Question

我需要使用 Repast Simphony 作为模拟器来开发 Java 版本的 Iterated Prisoner Dilemma 。

我们的想法是每个Player都是代理商，我们的n x n网格Player无法移动。每个Player必须与4个邻居（北部，南部，西部和东部）进行比赛，根据每轮4场不同比赛的结果找到最佳策略。

由于 Repast Simphony 中的代理商之间没有内置系统来交换消息，因此我必须实施某种解决方法来处理代理商问题。同步（A对B和B对A应该算作同一轮，这就是他们需要同步的原因）。

这是通过将每一轮视为：

来完成的

Player 我为4个敌人中的每一个选择下一步行动
Player 我向4个敌人中的每一个发送正确的动作
Player 我等待4个敌人中的每一个回复

根据我对 Repast Simphony 的理解，预定的方法是顺序的（没有代理级并行），这意味着我被迫以与发送方法不同的方法进行等待（以较低的优先级安排，以确保在开始等待之前完成所有发送。）

这里的问题是，尽管收到了所有4条预期的消息（至少这是打印的消息），一旦等待方法开始，它报告的接收元素少于4个。

以下是Player类：

的代码

// myPoint is the location inside the grid (unique, agents can't move and only one per cell is allowed)
public int hashCode() {
    final int prime = 31;
    int result = 1;
    result = prime * result + ((myPoint == null) ? 0 : myPoint.hashCode());
    return result;
}

// Returns enemy's choice in the previous round
private byte getLastPlay(Player enemy) {
    return (neighbors.get(enemy)[1]) ? COOPERATE : DEFECT;
}

// Elements are saved as (player, choice)
private void receivePlay(Player enemy, byte play) {
    System.out.println(this + " receives (" + play + ") from " + enemy);
    while (!playSharedQueue.add(new Object[] { enemy, play })){
        // This doesn't get printed, meaning that the insertion is successful!
        System.out.println(this + " failed inserting");
    }
}

@ScheduledMethod(start = 1, interval = 1, priority = 10)
public void play() {
    System.out.println(this + " started playing");
    // Clear previous plays
    playSharedQueue.clear();
    for (Player enemy : neighbors.keySet()) {
        // properties[0] = true if we already played together
        // properties[1] = true if enemy choose to cooperate on the previous round
        Boolean[] properties = neighbors.get(enemy);
        // Choose which side we take this time
        byte myPlay;
        if (properties[0]) {
            // First time that we play, use memory-less strategy
            myPlay = (Math.random() <= strategy[0]) ? COOPERATE : DEFECT;
            // Report that we played
            properties[0] = false;
            neighbors.put(enemy, properties);
        } else {
            // We already had a round, use strategy with memory
            byte enemyLastPlay = enemy.getLastPlay(this);
            // Choose which side to take based on enemy's previous decision
            myPlay = (Math.random() <= strategy[(enemyLastPlay) == COOPERATE ? 1 : 2]) ? COOPERATE : DEFECT;
        }
        // Send my choice to the enemy
        System.out.println(this + " sent (" + myPlay + ") to " + enemy);
        enemy.receivePlay(this, myPlay);
    }
}

// Waits for the results and processes them
@ScheduledMethod(start = 1, interval = 1, priority = 5)
public void waitResults() {
    // Clear previous score
    lastPayoff = 0;
    System.out.println(this + " waits for results [" + playSharedQueue.size() + "]");
    if (playSharedQueue.size() != 4) {
        // Well, this happens on the first agent :(
        System.exit(1);
    }
    // ... process ...
}

这是控制台输出，因此您可以看到所有内容似乎都没有问题地发送和接收（使用3 x 3网格）：

Player[2, 0] started playing
Player[2, 0] sent (0) to Player[2, 1]
Player[2, 1] receives (0) from Player[2, 0]
Player[2, 0] sent (0) to Player[2, 2]
Player[2, 2] receives (0) from Player[2, 0]
Player[2, 0] sent (0) to Player[0, 0]
Player[0, 0] receives (0) from Player[2, 0]
Player[2, 0] sent (0) to Player[1, 0]
Player[1, 0] receives (0) from Player[2, 0]
Player[1, 2] started playing
Player[1, 2] sent (1) to Player[2, 2]
Player[2, 2] receives (1) from Player[1, 2]
Player[1, 2] sent (1) to Player[0, 2]
Player[0, 2] receives (1) from Player[1, 2]
Player[1, 2] sent (1) to Player[1, 0]
Player[1, 0] receives (1) from Player[1, 2]
Player[1, 2] sent (1) to Player[1, 1]
Player[1, 1] receives (1) from Player[1, 2]
Player[0, 2] started playing
Player[0, 2] sent (1) to Player[2, 2]
Player[2, 2] receives (1) from Player[0, 2]
Player[0, 2] sent (1) to Player[0, 0]
Player[0, 0] receives (1) from Player[0, 2]
Player[0, 2] sent (1) to Player[0, 1]
Player[0, 1] receives (1) from Player[0, 2]
Player[0, 2] sent (1) to Player[1, 2]
Player[1, 2] receives (1) from Player[0, 2]
Player[0, 1] started playing
Player[0, 1] sent (1) to Player[2, 1]
Player[2, 1] receives (1) from Player[0, 1]
Player[0, 1] sent (1) to Player[0, 0]
Player[0, 0] receives (1) from Player[0, 1]
Player[0, 1] sent (1) to Player[0, 2]
Player[0, 2] receives (1) from Player[0, 1]
Player[0, 1] sent (1) to Player[1, 1]
Player[1, 1] receives (1) from Player[0, 1]
Player[1, 0] started playing
Player[1, 0] sent (0) to Player[2, 0]
Player[2, 0] receives (0) from Player[1, 0]
Player[1, 0] sent (0) to Player[0, 0]
Player[0, 0] receives (0) from Player[1, 0]
Player[1, 0] sent (0) to Player[1, 1]
Player[1, 1] receives (0) from Player[1, 0]
Player[1, 0] sent (0) to Player[1, 2]
Player[1, 2] receives (0) from Player[1, 0]
Player[1, 1] started playing
Player[1, 1] sent (0) to Player[2, 1]
Player[2, 1] receives (0) from Player[1, 1]
Player[1, 1] sent (0) to Player[0, 1]
Player[0, 1] receives (0) from Player[1, 1]
Player[1, 1] sent (0) to Player[1, 0]
Player[1, 0] receives (0) from Player[1, 1]
Player[1, 1] sent (0) to Player[1, 2]
Player[1, 2] receives (0) from Player[1, 1]
Player[2, 2] started playing
Player[2, 2] sent (0) to Player[2, 0]
Player[2, 0] receives (0) from Player[2, 2]
Player[2, 2] sent (0) to Player[2, 1]
Player[2, 1] receives (0) from Player[2, 2]
Player[2, 2] sent (0) to Player[0, 2]
Player[0, 2] receives (0) from Player[2, 2]
Player[2, 2] sent (0) to Player[1, 2]
Player[1, 2] receives (0) from Player[2, 2]
Player[0, 0] started playing
Player[0, 0] sent (1) to Player[2, 0]
Player[2, 0] receives (1) from Player[0, 0]
Player[0, 0] sent (1) to Player[0, 1]
Player[0, 1] receives (1) from Player[0, 0]
Player[0, 0] sent (1) to Player[0, 2]
Player[0, 2] receives (1) from Player[0, 0]
Player[0, 0] sent (1) to Player[1, 0]
Player[1, 0] receives (1) from Player[0, 0]
Player[2, 1] started playing
Player[2, 1] sent (1) to Player[2, 0]
Player[2, 0] receives (1) from Player[2, 1]
Player[2, 1] sent (1) to Player[2, 2]
Player[2, 2] receives (1) from Player[2, 1]
Player[2, 1] sent (1) to Player[0, 1]
Player[0, 1] receives (1) from Player[2, 1]
Player[2, 1] sent (1) to Player[1, 1]
Player[1, 1] receives (1) from Player[2, 1]
Player[2, 2] waits for results [1]

正如您在最后一行中所看到的，playSharedQueue.size()是1，我真的不明白为什么。

如果方法调用是顺序的waitResults（）methos is invoked after the 9 play（）`执行，并且假设每个正确发送4条消息，我找不到该大小仍为1的原因。

当然，所有顺序意味着没有synchronization问题，即使我使用LinkedBlockingQueue而不是HashSet遇到同样的问题。

你们对此有任何暗示吗？

Answer 1

一段时间后，我再次打开代码，发现我做了一个简单而严重的错误：

@ScheduledMethod(start = 1, interval = 1, priority = 10)
public void play() {
    System.out.println(this + " started playing");
    // Clear previous plays
    playSharedQueue.clear();

执行playSharedQueue.clear();以清除之前的结果，但由于调用是连续的，第二个玩家将在第一个玩家向他发送他的游戏后调用它，以便该游戏被丢弃。

在waitResults的末尾移动该行解决了它。

使用Repast Simphony

1 个答案: