The methodname:
blockHeightAtTime()
makes the reader think about the actual height of the chain at that
time. Returning that value until the timestamp of the next block is
reached.
Now the method actally returns that number.
The code does not do any work to account for blocks going backwards in
time compared to the block before.
What we did previously is load a static chain which was to avoid lots of
work by simply memory-mapping the data instead of inserting it in a
vector.
This improves upon that by also having a metadata file which holds the
block-hashes directly readable. This avoids us having to iterate over
the blockheaders and hashing them.
Additionally we now have a single chain-work field that is the total
amount added work for the headers. This saves us from doing 256-bit
divisions and work for each blockheader as well.
Result is that we make the statup mostly about memory moving and remove
all CPU intensive stuff. Going from 1450ms to 400ms on desktop.
I expect an even greater gain on mobile CPUs.
tomFlowee