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ascopes / protobuf-maven-plugin

Modern Protobuf and gRPC integration with Maven, with support for custom binary and pure Java protoc plugins.
https://ascopes.github.io/protobuf-maven-plugin/
Apache License 2.0
25 stars 7 forks source link

Feature Request: Skip recompilation if .proto file unchanged #438

Open ivu-mawi opened 6 days ago

ivu-mawi commented 6 days ago

Running both the protoc compiler and then the java compiler takes a non-negligible amount of time, depending on the size and amount of your .proto files. I would like to have the fastest possible edit-rebuild-debug cycle.

Even when not actually changing any code, this plugin always recompiles all proto files, so we can not take advantage of incremental rebuilding as needed.

We currently use https://github.com/os72/protoc-jar-maven-plugin and it provides a config property very non-aptly named optimizeProtogen which is true by default and skips running protoc if the last build time is more recent than any of the source .proto file last-modified-timestamps. This in turn allows maven to skip running javac in many cases.

I'd love some similar mechanism in this project. I'm not sure if the timestamp comparison from the linked project is the best way. Maybe a hash over the .proto file contents and the used protoc compiler version would be the better. (In contrast to the is-timestamp-newer-check, a hash-check would correctly detect downgrade of a .proto file to an older version as needing a recompilation. It would also keep working if the original timestamp of any proto file gets lost somewhere along the way. But the hash could potentially be much slower than timestamp checking.)

ascopes commented 6 days ago

Hey, thanks for the issue.

This has already been asked by someone else before, but at the time I could not think of a good way to consistently do this. If we can ensure that timestamp data for protobuf sources remains consistent when being unpacked from sources like existing archives or dependencies, then this sounds like a good idea and something we should definitely support. We can also hash the files instead as suggested potentially, although we'd need to also keep some kind of persistent file listing so that we know if new sources have been added.

Incremental compilation of subsets of the sources may be a little more complex and require more thought.

Would this be something you'd be interested in working on? If not, it might take me a couple of weeks to be able to pick this up as my schedule is a bit packed at the moment.

ivu-mawi commented 6 days ago

I'll see if I can get my employer to allow me to work on this :)

ascopes commented 1 day ago

@ivu-mawi I have some time this afternoon, so will crack on with this if that is okay with you!