Move Perturber to Composer.Perturber

[mzweilin]

What does this PR do?

This PR simplifies the abstraction of Adversary by moving adversary.perturber into adversary.composer.perturber

A Composer is a module that generates perturbed input from the benign input and the perturbation. The perturbation is the weights of the Composer module. Perturber is an object to manage the perturbation (e.g. initialization, projection) and return perturbation for Composer to work on.

A universal adversary should be able to use a Composer in the same way.

In the future, we may try to better integrate components in Perturber, such as Initializer and Projector, into Composer directly. For example, the image initializer should be implemented in Composer instead, so that we can easily constrain Lp bound on perturbation.

Type of change

Please check all relevant options.

• [ ] Improvement (non-breaking)
• [ ] Bug fix (non-breaking)
• [ ] New feature (non-breaking)
• [x] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] This change requires a documentation update

Testing

Please describe the tests that you ran to verify your changes. Consider listing any relevant details of your test configuration.

• [x] pytest
• [x] CUDA_VISIBLE_DEVICES=0 python -m mart experiment=CIFAR10_CNN_Adv trainer=gpu trainer.precision=16 reports 70% (21 sec/epoch).
• [x] CUDA_VISIBLE_DEVICES=0,1 python -m mart experiment=CIFAR10_CNN_Adv trainer=ddp trainer.precision=16 trainer.devices=2 model.optimizer.lr=0.2 trainer.max_steps=2925 datamodule.ims_per_batch=256 datamodule.world_size=2 reports 70% (14 sec/epoch).

Before submitting

• [x] The title is self-explanatory and the description concisely explains the PR
• [x] My PR does only one thing, instead of bundling different changes together
• [ ] I list all the breaking changes introduced by this pull request
• [x] I have commented my code
• [ ] I have added tests that prove my fix is effective or that my feature works
• [x] New and existing unit tests pass locally with my changes
• [x] I have run pre-commit hooks with pre-commit run -a command without errors

Did you have fun?

Make sure you had fun coding 🙃

[mzweilin]

LGTM. Can you make sure the DDP test runs fine?

I confirm that DDP test runs fine. I'm merging this PR.