ABA問題とタグ付きポインタ

def make_stack(values, tagged=False):    top = 0 if values else -1    shared = {"head": (top, 0) if tagged else top, "popped": ()}    for i, value in enumerate(values):        shared["val%d" % i] = value        shared["next%d" % i] = i + 1 if i + 1 < len(values) else -1    return shareddef push(shared, node, value, tagged=False):    shared["val%d" % node] = value    while True:        yield        old = shared["head"]        yield        shared["next%d" % node] = old[0] if tagged else old        yield        new = (node, old[1] + 1) if tagged else node        if compare_and_swap(shared, "head", old, new):            returndef pop(shared, tagged=False):    while True:        yield        old = shared["head"]        idx = old[0] if tagged else old        if idx == -1:            return None        yield        nxt = shared["next%d" % idx]        value = shared["val%d" % idx]        yield        new = (nxt, old[1] + 1) if tagged else nxt        if compare_and_swap(shared, "head", old, new):            shared["popped"] = shared["popped"] + (value,)            return valuedef alone(shared):    def thread():        for _ in range(3):            print("popped", (yield from pop(shared)))    return [thread()]final, alive = run_prefix(alone, [0] * 20, make_stack([10, 20]))print(final["head"], final["popped"])

popped 10
popped 20
popped None
-1 (10, 20)

def walk(shared, tagged=False):    values = []    idx = shared["head"][0] if tagged else shared["head"]    while idx != -1 and len(values) < 10:        values.append(shared["val%d" % idx])        idx = shared["next%d" % idx]    return valuesdef conserved(shared, expected, tagged=False):    return sorted(list(shared["popped"]) + walk(shared, tagged)) == sorted(expected)def aba_program(tagged=False):    def make_threads(shared):        def victim():            yield from pop(shared, tagged)        def churner():            yield from pop(shared, tagged)            yield from pop(shared, tagged)            yield from push(shared, 0, 99, tagged)        return [victim(), churner()]    return make_threadsprefix = [0, 0] + [1] * 9 + [0]final, alive = run_prefix(aba_program(), prefix, make_stack([10, 20]))print(final)print("still on the stack:", walk(final), "| conserved:", conserved(final, [10, 20, 99]))

{'head': 1, 'popped': (10, 20, 10), 'val0': 99, 'next0': -1, 'val1': 20, 'next1': -1}
still on the stack: [20] | conserved: False

final, alive = run_prefix(aba_program(True), prefix, make_stack([10, 20], True))print(final["head"], "victim alive:", alive == [0])final, alive = run_prefix(aba_program(True), prefix + [0] * 6, make_stack([10, 20], True))print(final["popped"], walk(final, True), "| conserved:", conserved(final, [10, 20, 99], True))

(0, 3) victim alive: True
(10, 20, 99) [] | conserved: True

values = [int(round(float(c) * 100)) for c in load_bars()["close"].iloc[:2]]for tagged in (False, True):    outcomes = explore_all(aba_program(tagged), make_stack(values, tagged))    corrupt = sum(n for key, n in outcomes.items() if not conserved(dict(key), values + [99], tagged))    print("tagged" if tagged else "plain ", sum(outcomes.values()), "schedules,", corrupt, "corrupt")

plain  3021 schedules, 21 corrupt
tagged 3021 schedules, 0 corrupt