Controlled recursion in python

controlled_recursion.py

def controlled_recursion(default=None, depth=0):
    def entangle(f):
        lock = threading.Lock()
        f.call_counts = {}

        def increment():
            with lock:
                call_count = f.call_counts.get(threading.currentThread().ident, 0)
                call_count += 1
                f.call_counts[threading.currentThread().ident] = call_count
                return call_count

        def decrement():
            with lock:
                f.call_counts[threading.currentThread().ident] -= 1
                if f.call_counts[threading.currentThread().ident] <= 0:
                    del f.call_counts[threading.currentThread().ident]

        def inner(*args, **kwargs):
            call_count = increment()
            try:
                if call_count > (depth + 1):
                    logger.warning("Recursion depth(%s) crossed the allowed depth (%s)."
                                   "Returning default value(%s).", call_count - 1, depth, default)
                    return default
                else:
                    return f(*args, **kwargs)
            finally:
                decrement()
        return inner
    return entangle

Usage

import threading
import logging as logger

@controlled_recursion(depth=3)
def info():
    print "info() called."
    info()

info()

Output:

info() called.
info() called.
info() called.
info() called.