Add locking in common zkhander

Ensures that every changed made here is locked, thus preventing
duplicate updates, etc.
This commit is contained in:
Joshua Boniface 2020-10-21 03:04:50 -04:00
parent 351076c15e
commit 53c0d2b4f6
1 changed files with 82 additions and 12 deletions

View File

@ -35,15 +35,33 @@ def exists(zk_conn, key):
# Child list function
def listchildren(zk_conn, key):
children = zk_conn.get_children(key)
return children
try:
children = zk_conn.get_children(key)
return children
except:
return None
# Delete key function
# Key deletion function
def deletekey(zk_conn, key, recursive=True):
zk_conn.delete(key, recursive=recursive)
lock = exclusivelock(zk_conn, key)
lock.acquire()
try:
zk_conn.delete(key, recursive=recursive)
lock.release()
return True
except:
lock.release()
return False
# Rename key recursive function
def rename_key_element(zk_conn, zk_transaction, source_key, destination_key):
lock_source = exclusivelock(zk_conn, source_key)
lock_source.acquire()
lock_destination = exclusivelock(zk_conn, destination_key)
lock_destination.acquire()
data_raw = zk_conn.get(source_key)
data = data_raw[0]
zk_transaction.create(destination_key, data)
@ -56,6 +74,9 @@ def rename_key_element(zk_conn, zk_transaction, source_key, destination_key):
zk_transaction.delete(source_key)
lock_source.release()
lock_destination.release()
# Rename key function
def renamekey(zk_conn, kv):
# Start up a transaction
@ -83,10 +104,18 @@ def renamekey(zk_conn, kv):
# Data read function
def readdata(zk_conn, key):
data_raw = zk_conn.get(key)
data = data_raw[0].decode('utf8')
meta = data_raw[1]
return data
lock = readlock(zk_conn, key)
lock.acquire()
try:
data_raw = zk_conn.get(key)
data = data_raw[0].decode('utf8')
meta = data_raw[1]
lock.release()
return data
except:
return False
# Data write function
def writedata(zk_conn, kv):
@ -95,6 +124,9 @@ def writedata(zk_conn, kv):
# Proceed one KV pair at a time
for key in sorted(kv):
lock = writelock(zk_conn, key)
lock.acquire()
data = kv[key]
# Check if this key already exists or not
@ -117,7 +149,9 @@ def writedata(zk_conn, kv):
zk_transaction.check(key, new_version)
except TypeError:
print('Zookeeper key "{}" does not match expected version'.format(key))
lock.release()
return False
lock.release()
# Commit the transaction
try:
@ -128,12 +162,48 @@ def writedata(zk_conn, kv):
# Write lock function
def writelock(zk_conn, key):
lock_id = str(uuid.uuid1())
lock = zk_conn.WriteLock('{}'.format(key), lock_id)
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:
continue
return lock
# Read lock function
def readlock(zk_conn, key):
lock_id = str(uuid.uuid1())
lock = zk_conn.ReadLock('{}'.format(key), lock_id)
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:
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:
continue
return lock