State implementations

State inherits the Database trait and implements fetching of external state and storage, and various functionality on output of the EVM execution. Most notably, caching changes while execution multiple transactions.

Database Abstractions

You can implement the traits Database, DatabaseRef or Database + DatabaseCommit depending on the desired handling of the struct.

• Database: Has mutable self in its functions. It is useful if you want to modify your cache or update some statistics on get calls. This trait enables preverify_transaction, transact_preverified, transact and inspect functions.
• DatabaseRef: Takes a reference on the object. It is useful if you only have a reference on the state and don't want to update anything on it. It enables preverify_transaction, transact_preverified_ref, transact_ref and inspect_ref functions.
• Database + DatabaseCommit: Allows directly committing changes of a transaction. It enables transact_commit and inspect_commit functions.