From 8165da581c45405655195bf536ed554276ad4dda Mon Sep 17 00:00:00 2001
From: Helena Pankov <helenapankov@pm.me>
Date: Sun, 27 Apr 2025 10:59:36 -0700
Subject: [PATCH] Enable futex support in macOS 14.4+ through
 os_sync_wait_on_address

---
 include/boost/fiber/detail/config.hpp | 11 +++++++++--
 include/boost/fiber/detail/futex.hpp  | 15 ++++++++++++++-
 2 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/include/boost/fiber/detail/config.hpp b/include/boost/fiber/detail/config.hpp
index b29102b4..69b2292c 100644
--- a/include/boost/fiber/detail/config.hpp
+++ b/include/boost/fiber/detail/config.hpp
@@ -10,9 +10,15 @@
 #include <cstddef>
 
 #include <boost/config.hpp>
-#include <boost/predef.h> 
+#include <boost/predef.h>
 #include <boost/detail/workaround.hpp>
 
+#if BOOST_OS_MACOS
+#include <Availability.h>
+#define BOOST_OS_SYNC_WAIT_ON_ADDRESS_AVAILABLE \
+    __MAC_OS_X_VERSION_MIN_REQUIRED >= MAC_OS_VERSION_14_4
+#endif
+
 #ifdef BOOST_FIBERS_DECL
 # undef BOOST_FIBERS_DECL
 #endif
@@ -38,7 +44,8 @@
 # include <boost/config/auto_link.hpp>
 #endif
 
-#if BOOST_OS_LINUX || BOOST_OS_BSD_OPEN || BOOST_OS_WINDOWS
+#if BOOST_OS_LINUX || BOOST_OS_BSD_OPEN || BOOST_OS_WINDOWS || (BOOST_OS_MACOS && \
+    BOOST_OS_SYNC_WAIT_ON_ADDRESS_AVAILABLE)
 # define BOOST_FIBERS_HAS_FUTEX
 #endif
 
diff --git a/include/boost/fiber/detail/futex.hpp b/include/boost/fiber/detail/futex.hpp
index daf75646..ad864d52 100644
--- a/include/boost/fiber/detail/futex.hpp
+++ b/include/boost/fiber/detail/futex.hpp
@@ -8,7 +8,7 @@
 #define BOOST_FIBERS_DETAIL_FUTEX_H
 
 #include <boost/config.hpp>
-#include <boost/predef.h> 
+#include <boost/predef.h>
 
 #include <boost/fiber/detail/config.hpp>
 
@@ -27,6 +27,8 @@ extern "C" {
 }
 #elif BOOST_OS_WINDOWS
 #include <windows.h>
+#elif (BOOST_OS_MACOS && BOOST_OS_SYNC_WAIT_ON_ADDRESS_AVAILABLE)
+#include <os/os_sync_wait_on_address.h>
 #endif
 
 namespace boost {
@@ -71,6 +73,17 @@ int futex_wait( std::atomic< std::int32_t > * addr, std::int32_t x) {
     ::WaitOnAddress( static_cast< volatile void * >( addr), & x, sizeof( x), INFINITE);
     return 0;
 }
+#elif (BOOST_OS_MACOS && BOOST_OS_SYNC_WAIT_ON_ADDRESS_AVAILABLE)
+BOOST_FORCEINLINE
+int futex_wake( std::atomic< std::int32_t > * addr) {
+    return 0 <= os_sync_wake_by_address_any(addr, 4, OS_SYNC_WAKE_BY_ADDRESS_NONE) ? 0 : -1;
+}
+
+BOOST_FORCEINLINE
+int futex_wait( std::atomic< std::int32_t > * addr, std::int32_t x) {
+    return 0 <= os_sync_wait_on_address(static_cast< void * >( addr), x, sizeof(x),
+                                  OS_SYNC_WAIT_ON_ADDRESS_NONE) ? 0 : -1;
+}
 #else
 # warn "no futex support on this platform"
 #endif