code release

xlib/mp/MPAtomicInt32.py

@@ -0,0 +1,64 @@
+import multiprocessing
+
+
+class MPAtomicInt32:
+    """
+    Multiprocess atomic int32 variable
+    using multiprocessing.RawArray at specified index
+    """
+    def __init__(self, ar : multiprocessing.RawArray=None, index=None):
+        if ar is None:
+            ar = multiprocessing.RawArray('B', 4)
+        self._ar = ar
+        if index is None:
+            index = 0
+        self._index = index
+        self._mv = memoryview(ar).cast('B')[index:index+4].cast('i')
+        self._mv[0] = 0
+        self._lock = multiprocessing.Lock()
+
+    def compare_exchange(self, cmp_val, new_val):
+        mv = self._mv
+        initial_val = mv[0]
+        if initial_val == cmp_val:
+            self._lock.acquire()
+            initial_val = mv[0]
+            if initial_val == cmp_val:
+                mv[0] = new_val
+            self._lock.release()
+        return initial_val
+
+    def multi_compare_exchange(self, val_or_list, new_val):
+        if not isinstance(val_or_list, (tuple,list)):
+            val_or_list = (val_or_list,)
+
+        mv = self._mv
+        initial_val = mv[0]
+        if any( initial_val == val for val in val_or_list ):
+            self._lock.acquire()
+            initial_val = mv[0]
+            if any( initial_val == val for val in val_or_list ):
+                mv[0] = new_val
+            self._lock.release()
+        return initial_val
+
+    def get(self):
+        return self._mv[0]
+
+    def set(self, new_val, with_lock=True):
+        if with_lock:
+            self._lock.acquire()
+        self._mv[0] = new_val
+        if with_lock:
+            self._lock.release()
+
+    def __getstate__(self):
+        d = self.__dict__.copy()
+        # pop unpicklable memoryview object
+        d.pop('_mv')
+        return d
+
+    def __setstate__(self, d):
+        # restore memoryview of RawArray
+        self.__dict__.update(d)
+        self._mv = memoryview(self._ar).cast('B')[self._index:self._index+4].cast('i')