first commit

swingmusic/utils/threading.py

@@ -0,0 +1,45 @@
+import threading
+from multiprocessing import Pipe, Process
+
+
+def background(func):
+    """
+    Runs the decorated function in a background thread.
+    """
+
+    def background_func(*a, **kw):
+        threading.Thread(target=func, args=a, kwargs=kw).start()
+
+    return background_func
+
+
+class ProcessWithReturnValue(Process):
+    """
+    A process class that returns a value on join.
+    Uses a pipe to communicate the return value back to the parent process.
+    """
+
+    def __init__(
+        self, group=None, target=None, name=None, args=(), kwargs=None, Verbose=None
+    ):
+        if kwargs is None:
+            kwargs = {}
+        Process.__init__(
+            self, group=group, target=target, name=name, args=args, kwargs=kwargs
+        )
+        self._parent_conn, self._child_conn = Pipe()
+        self._target = target
+        self._args = args
+        self._kwargs = kwargs
+
+    def run(self):
+        if self._target is not None:
+            result = self._target(*self._args, **self._kwargs)
+            self._child_conn.send(result)
+        self._child_conn.close()
+
+    def join(self, *args):
+        Process.join(self, *args)
+        if self._parent_conn.poll():
+            return self._parent_conn.recv()
+        return None