The patch adjust the code of the base, base-<kernel>, and os repository.
To adapt existing components to fix violations of the best practices
suggested by "Effective C++" as reported by the -Weffc++ compiler
argument. The changes follow the patterns outlined below:
* A class with virtual functions can no longer publicly inherit base
classed without a vtable. The inherited object may either be moved
to a member variable, or inherited privately. The latter would be
used for classes that inherit 'List::Element' or 'Avl_node'. In order
to enable the 'List' and 'Avl_tree' to access the meta data, the
'List' must become a friend.
* Instead of adding a virtual destructor to abstract base classes,
we inherit the new 'Interface' class, which contains a virtual
destructor. This way, single-line abstract base classes can stay
as compact as they are now. The 'Interface' utility resides in
base/include/util/interface.h.
* With the new warnings enabled, all member variables must be explicitly
initialized. Basic types may be initialized with '='. All other types
are initialized with braces '{ ... }' or as class initializers. If
basic types and non-basic types appear in a row, it is nice to only
use the brace syntax (also for basic types) and align the braces.
* If a class contains pointers as members, it must now also provide a
copy constructor and assignment operator. In the most cases, one
would make them private, effectively disallowing the objects to be
copied. Unfortunately, this warning cannot be fixed be inheriting
our existing 'Noncopyable' class (the compiler fails to detect that
the inheriting class cannot be copied and still gives the error).
For now, we have to manually add declarations for both the copy
constructor and assignment operator as private class members. Those
declarations should be prepended with a comment like this:
/*
* Noncopyable
*/
Thread(Thread const &);
Thread &operator = (Thread const &);
In the future, we should revisit these places and try to replace
the pointers with references. In the presence of at least one
reference member, the compiler would no longer implicitly generate
a copy constructor. So we could remove the manual declaration.
Issue #465
Since all Audio_out server components loop over the packet stream
queue it is save to reset the tail position to one after the play
position. We have to do this because we do not know exactly when
the play position changes (i.e. the driver has processed the packet)
and we might end up with a tail position before the current play
position.
Issue #1796.
When a stream was stopped it may still contain valid packets that
will be played automatically when the stream is started again. The
invalidate_all() method may be called after stopping the stream to
prevent this.
Issue #1647.
To archive lower latency the length of a period was reduced from
2048 (~46ms) to 512 (~11.6ms) samples.
It should be noted that this change probably breaks audio in Qemu on
most systems.
Issue #1644.
This patch changes the top-level directory layout as a preparatory
step for improving the tools for managing 3rd-party source codes.
The rationale is described in the issue referenced below.
Issue #1082
Josef Söntgen
Norman Feske