Should you have a hub already running then starting a second aborts
at startup.
Since the shutdown sequence is run it tries to save everything.
This fix avoids a nullptr dereference in this specific event.
This is really only relevant for people using btrfs on Linux, we will
set the utxo dir to be no-copy-on-write which causes all new databases
to follow this flag and be faster due to lack of copying on write.
The reason there are no standard library versions of lock-free
containers is because you want to always take full advantage of
the details in question.
In this case (read millions of times for each modification) it makes
no sense to use anything other than a standard container, but put in
a copy-on-write block. Simple and easy.
Replace the m_buckets unsorted map with a lock-free version
based on atomic pointers. (BucketMap)
remove the m_leafs and move those into the bucket struct.
Make the access to the jumptable transactional to avoid one big lock
over all datastructures.
On my threadripper 2990WX the entire 150GB BCH blockchain was
parsed and imported in under 3 hours.
As the miners have started using the block-version bits for their
own purposes this means that BIP9 checks are rather irrelevant.
Signalling using version bits is rather silly anyway.
In Flowee there will no longer be warnings generated based on
these now outdated assumptions.
And this means less code :)
During the BCH fork-off time we allowed the client to be started
as either BCH or BTC and as such there are several code-paths
that behave different based on this user setting.
We remove those as we no longer allow starting as BTC client.
This also removes the check for the min-block-size (rollback protection)
as this is accomplished by the checkpoints on the BCH chain.
At least 50% of the UTXO entries reuse the posOnDisk
because they are outputs on the same tx. This changes
such entries from using 2 bytes to 1 byte only when saved
in a bucket.
On low core-count machines the request to save could end up being
delayed since all threads are busy doing things like validating
transactions.
So when a really big block came in I ended up throttling while there
was no save method running in parallel at all.
This fixes this and also makes throtteling be a per-thread thing
instead of doing it inside the mutex.
TomZ