Little retry loop wrappers (handling return codes and exceptions)

retry.py

from functools import wraps

def retry(attempts, f):
    """
    Returns a callable that will invoke @f() and return result, suppressing
    exceptions up to @attempts times
    """
    @wraps(f)
    def wrapper(*args, **kwds):
        hardfail = None
        for i in range(attempts):
            try:
                return f(*args, **kwds)
            except Exception as e:
                hardfail = e
                if __debug__:
                    print("Failed to execute {0} -> {1}\n".format(f, e))
                time.sleep(i)
        raise hardfail
    return wrapper

def retry_until(attempts, f, until):
    """
    Retruns a callable that will call @f() until @until is returned or
    @attempts has been exceeded.
    """
    @wraps(f)
    def wrapper(*args, **kwds):
        hardfail = None
        for i in range(attempts):
            try:
                # only want to capture the last exception if it was the cause
                # of the failure
                hardfail = None
                if f(*args, **kwds) == until:
                    return True
            except Exception as e:
                hardfail = e
                if __debug__:
                    print("Failed to execute {0} -> {1}\n".format(f, e))
                time.sleep(i)
        if hardfail:
            raise hardfail
        return False
    return wrapper

import os

# The original use case of retry_until was transient erros when unmounting filesystems that may be busy for a couple seconds
retry_until(5, os.system, 0)("umount /tmp/foo")

# Useless example
retry_until(5, os.system, 0)("ls /foobar")
# ls: cannot access foo: No such file or directory
# ls: cannot access foo: No such file or directory
# ls: cannot access foo: No such file or directory
# ls: cannot access foo: No such file or directory
# ls: cannot access foo: No such file or directory
# False

# The original use of retry was for retry_until cases that involve exceptions being thrown
retry(10, shutil.rmtree)("/tmp/foo")