From 3b189eab64cb948fa0e731fdeb0a38c970a67771 Mon Sep 17 00:00:00 2001
From: Calvin Rose <calsrose@gmail.com>
Date: Sun, 29 Oct 2023 11:34:21 -0500
Subject: [PATCH] Fix #1321, poll event loop CPU usage issue

A stream may have a fiber attached for memory management purposes, but
not actually be waiting on anything. Be more seletive with poll, which
is not edge-triggered, to not poll for readiness on these streams.
---
 src/core/ev.c  | 4 ++--
 src/core/net.c | 5 ++---
 2 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/src/core/ev.c b/src/core/ev.c
index 0fe1bf7f..46be4862 100644
--- a/src/core/ev.c
+++ b/src/core/ev.c
@@ -1818,8 +1818,8 @@ void janet_loop1_impl(int has_timeout, JanetTimestamp timeout) {
         JanetStream *stream = janet_vm.streams[i];
         janet_vm.fds[i + 1].events = 0;
         janet_vm.fds[i + 1].revents = 0;
-        if (stream->read_fiber) janet_vm.fds[i + 1].events |= POLLIN;
-        if (stream->write_fiber) janet_vm.fds[i + 1].events |= POLLOUT;
+        if (stream->read_fiber && stream->read_fiber->ev_callback) janet_vm.fds[i + 1].events |= POLLIN;
+        if (stream->write_fiber && stream->write_fiber->ev_callback) janet_vm.fds[i + 1].events |= POLLOUT;
     }
 
     /* Poll for events */
diff --git a/src/core/net.c b/src/core/net.c
index 531cfcee..97e6418b 100644
--- a/src/core/net.c
+++ b/src/core/net.c
@@ -125,7 +125,7 @@ void net_callback_connect(JanetFiber *fiber, JanetAsyncEvent event) {
         default:
             break;
 #ifndef JANET_WINDOWS
-        /* Wait until we have an actually event before checking.
+        /* Wait until we have an actual event before checking.
          * Windows doesn't support async connect with this, just try immediately.*/
         case JANET_ASYNC_EVENT_INIT:
 #endif
@@ -160,7 +160,7 @@ void net_callback_connect(JanetFiber *fiber, JanetAsyncEvent event) {
     janet_async_end(fiber);
 }
 
-static void net_sched_connect(JanetStream *stream) {
+static JANET_NO_RETURN void net_sched_connect(JanetStream *stream) {
     NetStateConnect *state = janet_malloc(sizeof(NetStateConnect));
     state->did_connect = 0;
     janet_async_start(stream, JANET_ASYNC_LISTEN_WRITE, net_callback_connect, state);
@@ -575,7 +575,6 @@ JANET_CORE_FN(cfun_net_connect,
     }
 
     net_sched_connect(stream);
-    janet_await();
 }
 
 static const char *serverify_socket(JSock sfd) {