parallelvirtualcluster
/
pvc
1
0
Fork 0
Code Issues 11 Pull Requests Projects Releases 111 Wiki Activity

Integrate schema handling within ZKHandler 

Abstracts away the schema management, especially when doing actions, to
prevent duplication in other areas.
This commit is contained in:
Joshua Boniface 2021-06-09 13:23:57 -04:00
parent 76c37e6628
commit a9a57533a7
1 changed files with 77 additions and 32 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

109
daemon-common/zkhandler.py
View File

@ -49,6 +49,7 @@ class ZKConnection(object):
def connection(*args, **kwargs):
zkhandler = ZKHandler(self.config)
zkhandler.connect()
zkhandler.schema.load(zkhandler.read(zkhandler.schema.path('base.schema.version')), quiet=True)
ret = function(zkhandler, *args, **kwargs)
@ -87,11 +88,14 @@ class ZKHandler(object):
Initialize an instance of the ZKHandler class with config
A zk_conn object will be created but not started
A ZKSchema instance will be created
"""
self.encoding = 'utf8'
self.coordinators = config['coordinators']
self.logger = logger
self.zk_conn = KazooClient(hosts=self.coordinators)
self._schema = ZKSchema()
#
# Class meta-functions
@ -105,6 +109,13 @@ class ZKHandler(object):
else:
print(message)
#
# Properties
#
@property
def schema(self):
return self._schema
#
# State/connection management
#
@ -130,7 +141,7 @@ class ZKHandler(object):
def connect(self, persistent=False):
"""
Start the zk_conn object and connect to the cluster
Start the zk_conn object and connect to the cluster, then load the current schema version
"""
try:
self.zk_conn.start()
@ -148,6 +159,23 @@ class ZKHandler(object):
self.zk_conn.stop()
self.zk_conn.close()
#
# Schema helper actions
#
def get_schema_path(self, key):
if isinstance(key, tuple):
# This is a key tuple with both an ipath and an item
ipath, item = key
elif isinstance(key, str):
# This is a key string with just an ipath
ipath = key
item = None
else:
# This is an invalid key
return None
return self.schema.path(ipath, item=item)
#
# Key Actions
#
@ -155,7 +183,8 @@ class ZKHandler(object):
"""
Check if a key exists
"""
stat = self.zk_conn.exists(key)
path = self.get_schema_path(key)
stat = self.zk_conn.exists(path)
if stat:
return True
else:
@ -165,7 +194,8 @@ class ZKHandler(object):
"""
Read data from a key
"""
return self.zk_conn.get(key)[0].decode(self.encoding)
path = self.get_schema_path(key)
return self.zk_conn.get(path)[0].decode(self.encoding)
def write(self, kvpairs):
"""
@ -185,26 +215,28 @@ class ZKHandler(object):
key = kvpair[0]
value = kvpair[1]
if not self.exists(key):
path = self.get_schema_path(key)
if not self.exists(path):
# Creating a new key
transaction.create(key, str(value).encode(self.encoding))
transaction.create(path, str(value).encode(self.encoding))
else:
# Updating an existing key
data = self.zk_conn.get(key)
data = self.zk_conn.get(path)
version = data[1].version
# Validate the expected version after the execution
new_version = version + 1
# Update the data
transaction.set_data(key, str(value).encode(self.encoding))
transaction.set_data(path, str(value).encode(self.encoding))
# Check the data
try:
transaction.check(key, new_version)
transaction.check(path, new_version)
except TypeError:
self.log("ZKHandler error: Key '{}' does not match expected version".format(key), state='e')
self.log("ZKHandler error: Key '{}' does not match expected version".format(path), state='e')
return False
try:
@ -222,11 +254,12 @@ class ZKHandler(object):
keys = [keys]
for key in keys:
if self.exists(key):
path = self.get_schema_path(key)
if self.exists(path):
try:
self.zk_conn.delete(key, recursive=recursive)
self.zk_conn.delete(path, recursive=recursive)
except Exception as e:
self.log("ZKHandler error: Failed to delete key {}: {}".format(key, e), state='e')
self.log("ZKHandler error: Failed to delete key {}: {}".format(path, e), state='e')
return False
return True
@ -235,7 +268,8 @@ class ZKHandler(object):
"""
Lists all children of a key
"""
return self.zk_conn.get_children(key)
path = self.get_schema_path(key)
return self.zk_conn.get_children(path)
def rename(self, kkpairs):
"""
@ -247,17 +281,17 @@ class ZKHandler(object):
transaction = self.zk_conn.transaction()
def rename_element(transaction, source_key, destnation_key):
data = self.zk_conn.get(source_key)[0]
transaction.create(destination_key, data)
def rename_element(transaction, source_path, destnation_path):
data = self.zk_conn.get(source_path)[0]
transaction.create(destination_path, data)
if self.children(source_key):
for child_key in self.children(source_key):
child_source_key = "{}/{}".format(source_key, child_key)
child_destination_key = "{}/{}".format(destination_key, child_key)
rename_element(transaction, child_source_key, child_destination_key)
if self.children(source_path):
for child_path in self.children(source_path):
child_source_path = "{}/{}".format(source_path, child_path)
child_destination_path = "{}/{}".format(destination_path, child_path)
rename_element(transaction, child_source_path, child_destination_path)
transaction.delete(source_key)
transaction.delete(source_path)
for kkpair in (kkpairs):
if type(kkpair) is not tuple:
@ -265,16 +299,19 @@ class ZKHandler(object):
return False
source_key = kkpair[0]
source_path = self.get_schema_path(source_key)
destination_key = kkpair[1]
destination_path = self.get_schema_path(destination_key)
if not self.exists(source_key):
self.log("ZKHander error: Source key '{}' does not exist".format(source_key), state='e')
if not self.exists(source_path):
self.log("ZKHander error: Source key '{}' does not exist".format(source_path), state='e')
return False
if self.exists(destination_key):
self.log("ZKHander error: Destination key '{}' already exists".format(destination_key), state='e')
if self.exists(destination_path):
self.log("ZKHander error: Destination key '{}' already exists".format(destination_path), state='e')
return False
rename_element(transaction, source_key, destination_key)
rename_element(transaction, source_path, destination_path)
try:
transaction.commit()
@ -293,10 +330,12 @@ class ZKHandler(object):
count = 1
lock = None
path = self.get_schema_path(key)
while True:
try:
lock_id = str(uuid.uuid1())
lock = self.zk_conn.ReadLock(key, lock_id)
lock = self.zk_conn.ReadLock(path, lock_id)
break
except Exception as e:
if count > 5:
@ -316,10 +355,12 @@ class ZKHandler(object):
count = 1
lock = None
path = self.get_schema_path(key)
while True:
try:
lock_id = str(uuid.uuid1())
lock = self.zk_conn.WriteLock(key, lock_id)
lock = self.zk_conn.WriteLock(path, lock_id)
break
except Exception as e:
if count > 5:
@ -339,10 +380,12 @@ class ZKHandler(object):
count = 1
lock = None
path = self.get_schema_path(key)
while True:
try:
lock_id = str(uuid.uuid1())
lock = self.zk_conn.Lock(key, lock_id)
lock = self.zk_conn.Lock(path, lock_id)
break
except Exception as e:
if count > 5:
@ -537,8 +580,10 @@ class ZKSchema(object):
return False
# Load the schema of a given version from a file
def load(self, version):
print(f'Loading schema version {version}')
def load(self, version, quiet=False):
if not quiet:
print(f'Loading schema version {version}')
with open(f'daemon_lib/migrations/versions/{version}.json', 'r') as sfh:
self.schema = json.load(sfh)
self.version = self.schema.get('version')