move block checksum from FileBuffer to BlockManager

[jkub]

Previously FileBuffer implements checksummed IO. However, different BlockManager implementations will want different Checksum implementations. It's much simpler to just move the checksum operations to the BlockManager. This then allowed me to devirtualize other functions, including ConstructManagedBuffer.

While doing this, I noticed that FileBuffer had some cruft. malloced_xx and internal_xx were always equivalent and thus redundant. I removed one.

Other nits:

• There were some compiler warnings about integer truncation in swizzleable_pointer.cpp, which I fixed.
• ReplayState was retrieving the catalog of the attached database in an odd way. (Which was actually causing a bug in some of my tests, due to a transaction not being active during attach.) Now it just calls db.GetCatalog().

[Tishj]

This now takes the Catalog from the current AttachedDatabase, no longer the default database
I wonder if that has any unwanted effect in this case?

[Mytherin]

Thanks for the PR! Looks good to me.

It has been a while - but from what I remember the three sizes were as follows:

• malloced_size was the total (sector-size aligned) size
• internal_size was the size requested for allocation (potentially not sector-size aligned)
• size was the actual size of the data that could be written (minus the checksum header)

If the size requested for allocation is always sector-size aligned then malloced_size and internal_size are always identical and we can indeed get rid of the separate malloced_size. As we don't require sector size alignment anymore and if it is not required for you either then I am definitely in favor of merging the two and simplifying the code.

[Mytherin]

This now takes the Catalog from the current AttachedDatabase, no longer the default database
I wonder if that has any unwanted effect in this case?

Actually that probably fixes a bug.

[Mytherin]

Thanks!