<分区>
我正在开发一个处理多个线程访问、存入和退出有界缓冲区容器的程序。我注意到线程存在一些主要问题，并怀疑我的缓冲区在某处部分或根本不正确。
为了确保我知道我在用它做什么，我希望能检查一下我的缓冲区代码。该类使用我在其他地方实现的信号量，我假设它现在可以工作(如果不能，我会尽快弄清楚!)我添加了试图解释我的推理的评论。
首先是.h文件:
#ifndef BOUNDED_BUFFER_H
#define BOUNDED_BUFFER_H
#include "Semaphore.H"
#include <string>
#include <vector>
using namespace std;
class Item{ //supposed to eventually be more extensible...seems silly with just a string for now
public:
Item(string _content){content = _content;}
string GetContent() {return content;}
private:
};
class BoundedBuffer{
public:
BoundedBuffer();
void Deposit(Item* _item);
Item* Retrieve();
int GetNumItems() {return count;}
vector<Item*> GetBuffer() {return buffer;}
void SetSize(int _size){
capacity = _size;
buffer.reserve(_size); //or do I need to call "resize"
}
private:
int capacity;
vector<Item*> buffer; //I originally wanted to use an array but had trouble with
//initilization/sizing, etc.
int nextin;
int nextout;
int count;
Semaphore notfull; //wait on this one before depositing an item
Semaphore notempty; //wait on this one before retrieving an item
};
#endif
接下来，.cpp:
#include "BoundedBuffer.H"
#include <iostream>
using namespace std;
BoundedBuffer::BoundedBuffer(){
notfull.SetValue(0);
notempty.SetValue(0);
nextin = 0;
nextout = 0;
count = 0;
}
void BoundedBuffer::Deposit(Item* _item){
if(count == capacity){
notfull.P(); //Cannot deposit into full buffer; wait
}
buffer[nextin] = _item;
nextin = (nextin + 1) % capacity; //wrap-around
count += 1;
notempty.V(); //Signal that retrieval is safe
}
Item* BoundedBuffer::Retrieve(){
if(count == 0){
notempty.P(); //cannot take from empty buffer; wait
}
Item* x = buffer[nextout];
nextout = (nextout + 1) % capacity;
buffer.pop_back(); //or a different erase methodology?
count -= 1;
notfull.V(); //Signal that deposit is safe
return x;
}
我认为问题可能源于我选择 vector 作为底层容器(或者更确切地说，不正确地使用它)，或者可能需要更多的安全阻塞机制(互斥锁等？)来自事情的样子，任何人都可以提供一些反馈吗？