This replaces the ErrDoubleSpend and ErrMissingTx error codes with a
single error code named ErrMissingTxOut and updates the relevant errors
and expected test results accordingly.
Once upon a time, the code relied on a transaction index, so it was able
to definitively differentiate between a transaction output that
legitimately did not exist and one that had already been spent.
However, since the code now uses a pruned utxoset, it is no longer
possible to reliably differentiate since once all outputs of a
transaction are spent, it is removed from the utxoset completely.
Consequently, a missing transaction could be either because the
transaction never existed or because it is fully spent.
This commit adds all of the infrastructure needed to support BIP0009
soft forks.
The following is an overview of the changes:
- Add new configuration options to the chaincfg package which allows the
rule deployments to be defined per chain
- Implement code to calculate the threshold state as required by BIP0009
- Use threshold state caches that are stored to the database in order
to accelerate startup time
- Remove caches that are invalid due to definition changes in the
params including additions, deletions, and changes to existing
entries
- Detect and warn when a new unknown rule is about to activate or has
been activated in the block connection code
- Detect and warn when 50% of the last 100 blocks have unexpected
versions.
- Remove the latest block version from wire since it no longer applies
- Add a version parameter to the wire.NewBlockHeader function since the
default is no longer available
- Update the miner block template generation code to use the calculated
block version based on the currently defined rule deployments and
their threshold states as of the previous block
- Add tests for new error type
- Add tests for threshold state cache
This commit contains the entire btcchain repository along with several
changes needed to move all of the files into the blockchain directory in
order to prepare it for merging. This does NOT update btcd or any of the
other packages to use the new location as that will be done separately.
- All import paths in the old btcchain test files have been changed to
the new location
- All references to btcchain as the package name have been changed to
blockchain
