This works around for compilers with non-static-data-member
initialization.
spinlock_t is-a struct { lockType _; } and BOOST_DETAIL_SPINLOCK_INIT
initializes the first member of the struct.
All defines of BOOST_DETAIL_SPINLOCK_INIT include c-style curly braces
to initialize the struct's data member.
However, modern C++ compiler interpret the braces differently resulting
in copy constriction of the initializer.
Depending on implementation, d8ae3fd may only construct the spinlock
once to `sl_init`. Later it is only copy-constructed and that leads to
compile and/or runtmime errors.
e.g. gcc-8.3 fails to compile
error: use of deleted function ‘boost::detail::spinlock::spinlock(const boost::detail::spinlock&)’
To facilitate a central registry with weak/shared pointer lookup,
enable_shared_from_this<ARDOUR::AutomationControl>
was migrated to
enable_shared_from_this<PBD::Controllable>
The main (and only) user is generic-midi surface's state interface :(
This fixes a bug on some modern mac systems. Related to
setup_logging() changing stderr to use ASL and write to com.apple.console.
When a forked application writes to stderr while ASL is used,
the child is terminated for some reason.
Keep track of safe reservation:
Data has been read (or was skipped) previously can be read again
up to the allocated "reservation" (which is never overwritten).
This is mainly a NO-OP, introducing a new PlaybackBuffer type
and preparing for its use.
At this point in time, the buffer is just a power-of-two sized
ringbuffer and the disk-reader's read-logic is still unchanged.
Eventually the read and write sample position that are currently
private to the disk-reader can be migrated to be owned by the buffer.
Also Diskreader::read() positions can be matched to read-position ..
+/- buffer reservation and de-click can read w/o committing the read.
