support: do not clear sys.exc_info if can be preserved (greenlet >= 0.3.2)

eventlet/support/__init__.py

@@ -1,4 +1,8 @@
 import sys
+
+from eventlet.support import greenlets
+
+
 def get_errno(exc):
     """ Get the error code out of socket.error objects.
     socket.error in <2.5 does not have errno attribute
@@ -18,7 +22,7 @@ def get_errno(exc):
     except IndexError:
         return None
 
-if sys.version_info[0]<3:
+if sys.version_info[0]<3 and not greenlets.preserves_excinfo:
     from sys import exc_clear as clear_sys_exc_info
 else:
     def clear_sys_exc_info():

eventlet/support/greenlets.py

@@ -1,7 +1,11 @@
+import distutils.version
+
 try:
     import greenlet
     getcurrent = greenlet.greenlet.getcurrent
     GreenletExit = greenlet.greenlet.GreenletExit
+    preserves_excinfo = (distutils.version.LooseVersion(greenlet.__version__)
+            >= distutils.version.LooseVersion('0.3.2'))
     greenlet = greenlet.greenlet
 except ImportError, e:
     raise
@@ -9,14 +13,17 @@ except ImportError, e:
         from py.magic import greenlet
         getcurrent = greenlet.getcurrent
         GreenletExit = greenlet.GreenletExit
+        preserves_excinfo = False
     except ImportError:
         try:
             from stackless import greenlet
             getcurrent = greenlet.getcurrent
             GreenletExit = greenlet.GreenletExit
+            preserves_excinfo = False
         except ImportError:
             try:
                 from support.stacklesss import greenlet, getcurrent, GreenletExit
+                preserves_excinfo = False
                 (greenlet, getcurrent, GreenletExit) # silence pyflakes
             except ImportError, e:
                 raise ImportError("Unable to find an implementation of greenlet.")

tests/hub_test.py

@@ -1,10 +1,14 @@
 from __future__ import with_statement
+import sys
 
-from tests import LimitedTestCase, main, skip_with_pyevent, skip_if_no_itimer
+from tests import LimitedTestCase, main, skip_with_pyevent, skip_if_no_itimer, skip_unless
 import time
 import eventlet
 from eventlet import hubs
 from eventlet.green import socket
+from eventlet.event import Event
+from eventlet.semaphore import Semaphore
+from eventlet.support import greenlets
 
 DELAY = 0.001
 def noop():
@@ -132,6 +136,62 @@ class TestExceptionInMainloop(LimitedTestCase):
         assert delay >= DELAY*0.9, 'sleep returned after %s seconds (was scheduled for %s)' % (delay, DELAY)
 
 
+class TestExceptionInGreenthread(LimitedTestCase):
+    @skip_unless(greenlets.preserves_excinfo)
+    def test_exceptionpreservation(self):
+        # events for controlling execution order
+        gt1event = Event()
+        gt2event = Event()
+
+        def test_gt1():
+            try:
+                raise KeyError()
+            except KeyError:
+                gt1event.send('exception')
+                gt2event.wait()
+                assert sys.exc_info()[0] is KeyError
+                gt1event.send('test passed')
+
+        def test_gt2():
+            gt1event.wait()
+            gt1event.reset()
+            assert sys.exc_info()[0] is None
+            try:
+                raise ValueError()
+            except ValueError:
+                gt2event.send('exception')
+                gt1event.wait()
+                assert sys.exc_info()[0] is ValueError
+
+        g1 = eventlet.spawn(test_gt1)
+        g2 = eventlet.spawn(test_gt2)
+        try:
+            g1.wait()
+            g2.wait()
+        finally:
+            g1.kill()
+            g2.kill()
+
+    def test_exceptionleaks(self):
+        # tests expected behaviour with all versions of greenlet
+        def test_gt(sem):
+            try:
+                raise KeyError()
+            except KeyError:
+                sem.release()
+                hubs.get_hub().switch()
+
+        # semaphores for controlling execution order
+        sem = Semaphore()
+        sem.acquire()
+        g = eventlet.spawn(test_gt, sem)
+        try:
+            sem.acquire()
+            assert sys.exc_info()[0] is None
+        finally:
+            g.kill()
+
+
 class TestHubSelection(LimitedTestCase):
     def test_explicit_hub(self):
         if getattr(hubs.get_hub(), 'uses_twisted_reactor', None):