Switch from pyo3::internal_utils::ensure_gil to with_gil

In PyO3/pyo3#1115 the internal_utils module was removed from pyo3. There
is a note in the review that rust-numpy will need to migrate to using
with_gil() instead. This commit makes this change to enable running with
pyo3 0.12.0.

Author: mtreinish

Cargo.toml

@@ -15,7 +15,7 @@ libc = "0.2"
 num-complex = "0.2"
 num-traits = "0.2"
 ndarray = ">=0.13"
-pyo3 = { git = "https://github.com/PyO3/pyo3" }
+pyo3 = "0.12.0"
 
 [features]
 # In default setting, python version is automatically detected

src/npyffi/array.rs

@@ -42,9 +42,10 @@ impl PyArrayAPI {
     }
     fn get(&self, offset: isize) -> *const *const c_void {
         if self.api.get().is_null() {
-            let ensure_gil = pyo3::internal_utils::ensure_gil();
-            let api = get_numpy_api(unsafe { ensure_gil.python() }, MOD_NAME, CAPSULE_NAME);
-            self.api.set(api);
+            Python::with_gil(|py| {
+                let api = get_numpy_api(py, MOD_NAME, CAPSULE_NAME);
+                self.api.set(api);
+            })
         }
         unsafe { self.api.get().offset(offset) }
     }

src/npyffi/ufunc.rs

@@ -4,6 +4,7 @@ use std::os::raw::*;
 use std::{cell::Cell, ptr};
 
 use pyo3::ffi::PyObject;
+use pyo3::Python;
 
 use super::get_numpy_api;
 use super::objects::*;
@@ -28,9 +29,10 @@ impl PyUFuncAPI {
     }
     fn get(&self, offset: isize) -> *const *const c_void {
         if self.api.get().is_null() {
-            let ensure_gil = pyo3::internal_utils::ensure_gil();
-            let api = get_numpy_api(unsafe { ensure_gil.python() }, MOD_NAME, CAPSULE_NAME);
-            self.api.set(api);
+            Python::with_gil(|py| {
+                let api = get_numpy_api(py, MOD_NAME, CAPSULE_NAME);
+                self.api.set(api);
+            })
         }
         unsafe { self.api.get().offset(offset) }
     }