A library for replicating your python class between multiple servers, based on raft protocol
Project description
PySyncObj is a python library for building fault-tolerant distributed systems. It provides the ability to replicate your application data between multiple servers. It has following features:
raft protocol for leader election and log replication
Log compaction - it use fork for copy-on-write while serializing data on disk
Dynamic membership changes - you can do it with syncobj_admin utility or directly from your code
Zero downtime deploy - no need to stop cluster to update nodes
In-memory and on-disk serialization - you can use in-memory mode for small data and on-disk for big one
Encryption - you can set password and use it in external network
Python2 and Python3 on linux, macos and windows - no dependencies required (only optional one, eg. cryptography)
Configurable event loop - it can works in separate thread with it’s own event loop - or you can call onTick function inside your own one
Convenient interface - you can easily transform arbitrary class into a replicated one (see example below).
Content
Install
PySyncObj itself:
pip install pysyncobj
Cryptography for encryption (optional):
pip install cryptography
Usage
Consider you have a class that implements counter:
class MyCounter(object):
def __init__(self):
self.__counter = 0
def incCounter(self):
self.__counter += 1
def getCounter(self):
return self.__counter
So, to transform your class into a replicated one: - Inherit it from SyncObj - Initialize SyncObj with a self address and a list of partner addresses. Eg. if you have serverA, serverB and serverC and want to use 4321 port, you should use self address serverA:4321 with partners [serverB:4321, serverC:4321] for your application, running at serverA; self address serverB:4321 with partners [serverA:4321, serverC:4321] for your application at serverB; self address serverC:4321 with partners [serverA:4321, serverB:4321] for app at serverC. - Mark all your methods that modifies your class fields with @replicated decorator. So your final class will looks like:
class MyCounter(SyncObj):
def __init__(self):
super(MyCounter, self).__init__('serverA:4321', ['serverB:4321', 'serverC:4321'])
self.__counter = 0
@replicated
def incCounter(self):
self.__counter += 1
def getCounter(self):
return self.__counter
And thats all! Now you can call incCounter on serverA, and check counter value on serverB - they will be synchronized.
Batteries
If you just need some distributed data structures - try built-in “batteries”. Few examples: ### Counter & Dict
from pysyncobj import SyncObj
from pysyncobj.batteries import ReplCounter, ReplDict
counter1 = ReplCounter()
counter2 = ReplCounter()
dict1 = ReplDict()
syncObj = SyncObj('serverA:4321', ['serverB:4321', 'serverC:4321'], consumers=[counter1, counter2, dict1])
counter1.set(42, sync=True) # set initial value to 42, 'sync' means that operation is blocking
counter1.add(10, sync=True) # add 10 to counter value
counter2.inc(sync=True) # increment counter value by one
dict1.set('testKey1', 'testValue1', sync=True)
dict1['testKey2'] = 'testValue2' # this is basically the same as previous, but asynchronous (non-blocking)
print(counter1, counter2, dict1['testKey1'], dict1.get('testKey2'))
Lock
from pysyncobj import SyncObj
from pysyncobj.batteries import ReplLockManager
lockManager = ReplLockManager(timeout=75) # Lock will be released if connection dropped for more than 75 seconds
syncObj = SyncObj('serverA:4321', ['serverB:4321', 'serverC:4321'], consumers=[lockManager])
if lockManager.tryAcquire('testLockName', sync=True):
# do some actions
lockManager.release('testLockName')
You can look at batteries implementation, examples and unit-tests for more use-cases. Also there is an API documentation. Feel free to create proposals and/or pull requests with new batteries, features, etc. Join our gitter chat if you have any questions.
Performance
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