Fix crash when finalizing the same camera multiple times

Fix camera finalization when there are multiple of the same camera

When you have multiple camera objects referencing the same hardware, created either deliberately or from running a program multiple times without a full GC, the finalization of one camera can break interactions with the other cameras. This results in users of the other cameras getting the error SPINNAKER_ERR_NOT_INITIALIZED(-1002).

This commit introduces a deferred finalization method based on FFTW.jl, in combination with a method to avoid releasing a camera which is currently in use by another consumer.

There is an unwanted side effect of these changes, a crash at program exit from finalizing the System:

error in running finalizer: Spinnaker.SpinError(val=Spinnaker._spinError(0xfffffc14))
checkerror at /home/user/.julia/packages/Spinnaker/agc0J/src/Spinnaker.jl:31 [inlined]
spinSystemReleaseInstance at /home/user/.julia/packages/Spinnaker/agc0J/src/wrapper/spin_api.jl:101 [inlined]
_release! at /home/user/.julia/packages/Spinnaker/agc0J/src/System.jl:29
unknown function (ip: 0x7f8809310482)
_jl_invoke at /cache/build/default-amdci4-6/julialang/julia-release-1-dot-9/src/gf.c:2758 [inlined]
ijl_apply_generic at /cache/build/default-amdci4-6/julialang/julia-release-1-dot-9/src/gf.c:2940
run_finalizer at /cache/build/default-amdci4-6/julialang/julia-release-1-dot-9/src/gc.c:417
jl_gc_run_finalizers_in_list at /cache/build/default-amdci4-6/julialang/julia-release-1-dot-9/src/gc.c:507
run_finalizers at /cache/build/default-amdci4-6/julialang/julia-release-1-dot-9/src/gc.c:553
ijl_atexit_hook at /cache/build/default-amdci4-6/julialang/julia-release-1-dot-9/src/init.c:299
jl_repl_entrypoint at /cache/build/default-amdci4-6/julialang/julia-release-1-dot-9/src/jlapi.c:718
main at /cache/build/default-amdci4-6/julialang/julia-release-1-dot-9/cli/loader_exe.c:59
__libc_start_main at /lib/x86_64-linux-gnu/libc.so.6 (unknown line)
unknown function (ip: 0x401098)
julia: /vcpkg/installed/x64-linux/include/boost/thread/pthread/recursive_mutex.hpp:108: void boost::recursive_mutex::lock(): Assertion `!posix::pthread_mutex_lock(&m)' failed.

[27940] signal (6.-6): Aborted
in expression starting at none:0
Allocations: 4826084 (Pool: 4821646; Big: 4438); GC: 16
Aborted (core dumped)

I've tried to fix this, but I don't know why it's happening, so no solution yet. I think this is a minor issue because the System is a singleton, so it will never be finalized during normal program execution.

I also created a program to test this change, which requires access to a real camera:

module DebugSpinnakerCamera

using Spinnaker

export stress_start_stop

function stress_start_stop()
    stop = Ref(false)
    @async begin
        while !stop[]
            GC.gc(true)
            sleep(0.1)
        end
    end
    try
        t1 = @async begin
            while !stop[]
                camlist = CameraList()
                cam = camlist[0]
                start!(cam)
                try
                    sleep(0.01)
                    @show powersupplyvoltage(cam)
                    framerate!(cam, 55.0)
                    gain_lims = gain_limits(cam)
                    @async gain!(cam, rand(gain_lims[1]:gain_lims[2]))
                    getimage(cam)
                    sleep(0.01)
                finally
                    stop!(cam)
                end
                yield()
            end
        end
        t2 = @async begin
            while !stop[]
                camlist = CameraList()
                cam = camlist[0]
                start!(cam)
                try
                    sleep(0.01)
                    @show powersupplyvoltage(cam)
                    framerate!(cam, 55.0)
                    gain_lims = gain_limits(cam)
                    @async gain!(cam, rand(gain_lims[1]:gain_lims[2]))
                    getimage(cam)
                    sleep(0.01)
                finally
                    stop!(cam)
                end
                yield()
            end
        end
        fetch(t1)
        fetch(t2)
    finally
        stop[] = true
    end
end

end

samuelpowell / Spinnaker.jl

Fix crash when finalizing the same camera multiple times #88