Maximum expression length for autoref.BDD.add_expr() about dd HOT 2 CLOSED

"""How to configure CPython for long `dd` expressions."""
import faulthandler
import sys
import threading
import time

import dd.autoref as _bdd


N = 10**5


def runner():
    """Configure CPython, then run."""
    sys.setrecursionlimit(10**3 * N)
    faulthandler.enable()
    threading.stack_size(N * 4096)
    thread = threading.Thread(
        target=test_long_expressions)
    thread.start()
    thread.join()


def test_long_expressions():
    """Create BDDs from two long expressions."""
    bdd = _bdd.BDD()
    bdd.declare('x')
    expr = 'TRUE'
    # requires increasing the recursion limit
    u = add_long_expression(expr, bdd)
    if u != bdd.true:
        raise AssertionError(u)
    print(
        'success with first expression, '
        f'result: {u!r}')
    expr = 'x'
    # requires both:
    #
    # - increasing the recursion limit
    # - increasing the stack size
    #
    # (otherwise the CPython interpreter
    #  exits with a segmentation fault)
    u = add_long_expression(expr, bdd)
    if u != bdd.var('x'):
        raise AssertionError(u)
    print(
        'success with second expression, '
        f'result: {u!r}')


def add_long_expression(expr, bdd):
    """Add BDD to `bdd`, from `expr`."""
    k = round(N / len(expr))
    long_expr = rf'{expr} /\ ' * k + expr
    print(
        'attempting to add expression that '
        f'contains {len(long_expr)} characters')
    t_before = time.time()
    u = bdd.add_expr(long_expr)
    t_after = time.time()
    dt = t_after - t_before
    print(
        'expression converted '
        f'to BDD in {dt:.2f} seconds')
    return u


if __name__ == '__main__':
    runner()