S.l.e!ep.￠%

class BankAccount {
    private decimal m_balance = 0.0M;
    private object m_balanceLock = new object();
    internal void Deposit(decimal delta) {
        lock (m_balanceLock) { m_balance += delta; }
    }
    internal void Withdraw(decimal delta) {
        lock (m_balanceLock) {
            if (m_balance < delta)
                throw new Exception("Insufficient funds");
            m_balance -= delta;
        }
    }
}

internal static volatile long s_x;
void ThreadA() {
    int i = 0;
    while (true) {
        s_x = (i & 1) == 0 ? 0x0L : 0xaaaabbbbccccddddL;
        i++;
    }
}
void ThreadB() {
    while (true) {
        long x = s_x;
        Debug.Assert(x == 0x0L || x == 0xaaaabbbbccccddddL);
    }
}

class BankAccount {
    private int m_id; // Unique bank account ID.
    internal static void Transfer(
      BankAccount a, BankAccount b, decimal delta) {
        if (a.m_id < b.m_id) {
            Monitor.Enter(a.m_balanceLock); // A first
            Monitor.Enter(b.m_balanceLock); // ...and then B
        } else {
            Monitor.Enter(b.m_balanceLock); // B first
            Monitor.Enter(a.m_balanceLock); // ...and then A 
        }
        try {
            Withdraw(a, delta);
            Deposit(b, delta);
        } finally {
            Monitor.Exit(a.m_balanceLock);
            Monitor.Exit(b.m_balanceLock);
        }
    }
    // As before ...
}

public class ImmutableStack<T> {
    private readonly T m_value;
    private readonly ImmutableStack<T> m_next;
    private readonly bool m_empty;
    public ImmutableStack() { m_empty = true; }
    internal ImmutableStack(T value, Node next) {
        m_value = value;
        m_next = next;
        m_empty = false;
    }
    public ImmutableStack<T> Push(T value) {
        return new ImmutableStack(value, this);
    }
    public ImmutableStack<T> Pop(out T value) {
        if (m_empty) throw new Exception("Empty.");
        return m_next;
    }
}