std::priority_queue

场景:

1. 对于一个任务队列，任务的优先级由任务的priority属性指明，这时候就须要优先级越高的先运行。而queue并没有排序功能，这时priority_queue是比較好的选择.

2 对于异步的task也是一样。在不断加入新的task时,当然希望优先级越高的先运行.

解析:

1. 假设须要把优先级最高的先pop,那么comp比較时须要返回false.

代码:

//1.Elements are popped from the "back" of the specific container, //which is known as the top of the priority queue.//2.shall return true if a is considered to go before b // in the strict weak ordering the function defines#include 
     
      #include 
      
       #include 
       
        #include 
        
         using namespace std;class Task{public:	Task(int priority):priority_(priority)	{	}	~Task(){}	int priority_;	void DoWork()	{		cout << "DoWork: " << (int)this << " priority: " << priority_ << endl;	}};class PriorityCompare{public:	bool operator()(Task* t1,Task* t2)	{		return t1->priority_ > t2->priority_;	}	/* data */};int main(int argc, char const *argv[]){	PriorityCompare pc;	priority_queue
         
          
           ,PriorityCompare> tasks(pc); Task t1(1); Task t2(10); Task t3(3); Task t4(1); Task t5(8); Task t6(9); tasks.push(&t1); tasks.push(&t2); tasks.push(&t3); tasks.push(&t4); tasks.push(&t5); tasks.push(&t6); while(!tasks.empty()) { Task* task = tasks.top(); tasks.pop(); task->DoWork(); } return 0;}
          
         
        
       
      
     

输出:

DoWork: 2293456 priority: 1DoWork: 2293444 priority: 1DoWork: 2293448 priority: 3DoWork: 2293440 priority: 8DoWork: 2293436 priority: 9DoWork: 2293452 priority: 10

參考: http://www.cplusplus.com/reference/queue/priority_queue/