Set default sizes of DbLedgerStorage read and write cache to be proportional to JVM direct memory

[merlimat]

Motivation

To simplify Bookie configuration when using DbLedgerStorage, set the memory size defaults for WriteCache, ReadCache and RocksDB block cache to be pegged to the available direct memory configured in the JVM.

User can always configure specific values and override this behavior.

[eolivelli]

Should be change this default config file and explain how the value is calculated ?

Overall the change is good, just a few nits

[eolivelli]

This comment can be removed as well

[eolivelli]

Mmm
But if we wat to use it we should remove it from the blacklist.
Otherwise who reads checkstyle config thinks that we are not using it...

What do you think?
Do you know why it was blacklisted?

[merlimat]

What do you think?
Do you know why it was blacklisted?

I have no idea why it was blacklisted. I guess io.netty.util.internal could be regarded as non-public API package. Maybe it's because there are also some shaded classes under that package.

In my opinion, the override here is fine. We should only using things from io.netty.util.internal if there's a good reason for it and no other way around.

[eolivelli]

Good

#shipit

[sijie]

the reason why it is in blacklist is internal classes are not encouraged to use in general, if there are exceptions, those imports should be highlighted with these checkstyle annotations. so we know these packages are used intentionally.

[sijie]

@merlimat : as we talked offline, I would like to have some simple validation in the server configuration, if the total memory size configured to be used for db ledger storage exceed the jvm memory, we should fail startup with an explicit logging.

[merlimat]

@sijie Updated

[merlimat]

run integration tests