saga-demo.py

# pip install saga_py
from saga import SagaBuilder, SagaError

counter1 = 0
counter2 = 0

def _print_counters():
    global counter1, counter2
    print(f'After this action, {counter1=}, {counter2=} \n')

def incr_counter1(amount):
    print('action 1 runs')
    global counter1
    counter1 += amount
    _print_counters()

def incr_counter2(amount):
    print('action 2 runs. it will fail soon')
    global counter2
    counter2 += amount
    _print_counters()
    raise BaseException('some error happened')

def decr_counter1(amount):
    print('compensation 1 runs')
    global counter1
    counter1 -= amount
    _print_counters()

def decr_counter2(amount):
    print('compensation 2 runs')
    global counter2
    counter2 -= amount
    _print_counters()

try:
    SagaBuilder \
        .create() \
        .action(lambda: incr_counter1(15), lambda: decr_counter1(15)) \
        .action(lambda: incr_counter2(1), lambda: decr_counter2(1)) \
        .build() \
        .execute()
except SagaError as e:
    print('saga error: ', e)  # wraps the BaseException('some error happened')

_print_counters()