debug: use C __atomic builtins for counters

Author: fantix

uvloop/cbhandles.pyx

@@ -10,7 +10,8 @@ cdef class Handle:
         self.loop = loop
         if UVLOOP_DEBUG:
             loop._debug_cb_handles_total += 1
-            loop._debug_cb_handles_count += 1
+            system.__atomic_fetch_add(
+                &loop._debug_cb_handles_count, 1, system.__ATOMIC_RELAXED)
         if loop._debug:
             self._source_traceback = extract_stack()
 
@@ -21,7 +22,8 @@ cdef class Handle:
 
     def __dealloc__(self):
         if UVLOOP_DEBUG and self.loop is not None:
-            self.loop._debug_cb_handles_count -= 1
+            system.__atomic_fetch_sub(
+                &self.loop._debug_cb_handles_count, 1, system.__ATOMIC_RELAXED)
         if self.loop is None:
             raise RuntimeError('Handle.loop is None in Handle.__dealloc__')
 

uvloop/includes/system.pxd

@@ -94,3 +94,11 @@ cdef extern from "includes/fork_handler.h":
     void setForkHandler(OnForkHandler handler)
     void resetForkHandler()
     void setMainThreadID(uint64_t id)
+
+
+cdef extern from * nogil:
+    uint64_t __atomic_fetch_add(uint64_t *ptr, uint64_t val, int memorder)
+    uint64_t __atomic_fetch_sub(uint64_t *ptr, uint64_t val, int memorder)
+
+    cdef enum:
+        __ATOMIC_RELAXED