      .fd = main_birdloop.thread->wakeup.fd[0],
+      .events = POLLIN,
+    };
+
+    poll(&pfd, 1, poll_tout);
+  }
+}