Gitignore is very slow

[durka]

The gitignore modifier causes a >100x slowdown in the case I am testing:

$ time fselect path from . where name = 'AP_HAL*'
./libraries/AP_HAL_Linux
./libraries/AP_HAL_SITL
./libraries/AP_HAL_ChibiOS
./libraries/AP_HAL
./libraries/AP_HAL_Empty
./libraries/AP_HAL_Linux/AP_HAL_Linux.h
./libraries/AP_HAL_SITL/AP_HAL_SITL_Private.h
./libraries/AP_HAL_SITL/AP_HAL_SITL.h
./libraries/AP_HAL_SITL/AP_HAL_SITL_Namespace.h
./libraries/AP_HAL_ChibiOS/AP_HAL_ChibiOS_Private.h
./libraries/AP_HAL_ChibiOS/AP_HAL_ChibiOS_Namespace.h
./libraries/AP_HAL_ChibiOS/AP_HAL_ChibiOS.h
./libraries/AP_HAL/AP_HAL_Main.h
./libraries/AP_HAL/AP_HAL_Boards.h
./libraries/AP_HAL/AP_HAL.h
./libraries/AP_HAL/AP_HAL_Namespace.h
./libraries/AP_HAL/AP_HAL_Macros.h
./libraries/AP_HAL_Empty/AP_HAL_Empty.h
./libraries/AP_HAL_Empty/AP_HAL_Empty_Private.h
./libraries/AP_HAL_Empty/AP_HAL_Empty_Namespace.h
./build/sitl/libraries/AP_HAL_SITL
./build/sitl/libraries/AP_HAL
./build/sitl/libraries/AP_HAL_Empty
./build/CubeBlack/libraries/AP_HAL_ChibiOS
./build/CubeBlack/libraries/AP_HAL
./build/CubeBlack/libraries/AP_HAL_Empty
./build/CubeOrange/libraries/AP_HAL_ChibiOS
./build/CubeOrange/libraries/AP_HAL
./build/CubeOrange/libraries/AP_HAL_Empty
./build/PH4-mini/libraries/AP_HAL_ChibiOS
./build/PH4-mini/libraries/AP_HAL
./build/PH4-mini/libraries/AP_HAL_Empty

real	0m0.087s
user	0m0.032s
sys	0m0.055s

$ time fselect path from . gitignore where name = 'AP_HAL*'
./libraries/AP_HAL_Linux
./libraries/AP_HAL_SITL
./libraries/AP_HAL_ChibiOS
./libraries/AP_HAL
./libraries/AP_HAL_Empty
./libraries/AP_HAL_Linux/AP_HAL_Linux.h
./libraries/AP_HAL_SITL/AP_HAL_SITL_Private.h
./libraries/AP_HAL_SITL/AP_HAL_SITL.h
./libraries/AP_HAL_SITL/AP_HAL_SITL_Namespace.h
./libraries/AP_HAL_ChibiOS/AP_HAL_ChibiOS_Private.h
./libraries/AP_HAL_ChibiOS/AP_HAL_ChibiOS_Namespace.h
./libraries/AP_HAL_ChibiOS/AP_HAL_ChibiOS.h
./libraries/AP_HAL/AP_HAL_Main.h
./libraries/AP_HAL/AP_HAL_Boards.h
./libraries/AP_HAL/AP_HAL.h
./libraries/AP_HAL/AP_HAL_Namespace.h
./libraries/AP_HAL/AP_HAL_Macros.h
./libraries/AP_HAL_Empty/AP_HAL_Empty.h
./libraries/AP_HAL_Empty/AP_HAL_Empty_Private.h
./libraries/AP_HAL_Empty/AP_HAL_Empty_Namespace.h

real	0m11.308s
user	0m11.175s
sys	0m0.132s

For comparison, fd 'AP_HAL*', which is doing the same as the gitignore version, matches the faster time.

You might want to consider using the ignore crate, used by the likes of fd and rg to do this super fast.