RetroAchievements disables pausing too frequently when running but there's no sense of doing this if RetroAchievements does not currently have a game running.
Some games open two USB interfaces, e.g. /dev/usb/oh0 and /dev/usb/hid.
This was causing us to run two scanning threads at once, using up more
CPU time for scanning than we need to.
We have identified that a failed RetroAchievements game load (most easily done when closing a game before the server can finish responding) can leave data behind that causes problems. As such, refactored CloseGame to always delete data even if there wasn't a game loaded when it was called, and call it on the failure paths of LoadGameCallback.
Instead of having USBScanner create "hooks" as it scans for devices,
let's have USBScanner present a list of devices to USBHost and have
USBHost diff the new device list with its old device list to create the
hook calls instead. This gets rid of some complex edge cases that the
next commit otherwise would have to deal with, in particular regarding
toggling determinism and adding new USBHosts to a USBScanner.
Note: After adding the missing locking of m_devices_mutex, I had to move
the locking of m_hooks_mutex to avoid a random deadlock between the CPU
thread and USB scanning thread. (Either that or I would have to lock
m_devices_mutex before m_hooks_mutex.)
This gets rid of the ugly direct access to USBScanner::m_devices that
was introduced by the previous commit.
This also fixes a potential thread safety issue.
USB_HIDv4::TriggerDeviceChangeReply loops through m_devices and calls
GetDeviceEntry for each device. If USB_HIDv4::TriggerDeviceChangeReply
is called after a new device is added to m_devices but before hooks are
dispatched, GetDeviceEntry crashes, because the hook that's supposed to
update m_device_ids hasn't run yet. With this commit, this issue can no
longer happen, because USBHost::m_devices_mutex doesn't get unlocked in
between updating m_devices and dispatching the hooks.
Due to requests from RA Devs, updating the AchievementManager LoadGameCallback to still set MemoryPeeker (and set m_system) if the load game response is NO_GAME_LOADED, so that the memory inspector et al continue function properly on unidentified hashes. Without this, no memory is loaded and the memory inspector will show all zeroes.
