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July 4, 2019 17:16
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Use TreeCache of Kazoo to get node data.
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import logging | |
import threading | |
from kazoo.client import KazooClient | |
from kazoo.recipe.cache import TreeCache, TreeEvent | |
class TreeCacheListener(object): | |
CONNECTIVE_EVENTS = { | |
TreeEvent.CONNECTION_SUSPENDED: 'SUSPENDED', | |
TreeEvent.CONNECTION_RECONNECTED: 'RECONNECTED', | |
TreeEvent.CONNECTION_LOST: 'LOST', | |
} | |
def __init__(self, tree_cache): | |
self._log = logging.getLogger('{0}.{1}'.format( | |
__name__, self.__class__.__name__)) | |
self._cache = tree_cache | |
self._initialized = threading.Event() | |
def start(self, timeout=5): | |
self._cache.listen(self._handle_event) | |
self._cache.listen_fault(self._handle_fault) | |
self._cache.start() | |
return self._initialized.wait(timeout) | |
def _handle_event(self, event): | |
if not self._initialized.is_set(): | |
if event.event_type == TreeEvent.INITIALIZED: | |
self._initialized.set() | |
return | |
if event.event_type in self.CONNECTIVE_EVENTS: | |
event_name = self.CONNECTIVE_EVENTS[event.event_type] | |
self._log.info('Connective event %s happened', event_name) | |
return | |
if event.event_type in ( | |
TreeEvent.NODE_ADDED, | |
TreeEvent.NODE_UPDATED, | |
TreeEvent.NODE_REMOVED): | |
# NOTE We are able to do something on the tree cache now | |
return | |
def _handle_fault(self, error): | |
self._log.exception(error) | |
def example(): | |
client = KazooClient() | |
client.start() | |
tree_cache = TreeCache(client, '/kazoo-treecache-example') | |
tree_listener = TreeCacheListener(tree_cache) | |
tree_listener.start() # block until the tree cache is initialized | |
path, data, stat = tree_cache.get_data('/kazoo-treecache-example') | |
print('\n=> {0} = {1!r}; {2}'.format(path, data, stat)) | |
if __name__ == '__main__': | |
logging.basicConfig(level=logging.DEBUG) | |
example() |
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