milesfrain / ffi-reload Goto Github PK

This repo demonstrates an issue where parcel won't pickup changes to FFI .js code.

Initial setup:

git clone https://github.com/milesfrain/ffi-reload.git
cd ffi-reload
spago build
parcel src/index.html --open

Open the browser's console logs and note this output

JS v1 Purs v1

Edit src/Main.js to print JS v2.

Re-run spago build and note browser's console logs are updated to:

JS v2 Purs v1

Edit src/Main.js to print JS v3.

Re-run spago build and note that parcel does not re-bundle or refresh the page, and logs remain as:

JS v2 Purs v1

Edit src/Main.purs to print Purs v4. Re-run spago build and note:

• Parcel rebundles
• Browsers log only updated to reflect changes in purs files, but not FFI .js files.

JS v2 Purs v4

Changes to .js FFI files are ignored because the parcel filewatcher looses track of output/**/foreign.js, which are copied atomically by purs from src/**.js.

Changes to .purs files are always picked-up by parcel because their resulting .js files are written to directly, instead of copied over.

inotifywait shows the difference in more detail. To see for yourself:

1. Edit both src/Main.purs and src/Main.js.
2. Launch inotifywait -r -m output/Main
3. Run spago build

Here is the problematic atomic copy:

output/Main/ CREATE .copyFile2908-0.tmp
output/Main/ OPEN .copyFile2908-0.tmp
output/Main/ MODIFY .copyFile2908-0.tmp
output/Main/ CLOSE_WRITE,CLOSE .copyFile2908-0.tmp
output/Main/ ATTRIB .copyFile2908-0.tmp
output/Main/ MOVED_FROM .copyFile2908-0.tmp
output/Main/ MOVED_TO foreign.js

This style of file editing is fine:

output/Main/ OPEN index.js
output/Main/ MODIFY index.js
output/Main/ MODIFY index.js
output/Main/ CLOSE_WRITE,CLOSE index.js