嘗試等待信號量時出錯

Question

我有一個包含信號量的類。 在執行類時運行方法。 它創建一個線程，並傳遞我的類的函數和對象指針。 然后，該函數嘗試訪問該對象及其內部的信號量並調用wait。 但是編譯器不允許我這樣做。

錯誤：

myNode.cpp: In function 'void* MyProjectGraph::compute(void*)':
myNode.cpp:70: error: request for member 'sem' in 'node->MyProjectGraph::MyNode::in.std::vector<_Tp, _Alloc>::operator[] [with _Tp = MyProjectGraph::MyEdge*, _Alloc = std::allocator<MyProjectGraph::MyEdge*>](((long unsigned int)i))', which is of non-class type 'MyProjectGraph::MyEdge*'
myNode.cpp:82: error: request for member 'sem' in 'node->MyProjectGraph::MyNode::in.std::vector<_Tp, _Alloc>::operator[] [with _Tp = MyProjectGraph::MyEdge*, _Alloc = std::allocator<MyProjectGraph::MyEdge*>](((long unsigned int)i))', which is of non-class type 'MyProjectGraph::MyEdge*'
myNode.cpp:87: error: request for member 'sem' in 'node->MyProjectGraph::MyNode::out.std::vector<_Tp, _Alloc>::operator[] [with _Tp = MyProjectGraph::MyEdge*, _Alloc = std::allocator<MyProjectGraph::MyEdge*>](((long unsigned int)i))', which is of non-class type 'MyProjectGraph::MyEdge*'
make: *** [myNode.o] Error 1

在pthread_create上傳遞的方法

void *compute(void *ptr){
        MyNode* node = (MyNode*)ptr; 
        time_t end;

        cout<<"Node Running: "<<node->ltr<<endl;

        //wait on all incoming edges
        for(int i = 0; i < node->in.size();i++){
            sem_wait(&(node->in[i].sem));   
            //node->in[i].edgeWait();   
        }

        sleep(node->time);
        sem_wait(&count_sem);
        graphCount += node->value;
        sem_post(&count_sem);
        time(&end);

        //destory dependent semaphores
        for(int i = 0; i < node->in.size();i++){
            sem_destroy(&(node->in[i].sem));        
        }

        //post all outgoing edges
        for(int i = 0; i < node->out.size();i++){
            sem_post(&(node->out[i].sem));  
            //node->out[i].edgePost();          
        }

        printf("Node %c computed a value of %d after %.2lf second.",node->ltr,node->value,difftime(end,start)); 
        pthread_exit(NULL);
        return 0;
    }

節點和邊緣類的基本設計

class MyNode{
        public: 
            int tid;
            int value;
            int time;
            char ltr;

            pthread_t thread;

            std::vector<MyEdge*> in;
            std::vector<MyEdge*> out;

            MyNode( );
            MyNode(char ltr, int val, int time);
            void addInEdge(MyEdge* edge); 
            void addOutEdge(MyEdge* edge); 
            void run( );
            void signalEdges( );
            void waitEdges( ); //Implementation is not known atm
            void toString( );
    };

 class MyEdge{
        public:
            MyNode* in;
            MyNode* out;

            sem_t sem;

            MyEdge(int init, MyNode* in, MyNode* out);
            int edgeWait( );
            int edgePost( );    
    };
}

Answer 1

  sem_wait(&(node->in[i].sem));

您in班級成員是：

  std::vector<MyEdge*> in;

因此， in[i]是MyEdge * 。

因此，要訪問其sem成員，應為：

  sem_wait(&(node->in[i]->sem));

其他編譯錯誤是相同的問題。