Make byte* iterators atomic to fix a shared list/bytearray test

Author: coolreader18

Lib/test/list_tests.py

@@ -565,8 +565,6 @@ def __iter__(self):
                 raise KeyboardInterrupt
         self.assertRaises(KeyboardInterrupt, list, F())
 
-    # TODO: RUSTPYTHON
-    @unittest.expectedFailure
     def test_exhausted_iterator(self):
         a = self.type2test([1, 2, 3])
         exhit = iter(a)

vm/src/obj/objbytearray.rs

@@ -1,5 +1,5 @@
 //! Implementation of the python bytearray object.
-use std::cell::Cell;
+use crossbeam_utils::atomic::AtomicCell;
 use std::convert::TryFrom;
 use std::sync::{RwLock, RwLockReadGuard, RwLockWriteGuard};
 
@@ -150,7 +150,7 @@ impl PyByteArray {
     #[pymethod(name = "__iter__")]
     fn iter(zelf: PyRef<Self>) -> PyByteArrayIterator {
         PyByteArrayIterator {
-            position: Cell::new(0),
+            position: AtomicCell::new(0),
             bytearray: zelf,
         }
     }
@@ -605,7 +605,7 @@ impl PyByteArray {
 #[pyclass]
 #[derive(Debug)]
 pub struct PyByteArrayIterator {
-    position: Cell<usize>,
+    position: AtomicCell<usize>,
     bytearray: PyByteArrayRef,
 }
 
@@ -619,9 +619,9 @@ impl PyValue for PyByteArrayIterator {
 impl PyByteArrayIterator {
     #[pymethod(name = "__next__")]
     fn next(&self, vm: &VirtualMachine) -> PyResult<u8> {
-        if self.position.get() < self.bytearray.borrow_value().len() {
-            let ret = self.bytearray.borrow_value().elements[self.position.get()];
-            self.position.set(self.position.get() + 1);
+        let bytearr = self.bytearray.borrow_value();
+        let pos = self.position.fetch_add(1);
+        if let Some(&ret) = bytearr.elements.get(pos) {
             Ok(ret)
         } else {
             Err(objiter::new_stop_iteration(vm))

vm/src/obj/objbytes.rs

@@ -1,4 +1,4 @@
-use std::cell::Cell;
+use crossbeam_utils::atomic::AtomicCell;
 use std::mem::size_of;
 use std::ops::Deref;
 
@@ -144,7 +144,7 @@ impl PyBytes {
     #[pymethod(name = "__iter__")]
     fn iter(zelf: PyRef<Self>) -> PyBytesIterator {
         PyBytesIterator {
-            position: Cell::new(0),
+            position: AtomicCell::new(0),
             bytes: zelf,
         }
     }
@@ -484,7 +484,7 @@ impl PyBytes {
 #[pyclass]
 #[derive(Debug)]
 pub struct PyBytesIterator {
-    position: Cell<usize>,
+    position: AtomicCell<usize>,
     bytes: PyBytesRef,
 }
 
@@ -498,9 +498,8 @@ impl PyValue for PyBytesIterator {
 impl PyBytesIterator {
     #[pymethod(name = "__next__")]
     fn next(&self, vm: &VirtualMachine) -> PyResult<u8> {
-        if self.position.get() < self.bytes.inner.len() {
-            let ret = self.bytes[self.position.get()];
-            self.position.set(self.position.get() + 1);
+        let pos = self.position.fetch_add(1);
+        if let Some(&ret) = self.bytes.get_value().get(pos) {
             Ok(ret)
         } else {
             Err(objiter::new_stop_iteration(vm))