replay

When it work?

With `config.replay_mode=True` ,the Bot will turn replay mode. when an exception is raised at step N, you don’t need to run from setup 1 to N. Databot will replay the data from nearest completed node, usually step N-1. It will save a lot of time in the development phase.

There are two mandatory condition for replay mode.

1. Exception raised.
2. Node completable. for unlimited stream pipe. it is unable to replay.

for below example .when restart application after exception raised, the double function will not be executed any more.

from databot.flow import Pipe, Loop, Fork
from databot.botframe import BotFrame
from databot.config import config
import time

def double(a):
    print('double %d'%a)
    time.sleep(1)
    return 2*a


count=0
def triple(a):
    global  count
    count+=1
    if count>6:
        raise Exception()
        pass
    return 3*a

#
config.replay_mode=True

def main():
    Pipe(

        Loop(range(10)),
        double,
        triple,
        print


    )

    BotFrame.run()



main()

How it work?

When exception raised , botframe will dump the cached data of the nearest completed node to disk. it will restore from disk when restart. And the completed node of previous running will not be start again.

Warning

Current version 0.1.7 ,in reply mode the data is cached in RAM. so not use when processing big data.