LedgerHandle#readEntries leaks ByteBufs if getEntry not called or getEntryInputStream() not called and closed

[apache]

LedgerHandle#readEntries leaks ByteBufs if getEntry not called or getEntryInputStream() not called and closed

[eolivelli]

My proposal is not good, because the ByteBufInputStream will usually survive after the LedgerHandle#close.

We need to find a solution at least for errors during asyncAddEntry callback execution

But I think that we could introduce some leaks in existing downstream applications, because in 4.4 it clients are not required to fully consume every read entry

The best would be not to return a simple "Enumeration" but at least a subclass with an explicit "close" method (implementing AutoCloseable for instance) and document that such 'resource' must be closed

public interface EntriesEnumeration extends Enumeration, AutoCloseable {
       ...
}

This will be a breaking change, but I think that we already have introduced many breaking changes in the API (PlacementPolicy and Netty4 HashedWheelTimer.....)

a breaking API change will make downstream application need to be reviewed

[eolivelli]

After discussion on the mailing list we decided to:

• create a configuration option to use pooled/unpooled netty buffers
• document in LedgerEntry that in case of v2 wire protocol the application is responsible for 'releasing' the ByteBuf