garnet
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microsoft
Fix for TYPE command for nonexistent objects
This is a fix for a bug when running the TYPE command on a nonexistent, or recently expired object.
I was having an issue running RedisInsight and Another Redis Desktop Manager when I would add an object, and then it expired, both apps would hang and stop responding.
Using memurai-cli, for both Redis and Garnet, Redis normally returns "none" if it cannot find the object. Tested on Garnet v1.0.1, built in VS2022 in Release/Any CPU mode and using the .NET 8.0 GarnetServer, the session would just hang and I would have to Ctrl-C out of the session. According to the Generic API docs, it should also return "none".
When loading keys, RedisInsight and ARDM would run a SCAN command, then a TYPE command on each of the objects it would find. This is where Garnet would stop responding, causing the apps to also stop responding.
My proposed fix is to add a "none" status returned, and make sure the response string is generated even if the object is not found, so the Send() methods get called.
Also I wonder if this is a general bug - if dcurr is not modified, e.g. no simple string is appended to dcurr, then no response gets sent. Refer to RespServerSession.cs line 292.
My original tests were on Windows 11, using .NET 8.0.3 and VS 2022 Preview 17.10 Preview 1. I'm also able to replicate this using redis-cli with Garnet running on Ubuntu 22.04.3 LTS with .NET 8.0.3 in Release mode.
Also I wonder if this is a general bug - if dcurr is not modified, e.g. no simple string is appended to dcurr, then no response gets sent. Refer to RespServerSession.cs line 292.
I don't think this is a real issue since we should be generating a response for every request. More like a safe guard right now to make sure that this is happening else client will hang. We are working on revising the parser so this may or may not go away.
