并发编程之基础( 五)

  1 package com.dy.xidian;
  2 
  3 import java.util.LinkedList;
  4 import java.util.PriorityQueue;
  5 import java.util.Queue;
  6 import java.util.Random;
  7 import java.util.concurrent.ArrayBlockingQueue;
  8 import java.util.concurrent.ExecutorService;
  9 import java.util.concurrent.Executors;
 10 import java.util.concurrent.TimeUnit;
 11 
 12 class Customer {
 13     private final int serviceTime;
 14     public Customer(int tm) {
 15         serviceTime = tm;
 16     }
 17     public int getService() {
 18         return serviceTime;
 19     }
 20     public String toString() {
 21         return "[" + serviceTime + "]";
 22     }
 23 }
 24 
 25 @SuppressWarnings("serial")
 26 class CustomerLine extends ArrayBlockingQueue<Customer> {
 27 
 28     public CustomerLine(int maxLineSize) {
 29         super(maxLineSize);
 30     }
 31 
 32     public String toString() {
 33         if (this.size() == 0)
 34             return "[Empty]";
 35         StringBuilder result = new StringBuilder();
 36         for (Customer customer : this)
 37             result.append(customer);
 38         return result.toString();
 39     }
 40 
 41 }
 42 
 43 class CustomerGenerator implements Runnable {
 44     private CustomerLine customers;
 45     private static Random rand = new Random(47);
 46 
 47     public CustomerGenerator(CustomerLine cq) {
 48         customers = cq;
 49     }
 50 
 51     @Override
 52     public void run() {
 53         try {
 54             while (!Thread.interrupted()) {
 55                 TimeUnit.MILLISECONDS.sleep(rand.nextInt(300));
 56                 customers.put(new Customer(rand.nextInt(1000)));
 57             }
 58         } catch (InterruptedException e) {
 59             System.out.println("CustomerGenerator interrupted!");
 60         }
 61         System.out.println("CustomerGenerator terminating");
 62     }
 63 }
 64 
 65 class Teller implements Runnable {
 66     private static int counter = 0;
 67     private final int id = counter++;
 68     private int customerServed = 0;
 69     private CustomerLine customers;
 70     private boolean servingCustomerLine = true;
 71 
 72     public Teller(CustomerLine customers) {
 73         super();
 74         this.customers = customers;
 75     }
 76 
 77     @Override
 78     public void run() {
 79         try {
 80             while (!Thread.interrupted()) {
 81                 Customer customer = customers.take();
 82                 TimeUnit.MILLISECONDS.sleep(customer.getService());
 83                 synchronized (this) {
 84                     customerServed++;
 85                     while (!servingCustomerLine)
 86                         wait();
 87                 }
 88             }
 89         } catch (InterruptedException e) {
 90             System.out.println(this + "interrupted!");
 91         }
 92         System.out.println(this + "terminating!");
 93     }
 94 
 95     public synchronized void doSomethingElse() {
 96         customerServed = 0;
 97         servingCustomerLine = false;
 98     }
 99 
100     public synchronized void serveCustomerLine() {
101         assert !servingCustomerLine : "already serving" + this;
102         servingCustomerLine = true;
103         notifyAll();
104     }
105 
106     public String toString() {
107         return "Teller " + id + " ";
108     }
109 
110     public String shortString() {
111         return "T" + id;
112     }
113 
114     public synchronized int compateTo(Teller other) {
115         if (customerServed > other.customerServed)
116             return 1;
117         if (customerServed < other.customerServed)
118             return -1;
119         return 0;
120     }
121 }
122 
123 class TellerManger implements Runnable {
124     private ExecutorService exec;
125     private CustomerLine customers;
126     private PriorityQueue<Teller> workingTellers = new PriorityQueue<Teller>();
127     private Queue<Teller> tellersDoingOtherThings = new LinkedList<Teller>();
128     private int adjustmentPeriod;
129 
130     public TellerManger(ExecutorService ex, CustomerLine customers,
131             int adjustmentPeriod) {
132         super();
133         this.exec = ex;
134         this.customers = customers;
135         this.adjustmentPeriod = adjustmentPeriod;
136         Teller teller = new Teller(customers);
137         exec.execute(teller);
138         workingTellers.add(teller);
139     }
140 
141     public void adjustTellerNumber() {
142         if (customers.size() / workingTellers.size() > 2) {
143             Teller teller = tellersDoingOtherThings.remove();
144             teller.serveCustomerLine();
145             workingTellers.offer(teller);
146             return;
147         }
148         if (workingTellers.size() > 1
149                 && customers.size() / workingTellers.size() < 2)
150             reassignOneTeller();
151         if (customers.size() == 0)
152             while (workingTellers.size() > 1)
153                 reassignOneTeller();
154 
155     }
156 
157     private void reassignOneTeller() {
158         Teller teller = workingTellers.poll();
159         teller.doSomethingElse();
160         tellersDoingOtherThings.offer(teller);
161     }
162 
163     @Override
164     public void run() {
165         try {
166             while (!Thread.interrupted()) {
167                 TimeUnit.MILLISECONDS.sleep(adjustmentPeriod);
168                 adjustTellerNumber();
169                 System.out.println(customers + " { ");
170                 for (Teller teller : workingTellers) {
171                     System.out.println(teller.shortString() + " ");
172                 }
173                 System.out.println("}");
174             }
175         } catch (InterruptedException e) {
176             System.out.println(this + "interrupted");
177         }
178         System.out.println(this + "terminating");
179     }
180 }
181 
182 public class BankTellerSimulation {
183     static final int MAX_LINE_SIZE = 50;
184     static final int ADJUSTMENT_PERIOD = 1000;
185 
186     public static void main(String[] args) throws Exception {
187         ExecutorService exec = Executors.newCachedThreadPool();
188         CustomerLine customers = new CustomerLine(MAX_LINE_SIZE);
189         exec.execute(new CustomerGenerator(customers));
190         exec.execute(new TellerManger(exec, customers, ADJUSTMENT_PERIOD));
191         if (args.length > 0)
192             TimeUnit.SECONDS.sleep(new Integer(args[0]));
193         else {
194             System.out.println("press ‘Enter‘ to quit");
195             System.in.read();
196         }
197         exec.shutdownNow();
198     }
199 }