device-sdk-go use DBclient

[mlz960820]

@cloudxxx8 device-sdk-go How to use redis cache mechanism。In device-mqtt-go, the result cache of Subscribe is stored in the local CommandResponses sync.Map. Will there be a risk of memory leak? I think one way is to store it in Redis and set the expiration time

[cloudxxx8]

@mlz960820 we don't obsever memory leak in device-mqtt-go until now. you can open an issue if you observe it.
However, device-mqtt-go is just a reference implementation. You may implement your own Device Service to meet your production requirement.

Since the event reading cache is not a general requirement and Redis is not the only database in EdgeX, we don't have a plan to implement Redis cache in Device SDK. It can be implemented in the individual device service.
From my point of view, the Golang map is good enough for the cache because Core Data persists all the Events / Readings into the database.