我需要在进程之间共享一堆字符串（将来可能会更复杂的对象）。我决定使用 boost::interprocess 但我无法让它工作。我确定这是因为我不理解某些东西。我遵循了他们的示例，但是如果有使用该库经验的人可以查看我的代码并告诉我出了什么问题，我将不胜感激。问题是它似乎可以工作，但是经过几次迭代后，我在阅读器进程和有时在编写器进程上都遇到了各种异常。这是我的实现的简化版本：
using namespace boost::interprocess;
class SharedMemoryWrapper
{
public:
SharedMemoryWrapper(const std::string & name, bool server) :
m_name(name),
m_server(server)
{
if (server)
{
named_mutex::remove("named_mutex");
shared_memory_object::remove(m_name.c_str());
m_segment = new managed_shared_memory (create_only,name.c_str(),65536);
m_stackAllocator = new StringStackAllocator(m_segment->get_segment_manager());
m_stack = m_segment->construct<StringStack>("MyStack")(*m_stackAllocator);
}
else
{
m_segment = new managed_shared_memory(open_only ,name.c_str());
m_stack = m_segment->find<StringStack>("MyStack").first;
}
m_mutex = new named_mutex(open_or_create, "named_mutex");
}
~SharedMemoryWrapper()
{
if (m_server)
{
named_mutex::remove("named_mutex");
m_segment->destroy<StringStack>("MyStack");
delete m_stackAllocator;
shared_memory_object::remove(m_name.c_str());
}
delete m_mutex;
delete m_segment;
}
void push(const std::string & in)
{
scoped_lock<named_mutex> lock(*m_mutex);
boost::interprocess::string inStr(in.c_str());
m_stack->push_back(inStr);
}
std::string pop()
{
scoped_lock<named_mutex> lock(*m_mutex);
std::string result = "";
if (m_stack->size() > 0)
{
result = std::string(m_stack->begin()->c_str());
m_stack->erase(m_stack->begin());
}
return result;
}
private:
typedef boost::interprocess::allocator<boost::interprocess::string, boost::interprocess::managed_shared_memory::segment_manager> StringStackAllocator;
typedef boost::interprocess::vector<boost::interprocess::string, StringStackAllocator> StringStack;
bool m_server;
std::string m_name;
boost::interprocess::managed_shared_memory * m_segment;
StringStackAllocator * m_stackAllocator;
StringStack * m_stack;
boost::interprocess::named_mutex * m_mutex;
};
编辑编辑使用named_mutex。原始代码使用了不正确的 interprocess_mutex，但这不是问题。
EDIT2我还应该注意，事情在一定程度上起作用。writer 进程可以在 reader 中断之前推送几个小字符串（或一个非常大的字符串）。阅读器以 m_stack->begin() 行不引用有效字符串的方式中断。是垃圾。然后进一步执行会引发异常。
EDIT3我已经修改了类以使用 boost::interprocess::string 而不是 std::string。阅读器仍然失败，内存地址无效。这是读者/作者
//reader process
SharedMemoryWrapper mem("MyMemory", true);
std::string myString;
int x = 5;
do
{
myString = mem.pop();
if (myString != "")
{
std::cout << myString << std::endl;
}
} while (1); //while (myString != "");
//writer
SharedMemoryWrapper mem("MyMemory", false);
for (int i = 0; i < 1000000000; i++)
{
std::stringstream ss;
ss << i; //causes failure after few thousand iterations
//ss << "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA" << i; //causes immediate failure
mem.push(ss.str());
}
return 0;