## Motivation
The zebra-state service needs to be able to handle duplicate blocks.
## Solution
This implements changes already outlined by [The State
RFC](https://zebra.zfnd.org/dev/rfcs/0005-state-updates.html). We check for
successfully committed blocks first, since interacting with the queued blocks
struct at this point just complicates the implimentation. If the block has not
already been committed we then check if the block has already been queued, if
not we handle the block normally (normally here being the bit we already had
implemented).
## Documentation Changes
- [x] Update the state RFC to match the ways this fix departs from the design
- the main thing is that I switched the order of checking for duplicates
- [x] ~~Add newly added functions to the state rfc~~ Decided not to do this because they're minor getters that don't influence the rest of the design and aren't exposed as part of the API
- [x] Document newly added functions inline
## Testing
## Related Issues
- fixes https://github.com/ZcashFoundation/zebra/issues/1182
- tracking issue https://github.com/ZcashFoundation/zebra/issues/1049
Co-authored-by: teor <teor@riseup.net>
This commit begins the process of integrating `zcash_script` with the rest of the system for verifying scripts while syncing the block chain. It does so by adding the necessary support for looking up UTXOs from the state service and implements the first parts of the `script::Verifier` for looking up the necessary UTXOs in the state and then generating the necessary call to `zcash_script` to verify the script itself.
Co-authored-by: teor <teor@riseup.net>
* implement most of the chain functions
* implement fork
* fix outpoint handling in Chain struct
* update expect for work
* split utxo into two sets
* update the Chain definition
* remove allow attribute in zebra-state/lib.rs
* merge ChainSet type into MemoryState
* Add error messages to asserts
* export proptest impls for use in downstream crates
* add testjob for disabled feature in zebra-chain
* try to fix github actions syntax
* add module doc comment
* update RFC for utxos
* add missing header
* working proptest for Chain
* propagate back results over channel
* Start updating RFC to match changes
* implement queued block pruning
* and now it syncs wooo!
* remove empty modules
* setup config for proptests
* re-enable missing_docs lint
* update RFC to match changes in impl
* add documentation
* use more explicit variable names
teor
Jane Lusby