From a8e2c8e5b8aee67da562d8a3a87aee5b3b403005 Mon Sep 17 00:00:00 2001
From: Calvin Rose <calsrose@gmail.com>
Date: Fri, 16 May 2025 18:03:32 -0500
Subject: [PATCH] Address #1596 - Use atomic intrinsics to check
 allow_interrupt flag.

Use a relaxed memory order if possible to mitigate performance issues as
much as possible. relaxed memory order should be sufficient.
---
 src/core/capi.c     | 10 ++++++++++
 src/core/ev.c       |  3 ++-
 src/core/vm.c       |  2 +-
 src/include/janet.h |  1 +
 4 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/src/core/capi.c b/src/core/capi.c
index 5a6a2e68..628394e1 100644
--- a/src/core/capi.c
+++ b/src/core/capi.c
@@ -589,6 +589,16 @@ JanetAtomicInt janet_atomic_load(JanetAtomicInt volatile *x) {
 #endif
 }
 
+JanetAtomicInt janet_atomic_load_relaxed(JanetAtomicInt volatile *x) {
+#ifdef _MSC_VER
+    return _InterlockedOrNoFence(x, 0);
+#elif defined(JANET_USE_STDATOMIC)
+    return atomic_load_explicit(x, memory_order_relaxed);
+#else
+    return __atomic_load_n(x, __ATOMIC_RELAXED);
+#endif
+}
+
 /* Some definitions for function-like macros */
 
 JANET_API JanetStructHead *(janet_struct_head)(JanetStruct st) {
diff --git a/src/core/ev.c b/src/core/ev.c
index d9ce3f48..d0fbca56 100644
--- a/src/core/ev.c
+++ b/src/core/ev.c
@@ -1457,7 +1457,7 @@ JanetFiber *janet_loop1(void) {
     /* Run scheduled fibers unless interrupts need to be handled. */
     while (janet_vm.spawn.head != janet_vm.spawn.tail) {
         /* Don't run until all interrupts have been marked as handled by calling janet_interpreter_interrupt_handled */
-        if (janet_vm.auto_suspend) break;
+        if (janet_atomic_load_relaxed(&janet_vm.auto_suspend)) break;
         JanetTask task = {NULL, janet_wrap_nil(), JANET_SIGNAL_OK, 0};
         janet_q_pop(&janet_vm.spawn, &task, sizeof(task));
         if (task.fiber->gc.flags & JANET_FIBER_EV_FLAG_SUSPENDED) janet_ev_dec_refcount();
@@ -3231,6 +3231,7 @@ JANET_CORE_FN(cfun_ev_deadline,
             janet_free(tto);
             janet_panicf("%s", janet_strerror(err));
         }
+        janet_assert(!pthread_detach(worker), "pthread_detach");
 #endif
         to.has_worker = 1;
         to.worker = worker;
diff --git a/src/core/vm.c b/src/core/vm.c
index 6ad79053..a0dae1c8 100644
--- a/src/core/vm.c
+++ b/src/core/vm.c
@@ -115,7 +115,7 @@
 #define vm_maybe_auto_suspend(COND)
 #else
 #define vm_maybe_auto_suspend(COND) do { \
-    if ((COND) && janet_vm.auto_suspend) { \
+    if ((COND) && janet_atomic_load_relaxed(&janet_vm.auto_suspend)) { \
         fiber->flags |= (JANET_FIBER_RESUME_NO_USEVAL | JANET_FIBER_RESUME_NO_SKIP); \
         vm_return(JANET_SIGNAL_INTERRUPT, janet_wrap_nil()); \
     } \
diff --git a/src/include/janet.h b/src/include/janet.h
index 8e6ca968..74d0661f 100644
--- a/src/include/janet.h
+++ b/src/include/janet.h
@@ -667,6 +667,7 @@ typedef int32_t JanetAtomicInt;
 JANET_API JanetAtomicInt janet_atomic_inc(JanetAtomicInt volatile *x);
 JANET_API JanetAtomicInt janet_atomic_dec(JanetAtomicInt volatile *x);
 JANET_API JanetAtomicInt janet_atomic_load(JanetAtomicInt volatile *x);
+JANET_API JanetAtomicInt janet_atomic_load_relaxed(JanetAtomicInt volatile *x);
 
 /* We provide three possible implementations of Janets. The preferred
  * nanboxing approach, for 32 or 64 bits, and the standard C version. Code in the rest of the