[Solved]-Celery: clean way of revoking the entire chain from within a task

I think I found the answer to this issue: this seems the right way to proceed, indeed. I wonder why such common scenario is not documented anywhere, though.

For completeness I post the basic code snapshot:

@app.task(bind=True)  # Note that we need bind=True for self to work
def task1(self, other_args):
    #do_stuff
    if end_chain:
        self.request.callbacks[:] = []
    ....

Update

I implemented a more elegant way to cope with the issue and I want to share it with you. I am using a decorator called revoke_chain_authority, so that it can revoke automatically the chain without rewriting the code I previously described.

from functools import wraps

class RevokeChainRequested(Exception):
    def __init__(self, return_value):
        Exception.__init__(self, "")

        # Now for your custom code...
        self.return_value = return_value


def revoke_chain_authority(a_shared_task):
    """
    @see: https://gist.github.com/bloudermilk/2173940
    @param a_shared_task: a @shared_task(bind=True) celery function.
    @return:
    """
    @wraps(a_shared_task)
    def inner(self, *args, **kwargs):
        try:
            return a_shared_task(self, *args, **kwargs)
        except RevokeChainRequested, e:
            # Drop subsequent tasks in chain (if not EAGER mode)
            if self.request.callbacks:
                self.request.callbacks[:] = []
            return e.return_value

    return inner

This decorator can be used on a shared task as follows:

@shared_task(bind=True)
@revoke_chain_authority
def apply_fetching_decision(self, latitude, longitude):
    #...

    if condition:
        raise RevokeChainRequested(False)

Please note the use of @wraps. It is necessary to preserve the signature of the original function, otherwise this latter will be lost and celery will make a mess at calling the right wrapped task (e.g. it will call always the first registered function instead of the right one)