def _get_watcher(self, path, callback=None):
"""Creates a Watcher object for the supplid path.
Creates a Watcher object for the supplied path and returns the
object. Triggers callbacks immediately.
This is broken into its own function so that it can leverage
the @_health_check decorator. This function should never be
called from outside of this class.
Args:
path: A string representing the path to the servers.
callback: (optional) reference to function to call if the path
changes.
Returns:
nd_service_registry.Watcher object
"""
# Ok, so the cache is missing the key. Lets look for it in Zookeeper
self.log.debug('[%s] Creating Watcher object...' % path)
watcher = Watcher(self._zk,
path,
watch_children=True,
callback=callback)
# Always register our dictionary saver callback, in addition to
# whatever our user has supplied
watcher.add_callback(self._save_watcher_to_dict)
return watcher
def _get_watcher(self, path, callback=None):
"""Creates a Watcher object for the supplid path.
Creates a Watcher object for the supplied path and returns the
object. Triggers callbacks immediately.
This is broken into its own function so that it can leverage
the @_health_check decorator. This function should never be
called from outside of this class.
Args:
path: A string representing the path to the servers.
callback: (optional) reference to function to call if the path
changes.
Returns:
nd_service_registry.Watcher object
"""
# Ok, so the cache is missing the key. Lets look for it in Zookeeper
log.debug('[%s] Creating Watcher object...' % path)
watcher = Watcher(self._zk,
path,
watch_children=True,
callback=callback)
# Always register our dictionary saver callback, in addition to
# whatever our user has supplied
watcher.add_callback(self._save_watcher_to_dict)
return watcher
def test_watch_on_nonexistent_path_with_multiple_data_changes(self):
path = '%s/nonexistent-path-%s' % (self.sandbox, uuid.uuid4().hex)
watch = Watcher(zk=self.zk, path=path)
# In order to track the number of callbacks that are registered,
# we register a mocked method in the callbacks.
callback_checker = mock.Mock()
callback_checker.test.return_value = True
watch.add_callback(callback_checker.test)
# Initially, we expect the data, children count and stat data
# to be None because the node doesn't exist.
self.assertEquals(None, watch.get()['data'])
self.assertEquals(None, watch.get()['stat'])
self.assertEquals([], watch.get()['children'])
# Now register a child node under the path, and expect the
# data to change
child_path = '%s/my_child_test' % path
self.zk.create(child_path, makepath=True)
# Wait until the children list changes
def get_children():
return watch.get()['children']
waituntil(get_children, [], timeout=5)
# Now verify that the data has been updated in our Watcher
self.assertTrue('my_child_test' in watch.get()['children'])
# Now make a series of data changes and wait for each one to
# take effect before moving on to the next one.
def get_data():
return watch.get()['data']
for i in range(1, 5):
self.zk.set(path, value=('%s' % i).encode('UTF-8'))
waituntil(get_data, {'string_value': '%s' % i}, timeout=5, mode=2)
# The right number of calls is 6. There are a few upfront calls when
# the Watcher object is initialized, and after that there are a few
# calls for the updated node-data when new children are added. The
# call count would be MUCH higher (11++) if we were recursively
# creating Watches though.
self.assertEquals(6, len(callback_checker.test.mock_calls))
def test_watch_on_nonexistent_path_with_multiple_data_changes(self):
path = '%s/nonexistent-path-%s' % (self.sandbox, uuid.uuid4().hex)
watch = Watcher(zk=self.zk, path=path)
# In order to track the number of callbacks that are registered,
# we register a mocked method in the callbacks.
callback_checker = mock.Mock()
callback_checker.test.return_value = True
watch.add_callback(callback_checker.test)
# Initially, we expect the data, children count and stat data
# to be None because the node doesn't exist.
self.assertEquals(None, watch.get()['data'])
self.assertEquals(None, watch.get()['stat'])
self.assertEquals([], watch.get()['children'])
# Now register a child node under the path, and expect the
# data to change
child_path = '%s/my_child_test' % path
self.zk.create(child_path, makepath=True)
# Wait until the children list changes
def get_children():
return watch.get()['children']
waituntil(get_children, [], timeout=5)
# Now verify that the data has been updated in our Watcher
self.assertTrue('my_child_test' in watch.get()['children'])
# Now make a series of data changes and wait for each one to
# take effect before moving on to the next one.
def get_data():
return watch.get()['data']
for i in xrange(1, 5):
self.zk.set(path, value='%s' % i)
waituntil(get_data, {'string_value': '%s' % i}, timeout=5, mode=2)
# The right number of calls is 6. There are a few upfront calls when
# the Watcher object is initialized, and after that there are a few
# calls for the updated node-data when new children are added. The
# call count would be MUCH higher (11++) if we were recursively
# creating Watches though.
self.assertEquals(6, len(callback_checker.test.mock_calls))
