/usr/share/pyshared/juju/state/utils.py is in juju-0.7 0.7-0ubuntu2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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from UserDict import DictMixin
import socket
import errno
import time
from twisted.internet.defer import inlineCallbacks, returnValue
from twisted.internet.threads import deferToThread
from txzookeeper.utils import retry_change
import zookeeper
from juju.lib import serializer
from juju.state.errors import StateChanged
from juju.state.errors import StateNotFound
class PortWatcher(object):
def __init__(self, host, port, timeout, listen=False):
"""Watches a `port` on `host` until available.
Used with `sync_wait` or `async_wait` methods.
Times out after `timeout` seconds. Normally the watcher is
used to determine when a port starts listening for client use,
but the parameter `listen` may be used to wait for when the
port can be used by a server (because of previous usage
without properly closing).
"""
self._host = host
self._port = port
self._timeout = timeout
self._stop = False
self._listen = listen
def stop(self, result=None):
"""Interrupt port watching in its loop."""
self._stop = True
return result
def sync_wait(self):
"""Waits until the port is available, or `socket.error`."""
until = time.time() + self._timeout
while time.time() < until and not self._stop:
sock = socket.socket()
sock.settimeout(1)
try:
if self._listen:
sock.bind((self._host, self._port))
else:
sock.connect((self._host, self._port))
except socket.timeout:
time.sleep(0.5)
except socket.error, e:
if e.args[0] not in (
errno.EWOULDBLOCK, errno.ECONNREFUSED, errno.EADDRINUSE):
raise
else:
# Sleep, otherwise this code will create useless sockets
time.sleep(0.5)
else:
sock.close()
return True
if self._stop:
return
raise socket.timeout("could not connect before timeout")
def async_wait(self, *ignored):
"""Returns a deferred that is called back on port available.
An exception is returned through the deferred errback if the
port wait timed out, or another problem occurs."""
return deferToThread(self.sync_wait)
@inlineCallbacks
def remove_tree(client, path):
children = yield client.get_children(path)
for child in children:
yield remove_tree(client, "%s/%s" % (path, child))
yield client.delete(path)
def dict_merge(d1, d2):
"""Return a union of dicts if they have no conflicting values.
Else raise a StateChanged error.
"""
must_match = set(d1).intersection(d2)
for k in must_match:
if not d1[k] == d2[k]:
raise StateChanged()
d = {}
d.update(d1)
d.update(d2)
return d
class DeletedItem(namedtuple("DeletedItem", "key old")):
"""Represents deleted items when :class:`YAMLState` writes."""
def __str__(self):
return "Setting deleted: %r (was %.100r)" % (self.key, self.old)
class ModifiedItem(namedtuple("ModifiedItem", "key old new")):
"""Represents modified items when :class:`YAMLState` writes."""
def __str__(self):
return "Setting changed: %r=%.100r (was %.100r)" % \
(self.key, self.new, self.old)
class AddedItem(namedtuple("AddedItem", "key new")):
"""Represents added items when :class:`YAMLState` writes."""
def __str__(self):
return "Setting changed: %r=%.100r (was unset)" % \
(self.key, self.new)
class YAMLState(DictMixin, object):
"""Provides a dict like interface around a Zookeeper node
containing serialised YAML data. The dict provided represents the
local view of all node data.
`write` writes this information into the Zookeeper node, using a
retry until success and merges against any existing keys in ZK.
YAMLState(client, path)
`client`: a Zookeeper client
`path`: the path of the Zookeeper node to manage
The state of this object always represents the product of the
pristine settings (from Zookeeper) and the pending writes.
All mutation to the dict expects the use of inlineCallbacks and a
yield. This includes set and update.
"""
# By always updating 'self' on mutation we don't need to do any
# special handling on data access (gets).
def __init__(self, client, path):
self._client = client
self._path = path
self._pristine_cache = None
self._cache = {}
@inlineCallbacks
def read(self, required=False):
"""Read Zookeeper state.
Read in the current Zookeeper state for this node. This
operation should be called prior to other interactions with
this object.
`required`: boolean indicating if the node existence should be
required at read time. Normally write will create the node if
the path is possible. This allows for simplified catching of
errors.
"""
self._pristine_cache = {}
self._cache = {}
try:
data, stat = yield self._client.get(self._path)
data = serializer.load(data)
if data:
self._pristine_cache = data
self._cache = data.copy()
except zookeeper.NoNodeException:
if required:
raise StateNotFound(self._path)
def _check(self):
"""Verify that sync was called for operations which expect it."""
if self._pristine_cache is None:
raise ValueError(
"You must call .read() on %s instance before use." % (
self.__class__.__name__,))
## DictMixin Interface
def keys(self):
return self._cache.keys()
def __getitem__(self, key):
self._check()
return self._cache[key]
def __setitem__(self, key, value):
self._check()
self._cache[key] = value
def __delitem__(self, key):
self._check()
del self._cache[key]
@inlineCallbacks
def write(self):
"""Write object state to Zookeeper.
This will write the current state of the object to Zookeeper,
taking the final merged state as the new one, and resetting
any write buffers.
"""
self._check()
cache = self._cache
pristine_cache = self._pristine_cache
self._pristine_cache = cache.copy()
# Used by `apply_changes` function to return the changes to
# this scope.
changes = []
def apply_changes(content, stat):
"""Apply the local state to the Zookeeper node state."""
del changes[:]
current = serializer.load(content) if content else {}
missing = object()
for key in set(pristine_cache).union(cache):
old_value = pristine_cache.get(key, missing)
new_value = cache.get(key, missing)
if old_value != new_value:
if new_value != missing:
current[key] = new_value
if old_value != missing:
changes.append(
ModifiedItem(key, old_value, new_value))
else:
changes.append(AddedItem(key, new_value))
elif key in current:
del current[key]
changes.append(DeletedItem(key, old_value))
return serializer.dump(current)
# Apply the change till it takes.
yield retry_change(self._client, self._path, apply_changes)
returnValue(changes)
class YAMLStateNodeMixin(object):
"""Enables simpler setters/getters.
Mixee requires ._zk_path and ._client attributes, and a ._node_missing
method.
"""
@inlineCallbacks
def _get_node_value(self, key, default=None):
node_data = YAMLState(self._client, self._zk_path)
try:
yield node_data.read(required=True)
except StateNotFound:
self._node_missing()
returnValue(node_data.get(key, default))
@inlineCallbacks
def _set_node_value(self, key, value):
node_data = YAMLState(self._client, self._zk_path)
try:
yield node_data.read(required=True)
except StateNotFound:
self._node_missing()
node_data[key] = value
yield node_data.write()
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