We do not need to be able to calculate multiple SignatureHash versions for a
single transaction format; instead, we use the transaction format to determine
the SigVersion.
The consensus branch ID *does* need to be passed in from the outside, as only
the caller knows the context in which the SignatureHash is being calculated
(ie. mempool acceptance vs. block validation).
JoinSplit signature verification has been moved into ContextualCheckTransaction,
where the consensus branch ID can be obtained.
The argument to the sign command for zcash-tx has been modified to take a height
in addition to the optional sigtype flags.
Mempool improvements, branch ID awareness
Whenever the local chain tip is updated, transactions in the mempool which commit to an
unmineable branch ID (for example, just before a network upgrade activates, where the
next block will have a different branch ID) will be removed.
Includes commits cherry-picked from the following upstream PRs:
- bitcoin/bitcoin#6654
- Only the mempool index change.
- bitcoin/bitcoin#6776
- bitcoin/bitcoin#7020
- bitcoin/bitcoin#6915
Part of #2074.
No longer relevant after #5957. This hack existed because of another
hack where the numthreads parameter, on regtest, doubled as how many
blocks to generate.
To determine the default for `-par`, the number of script verification
threads, use [boost::thread::physical_concurrency()](http://www.boost.org/doc/libs/1_58_0/doc/html/thread/thread_management.html#thread.thread_management.thread.physical_concurrency)
which counts only physical cores, not virtual cores.
Virtual cores are roughly a set of cached registers to avoid context
switches while threading, they cannot actually perform work, so spawning
a verification thread for them could even reduce efficiency and will put
undue load on the system.
Should fix issue #6358, as well as some other reported system overload
issues, especially on Intel processors.
The function was only introduced in boost 1.56, so provide a utility
function `GetNumCores` to fall back for older Boost versions.
