multi-threaded board game

board.py

import random
import threading
import time

num_p = 10
m, n = 5, 5

# position (y,x) - lock, players in pos
board_locks = {(i//m, i % n): threading.Lock() for i in range(m*n)}
board_players = {(i//m, i % n): set() for i in range(m*n)}


class Player(threading.Thread):
    def __init__(self, id, turns=10):
        super().__init__()
        self.id = id
        self.turns = turns
        self.pos_lock = threading.Lock()  # locks all attr
        self.pos = (random.randint(0, m-1), random.randint(0, n-1))
        self.strength = 0
        self.alive = True  # can be set by other player

    def run(self):
        for _ in range(self.turns):
            time.sleep(random.randint(0, 50)/10)  # sleep 0-5s
            if not self.alive:  # other init and kiled you
                return
            other_ps = self.move()
            for p in other_ps:
                you_died = self.battle(p)  # you init
                if you_died:
                    self.alive = False
                    return

    def battle(self, other):
        # check other is alive
        if not other.alive:
            return
        (lock1, lock2) = (self.pos_lock, other.pos_lock) if self.id < other.id else (
            other.pos_lock, self.pos_lock)
        # prevent deadlock if both acquire their own pos_lock, then try acquire the other
        with lock1:
            with lock2:  # prevent player from moving (and fighting other)
                print(f"===\nP{self.id} fights P{other.id} at {self.pos}")
                if self.strength < other.strength:
                    self.remove_pos()
                    self.alive = False
                    print(f"P{self.id} has died\n")
                    return True  # you died
                elif self.strength > other.strength:
                    other.remove_pos()
                    other.alive = False
                    print(f"P{other.id} has died")
                    print(f"P{self.id} gained 4 str\n")
                    self.strength += 4
                    return False
                return False  # did not die

    def remove_pos(self):  # from other / self
        with board_locks[self.pos]:
            board_players[self.pos].discard(self.id)

    def move(self):  # locked self pos
        # get lock to remove prev
        with board_locks[self.pos]:
            board_players[self.pos].discard(self.id)
        # increase str when move
        # set new pos, return players there
        new_pos = (random.randint(0, m-1), random.randint(0, n-1))
        dist = abs(new_pos[0]-self.pos[0]) + abs(new_pos[1]-self.pos[1])
        self.strength += dist
        if dist > 0:
            print(f"P{self.id} gained {dist} str to {self.strength}")

        # acq lock to set new pos
        with board_locks[new_pos]:
            if not self.alive:  # someone killed you before you moved
                return []
            self.pos = new_pos
            other_ps = [players[i] for i in board_players[self.pos]]
            board_players[self.pos].add(self.id)
            return other_ps


players = {i: Player(i) for i in range(num_p)}

for p in players.values():
    p.start()  # run
for p in players.values():
    p.join()
for p in players.values():
    print(f'P{p.id} (str: {p.strength}) is {"alive" if p.alive else "dead"}')