Use new PyOS_BeforeFork and PyOS_AfterFork_* 3.7 APIs when available

Author: 1st1

uvloop/handles/process.pyx

@@ -77,7 +77,7 @@ cdef class UVProcess(UVHandle):
             __forking = 1
             __forking_loop = loop
 
-            _PyImport_AcquireLock()
+            PyOS_BeforeFork()
 
             err = uv.uv_spawn(loop.uvloop,
                               <uv.uv_process_t*>self._handle,
@@ -87,14 +87,7 @@ cdef class UVProcess(UVHandle):
             __forking_loop = None
             loop.active_process_handler = None
 
-            if _PyImport_ReleaseLock() < 0:
-                # See CPython/posixmodule.c for details
-                self._close_process_handle()
-                if err < 0:
-                    self._abort_init()
-                else:
-                    self._close()
-                raise RuntimeError('not holding the import lock')
+            PyOS_AfterFork_Parent()
 
             if err < 0:
                 self._close_process_handle()
@@ -176,7 +169,7 @@ cdef class UVProcess(UVHandle):
         if self._restore_signals:
             _Py_RestoreSignals()
 
-        PyOS_AfterFork()
+        PyOS_AfterFork_Child()
 
         err = uv.uv_loop_fork(self._loop.uvloop)
         if err < 0:

uvloop/includes/compat.h

@@ -79,3 +79,26 @@ int Context_Exit(PyObject *ctx) {
 }
 
 #endif
+
+
+#if PY_VERSION_HEX < 0x03070000
+
+void PyOS_BeforeFork(void)
+{
+    _PyImport_AcquireLock();
+}
+
+void PyOS_AfterFork_Parent(void)
+{
+    if (_PyImport_ReleaseLock() <= 0) {
+        Py_FatalError("failed releasing import lock after fork");
+    }
+}
+
+
+void PyOS_AfterFork_Child(void)
+{
+    PyOS_AfterFork();
+}
+
+#endif

uvloop/includes/python.pxd

@@ -9,9 +9,6 @@ cdef extern from "Python.h":
     object PyUnicode_EncodeFSDefault(object)
     void PyErr_SetInterrupt() nogil
 
-    void PyOS_AfterFork()
-    void _PyImport_AcquireLock()
-    int _PyImport_ReleaseLock()
     void _Py_RestoreSignals()
 
     object PyMemoryView_FromMemory(char *mem, ssize_t size, int flags)
@@ -26,3 +23,7 @@ cdef extern from "includes/compat.h":
     object Context_CopyCurrent()
     int Context_Enter(object) except -1
     int Context_Exit(object) except -1
+
+    void PyOS_BeforeFork()
+    void PyOS_AfterFork_Parent()
+    void PyOS_AfterFork_Child()

uvloop/loop.pyx

@@ -11,15 +11,14 @@ from .includes.python cimport PY_VERSION_HEX, \
                               PyMem_RawCalloc, PyMem_RawRealloc, \
                               PyUnicode_EncodeFSDefault, \
                               PyErr_SetInterrupt, \
-                              PyOS_AfterFork, \
-                              _PyImport_AcquireLock, \
-                              _PyImport_ReleaseLock, \
                               _Py_RestoreSignals, \
                               Context_CopyCurrent, \
                               Context_Enter, \
                               Context_Exit, \
                               PyMemoryView_FromMemory, PyBUF_WRITE, \
-                              PyMemoryView_FromObject, PyMemoryView_Check
+                              PyMemoryView_FromObject, PyMemoryView_Check, \
+                              PyOS_AfterFork_Parent, PyOS_AfterFork_Child, \
+                              PyOS_BeforeFork
 from .includes.flowcontrol cimport add_flowcontrol_defaults
 
 from libc.stdint cimport uint64_t