multilock.py

#!/usr/bin/env python3

import random
from collections import Counter, OrderedDict

class OrderedCounter(Counter, OrderedDict):
    pass


class FakeEtcd:
    def __init__(self, count):
        self.locks = [0 for _ in range(count)]

    def set(self):
        self.locks = [lock + 1 for lock in self.locks]
        return self.locks

    def rem(self, lock):
        self.locks[lock] = 0

    def __str__(self):
        return str(self.locks)

class MultiLock:
    def __init__(self, count):
        self.etcd = FakeEtcd(count)
        self.count = count

    def get(self):
        locks = self.etcd.set()
        print(locks)
        high = sum(1 for lock in locks if lock > self.count)
        if high == self.count:
            print("too high")
            return None
        elif len(set(locks)) > 1:
            print("don't all match")
            value = Counter(locks).most_common(1)[0][0]
            lock = len(locks) - list(reversed(locks)).index(value) - 1
            if locks[lock] == max(locks) and Counter(locks)[locks[lock]] == 1:
                return None
            else:
                if locks[lock] >= self.count:
                    return lock - 1
                else:
                    return lock
            for i, lock in enumerate(locks):
                if lock == 1:
                    print("lock == 1")
                    return i
        else:
            print("all match")
            return len(locks) - locks[0]
        print("fallthrough")
        return None

    def release(self, lock):
        self.etcd.rem(lock)

    def __str__(self):
        return str(self.etcd)

class Tracker:
    def __init__(self, count):
        self.multilock = MultiLock(count)
        self.count = count
        self.locks = set()
    def get(self):
        lock = self.multilock.get()
        print(lock)
        if lock is None:
            print(self.locks, "\n")
            if len(self.locks) != self.count:
                raise RuntimeError("Lock failed when expected to succeed")
        elif not (0 <= lock < self.count):
            print(self.locks, "\n")
            raise RuntimeError("Invalid lock number")
        elif lock in self.locks:
            print(self.locks, "\n")
            raise RuntimeError("Duplicate lock")
        else:
            self.locks.add(lock)
            print(self.locks, "\n")

    def rem(self):
        if self.locks:
            lock = self.locks.pop()
            self.multilock.release(lock)
        print("rem")
        print(self.locks, "\n")

def main():
    locks = Tracker(3)
    commands = []
    while True:
        commands.append(random.choice([locks.get, locks.get, locks.rem]))
        commands[-1]()

if __name__ == "__main__":
    main()
"""
+ - max min % * % ()
count value index offset 0 1 2
 3    1,2,   0,1,  0,1 of ones with same value
"""

"""
Two locks
get -> [1, 1] -> lock 0
get -> [2, 2] -> lock 1
get -> [3, 3] -> fail
del 0 -> [0, 3]
get -> [1, 4] -> lock 0
"""
"""
Three locks
get -> [1, 1, 1] -> lock 0
get -> [2, 2, 2] -> lock 1
get -> [3, 3, 3] -> lock 2
del 0 -> [0, 3, 3]
del 1 -> [0, 0, 3]
get -> [1, 1, 4] -> lock 0
get -> [2, 2, 4] -> lock 1
"""