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Star Citizen iCache & Persistence

Welcome to some more Star Citizen with a dev response video, looking at the iCache, Physical Inventory & Persistence. There was a Spectrum thread started by TheAlphaFlyer asking:
Where is iCache and Physicalised Inventory at now? 
CIG’s Chad McKinney gave us a load of information here.

“iCache, global persistence, and physical inventory are several very large features being worked on from multiple angles by multiple teams. It is one of our highest priorities as a company and is actively being worked on. At this point I think icache/global persistence tier 1 will land before the end of the year but I don’t want to specify exact dates, one thing to mention is that long term persistence did take some resources away from icache work, but we decided that it was worth it since the quality of life improvement to players would be such a benefit. Physical inventory heavily relies on icache and global persistence, and our entire system was designed around it (unlike the legacy system which was built entirely around itemports on players and ships and so concepts such as loose items and physical vs. legal ownership were unnatural to get working) . For that reason physical inventory will naturally come after that work is completed, though we are trying to find ways to get work started on it in parallel where possible.”

What is the Difference between pCache, iCache & Global Persistence?

“pCache (persistence cache) is the legacy system, using a monolithic cache for queries to the persistent item DB. As you can imagine, this does not scale well, and worse, when it goes down the game becomes essentially unplayable. For everyone! The new icache (item cache) uses a proliferated fleet of services to optimize querying in a scalable fashion, while using best practices for fault tolerance and recovery so for example all nodes have their data replicated in the network so even if one goes down, only partial data response is briefly lost and quickly a new one is rebuilt in it’s place, so automatic regeneration. The new icache is also being built with our gameplay systems in mind and understanding of how we need to query data from game servers. At this point we have a much better idea of how the game works than when the legacy p cache was created, so we can design our item data and query schema to make this new system efficient and minimal, which will also help with stability and scalability.

Global persistence is the term some of you may have noticed me bringing up in some of my comments and that’s because it is a related but different feature set that also needs to be implemented. Just because you have a database and cool querying system for that data doesn’t mean the game somehow automatically uses it in all the game systems, nor does it make servers/shards have persistent state, it just gives you a tool to use to enable that. In order to get server history persisted for everything you need to do a lot of work in server code to persist out and load back in said state, this is global persistence. I bring it up all the time because it touches so much, for example physical inventory. Inventories are just containers of items, but they are physicalized because they themselves are persistent entities with state. This means you can have a backpack with weapons or other items in it and have a way to stow/unstow from that inventory, but also that inventory can be instanced in the world and left in a vehicle or dropped off on the top of a mountain on a moon for another player to pick up. So physical inventory relies on global persistence, which relies on icache.

But there are other features that rely on global persistence as well, for example now we can explore gameplay that can permanently or on long term scales modify locations in the game, for example space station damage. Port Olisar could suffer an attack on a shard and it would be damaged for some time until repairs could take place. This would persist even if the server/shard went down as it is no longer just in memory state. There’s a ton more, such as full server recovery after a server crash. People often complain about losing cargo after a server crash, as we can’t get players back into their ships right now after a server crash unlike a client crash where we lose the state of the server. With global persistence this will be recorded in the shard record it was associated with, so quickly we spin up another instance, it recovers the shard record, then we can use matchmaking to get players back into the shard they just lost connection to, and boom, they’re back in action right where they left off.”

What About The Mission System & Reputation, are these handled by those services?

“The mission system is undergoing it’s own large refactor for server meshing and one of the big questions is of course how you deal with state. It won’t be with icache, but it could use a similar system with the same kinds of features but just not literally the item database.”

And that’s what we had from Chad… Plans for iCache before the end of the year, Physical Inventory after iCache. The iCache Replaces the old pCache. With Global Persistence in place crashes become less disartourious.