langchain[minor]: Experimental Masking Module

[Jordan-Gilliam]

Description: Addition of the Experimental Masking Module

Overview:

Dependencies: none
Tag maintainer: @jacoblee93
Co-Authors: @ddzmitry @HarishRN @dgaleally

This pull request introduces the MaskingParser and the RegexMaskingTransformer an extendable module for masking and rehydrating strings. One of the primary use cases for this module is to redact PII (Personal Identifiable Information) from a string before making a call to an llm.

Key Features:

MaskingParser

handles the process of masking and rehydrating.

• Add transformers for custom masking logic
• Parse strings
• Rehydrate masked strings
• State Management (Maintains a state map of masked values to their orignial counterparts - essential for rehydration)
• Hooks to run callback functions at various stages.
• Error handling

RegexMaskingTransformer

regex transformer that can be added to the MaskingParser for masking and rehydrating via defined regex patterns

• Overridable masking hash function (eg.[email-123***])
• Transformation Logic
• Rehydration Logic

Changes:

Langhchainjs core

Introduction of the experimental/masking module
MaskingParser class,
Abstract MaskingTransformer
RegexMaskingTransformer class extending the abstract MaskingTransformer

Documentation

Experimental Module Docs
Masking Docs
Nextjs masking example
Kitchen Sink masking example

Impact:

Inverted controls for consumers to mask and rehydrate strings
Groundwork for more comprehensive masking integrations in the future (eg. AWS comprehend)

[vercel]

The latest updates on your projects. Learn more about Vercel for Git ↗︎

Name	Status	Preview	Comments	Updated (UTC)
langchainjs-api-refs	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Dec 7, 2023 1:26am
langchainjs-docs	✅ Ready (Inspect)	Visit Preview		Dec 7, 2023 1:26am

[jacoblee93]

This can just be:

return new Response(stream, {
  headers: {
    "content-type": "text/plain; charset=utf-8"
  }
});

[jacoblee93]

Would it make more sense for the constructor to just take an array of MaskingTransformers?

[Jordan-Gilliam]

I will update the basic example to default to an array of transformers.

const piiMaskingTransformer = new RegexMaskingTransformer({
  email: { regex: /\S+@\S+\.\S+/g, mask: emailMask },
  phone: { regex: /\d{3}-\d{3}-\d{4}/g, mask: phoneMask },
});

const maskingParser = new MaskingParser({transformers: [piiMaskingTransformer]});

[jacoblee93]

Ah ok I see you have it as an option here - also a bit more conventional for us to prefer ?? but doesn't really matter

[jacoblee93]

Our linter does not allow instanceof since bundlers/chunking can make it unreliable in certain cases - I think it's fine here but you'll need to disable it with a comment:

langchainjs/langchain-core/src/prompts/chat.ts

Line 502 in dfd3271

// eslint-disable-next-line no-instanceof/no-instanceof

[jacoblee93]

parse -> mask? Don't feel too strongly

[jacoblee93]

I think it might be nice to allow async transform functions instead of just sync?

[jacoblee93]

Only other comment here is that I don't love mutating this.state internally within transformer.transform - could see some nasty bugs where a transformer implementation e.g. mistakenly clears state from previous transformers.

My preference would be to manually combine state at the parser level based on each transformer's output, but fine if you want to stick with this since it's in experimental.

[jacoblee93]

See above - might be nice to allow async rehydrate functions as well and then just use a for loop here

[jacoblee93]

Should this block?

[jacoblee93]

Should these block? Can be nice to avoid race conditions/hanging callbacks in serverless environments, and callbacks should be lightweight.

[jacoblee93]

I would phrase this more as Experimental modules whose abstractions have not fully settled

[jacoblee93]

Allow async functions here?

[jacoblee93]

Nicer to have this under examples/ since we populate API ref links and do more sophisticated code correctness checks

[jacoblee93]

Broadly looks great! Some questions/nits

[jacoblee93]

I think you can just do await this.config.onMaskingStart(message), will work for sync functions too?

[jacoblee93]

IMO you don't have to be so defensive, the typing will take care of things, but no problem to keep if you're worried about vanilla JS devs

[jacoblee93]

Thank you!