pvc/daemon-common/zkhandler.py

176 lines
5.0 KiB
Python

#!/usr/bin/env python3
# zkhandler.py - Secure versioned ZooKeeper updates
# Part of the Parallel Virtual Cluster (PVC) system
#
# Copyright (C) 2018-2020 Joshua M. Boniface <joshua@boniface.me>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <https://www.gnu.org/licenses/>.
#
###############################################################################
import time
import uuid
# Exists function
def exists(zk_conn, key):
stat = zk_conn.exists(key)
if stat:
return True
else:
return False
# Child list function
def listchildren(zk_conn, key):
children = zk_conn.get_children(key)
return children
# Delete key function
def deletekey(zk_conn, key, recursive=True):
zk_conn.delete(key, recursive=recursive)
# Rename key recursive function
def rename_key_element(zk_conn, zk_transaction, source_key, destination_key):
data_raw = zk_conn.get(source_key)
data = data_raw[0]
zk_transaction.create(destination_key, data)
if zk_conn.get_children(source_key):
for child_key in zk_conn.get_children(source_key):
child_source_key = "{}/{}".format(source_key, child_key)
child_destination_key = "{}/{}".format(destination_key, child_key)
rename_key_element(zk_conn, zk_transaction, child_source_key, child_destination_key)
zk_transaction.delete(source_key)
# Rename key function
def renamekey(zk_conn, kv):
# Start up a transaction
zk_transaction = zk_conn.transaction()
# Proceed one KV pair at a time
for source_key in sorted(kv):
destination_key = kv[source_key]
# Check if the source key exists or fail out
if not zk_conn.exists(source_key):
raise
# Check if the destination key exists and fail out
if zk_conn.exists(destination_key):
raise
rename_key_element(zk_conn, zk_transaction, source_key, destination_key)
# Commit the transaction
try:
zk_transaction.commit()
return True
except Exception:
return False
# Data read function
def readdata(zk_conn, key):
data_raw = zk_conn.get(key)
data = data_raw[0].decode('utf8')
return data
# Data write function
def writedata(zk_conn, kv):
# Start up a transaction
zk_transaction = zk_conn.transaction()
# Proceed one KV pair at a time
for key in sorted(kv):
data = kv[key]
# Check if this key already exists or not
if not zk_conn.exists(key):
# We're creating a new key
zk_transaction.create(key, str(data).encode('utf8'))
else:
# We're updating a key with version validation
orig_data = zk_conn.get(key)
version = orig_data[1].version
# Set what we expect the new version to be
new_version = version + 1
# Update the data
zk_transaction.set_data(key, str(data).encode('utf8'))
# Set up the check
try:
zk_transaction.check(key, new_version)
except TypeError:
print('Zookeeper key "{}" does not match expected version'.format(key))
return False
# Commit the transaction
try:
zk_transaction.commit()
return True
except Exception:
return False
# Write lock function
def writelock(zk_conn, key):
count = 1
while True:
try:
lock_id = str(uuid.uuid1())
lock = zk_conn.WriteLock('{}'.format(key), lock_id)
break
except Exception:
count += 1
if count > 5:
break
else:
time.sleep(0.5)
continue
return lock
# Read lock function
def readlock(zk_conn, key):
count = 1
while True:
try:
lock_id = str(uuid.uuid1())
lock = zk_conn.ReadLock('{}'.format(key), lock_id)
break
except Exception:
count += 1
if count > 5:
break
else:
time.sleep(0.5)
continue
return lock
# Exclusive lock function
def exclusivelock(zk_conn, key):
count = 1
while True:
try:
lock_id = str(uuid.uuid1())
lock = zk_conn.Lock('{}'.format(key), lock_id)
break
except Exception:
count += 1
if count > 5:
break
else:
time.sleep(0.5)
continue
return lock