I am not familiar with the route cache design, so the questions below need to be answered by someone who is familiar with it. CC @membphis @tzssangglass

1. do we need to clean the cache when we switch 'cache' to 'no cache'?
2. is it desirable to recreate cache once the router is rebuilt (a new route is added)?

If it is desirable, we need to switch the cache lookup way from key + ver to key as each ver has its own cache now. Also, we may not need to init the cache as it may be created in the first router building.

2. is it desirable to recreate cache once the router is rebuilt (a new route is added)?

no, if the router is rebuilt, the cache version(router.router_http.user_routes.conf_version) would be changed, so a new request comes in and generates the cache key as old would execute origin router_match and generates new matched_route, and cache new matched_route.

do we need to clean the cache when we switch 'cache' to 'no cache'?

I don't think it's needed because 'cache' to 'no cache' means router.router_http.user_routes.conf_version has changed, refer to the explanation above.

Do we need to recreate the lrucache when switching 'cache' to 'no cache'? @membphis

for the better performance and logic simple, I think we should renew the lrucache and ignore router.router_http.user_routes.conf_version, which is more simpler to read and understanding

I don't think it's needed because 'cache' to 'no cache' means router.router_http.user_routes.conf_version has changed, refer to the explanation above.

So it is acceptable to keep the unused cache when we move to 'no cache'?

BTW, look like we can remove the init in

So it is acceptable to keep the unused cache when we move to 'no cache'?

I think it's needed.