Merge "Allow a on_load_failure_callback to be provided"

9 files changed, 85 insertions, 24 deletions

diff --git a/setup.cfg b/setup.cfg
index 41d2a39..8cae156 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -34,6 +34,7 @@ stevedore.example.formatter =
 stevedore.test.extension =
     t1 = stevedore.tests.test_extension:FauxExtension
     t2 = stevedore.tests.test_extension:FauxExtension
+    e1 = stevedore.tests.test_extension:BrokenExtension
 
 
 [build_sphinx]
diff --git a/stevedore/dispatch.py b/stevedore/dispatch.py
index 2ff455d..3f7e1c7 100644
--- a/stevedore/dispatch.py
+++ b/stevedore/dispatch.py
@@ -133,7 +133,8 @@ class NameDispatchExtensionManager(DispatchExtensionManager):
 
     def __init__(self, namespace, check_func, invoke_on_load=False,
                  invoke_args=(), invoke_kwds={},
-                 propagate_map_exceptions=False):
+                 propagate_map_exceptions=False,
+                 on_load_failure_callback=None):
         super(NameDispatchExtensionManager, self).__init__(
             namespace=namespace,
             check_func=check_func,
@@ -141,6 +142,7 @@ class NameDispatchExtensionManager(DispatchExtensionManager):
             invoke_args=invoke_args,
             invoke_kwds=invoke_kwds,
             propagate_map_exceptions=propagate_map_exceptions,
+            on_load_failure_callback=on_load_failure_callback
         )
 
     def _init_plugins(self, extensions):
diff --git a/stevedore/driver.py b/stevedore/driver.py
index 4247e36..21f1f61 100644
--- a/stevedore/driver.py
+++ b/stevedore/driver.py
@@ -22,18 +22,21 @@ class DriverManager(NamedExtensionManager):
     """
 
     def __init__(self, namespace, name,
-                 invoke_on_load=False, invoke_args=(), invoke_kwds={}):
+                 invoke_on_load=False, invoke_args=(), invoke_kwds={},
+                 on_load_failure_callback=None):
         super(DriverManager, self).__init__(
             namespace=namespace,
             names=[name],
             invoke_on_load=invoke_on_load,
             invoke_args=invoke_args,
             invoke_kwds=invoke_kwds,
+            on_load_failure_callback=on_load_failure_callback
         )
 
     @classmethod
     def make_test_instance(cls, extension, namespace='TESTING',
-                           propagate_map_exceptions=False):
+                           propagate_map_exceptions=False,
+                           on_load_failure_callback=None):
         """Construct a test DriverManager
 
         Test instances are passed a list of extensions to work from rather
@@ -54,7 +57,8 @@ class DriverManager(NamedExtensionManager):
 
         o = super(DriverManager, cls).make_test_instance(
             [extension], namespace=namespace,
-            propagate_map_exceptions=propagate_map_exceptions)
+            propagate_map_exceptions=propagate_map_exceptions,
+            on_load_failure_callback=on_load_failure_callback)
         return o
 
     def _init_plugins(self, extensions):
diff --git a/stevedore/enabled.py b/stevedore/enabled.py
index b6260b1..c57882e 100644
--- a/stevedore/enabled.py
+++ b/stevedore/enabled.py
@@ -37,7 +37,8 @@ class EnabledExtensionManager(ExtensionManager):
 
     def __init__(self, namespace, check_func, invoke_on_load=False,
                  invoke_args=(), invoke_kwds={},
-                 propagate_map_exceptions=False):
+                 propagate_map_exceptions=False,
+                 on_load_failure_callback=None):
         self.check_func = check_func
         super(EnabledExtensionManager, self).__init__(
             namespace,
@@ -45,6 +46,7 @@ class EnabledExtensionManager(ExtensionManager):
             invoke_args=invoke_args,
             invoke_kwds=invoke_kwds,
             propagate_map_exceptions=propagate_map_exceptions,
+            on_load_failure_callback=on_load_failure_callback
         )
 
     def _load_one_plugin(self, ep, invoke_on_load, invoke_args, invoke_kwds):
diff --git a/stevedore/extension.py b/stevedore/extension.py
index d9e054c..56baa47 100644
--- a/stevedore/extension.py
+++ b/stevedore/extension.py
@@ -65,16 +65,23 @@ class ExtensionManager(object):
         are propagated up through the map call or whether they are logged and
         then ignored
     :type propagate_map_exceptions: bool
-
+    :param on_load_failure_callback: Callback function that will be called when
+        a entrypoint can not be loaded. The arguments that will be provided
+        when this is called (when an entrypoint fails to load) are
+        (manager, entrypoint, exception)
+    :type on_load_failure_callback: function
     """
 
     def __init__(self, namespace,
                  invoke_on_load=False,
                  invoke_args=(),
                  invoke_kwds={},
-                 propagate_map_exceptions=False):
+                 propagate_map_exceptions=False,
+                 on_load_failure_callback=None):
         self._init_attributes(
-            namespace, propagate_map_exceptions=propagate_map_exceptions)
+            namespace,
+            propagate_map_exceptions=propagate_map_exceptions,
+            on_load_failure_callback=on_load_failure_callback)
         extensions = self._load_plugins(invoke_on_load,
                                         invoke_args,
                                         invoke_kwds)
@@ -82,7 +89,8 @@ class ExtensionManager(object):
 
     @classmethod
     def make_test_instance(cls, extensions, namespace='TESTING',
-                           propagate_map_exceptions=False):
+                           propagate_map_exceptions=False,
+                           on_load_failure_callback=None):
         """Construct a test ExtensionManager
 
         Test instances are passed a list of extensions to work from rather
@@ -103,13 +111,16 @@ class ExtensionManager(object):
 
         o = cls.__new__(cls)
         o._init_attributes(namespace,
-                           propagate_map_exceptions=propagate_map_exceptions)
+                           propagate_map_exceptions=propagate_map_exceptions,
+                           on_load_failure_callback=on_load_failure_callback)
         o._init_plugins(extensions)
         return o
 
-    def _init_attributes(self, namespace, propagate_map_exceptions=False):
+    def _init_attributes(self, namespace, propagate_map_exceptions=False,
+                         on_load_failure_callback=None):
         self.namespace = namespace
         self.propagate_map_exceptions = propagate_map_exceptions
+        self._on_load_failure_callback = on_load_failure_callback
 
     def _init_plugins(self, extensions):
         self.extensions = extensions
@@ -140,6 +151,8 @@ class ExtensionManager(object):
             except Exception as err:
                 LOG.error('Could not load %r: %s', ep.name, err)
                 LOG.exception(err)
+                if self._on_load_failure_callback is not None:
+                    self._on_load_failure_callback(self, ep, err)
         return extensions
 
     def _load_one_plugin(self, ep, invoke_on_load, invoke_args, invoke_kwds):
diff --git a/stevedore/hook.py b/stevedore/hook.py
index b7cdef8..16fa37d 100644
--- a/stevedore/hook.py
+++ b/stevedore/hook.py
@@ -22,20 +22,24 @@ class HookManager(NamedExtensionManager):
     """
 
     def __init__(self, namespace, name,
-                 invoke_on_load=False, invoke_args=(), invoke_kwds={}):
+                 invoke_on_load=False, invoke_args=(), invoke_kwds={},
+                 on_load_failure_callback=None):
         super(HookManager, self).__init__(
             namespace,
             [name],
             invoke_on_load=invoke_on_load,
             invoke_args=invoke_args,
             invoke_kwds=invoke_kwds,
+            on_load_failure_callback=on_load_failure_callback
         )
 
     def _init_attributes(self, namespace, names, name_order=False,
-                         propagate_map_exceptions=False):
+                         propagate_map_exceptions=False,
+                         on_load_failure_callback=None):
         super(HookManager, self)._init_attributes(
             namespace, names,
-            propagate_map_exceptions=propagate_map_exceptions)
+            propagate_map_exceptions=propagate_map_exceptions,
+            on_load_failure_callback=on_load_failure_callback)
         self._name = names[0]
 
     def __getitem__(self, name):
diff --git a/stevedore/named.py b/stevedore/named.py
index b4f620c..c5697df 100644
--- a/stevedore/named.py
+++ b/stevedore/named.py
@@ -34,10 +34,12 @@ class NamedExtensionManager(ExtensionManager):
 
     def __init__(self, namespace, names,
                  invoke_on_load=False, invoke_args=(), invoke_kwds={},
-                 name_order=False, propagate_map_exceptions=False):
+                 name_order=False, propagate_map_exceptions=False,
+                 on_load_failure_callback=None):
         self._init_attributes(
             namespace, names, name_order=name_order,
-            propagate_map_exceptions=propagate_map_exceptions)
+            propagate_map_exceptions=propagate_map_exceptions,
+            on_load_failure_callback=on_load_failure_callback)
         extensions = self._load_plugins(invoke_on_load,
                                         invoke_args,
                                         invoke_kwds)
@@ -45,7 +47,8 @@ class NamedExtensionManager(ExtensionManager):
 
     @classmethod
     def make_test_instance(cls, extensions, namespace='TESTING',
-                           propagate_map_exceptions=False):
+                           propagate_map_exceptions=False,
+                           on_load_failure_callback=None):
         """Construct a test NamedExtensionManager
 
         Test instances are passed a list of extensions to use rather than
@@ -67,14 +70,17 @@ class NamedExtensionManager(ExtensionManager):
         o = cls.__new__(cls)
         names = [e.name for e in extensions]
         o._init_attributes(namespace, names,
-                           propagate_map_exceptions=propagate_map_exceptions)
+                           propagate_map_exceptions=propagate_map_exceptions,
+                           on_load_failure_callback=on_load_failure_callback)
         o._init_plugins(extensions)
         return o
 
     def _init_attributes(self, namespace, names, name_order=False,
-                         propagate_map_exceptions=False):
+                         propagate_map_exceptions=False,
+                         on_load_failure_callback=None):
         super(NamedExtensionManager, self)._init_attributes(
-            namespace, propagate_map_exceptions=propagate_map_exceptions)
+            namespace, propagate_map_exceptions=propagate_map_exceptions,
+            on_load_failure_callback=on_load_failure_callback)
 
         self._names = names
         self._name_order = name_order
diff --git a/stevedore/tests/test_callback.py b/stevedore/tests/test_callback.py
new file mode 100644
index 0000000..d80c7f2
--- /dev/null
+++ b/stevedore/tests/test_callback.py
@@ -0,0 +1,21 @@
+"""Tests for failure loading callback
+"""
+
+from stevedore import extension
+
+
+def test_extension_failure_custom_callback():
+    errors = []
+
+    def failure_callback(manager, entrypoint, error):
+        errors.append((manager, entrypoint, error))
+
+    em = extension.ExtensionManager('stevedore.test.extension',
+                                    invoke_on_load=True,
+                                    on_load_failure_callback=failure_callback)
+    extensions = list(em.extensions)
+    assert len(extensions) > 0
+    assert len(errors) == 1
+    (manager, entrypoint, error) = errors[0]
+    assert manager is em
+    assert isinstance(error, IOError)
diff --git a/stevedore/tests/test_extension.py b/stevedore/tests/test_extension.py
index 7a0349f..00ba52b 100644
--- a/stevedore/tests/test_extension.py
+++ b/stevedore/tests/test_extension.py
@@ -5,6 +5,9 @@ import mock
 
 from stevedore import extension
 
+ALL_NAMES = ['e1', 't1', 't2']
+WORKING_NAMES = ['t1', 't2']
+
 
 class FauxExtension(object):
     def __init__(self, *args, **kwds):
@@ -15,10 +18,15 @@ class FauxExtension(object):
         return self.args, self.kwds, data
 
 
+class BrokenExtension(object):
+    def __init__(self, *args, **kwds):
+        raise IOError("Did not create")
+
+
 def test_detect_plugins():
     em = extension.ExtensionManager('stevedore.test.extension')
     names = sorted(em.names())
-    assert names == ['t1', 't2']
+    assert names == ALL_NAMES
 
 
 def test_get_by_name():
@@ -73,7 +81,7 @@ def test_use_cache():
 def test_iterable():
     em = extension.ExtensionManager('stevedore.test.extension')
     names = sorted(e.name for e in em)
-    assert names == ['t1', 't2']
+    assert names == ALL_NAMES
 
 
 def test_invoke_on_load():
@@ -96,7 +104,7 @@ def test_map_return_values():
                                     invoke_on_load=True,
                                     )
     results = em.map(mapped)
-    assert sorted(results) == ['t1', 't2']
+    assert sorted(results) == WORKING_NAMES
 
 
 def test_map_arguments():
@@ -111,7 +119,7 @@ def test_map_arguments():
     em.map(mapped, 1, 2, a='A', b='B')
     assert len(objs) == 2
     names = sorted([o[0].name for o in objs])
-    assert names == ['t1', 't2']
+    assert names == WORKING_NAMES
     for o in objs:
         assert o[1] == (1, 2)
         assert o[2] == {'a': 'A', 'b': 'B'}