rust-cpython: require GIL to borrow immutable reference from PySharedRefCell

rust-cpython: require GIL to borrow immutable reference from PySharedRefCell

Since the inner value may be leaked, we probably need GIL to guarantee that
there's no data race.

inner(py).borrow() is replaced with inner_shared(py).borrow(), which basically
means any PySharedRefCell data should be accessed through PySharedRef wrapper.

--- a/rust/hg-cpython/src/dirstate/dirs_multiset.rs	Sun Sep 15 22:19:10 2019 +0900
+++ b/rust/hg-cpython/src/dirstate/dirs_multiset.rs	Sat Sep 21 17:15:50 2019 +0900
@@ -100,7 +100,7 @@
     }
 
     def __contains__(&self, item: PyObject) -> PyResult<bool> {
-        Ok(self.inner(py).borrow().contains(HgPath::new(
+        Ok(self.inner_shared(py).borrow().contains(HgPath::new(
             item.extract::<PyBytes>(py)?.data(py).as_ref(),
         )))
     }

--- a/rust/hg-cpython/src/dirstate/dirstate_map.rs	Sun Sep 15 22:19:10 2019 +0900
+++ b/rust/hg-cpython/src/dirstate/dirstate_map.rs	Sat Sep 21 17:15:50 2019 +0900
@@ -63,7 +63,7 @@
         default: Option<PyObject> = None
     ) -> PyResult<Option<PyObject>> {
         let key = key.extract::<PyBytes>(py)?;
-        match self.inner(py).borrow().get(HgPath::new(key.data(py))) {
+        match self.inner_shared(py).borrow().get(HgPath::new(key.data(py))) {
             Some(entry) => {
                 Ok(Some(make_dirstate_tuple(py, entry)?))
             },
@@ -170,7 +170,7 @@
     // TODO share the reference
     def nonnormalentries(&self) -> PyResult<PyObject> {
         let (non_normal, other_parent) =
-            self.inner(py).borrow().non_normal_other_parent_entries();
+            self.inner_shared(py).borrow().non_normal_other_parent_entries();
 
         let locals = PyDict::new(py);
         locals.set_item(
@@ -281,18 +281,18 @@
     }
 
     def __len__(&self) -> PyResult<usize> {
-        Ok(self.inner(py).borrow().len())
+        Ok(self.inner_shared(py).borrow().len())
     }
 
     def __contains__(&self, key: PyObject) -> PyResult<bool> {
         let key = key.extract::<PyBytes>(py)?;
-        Ok(self.inner(py).borrow().contains_key(HgPath::new(key.data(py))))
+        Ok(self.inner_shared(py).borrow().contains_key(HgPath::new(key.data(py))))
     }
 
     def __getitem__(&self, key: PyObject) -> PyResult<PyObject> {
         let key = key.extract::<PyBytes>(py)?;
         let key = HgPath::new(key.data(py));
-        match self.inner(py).borrow().get(key) {
+        match self.inner_shared(py).borrow().get(key) {
             Some(entry) => {
                 Ok(make_dirstate_tuple(py, entry)?)
             },
@@ -333,7 +333,7 @@
         Dirs::from_inner(
             py,
             DirsMultiset::from_dirstate(
-                &self.inner(py).borrow(),
+                &self.inner_shared(py).borrow(),
                 Some(EntryState::Removed),
             ),
         )
@@ -344,7 +344,7 @@
         Dirs::from_inner(
             py,
             DirsMultiset::from_dirstate(
-                &self.inner(py).borrow(),
+                &self.inner_shared(py).borrow(),
                 None,
             ),
         )
@@ -353,7 +353,7 @@
     // TODO all copymap* methods, see docstring above
     def copymapcopy(&self) -> PyResult<PyDict> {
         let dict = PyDict::new(py);
-        for (key, value) in self.inner(py).borrow().copy_map.iter() {
+        for (key, value) in self.inner_shared(py).borrow().copy_map.iter() {
             dict.set_item(
                 py,
                 PyBytes::new(py, key.as_ref()),
@@ -365,7 +365,7 @@
 
     def copymapgetitem(&self, key: PyObject) -> PyResult<PyBytes> {
         let key = key.extract::<PyBytes>(py)?;
-        match self.inner(py).borrow().copy_map.get(HgPath::new(key.data(py))) {
+        match self.inner_shared(py).borrow().copy_map.get(HgPath::new(key.data(py))) {
             Some(copy) => Ok(PyBytes::new(py, copy.as_ref())),
             None => Err(PyErr::new::<exc::KeyError, _>(
                 py,
@@ -378,12 +378,12 @@
     }
 
     def copymaplen(&self) -> PyResult<usize> {
-        Ok(self.inner(py).borrow().copy_map.len())
+        Ok(self.inner_shared(py).borrow().copy_map.len())
     }
     def copymapcontains(&self, key: PyObject) -> PyResult<bool> {
         let key = key.extract::<PyBytes>(py)?;
         Ok(self
-            .inner(py)
+            .inner_shared(py)
             .borrow()
             .copy_map
             .contains_key(HgPath::new(key.data(py))))
@@ -395,7 +395,7 @@
     ) -> PyResult<Option<PyObject>> {
         let key = key.extract::<PyBytes>(py)?;
         match self
-            .inner(py)
+            .inner_shared(py)
             .borrow()
             .copy_map
             .get(HgPath::new(key.data(py)))

--- a/rust/hg-cpython/src/ref_sharing.rs	Sun Sep 15 22:19:10 2019 +0900
+++ b/rust/hg-cpython/src/ref_sharing.rs	Sat Sep 21 17:15:50 2019 +0900
@@ -136,7 +136,7 @@
         }
     }
 
-    pub fn borrow(&self) -> Ref<T> {
+    pub fn borrow<'a>(&'a self, _py: Python<'a>) -> Ref<'a, T> {
         // py_shared_state isn't involved since
         // - inner.borrow() would fail if self is mutably borrowed,
         // - and inner.borrow_mut() would fail while self is borrowed.
@@ -180,7 +180,7 @@
     }
 
     pub fn borrow(&self) -> Ref<'a, T> {
-        self.data.borrow()
+        self.data.borrow(self.py)
     }
 
     pub fn borrow_mut(&self) -> PyResult<PyRefMut<'a, T>> {