[Utility] Cache session data in client

[adshmh]

Objective

Cache sessions client-side

Origin Document

#754 and #778

Cache the retrieved sessions client-side.

Goals

• Avoid repeatedly fetching sessions that have already been retrieved.

Deliverable

• PR that adds caching of sessions on client side
• PR that uses the cached sessions in the new servicer sub-command

Non-goals / Non-deliverables

General issue deliverables

• Update the appropriate CHANGELOG(s)
• Update any relevant local/global README(s)
• Update relevant source code tree explanations
• Add or update any relevant or supporting mermaid diagrams

Testing Methodology

• Task specific tests or benchmarks: make ...
• New tests or benchmarks: make ...
• All tests: make test_all
• LocalNet: verify a LocalNet is still functioning correctly by following the instructions at docs/development/README.md
• k8s LocalNet: verify a k8s LocalNet is still functioning correctly by following the instructions here

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Creator: @adshmh

[adshmh]

@Olshansk would appreciate a bit more context on the expectations here. More specifically, does this make sense?

1. Client checks the local cache for a stored session (on permanent storage, to allow sharing the session between multiple invocations of the client)
2. If a session is found --> verify against the current height
3. If a session is not found or the stored session has expired (i.e. does not match the current height): fetch the current session and store in cache (permanent storage)

Also, wondering if it makes sense to cache and store older sessions: if there is a need on client-side to access old sessions this would make sense, but I can't think of one right now.

[Olshansk]

I recently had to do this in v0 tx-bot and hacked (keyword hacked) it together. See https://github.com/pokt-network/tx-bot/blob/main/rpc/req.go#L93

Client checks the local cache for a stored session (on permanent storage, to allow sharing the session between multiple invocations of the client)

What is permanent storage here? If it's just something simple like a text/binary file under /tmp, then 👍

If a session is found --> verify against the current height

If validation means "check if session is still useful given the nodes", then 👍

Otherwise, please provide more details.

If a session is not found or the stored session has expired (i.e. does not match the current height): fetch the current session and store in cache (permanent storage)

👍

Also, wondering if it makes sense to cache and store older sessions: if there is a need on client-side to access old sessions this would make sense, but I can't think of one right now.

Can't think of any reasons right now. If it's important, it'll come back up.