The Consensus Cleanup soft fork proposal includes enforcing that coinbase transactions set their
locktime field to the block height, minus 1 (as well as their nSequence such as to not disable the
timelock). If such a fork were to be activated by Bitcoin users, miners need to be ready to produce
compliant blocks at the risk of losing substantial amounts mining would-be invalid blocks. As miners
are unfamously slow to upgrade, it's good to make this change as early as possible.
Although Bitcoin Core's GBT implementation does not provide the "coinbasetxn" field, and mining
pool software crafts the coinbase on its own, updating the Bitcoin Core mining code is a first step
toward convincing pools to update their (often closed source) code. A possible followup is also to
introduce new fields to GBT. In addition, this first step also makes it possible to test future
Consensus Cleanup changes.
The changes to the seemingly-unrelated RBF tests is because these tests assert an error message
which may vary depending on the txid of the transactions used in the test. This commit changes the
coinbase transaction structure and therefore impact the txid of transactions in all tests.
The change to the "Bad snapshot" error message in the assumeutxo functional test is because this
specific test case reads into the txid of the next transaction in the snapshot and asserts the error
message based it gets on deserializing this txid as a coin for the previous transaction. As this
commit changes this txid it impacts the deserialization error raised.
Rather than individually calling addUnchecked for each transaction added in a
changeset (after removing all the to-be-removed transactions), instead we can
take advantage of boost::multi_index's splicing features to extract and insert
entries directly from the staging multi_index into mapTx.
This has the immediate advantage of saving allocation overhead for mempool
entries which have already been allocated once. This also means that the memory
locations of mempool entries will not change when transactions go from staging
to the main mempool.
Additionally, eliminate addUnchecked and require all new transactions to enter
the mempool via a CTxMemPoolChangeSet.
It's preferable to use type-safe transaction identifiers to avoid
confusing txid and wtxid. The next commit will add a reference to this
set; we use this opportunity to change it to Txid ahead of time instead
of adding new uses of uint256.
Since the kernel library no longer depends on the system file, move it
to the common library instead in accordance to the diagram in
doc/design/libraries.md.
Test each component of the RBF policy in isolation. Unlike the RBF
functional tests, these do not rely on things like RPC results, mempool
submission, etc.
