Re: [boost] [gsoc] Boost.Process done

Subject: Re: [boost] [gsoc] Boost.Process done
From: Claude Quézel (cquezel_at_[hidden])
Date: 2011-02-02 08:08:15

The code is not exception safe if you have to call unlock explicitly.

Claude

2011/2/2 Mathias Gaunard <mathias.gaunard_at_[hidden]>

> On 01/02/2011 22:37, Claude Quézel wrote:
>
>> I noticed that the boost::process::child does not have a default
>> constructor. If I have a coding requirements like the following
>> example, I would be stuck:
>>
>>
>>
>> // Note the required default constructor
>> boost::process::child child;
>>
>> // Create a scope for the mutex guard
>> {
>>     boost::lock_guard<boost::mutex>  guard(process_launch);
>>
>>    // Here I must do something within guard scope
>>    // that must be done with the boost::process::launch
>>    do_something();
>>
>>    child = boost::process::launch(exec, args, ctx);
>> }
>>
>> // ...
>>
>> boost::process::status s = child.wait();
>>
>
>
> How about
>
> template<typename Lockable>
> struct lock_maybe_guard
> {
>    explicit lock_maybe_guard(Lockable& m_) : m(m_), locked(false)
>    {
>        lock();
>    }
>
>    void lock()
>    {
>        if(!locked)
>        {
>            m.lock();
>            locked = true;
>        }
>    }
>
>    unlock()
>    {
>        if(locked)
>        {
>            m.unlock();
>            locked = false;
>        }
>    }
>
>    ~lock_guard()
>    {
>        unlock();
>    }
>
> private:
>    Lockable& m;
>    bool locked;
> };
>
> boost::process::child child;
>
> lock_maybe_guard<boost::mutex> guard(process_launch);
>
>
> // Here I must do something within guard scope
> // that must be done with the boost::process::launch
> do_something();
>
> guard.unlock();
>
>
> child = boost::process::launch(exec, args, ctx);
>
>
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