Every std::mutex, lock_guard, unique_lock, scoped_lock,
condition_variable, call_once and semaphore left in Source/Core is
replaced by a lock-free design:
- Input: the device list, control bindings, stick calibration and
default device are published snapshots read under a quiesce; a
rebind requested while another thread is rebinding is handed to
that thread instead of waited for.
- WiimoteReal: the pool thread owns the slots and runs commands from
an MPSC queue; the active Wiimotes are atomic slots.
- EXI/SI/IOS devices: socket and packet traffic goes through SPSC
rings or MPSC handoffs owned by one thread; USB scanning publishes
its device list, and libusb transfers drain through a CallGate.
- Memory cards: the flush thread applies change records queued by
the CPU thread.
- Custom assets: loads are scheduled as a published batch with an
atomic cursor, results come back over an MPSC stack, and busy
assets are skipped and retried.
- D3D state and GL program caches use insert-only atomic maps
(Common/AtomicHashMap.h).
- Logging appends with O_APPEND / FILE_APPEND_DATA; FatFs reports
busy instead of waiting; per-socket WSAStartup/WSACleanup.
Deleted as unused by the libretro core: the profiler, the FIFO
recorder, the volume verifier, the touch InputOverrider and the
GameCube adapter's libusb path.
SPDX standardizes how source code conveys its copyright and licensing
information. See https://spdx.github.io/spdx-spec/1-rationale/ . SPDX
tags are adopted in many large projects, including things like the Linux
kernel.
Only remaining issue is that clicking on the titlebar of the window, to give it focus, is already interpreted as input. But clicking on the window in the task bar, or using alt tab works to get back, without causing an input event.
ControllerEmu::Control instances have a unique_ptr<ControlReference>
member, which is passed either an InputReference or OutputReference.
Without this virtual destructor, deleting a derived class through a
pointer to the base class is undefined behavior.
Better separation of concerns. Relegates `ControllerInterface` to
enumerating input controls, and the new `ControlReference` deals with
combining inputs and configuration expression parsing.