Cancelling image transformation

[patt1s0n]

Sometimes we have very large images which take a long time to transform; we'd like to be able to cancel the transformation if a time limit is reached.

I've tried implementing this using time.After and running the image transformation in a separate goroutine. Then cancelling the goroutine if the timeout is reached; however this causes a runtime error:

fatal error: unexpected signal during runtime execution
[signal SIGSEGV: segmentation violation code=0x1 addr=0x30d pc=0x7fff639a9d82]

runtime stack:
runtime.throw(0x4fec013, 0x2a)
        /usr/local/Cellar/go/1.13.3/libexec/src/runtime/panic.go:774 +0x72
runtime.sigpanic()
        /usr/local/Cellar/go/1.13.3/libexec/src/runtime/signal_unix.go:378 +0x47c

goroutine 83 [syscall]:
runtime.cgocall(0x44eed90, 0xc00027cdb8, 0xc00011d340)
        /usr/local/Cellar/go/1.13.3/libexec/src/runtime/cgocall.go:128 +0x5b fp=0xc00027cd88 sp=0xc00027cd50 pc=0x4004bdb
github.com/discordapp/lilliput._Cfunc_giflib_decoder_decode_frame_header(0x8b003e0, 0x0)
        _cgo_gotypes.go:303 +0x49 fp=0xc00027cdb8 sp=0xc00027cd88 pc=0x43e6229

Is there a graceful way to cancel a call to ImageOps.Transform?

[brian-armstrong-discord]

Hello,

No, I don't think that will be possible. The work is taking place in CGo and is performing computations until it completes, so there isn't any way to get its attention, so to speak. Your best bet is probably to use the header methods to inspect the dimensions and decide whether to proceed before starting the transform.

[patt1s0n]

Okay cheers for the response.