Kura cache

[mversic]

Do we need an implementation of cache in Kura? Can unbounded block_data cause an OOM? This can happen as the network grows, but also when restarting a peer when there was no snapshot

If we do make a block cache we should make sure that it's not susceptible to probing attacks from block_sync or simple FindBlocks query execution

[dima74]

@mversic why do we need a cache? Can't we always keep the latest N blocks in memory and any older block always load from the disk when needed?

[mversic]

@mversic why do we need a cache? Can't we always keep the latest N blocks in memory and any older block always load from the disk when needed?

that's a cache with the policy to keep N latest