added spawn_link function (with tests)

eventlet/coros.py

@@ -236,6 +236,35 @@ class event(object):
         # the arguments and the same as for greenlet.throw
         return self.send(None, args)
 
+
+class async_result(object):
+
+    def __init__(self, greenlet, event):
+        self.greenlet = greenlet
+        self.event = event
+
+    def wait(self):
+        return self.event.wait()
+
+    def kill(self):
+        return api.kill(self.greenlet)
+
+def _wrap_result_in_event(event, func, *args, **kwargs):
+    try:
+        result = func(*args, **kwargs)
+    except api.GreenletExit, ex:
+        event.send(ex)
+    except:
+        event.send_exception(*sys.exc_info())
+    else:
+        event.send(result)
+
+def spawn_link(func, *args, **kwargs):
+    result = event()
+    g = api.spawn(_wrap_result_in_event, result, func, *args, **kwargs)
+    return async_result(g, result)
+
+
 class semaphore(object):
     """Classic semaphore implemented with a counter and an event.
     Optionally initialize with a resource count, then acquire() and release()

greentest/test__event.py

@@ -1,8 +1,9 @@
 import unittest
-from eventlet.coros import event
-from eventlet.api import spawn, sleep
+import sys
+from eventlet.coros import event, spawn_link
+from eventlet.api import spawn, sleep, GreenletExit
 
-class Test(unittest.TestCase):
+class TestEvent(unittest.TestCase):
     
     def test_send_exc(self):
         log = []
@@ -20,6 +21,40 @@ class Test(unittest.TestCase):
         sleep(0)
         assert log == [('catched', 'Exception')], log
 
+
+class TestSpawnLink(unittest.TestCase):
+
+    def test_simple_return(self):
+        res = spawn_link(lambda: 25).wait()
+        assert res==25, res
+
+    def test_exception(self):
+        try:
+            spawn_link(sys.exit, 'bye').wait()
+        except SystemExit, ex:
+            assert ex.args == ('bye', )
+        else:
+            assert False, "Shouldn't get there"
+
+    def _test_kill(self, sync):
+        def func():
+            sleep(0.1)
+            return 101
+        res = spawn_link(func)
+        if sync:
+            res.kill()
+        else:
+            spawn(res.kill)
+        wait_result = res.wait()
+        assert isinstance(wait_result, GreenletExit), `wait_result`
+
+    def test_kill_sync(self):
+        return self._test_kill(True)
+
+    def test_kill_async(self):
+        return self._test_kill(False)
+
+
 if __name__=='__main__':
     unittest.main()