[IGNITE-16120] Return real page size if encryption is configured for a cache group even when keys are not injected yet

• Type: Improvement
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 2.13
• Component/s: cache
• Assignee: Roman Puchkovskiy
• Reporter: Roman Puchkovskiy
• Created: 14/Dec/21 15:07
• Updated: 15/Dec/21 06:38

Description

When encryption is enabled for a region in the configuration, PageMemory#realPageSize(int) returns a value reduced by some encryption-related data overhead. For instance, currently, when full page size (returned by PageMemory#pageSize()) is 4096, #realPageSize(int) returns 4064.

But #realPageSize(int) starts returning the 'real' realPageSize only when it has some keys for the provided group ID. The injection of keys happens on node join. The following comment explains why:

//We can't store keys before node join to cluster(on statically configured cache registration).
//Because, keys should be received from cluster.
//Otherwise, we would generate different keys on each started node.
//So, after starting, coordinator saves locally newly generated encryption keys.
//And sends that keys to every joining node.

This means that for short period of time (before the keys are injected) #realPageSize(int) returns full page size (4096); this happens when allocating pages with metadata for caches preconfigured in the region configuration, for example. These pages are initialized with wrong page size. Currently, this page size is not used for these pages during initialization, but in the future this might cause some problem.

My suggestion is to try remove this gap.

1. First of all, for the preconfigured groups (listed in IgniteConfiguration which is accessible to PageMemoryImpl constructor) we don't need to wait for keys injection: we just have the list of these groups
2. Another option (probably better) would be to employ some event system to mark a group as encrypted before it gets created. If such a mechanism exists If not, maybe it's not that hard to implement it.