This can definitely be improved with better trivial type detection and
by using the TypedTransfer template in more places.
It's a bit annoying that we can't get <type_traits> in Vector.h since
it's included in the toolchain compilation before we have libstdc++.
This is a complement to append() that works by constructing the new
element in-place via placement new and forwarded constructor arguments.
The STL calls this emplace_back() which looks ugly, so I'm inventing
a nice word for it instead. :^)
It's not possible to grow one of these vectors beyond what's already in them
since it's not possible to default-construct Nonnull{Own,Ref}Ptr.
Add Vector::shrink() which can be used when you want to shrink the Vector
and delete resize() from the specialized Vectors.
This allows you to do things like:
vector.insert_before_matching(value, [](auto& entry) {
return value < entry;
});
Basically it scans until it finds an element that matches the condition
callback and then inserts the new value before the matching element.
This is prep work for supporting HashMap with NonnullRefPtr<T> as values.
It's currently not possible because many HashTable functions require being
able to default-construct the value type.
The LibC build is a bit complicated, since the toolchain depends on it.
During the toolchain bootstrap, after we've built parts of GCC, we have
to stop and build Serenity's LibC, so that the rest of GCC can use it.
This means that during that specific LibC build, we don't yet have access
to things like std::initializer_list.
For now we solve this by defining SERENITY_LIBC_BUILD during the LibC
build and excluding the Vector/initializer_list support inside LibC.
This is a slot-in convenience replacement for Vector<NonnullRefPtr<T>> that
makes accessors return T& instead of NonnullRefPtr<T>&.
Since NonnullRefPtr guarantees non-nullness, this allows you to access these
vector elements using dot (.) rather than arrow (->). :^)
Put together a pretty well-performing queue using a Vector and an offset.
By using the new Vector::shift_left(int) instead of Vector::take_first()
we can avoid shifting the vector contents every time and instead only
do it every so often.
Maybe this could be generalized into a separate class, I'm not sure if it's
the best algorithm though, it's just what I came up with right now. :^)
Also run it across the whole tree to get everything using the One True Style.
We don't yet run this in an automated fashion as it's a little slow, but
there is a snippet to do so in makeall.sh.
It was depressing not being able to capture anything when passing a lambda
to qsort_r() so let's just have our own QuickSort. I was gonna have to do
this eventually anyway. :^)
It forgot to clear out the moved-from vector. It's easy to see where this bug
came from: I assumed m_impl was an OwnPtr. It would be comfy if move() on some
arbitrary T* would also null it out but alas that's not how things work.
I feel like this concept might be useful in more places. It's very naive
right now and uses dynamically growing buffers. It should really use static
size buffers and never kmalloc().
I was surprised to find that dup()'ed fds don't share the close-on-exec flag.
That means it has to be stored separately from the FileDescriptor object.
This was the fix:
-process.m_page_directory[0] = m_kernel_page_directory[0];
-process.m_page_directory[1] = m_kernel_page_directory[1];
+process.m_page_directory->entries[0] = m_kernel_page_directory->entries[0];
+process.m_page_directory->entries[1] = m_kernel_page_directory->entries[1];
I spent a good two hours scratching my head, not being able to figure out why
user process page directories felt they had ownership of page tables in the
kernel page directory.
It was because I was copying the entire damn kernel page directory into
the process instead of only sharing the two first PDE's. Dang!
