我正在尝试在C++中实现一个生产者/消费者模型的多线程程序，与我的项目相关。基本思路是主线程创建第二个线程来监视串口数据，处理数据并将结果放入定期轮询的缓冲区中。我以前从未编写过多线程程序。我一直在阅读许多教程，但它们都是用C语言编写的。我认为我已经掌握了基本概念，但我正在尝试将其转化为C++。对于缓冲区，我想创建一个带有互斥保护的数据类。这是我想出的方法。
1）我是否采取了错误的方法？是否有更聪明的方法来实现受保护的数据类？
2）如果两个线程同时尝试调用ProtectedBuffer::add_back()，以下代码会发生什么？
#include <deque>
#include "pthread.h"
template <class T>
class ProtectedBuffer {
std::deque<T> buffer;
pthread_mutex_t mutex;
public:
void add_back(T data) {
pthread_mutex_lock(&mutex);
buffer.push_back(data);
pthread_mutex_unlock(&mutex);
}
void get_front(T &data) {
pthread_mutex_lock(&mutex);
data = buffer.front();
buffer.pop_front();
pthread_mutex_unlock(&mutex);
}
};
编辑：感谢大家提供的建议。我已经尝试在下面实现它们。我还添加了一些错误检查，所以如果一个线程不知何故地尝试两次锁定同一个互斥量，它将优雅地失败。我想。
#include "pthread.h"
#include <deque>
class Lock {
pthread_mutex_t &m;
bool locked;
int error;
public:
explicit Lock(pthread_mutex_t & _m) : m(_m) {
error = pthread_mutex_lock(&m);
if (error == 0) {
locked = true;
} else {
locked = false;
}
}
~Lock() {
if (locked)
pthread_mutex_unlock(&m);
}
bool is_locked() {
return locked;
}
};
class TryToLock {
pthread_mutex_t &m;
bool locked;
int error;
public:
explicit TryToLock(pthread_mutex_t & _m) : m(_m) {
error = pthread_mutex_trylock(&m);
if (error == 0) {
locked = true;
} else {
locked = false;
}
}
~TryToLock() {
if (locked)
pthread_mutex_unlock(&m);
}
bool is_locked() {
return locked;
}
};
template <class T>
class ProtectedBuffer{
pthread_mutex_t mutex;
pthread_mutexattr_t mattr;
std::deque<T> buffer;
bool failbit;
ProtectedBuffer(const ProtectedBuffer& x);
ProtectedBuffer& operator= (const ProtectedBuffer& x);
public:
ProtectedBuffer() {
pthread_mutexattr_init(&mattr);
pthread_mutexattr_settype(&mattr, PTHREAD_MUTEX_ERRORCHECK);
pthread_mutex_init(&mutex, &mattr);
failbit = false;
}
~ProtectedBuffer() {
pthread_mutex_destroy(&mutex);
pthread_mutexattr_destroy(&mattr);
}
void add_back(T &data) {
Lock lck(mutex);
if (!lck.locked()) {
failbit = true;
return;
}
buffer.push_back(data);
failbit = false;
}
void get_front(T &data) {
Lock lck(mutex);
if (!lck.locked()) {
failbit = true;
return;
}
if (buffer.empty()) {
failbit = true;
return;
}
data = buffer.front();
buffer.pop_front();
failbit = false;
}
void try_get_front(T &data) {
TryToLock lck(mutex);
if (!lck.locked()) {
failbit = true;
return;
}
if (buffer.empty()) {
failbit = true;
return;
}
data = buffer.front();
buffer.pop_front();
failbit = false;
}
void try_add_back(T &data) {
TryToLock lck(mutex);
if (!lck.locked()) {
failbit = true;
return;
}
buffer.push_back(data);
failbit = false;
}
};