Scaffolding periodic calls

Refresh every: 1s 2s 5s 15s 1m 5m never

NamePeriodTarget run (UTC)Previous run (UTC)
cloud/ai/platform/dataplane/prediction/client/pt_demand_service_client_context.cc:655m07:24:31TODO
cloud/ai/platform/dataplane/common/memcache/memcache_context.cc:1975s07:23:16TODO