muduo网络库源码学习————无界队列和有界队列

muduo库里实现了两个队列模板类：无界队列为BlockingQueue.h，有界队列为BoundedBlockingQueue.h，两个测试程序实现了生产者和消费者模型。（这里以无界队列为例，有界队列和无界的差不多）代码如下：

BlockingQueue.h

#include <muduo/base/Condition.h>
#include <muduo/base/Mutex.h>

#include <boost/noncopyable.hpp>
#include <deque>
#include <assert.h>

namespace muduo
{

template<typename T>//队列模板
class BlockingQueue : boost::noncopyable
{
 public:
  BlockingQueue(): mutex_(), notEmpty_(mutex_),queue_()
  {//构造函数对3个成员进行初始化
  }

  void put(const T& x)//生产产品
  {
    MutexLockGuard lock(mutex_);//先加上锁对队列进行保护，构造函数中调用lock，析构函数会自动调用unlock
    queue_.push_back(x);//产品放进队列
    //队列不为空，通知消费者可以进行消费
    notEmpty_.notify(); // TODO: move outside of lock
  }

  T take()//消费产品
  {
    MutexLockGuard lock(mutex_);//加锁保护队列
    // always use a while-loop, due to spurious wakeup
    while (queue_.empty())//如果队列为空，则一直等待
    {
      notEmpty_.wait();
    }
    assert(!queue_.empty());//断言队列非空
    T front(queue_.front());//取出队首元素
    queue_.pop_front();//将队首元素弹出
    return front;//返回队首元素
  }

  size_t size() const//队列大小
  {
    MutexLockGuard lock(mutex_);//加锁保护
    return queue_.size();//返回队列大小
  }

 private:
  mutable MutexLock mutex_;//互斥锁
  Condition         notEmpty_;//条件变量
  std::deque<T>     queue_;//队列使用stl中的deque
};

}

#endif  // MUDUO_BASE_BLOCKINGQUEUE_H

测试代码有两个：

BlockingQueue_test.cc

#include <muduo/base/BlockingQueue.h>
#include <muduo/base/CountDownLatch.h>
#include <muduo/base/Thread.h>

#include <boost/bind.hpp>
#include <boost/ptr_container/ptr_vector.hpp>
#include <string>
#include <stdio.h>

class Test
{
 public://numThreads初始化为5，条件变量count初始化为5，线程个数也为5
  Test(int numThreads) : latch_(numThreads), threads_(numThreads)
  {
    for (int i = 0; i < numThreads; ++i)
    {//线程名称
      char name[32];
      snprintf(name, sizeof name, "work thread %d", i);
      //创建5个线程，threadFunc为线程回调函数
      threads_.push_back(new muduo::Thread(boost::bind(&Test::threadFunc, this), muduo::string(name)));
    }
    //启动线程
    for_each(threads_.begin(), threads_.end(), boost::bind(&muduo::Thread::start, _1));
  }

  void run(int times)
  {
    printf("waiting for count down latch\n");
    latch_.wait();//等待count被减为0
    printf("all threads started\n");
    for (int i = 0; i < times; ++i)//100次
    {
      char buf[32];
      snprintf(buf, sizeof buf, "hello %d", i);
      queue_.put(buf);//往队列中添加100个产品
      //打印信息
      printf("tid=%d, put data = %s, size = %zd\n", muduo::CurrentThread::tid(), buf, queue_.size());
    }
  }

  void joinAll()
  {
    for (size_t i = 0; i < threads_.size(); ++i)
    {//往5个线程添加stop
      queue_.put("stop");
    }
    //执行join
    for_each(threads_.begin(), threads_.end(), boost::bind(&muduo::Thread::join, _1));
  }

 private:
//线程回调函数
  void threadFunc()
  {//输出线程id和名称
    printf("tid=%d, %s started\n", muduo::CurrentThread::tid(),muduo::CurrentThread::name());
   //计数值减一
    latch_.countDown();//count减为0时将通知所有等待线程
    bool running = true;
    while (running)
    {
      std::string d(queue_.take());//消费产品
      //打印取出的值
      printf("tid=%d, get data = %s, size = %zd\n", muduo::CurrentThread::tid(), d.c_str(), queue_.size());
    //直到产品的名称==stop，跳出循环
      running = (d != "stop");
    }
   //打印停止信息
    printf("tid=%d, %s stopped\n",muduo::CurrentThread::tid(),muduo::CurrentThread::name());
  }

  muduo::BlockingQueue<std::string> queue_;//队列
  muduo::CountDownLatch latch_;//条件变量
  boost::ptr_vector<muduo::Thread> threads_;//线程数组
};

int main()
{//打印进程，线程id
  printf("pid=%d, tid=%d\n", ::getpid(), muduo::CurrentThread::tid());
  Test t(5);//定义test类
  t.run(100);
  t.joinAll();

  printf("number of created threads %d\n", muduo::Thread::numCreated());
}

单独编译后运行结果如下：

BlockingQueue_bench.cc

#include <muduo/base/BlockingQueue.h>
#include <muduo/base/CountDownLatch.h>
#include <muduo/base/Thread.h>
#include <muduo/base/Timestamp.h>

#include <boost/bind.hpp>
#include <boost/ptr_container/ptr_vector.hpp>
#include <map>
#include <string>
#include <stdio.h>

class Bench//Bench是用来度量时间的一个类
{
 public://count初始化为numThreads，创建numThreads个线程
  Bench(int numThreads) : latch_(numThreads),threads_(numThreads)
  {
    for (int i = 0; i < numThreads; ++i)
    {
      char name[32];
      snprintf(name, sizeof name, "work thread %d", i);
      //创建线程，设置回调
      threads_.push_back(new muduo::Thread( boost::bind(&Bench::threadFunc, this), muduo::string(name)));
    }
    //线程start
    for_each(threads_.begin(), threads_.end(), boost::bind(&muduo::Thread::start, _1));
  }

  void run(int times)//生产产品
  {//10000个
    printf("waiting for count down latch\n");
    latch_.wait();//等待count降为0
    printf("all threads started\n");
    for (int i = 0; i < times; ++i)
    {
      muduo::Timestamp now(muduo::Timestamp::now());
      queue_.put(now);//当前时间戳进队
      usleep(1000);//1000微秒一次
    }
  }

  void joinAll()
  {
    for (size_t i = 0; i < threads_.size(); ++i)
    {
      queue_.put(muduo::Timestamp::invalid());//产生非法时间，即产生跳出循环的条件
    }
    for_each(threads_.begin(), threads_.end(), boost::bind(&muduo::Thread::join, _1));
  }

 private:

  void threadFunc()//用于消费产品
  {
    printf("tid=%d, %s started\n",muduo::CurrentThread::tid(),muduo::CurrentThread::name());
    //Map是STL[1]  的一个关联容器，它提供一对一
    //（其中第一个可以称为关键字，每个关键字只能在map中出现一次，第二个可能称为该关键字的值）的数据处理能力
    //第一个是delay值，第二个是相同delay的次数
    std::map<int, int> delays;//map容器
    latch_.countDown();
    bool running = true;
    while (running)
    {
      muduo::Timestamp t(queue_.take());//取出队列中的时间戳
      muduo::Timestamp now(muduo::Timestamp::now());//建立当前时间戳对象
      if (t.valid())//如果是一个合法的时间
      {//计算差值
        int delay = static_cast<int>(timeDifference(now, t) * 1000000);//以微秒为单位
        // printf("tid=%d, latency = %d us\n", muduo::CurrentThread::tid(), delay);
        ++delays[delay];//??
      }
      running = t.valid();//t为非法的时间则跳出循环
    }
    printf("tid=%d, %s stopped\n", muduo::CurrentThread::tid(),muduo::CurrentThread::name());
    //使用迭代器遍历map容器
    for (std::map<int, int>::iterator it = delays.begin(); it != delays.end(); ++it)
    {
      printf("tid = %d, delay = %d, count = %d\n",muduo::CurrentThread::tid(),it->first, it->second);
    }
  }

  muduo::BlockingQueue<muduo::Timestamp> queue_;
  muduo::CountDownLatch latch_;
  boost::ptr_vector<muduo::Thread> threads_;
};

int main(int argc, char* argv[])
{//若参数大于1则是传入的参数，否则设为1
  int threads = argc > 1 ? atoi(argv[1]) : 1;

  Bench t(threads);//建立Bench对象
  t.run(10000);
  t.joinAll();
}

单独编译后运行结构如下：（输出过长，时间也太长，截图时中断了程序）