From 9f3fbea48aa604df503b4920fdb81262be548521 Mon Sep 17 00:00:00 2001
From: Joshua Harlow <harlowja@yahoo-inc.com>
Date: Fri, 22 Jan 2016 10:21:27 -0800
Subject: [PATCH] Add excutils.save_and_reraise_exception force_reraise +
 capture

Change-Id: Ie0972ca5634547ce3a71f7755905d3081008a2f8
---
 oslo_utils/excutils.py            | 22 ++++++++++++++++++---
 oslo_utils/tests/test_excutils.py | 33 +++++++++++++++++++++++++++++++
 2 files changed, 52 insertions(+), 3 deletions(-)

diff --git a/oslo_utils/excutils.py b/oslo_utils/excutils.py
index dbaf0f6..0d1517b 100644
--- a/oslo_utils/excutils.py
+++ b/oslo_utils/excutils.py
@@ -178,10 +178,26 @@ class save_and_reraise_exception(object):
         if logger is None:
             logger = logging.getLogger()
         self.logger = logger
+        self.type_, self.value, self.tb = (None, None, None)
+
+    def force_reraise(self):
+        if self.type_ is None and self.value is None:
+            raise RuntimeError("There is no (currently) captured exception"
+                               " to force the reraising of")
+        six.reraise(self.type_, self.value, self.tb)
+
+    def capture(self, check=True):
+        (type_, value, tb) = sys.exc_info()
+        if check and type_ is None and value is None:
+            raise RuntimeError("There is no active exception to capture")
+        self.type_, self.value, self.tb = (type_, value, tb)
+        return self
 
     def __enter__(self):
-        self.type_, self.value, self.tb, = sys.exc_info()
-        return self
+        # TODO(harlowja): perhaps someday in the future turn check here
+        # to true, because that is likely the desired intention, and doing
+        # so ensures that people are actually using this correctly.
+        return self.capture(check=False)
 
     def __exit__(self, exc_type, exc_val, exc_tb):
         if exc_type is not None:
@@ -192,7 +208,7 @@ class save_and_reraise_exception(object):
                                                              self.tb))
             return False
         if self.reraise:
-            six.reraise(self.type_, self.value, self.tb)
+            self.force_reraise()
 
 
 def forever_retry_uncaught_exceptions(infunc):
diff --git a/oslo_utils/tests/test_excutils.py b/oslo_utils/tests/test_excutils.py
index 60f752d..197bdb6 100644
--- a/oslo_utils/tests/test_excutils.py
+++ b/oslo_utils/tests/test_excutils.py
@@ -62,6 +62,39 @@ class CausedByTest(test_base.BaseTestCase):
 
 class SaveAndReraiseTest(test_base.BaseTestCase):
 
+    def test_save_and_reraise_exception_forced(self):
+
+        def _force_reraise():
+            try:
+                raise IOError("I broke")
+            except Exception:
+                with excutils.save_and_reraise_exception() as e:
+                    e.reraise = False
+                e.force_reraise()
+
+        self.assertRaises(IOError, _force_reraise)
+
+    def test_save_and_reraise_exception_capture_reraise(self):
+
+        def _force_reraise():
+            try:
+                raise IOError("I broke")
+            except Exception:
+                excutils.save_and_reraise_exception().capture().force_reraise()
+
+        self.assertRaises(IOError, _force_reraise)
+
+    def test_save_and_reraise_exception_capture_not_active(self):
+        e = excutils.save_and_reraise_exception()
+        self.assertRaises(RuntimeError, e.capture, check=True)
+
+    def test_save_and_reraise_exception_forced_not_active(self):
+        e = excutils.save_and_reraise_exception()
+        self.assertRaises(RuntimeError, e.force_reraise)
+        e = excutils.save_and_reraise_exception()
+        e.capture(check=False)
+        self.assertRaises(RuntimeError, e.force_reraise)
+
     def test_save_and_reraise_exception(self):
         e = None
         msg = 'foo'