Rev 5249: Implement a thread that can re-raise exceptions. in file:///home/vila/src/bzr/experimental/leaking-tests/

[Vincent Ladeuil]

At file:///home/vila/src/bzr/experimental/leaking-tests/

------------------------------------------------------------
revno: 5249
revision-id: v.ladeuil+lp at free.fr-20100526104407-0w315whpmsdeafjk
parent: v.ladeuil+lp at free.fr-20100526103818-1x38taslbkp097z9
committer: Vincent Ladeuil <v.ladeuil+lp at free.fr>
branch nick: propagate-exceptions
timestamp: Wed 2010-05-26 12:44:07 +0200
message:
  Implement a thread that can re-raise exceptions.
  
  * bzrlib/tests/test_transport.py:
  (TestThreadWithException): Test that the execption is re-raised at
  join() time.
  
  * bzrlib/tests/test_server.py:
  (ThreadWithException): We need a thread that catch and re-raise
  any exception.
-------------- next part --------------
=== modified file 'bzrlib/tests/test_server.py'
--- a/bzrlib/tests/test_server.py	2010-05-24 01:05:14 +0000
+++ b/bzrlib/tests/test_server.py	2010-05-26 10:44:07 +0000
@@ -16,6 +16,8 @@
 
 import socket
 import select
+import sys
+import threading
 
 
 from bzrlib import (
@@ -227,6 +229,35 @@
         raise NotImplementedError
 
 
+class ThreadWithException(threading.Thread):
+    """A catching exception thread.
+
+    If an exception occurs during the thread execution, it's caught and
+    re-raised when the thread is joined().
+    """
+
+    def __init__(self, *args, **kwargs):
+        super(ThreadWithException, self).__init__(*args, **kwargs)
+        self.exception = None
+
+    def run(self):
+        """Overrides Thread.run to capture any exception."""
+        try:
+            super(ThreadWithException, self).run()
+        except Exception, e:
+            self.exception = sys.exc_info()
+
+    def join(self, *args, **kwargs):
+        """Overrides Thread.join to raise any exception caught."""
+        # Note that we don't care about the timeout parameter here: either the
+        # thread has raised an exception and it should be raised (and join()
+        # should succeed whatever the timeout is) or it's still alive which
+        # means it didn't encounter an exception.
+        super(ThreadWithException, self).join(*args, **kwargs)
+        if self.exception is not None:
+            raise self.exception
+
+
 class SmartTCPServer_for_testing(server.SmartTCPServer):
     """Server suitable for use by transport tests.
 

=== modified file 'bzrlib/tests/test_transport.py'
--- a/bzrlib/tests/test_transport.py	2010-02-23 07:43:11 +0000
+++ b/bzrlib/tests/test_transport.py	2010-05-26 10:44:07 +0000
@@ -989,3 +989,25 @@
         # And the rest are threads
         for t in started[1:]:
             t.join()
+
+
+class TestThreadWithException(tests.TestCase):
+
+    def test_start_and_join_smoke_test(self):
+        def do_nothing():
+            pass
+
+        tt = test_server.ThreadWithException(target=do_nothing)
+        tt.start()
+        tt.join()
+
+    def test_exception_is_re_raised(self):
+        class MyException(Exception):
+            pass
+
+        def raise_my_exception():
+            raise MyException()
+
+        tt = test_server.ThreadWithException(target=raise_my_exception)
+        tt.start()
+        self.assertRaises(MyException, tt.join)