Re: [Boost-users] [Thread] What do I #include?

From: Khandelwal, Amit (amit.khandelwal_at_[hidden])
Date: 2008-07-11 09:56:24

Agreed. I didn't realize that I had typed return by reference. My bad.

-----Original Message-----
From: boost-users-bounces_at_[hidden]
[mailto:boost-users-bounces_at_[hidden]] On Behalf Of Johan Nilsson
Sent: Friday, July 11, 2008 9:42 AM
To: boost-users_at_[hidden]
Subject: Re: [Boost-users] [Thread] What do I #include?

Khandelwal, Amit wrote:
> The way I use mutex is to protect one shared resource. Here is sample 
> code that I cooked up. I am not sure why you want to use a single 
> mutex to protect multiple resources. However, if your use case demands

> it than wrap those resources in a class and have a mutex as a member 
> variable of that class.
>
> HTH.
>
>
> Call this file let say ThreadSafeQueue.hpp
>
> #include <boost/thread.hpp>
> #include <iostream>
> #include <queue>
> #include <deque>
>
> namespace std {
> namespace threadsafe {
>
> template <typename T, typename SEQUENCE = std::deque<T> > class 
> tsqueue {
>
>    private:
>        std::queue<T, SEQUENCE> m_queue;
>        boost::mutex mutex;
>
>    public:

[snip]

>        const T& front() {
>            boost::lock_guard<boost::mutex> lock(mutex);
>            std::cout << "Pop element: " << m_queue.front() << 
> std::endl;
>            return m_queue.front();
>        }

Ouch. Returning an element by reference could easily lead to trouble
when the container is accessed from multiple threads.

/ Johan

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