Command Migration: ('HEXISTS', 'HKEYS', 'HVALS')

[AshwinKul28]

This issue tracks the migration of the mentioned commands - ('HEXISTS', 'HKEYS', 'HVALS') to make them compatible across the three protocols supported by the Dice database: RESP, HTTP, and WebSocket.
DiceDB now supports more than one protocols (Resp/http/websocket). We don't want eval operation of each command to be strictly bound with any of the protocols. Currently eval function return statements of each command is bounded to the RESP protocol.

The migration is required because:

• The current implementation is specific to the RESP protocol
• Evaluation functions of each command must be refactored to ensure protocol-agnostic behavior.
• Evaluation functions should return raw responses instead of protocol specific responses.

The goal is to make the command logic protocol-independent, allowing all three protocols to call the same core functionality seamlessly.

Requirements

• Refactor the evaluation function of [Command Name] to be generic.
• Ensure the evaluation function does not include protocol-specific logic.

Migration Steps

1. Analyze Current Implementation

   • Review the current codebase to understand how the command logic is implemented.

2. Refactor Return Logic

   • Create a new function with the function definition as evalXXX(args []string, store *dstore.Store) *EvalResponse under the file /internal/eval/store_eval.go
   • Analyse return statements of the eval and modify them to send raw types without encoding
   • Use errors in the return statements from /errors/migrated_errors.go file
   • Use perdefined responses from /internal/clientio/resp.go file as RespType variables

3. Command/Worker specific Changes

   • Make IsMigrated flag to true in the commands information under /internal/eval/commands.go file.
   • Use the newly written eval function against the NewEval parameter in the same command structure.
   • Delete the old eval function from the /internal/eval/eval.go file.
   • Add the migrated command to the /internal/worker/CommandsMeta map and make it's type as SingleShard

4. Update Unit Tests

   • Refactor existing unit tests to accommodate the new implementation.
   • Add new unit tests if necessary to cover all possible cases.

5. Integration Tests

   • Run all integration tests to ensure successful migration.
   • Ensure that each protocol (RESP, HTTP, WebSocket) works correctly after migration.

Checklist

• Migrated the evalXXX function with the latest definition
• Update or add unit tests for the new implementation.
• All unit tests pass successfully.
• Ensure all integration tests pass successfully.

Additional Notes

• Describe any edge cases that need to be handled in the generic function.
• Mention any protocol-specific optimizations required in wrappers.

If there are any questions or concerns about this migration, please mention them here.

Related Issues/PRs

• Sample implementation for the Get, Set, GetSet and SetEx can be found in this Pull Request.

[tarungka]

@AshwinKul28 , can I pick this up?

[AshwinKul28]

Thanks @tarungka go for it! 🚀

[AshwinKul28]

HI @tarungka , I hope you are doing well. Do you happen to have any updates on this? If you've any doubts please let us know on the discord.

[tarungka]

Hey @AshwinKul28, doing good. Hope you are doing good too. I am working on this, will have an update by EOD. Apologies for the delay, been a busy week.

[tarungka]

#1087

[soumya-codes]

@tarungka hope you are doing well. If the PR is ready for review, please move it out of draft stage. Please let me or @AshwinKul28 know if you are facing any issues are have any concerns.

[arpitbbhayani]

Hello @tarungka,

There has been no activity on this issue for the past 5 days.
It would be awesome if you keep posting updates to this issue so that we know you are actively working on it.

We are really eager to close this issue at the earliest, hence if we continue to see the inactivity, we will have to reassign the issue to someone else. We are doing this to ensure that the project maintains its momentum and others are not blocked on this work.

Just drop a comment with the current status of the work or share any issues you are facing. We can always chip in to help you out.

Thanks again.

[tarungka]

Hey @arpitbbhayani,

There is a PR (#1087) currently in progress, and it's almost ready to be merged. The only remaining task is to fix the unit test cases that are breaking after resolving the conflicts. Once that's done, the issue will be resolved. I'll ensure the issue is wrapped up as soon as possible.