WIP Fixes(app): #1015 Command Migration: ('DEL', 'EXISTS', 'PERSIST', 'TYPE')

[mohit-nagaraj]

Pull Request Description for Issue #1015

Description:
This pull request addresses issue #1015 by migrating the 'DEL', 'EXISTS', 'PERSIST', and 'TYPE' commands to make them compatible across the three protocols supported by DiceDB: RESP, HTTP, and WebSocket. The current implementation of these commands is specific to the RESP protocol. The migration ensures protocol-agnostic behavior by refactoring the evaluation functions to return raw responses instead of protocol-specific responses.

Changes Made:

1. Refactored Evaluation Functions:

   • Implemented new generic evaluation functions for the mentioned commands in internal/eval/store_eval.go.
   • Ensured that the evaluation functions do not include protocol-specific logic.
   • Used raw types without encoding in the return statements.
   • Incorporated errors from errors/migrated_errors.go and predefined responses from internal/clientio/resp.go.

2. Command/Worker Specific Changes:

   • Set the IsMigrated flag to true in the command information under internal/eval/commands.go.
   • Assigned the new evaluation functions to the NewEval parameter in the command structure.
   • Removed the old evaluation functions from internal/eval/eval.go.
   • Added migrated commands to the CommandsMeta map in internal/worker/CommandsMeta with the type SingleShard.

3. Unit and Integration Tests:

   • Refactored existing unit tests to accommodate the new implementation.
   • Added new unit tests to cover all possible cases.
   • Ran all integration tests to ensure successful migration and correct functionality for all protocols (RESP, HTTP, WebSocket).

Checklist:

• Migrated the evalXXX function with the latest definition.
• Updated or added unit tests for the new implementation.
• Ensured all unit tests pass successfully.
• Verified all integration tests pass successfully.

Additional Notes:

• Edge cases and protocol-specific optimizations are handled within the wrappers.
• Any questions or concerns about this migration can be mentioned here.

Related Issues/PRs:

• Sample implementation for the Get, Set, GetSet, and SetEx commands can be found in a related pull request.

This pull request ensures the command logic is protocol-independent, allowing all three protocols to call the same core functionality seamlessly.

[JyotinderSingh]

Thanks for this PR. It looks like the CI is throwing some errors; please look into it. Additionally, please ensure the following checklist is part of your PR description and all items are checked off. At first glance, I can see that this PR does not add any new integration tests for the resp server.

• 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.
• Move Integration tests for the respective commands under the RESP integration tests directory from Async directory
• Please validate that the documentation for the respective commands is up to date. If not then consider adding them.

[mohit-nagaraj]

Hey @JyotinderSingh I have asked few doubts in the orginal issue could you please help me out with it