[Params, Clients] add generic ParamsQuerier

[bryanchriswhite]

Summary

Adds the the ParamsQuerier interface, cachedParamsQuerier implementation, config, and options functions.

ParamsQuerier is a generic implementation of a "params querier" (i.e. interface { GetParams(ctx) (P, error }, where P is the params type) that can be embedded in any module-specific query client implementation. It implements configurable params caching for historical heights (incl. current height).

---
title: Legend
---

classDiagram-v2

class GenericInterface__T__any {
    <<interface>>
    GenericMethod() T
}

class Implemenetation {
    ExportedField FieldType
    unexportedField FieldType
}

Implemenetation --|> GenericInterface__T__any: implements

class Embedder__T__any {
    <<interface>>
    GenericInterface[T]
}

Embedder__T__any ..|> GenericInterface__T__any: embeds

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---
title: Client caching options
---

classDiagram-v2

class ParamsQuerier__P__sdk_Msg {
    <<interface>>
    GetParams(ctx context.Context) (params P, err error)
    GetParamsAtHeight(ctx context.Context, height int64) (params P, err error)
}

%% class paramsQuerier__P__sdk_Msg {
%%     <<interface>>
%%     GetParams(ctx context.Context) (P, error)
%% }

class cachedParamsQuerier__P__sdk_Msg__Q__paramsQuerier:::cacheImpl {
    queryClient Q__paramsQuerier[P]
    paramsCache HistoricalQueryCache[P]
    ...
}
ParamsQuerier__P__sdk_Msg --|> cachedParamsQuerier__P__sdk_Msg__Q__paramsQuerier
cachedParamsQuerier__P__sdk_Msg__Q__paramsQuerier --* InMemoryCache: EITHER
cachedParamsQuerier__P__sdk_Msg__Q__paramsQuerier ..* BadgerCache: OR
%% cachedParamsQuerier__P__sdk_Msg__Q__paramsQuerier --> paramsQuerier__P__sdk_Msg


class HistoricalQueryCache__T__any {
    <<interface>>
    GetLatestVersion(key string) (value T, err error)
    GetVersion(key string, version int64) (value T, err error)
    SetVersion(key string, value T, version int64) (err error)
}
%% HistoricalQueryCache__T__any --|> QueryCache__T__any

class InMemoryCache:::cacheImpl
InMemoryCache --|> HistoricalQueryCache__T__any

class BadgerCache:::cacheImpl {
    // TODO
}
BadgerCache --|> HistoricalQueryCache__T__any

%% TODO_IN_THIS_COMMIT: uncomment classDef in docs - github can't parse it.
%%classDef cacheImpl fill:#074,color:#fff;

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Issue

• [Off-Chain] ModuleParamsClient & Historical Params #543

Type of change

Select one or more from the following:

• New feature, functionality or library
• Consensus breaking; add the consensus-breaking label if so. See [Infra] Automatically add the consensus-breaking label #791 for details
• Bug fix
• Code health or cleanup
• Documentation
• Other (specify)

Testing

• Documentation: make docusaurus_start; only needed if you make doc changes
• Unit Tests: make go_develop_and_test
• LocalNet E2E Tests: make test_e2e
• DevNet E2E Tests: Add the devnet-test-e2e label to the PR.

Sanity Checklist

• I have tested my changes using the available tooling
• I have commented my code
• I have performed a self-review of my own code; both comments & source code
• I create and reference any new tickets, if applicable
• I have left TODOs throughout the codebase, if applicable

[red-0ne]

Is this needed at the cachedParamsQuerier level?

[bryanchriswhite]

Yes, indeed. The cachedParamsQuerier has to hold a reference to this because it's a dependency of all query clients, and it also has to know how to generically construct a given modules query client. See NewCachedParamsQuerier():

	if err = depinject.Inject(
		deps,
		&querier.clientConn,
	); err != nil {
		return nil, err
	}

	querier.queryClient = queryClientConstructor(querier.clientConn)

[red-0ne]

We should consider the case where paramsCache is in historical mode, otherwise this call might fail.

Additionally, I think we should find a way to get the height/version of the retrieved params in order to set it using SetAsOfVersion.

Maybe add the height to the QueryParamsResponse?

[bryanchriswhite]

As discussed:

1. cachedParamsQuerier's cache is ALWAYS in historical mode.
2. This isn't possible anymore due to the decision we made to disable #Set() in historical mode.
3. We're going to transition to event-driven cache warming.

[Olshansk]

We're going to transition to event-driven cache warming.

Can you add a TODO for that somewhere?

[Olshansk]

cachedParamsQuerier's cache is ALWAYS in historical mode.

#PUC

[Olshansk]

Nothing big. Appreciate all the TODOs, comments and explanations.

Will approve after we merge in the base!

[Olshansk]

Suggested change

	// This interface should be implemented by any module-specific querier
	// This interface SHOULD be implemented by any module-specific querier

[Olshansk]

Suggested change

	defaultMaxVersionAge = 100
	defaultMaxKeys = 1000
	// These are sensible defaults that can be customized below.
	// The default oldest version (relative to the latest) that'll be considered
	// a cache hit by the client.
	defaultMaxVersionAge = 100
	// The default maximum number of (key, value) pairs that'll be maintained
	// in the cache irrespective of the key or value size.
	defaultMaxKeys = 1000

[Olshansk]

This is clean!

[Olshansk]

We're going to transition to event-driven cache warming.

Can you add a TODO for that somewhere?

[Olshansk]

cachedParamsQuerier's cache is ALWAYS in historical mode.

#PUC

[Olshansk]