inigolabs / revgen

Speed up go:generate by auto detecting code changes.

At Inigo we generate a lot of go code. While our compile and build time runs in a matter of seconds thanks to the great go toolchain, running all the generators takes a few minutes on a good day. Running a single generator is fairly fast, but having to keep track of which generator to run gets annoying very fast.
Revgen keeps track of all the go:generate dependencies and only runs the generators for code that has been updated. By running one to a handful of generators at most, the go:generate run time goes down from minutes to seconds.
Each go:generate command is configured with a list of dependent files. When revgen is run, it calculates the hash of all these files, compares it with the latest hash, if they differ, runs the corresponding go:generate command and updates the stored hash.

Installation

Go

> go install github.com/inigolabs/revgen@latest

Brew

> brew tap inigolabs/homebrew-tap
> brew install revgen

Manual

Download the right pre-compiled binary for your system from the releases page and install.

Operation

> revgen init

The very first time, run revgen init to initialize and create a .revgen.yml config file.
Run this command in the root go dir, the config file will be created in this directory. See the configuration section for more information on setting go generate file dependecies.

> revgen

Run revgen anywhere inside your go workspace to call all the generators for code that has changed.

> revgen --force

Run revgen --force to run all the genrators regardless of code updates.

> revgen update

Run revgen update to update the config file when go::generate commands are added or removed from the code.

> revgen check

Run revgen check to check that all hashes match the current state of the code.
Can be useful in continious integration pipelines to make sure all needed code has been generated.

Configuration

• Each go:generate command has a list of file dependencies which can be configured in .revgen.yml.
• Gen deps can be configured with one or more glob strings. Revgen will compute the hash of all the files matched by the list of globs, and use this hash to determine if the generator needs to be called.
• File deps can be configured to make sure generated code isn't edited manutally without calling generate. Running revgen check will check both the gen deps and file deps to make sure all the generated code is generated and not manually tampered.
• Revgen stores the currently generated hashes in .revgen.sum, in general this file doesn't need to be edited. When in doubt, entries from .revgen.sum can be safely removed or the hash edited, they will be recomputed the next time revgen runs.

Example .revgen.yml:

auto_update: true
configs:
    - path: super/cool/generator.go
      gen_cmd: go run github.com/super/cool
      gen_deps:
        - super/cool/generator.yml
        - super/cool/*.go
      file_deps:
        - super/cool/gen/generated.go
    - path: another/cool/generator.go
      gen_cmd: go run github.com/another/generator
      gen_deps:
        - another/cool/generator.yml

License

• MIT License

Happy Coding!