From 9f2adb4d593f58c92e73e33c0305a679eaf6b819 Mon Sep 17 00:00:00 2001
From: Chris Yeoh <cyeoh@au1.ibm.com>
Date: Thu, 20 Jun 2013 13:32:52 +0930
Subject: [PATCH] Adds ability to propogate exceptions within map

Adds init variable for extension managers to specify whether
or not exceptions are propated up by map or are logged and supressed
---
 stevedore/dispatch.py             |  4 +++-
 stevedore/enabled.py              |  4 +++-
 stevedore/extension.py            | 14 ++++++++------
 stevedore/named.py                |  3 ++-
 stevedore/tests/test_extension.py | 18 ++++++++++++++++++
 5 files changed, 34 insertions(+), 9 deletions(-)

diff --git a/stevedore/dispatch.py b/stevedore/dispatch.py
index 9f7a4c8..f96e731 100644
--- a/stevedore/dispatch.py
+++ b/stevedore/dispatch.py
@@ -99,13 +99,15 @@ class NameDispatchExtensionManager(DispatchExtensionManager):
     """
 
     def __init__(self, namespace, check_func, invoke_on_load=False,
-                 invoke_args=(), invoke_kwds={}):
+                 invoke_args=(), invoke_kwds={},
+                 propagate_map_exceptions=False):
         super(NameDispatchExtensionManager, self).__init__(
             namespace=namespace,
             check_func=check_func,
             invoke_on_load=invoke_on_load,
             invoke_args=invoke_args,
             invoke_kwds=invoke_kwds,
+            propagate_map_exceptions=propagate_map_exceptions,
         )
         self.by_name = dict((e.name, e) for e in self.extensions)
 
diff --git a/stevedore/enabled.py b/stevedore/enabled.py
index 6157554..0c96a1b 100644
--- a/stevedore/enabled.py
+++ b/stevedore/enabled.py
@@ -32,13 +32,15 @@ class EnabledExtensionManager(ExtensionManager):
     """
 
     def __init__(self, namespace, check_func, invoke_on_load=False,
-                 invoke_args=(), invoke_kwds={}):
+                 invoke_args=(), invoke_kwds={},
+                 propagate_map_exceptions=False):
         self.check_func = check_func
         super(EnabledExtensionManager, self).__init__(
             namespace,
             invoke_on_load=invoke_on_load,
             invoke_args=invoke_args,
             invoke_kwds=invoke_kwds,
+            propagate_map_exceptions=propagate_map_exceptions,
         )
 
     def _load_one_plugin(self, ep, invoke_on_load, invoke_args, invoke_kwds):
diff --git a/stevedore/extension.py b/stevedore/extension.py
index 076b49d..063cf1a 100644
--- a/stevedore/extension.py
+++ b/stevedore/extension.py
@@ -57,8 +57,10 @@ class ExtensionManager(object):
     def __init__(self, namespace,
                  invoke_on_load=False,
                  invoke_args=(),
-                 invoke_kwds={}):
+                 invoke_kwds={},
+                 propagate_map_exceptions=False):
         self.namespace = namespace
+        self.propagate_map_exceptions = propagate_map_exceptions
         self.extensions = self._load_plugins(invoke_on_load,
                                              invoke_args,
                                              invoke_kwds)
@@ -136,11 +138,11 @@ class ExtensionManager(object):
         try:
             response_callback(func(e, *args, **kwds))
         except Exception as err:
-            # FIXME: Provide an argument to control
-            # whether to ignore exceptions in each
-            # plugin or stop processing.
-            LOG.error('error calling %r: %s', e.name, err)
-            LOG.exception(err)
+            if self.propagate_map_exceptions:
+                raise
+            else:
+                LOG.error('error calling %r: %s', e.name, err)
+                LOG.exception(err)
 
     def __iter__(self):
         """Produce iterator for the manager.
diff --git a/stevedore/named.py b/stevedore/named.py
index 2a3f054..63ee386 100644
--- a/stevedore/named.py
+++ b/stevedore/named.py
@@ -29,13 +29,14 @@ class NamedExtensionManager(ExtensionManager):
 
     def __init__(self, namespace, names,
                  invoke_on_load=False, invoke_args=(), invoke_kwds={},
-                 name_order=False):
+                 name_order=False, propagate_map_exceptions=False):
         self._names = names
         super(NamedExtensionManager, self).__init__(
             namespace,
             invoke_on_load=invoke_on_load,
             invoke_args=invoke_args,
             invoke_kwds=invoke_kwds,
+            propagate_map_exceptions=propagate_map_exceptions,
         )
 
         if name_order:
diff --git a/stevedore/tests/test_extension.py b/stevedore/tests/test_extension.py
index bc76bbd..fb9fdd8 100644
--- a/stevedore/tests/test_extension.py
+++ b/stevedore/tests/test_extension.py
@@ -126,6 +126,24 @@ def test_map_eats_errors():
     assert results == []
 
 
+def test_map_propagate_exceptions():
+
+    def mapped(ext, *args, **kwds):
+        raise RuntimeError('hard coded error')
+
+    em = extension.ExtensionManager('stevedore.test.extension',
+                                    invoke_on_load=True,
+                                    propagate_map_exceptions=True
+                                    )
+
+    try:
+        em.map(mapped, 1, 2, a='A', b='B')
+        assert False
+    except:
+        pass
+
+
+
 def test_map_errors_when_no_plugins():
 
     def mapped(ext, *args, **kwds):