C++ blocking API needs updating Topic is solved

[Giovanni]

Hi,

I added const modifiers and replaced NULL with nullptr, I still fail to see how BaseThread is a descendant of ThreadReference (which I made final). Could you point out where this slicing would occur?

Giovanni

[Spym]

Sorry! I just looked at the code again and indeed, the problem is gone. Previously I was looking at an outdated file.

It's an unexpected solution but it works. It would make sense for the reference to be a base class of BaseThread, but it certainly isn't necessary.

[Giovanni]

Some kind of object is needed for all those functions that return a pointer to threads, it is basically just an encapsulated pointer.

Giovanni

[Spym]

Thanks. It also occurred to me that we're missing RAII helpers for mutexes and critical sections. I have them defined in my application, but there's no reason why they shouldn't be part of the OS. Consider the following code (copy-pasted from my application with minimal changes):

Code: Select all

namespace impl_
{
    class MutexLockerImpl
    {
        chibios_rt::Mutex& mutex_;
    public:
        MutexLockerImpl(chibios_rt::Mutex& m) : mutex_(m) { mutex_.lock(); }
        ~MutexLockerImpl() { mutex_.unlock(); }
    };

    class CriticalSectionLockerImpl
    {
        volatile const ::syssts_t st_ = chSysGetStatusAndLockX();
    public:
        ~CriticalSectionLockerImpl() { chSysRestoreStatusX(st_); }
    };
}

/**
 * RAII mutex locker.
 * Must be volatile in order to prevent the optimizer from throwing it away.
 */
using MutexLocker = volatile impl_::MutexLockerImpl;

/**
 * RAII critical section locker.
 * Must be volatile in order to prevent the optimizer from throwing it away.
 */
using CriticalSectionLocker = volatile impl_::CriticalSectionLockerImpl;


Would you be up to adding that to the wrapper?

[Giovanni]

Merged.

Giovanni

[Giovanni]

I added a "Monitor" construct but there is no obvious way to implement Java-like synchronized methods, locking and unlocking the inner mutex must be done explicitly.

Several other refinements and documentation fixes.

I think it needs more work before making it "official".

Giovanni.

[Spym]

RAII is a common pattern in C++. The code I posted is a complete solution that requires no further modifications, it's quite well tested as well.

[Giovanni]

By "it" I meant the whole wrapper.

Giovanni