Added class to abstract away platform specific thread primitives.

src/Makefile

@@ -245,7 +245,8 @@ BOOT_CMXS := $(BOOT_MLS:.ml=.cmx)
 BOOT_OBJS := $(BOOT_MLS:.ml=.o)
 BOOT_CMIS := $(BOOT_MLS:.ml=.cmi)
 
-RUNTIME_CS := rt/sync/spin_lock.cpp \
+RUNTIME_CS := rt/sync/sync.cpp \
+			  rt/sync/spin_lock.cpp \
               rt/sync/lock_free_queue.cpp \
               rt/sync/condition_variable.cpp \
               rt/rust.cpp \
@@ -279,7 +280,8 @@ RUNTIME_HDR := rt/globals.h \
                rt/rust_message.h \
                rt/circular_buffer.h \
                rt/util/array_list.h \
-               rt/util/hash_map.h
+               rt/util/hash_map.h \
+               rt/sync/sync.h
 
 RUNTIME_INCS := -Irt/isaac -Irt/uthash
 RUNTIME_OBJS := $(RUNTIME_CS:.cpp=$(CFG_OBJ_SUFFIX))

src/rt/sync/sync.cpp

@@ -0,0 +1,12 @@
+#include "../globals.h"
+#include "sync.h"
+
+void sync::yield() {
+#ifdef __APPLE__
+    pthread_yield_np();
+#elif __WIN32__
+
+#else
+    pthread_yield();
+#endif
+}

src/rt/sync/sync.h

@@ -0,0 +1,9 @@
+#ifndef SYNC_H
+#define SYNC_H
+
+class sync {
+public:
+    static void yield();
+};
+
+#endif /* SYNC_H */