template<typename T>
BlockingQueue<T>::BlockingQueue()        : sync_(new sync()) {
}

// 这个类是在BlockingQueue类中定义的
template<typename T>
class BlockingQueue<T>::sync {                                       public:                                                                   mutable boost::mutex mutex_;                                      boost::condition_variable condition_;
};

#include <boost/thread.hpp>
#include <string>#include "caffe/data_reader.hpp"
#include "caffe/layers/base_data_layer.hpp"
#include "caffe/parallel.hpp"
#include "caffe/util/blocking_queue.hpp"namespace caffe {template<typename T>
class BlockingQueue<T>::sync {public:mutable boost::mutex mutex_;             //实现了一个mutex对象;boost::condition_variable condition_;   //也是实现了一个对象;
};template<typename T>
BlockingQueue<T>::BlockingQueue()        : sync_(new sync()) {
}template<typename T>
void BlockingQueue<T>::push(const T& t) {// 在push操作过程中,创建一个scoped_lock的对象lock,利用它的构造函数来对// mutex_进行加锁;boost::mutex::scoped_lock lock(sync_->mutex_);  queue_.push(t);lock.unlock();   //对互斥体解锁;sync_->condition_.notify_one(); //给相应的wait中的线程发出通知;
}template<typename T>
bool BlockingQueue<T>::try_pop(T* t) {boost::mutex::scoped_lock lock(sync_->mutex_);if (queue_.empty()) {return false;}*t = queue_.front();queue_.pop();return true;
}template<typename T>
T BlockingQueue<T>::pop(const string& log_on_wait) {boost::mutex::scoped_lock lock(sync_->mutex_);while (queue_.empty()) {if (!log_on_wait.empty()) {LOG_EVERY_N(INFO, 1000)<< log_on_wait; //当空的时候,输入相应的等待信息;
    }sync_->condition_.wait(lock);           //线程进入wait的过程;等相应的通知;
}T t = queue_.front();queue_.pop();return t;
}template<typename T>
bool BlockingQueue<T>::try_peek(T* t) {boost::mutex::scoped_lock lock(sync_->mutex_);if (queue_.empty()) {return false;}*t = queue_.front();return true;
}template<typename T>
T BlockingQueue<T>::peek() {boost::mutex::scoped_lock lock(sync_->mutex_);while (queue_.empty()) {sync_->condition_.wait(lock);}return queue_.front();
}template<typename T>
size_t BlockingQueue<T>::size() const {boost::mutex::scoped_lock lock(sync_->mutex_);return queue_.size();
}template class BlockingQueue<Batch<float>*>;
template class BlockingQueue<Batch<double>*>;
template class BlockingQueue<Datum*>;
template class BlockingQueue<shared_ptr<DataReader::QueuePair> >;
template class BlockingQueue<P2PSync<float>*>;
template class BlockingQueue<P2PSync<double>*>;}  // namespace caffe