feat: db connect trait (#62)

Author: prestwich

src/connect.rs

@@ -0,0 +1,30 @@
+use core::convert::Infallible;
+use revm::{Database, DatabaseCommit};
+
+/// Trait for types that can be used to connect to a database. Connectors
+/// should contain configuration information like filesystem paths. They are
+/// intended to enable parallel instantiation of multiple EVMs in multiple
+/// threads sharing some database configuration
+pub trait DbConnect: Sync {
+    /// The database type returned when connecting.
+    type Database: Database + DatabaseCommit;
+
+    /// The error type returned when connecting to the database.
+    type Error: core::error::Error;
+
+    /// Connect to the database.
+    fn connect(&self) -> Result<Self::Database, Self::Error>;
+}
+
+impl<Db> DbConnect for Db
+where
+    Db: Database + DatabaseCommit + Clone + Sync,
+{
+    type Database = Self;
+
+    type Error = Infallible;
+
+    fn connect(&self) -> Result<Self::Database, Self::Error> {
+        Ok(self.clone())
+    }
+}

src/lib.rs

@@ -363,6 +363,9 @@
 
 extern crate alloc;
 
+mod connect;
+pub use connect::DbConnect;
+
 mod driver;
 pub use driver::{
     BlockDriver, BundleDriver, ChainDriver, DriveBlockResult, DriveBundleResult, DriveChainResult,
@@ -405,7 +408,8 @@ pub mod test_utils;
 
 use revm::{Database, DatabaseCommit, EvmBuilder};
 
-/// Ext trait for [`EvmBuilder`] that builds a [`Trevm`].
+/// Ext trait for [`EvmBuilder`] that builds a [`Trevm`], and adds features for
+/// [`DbConnect`].
 pub trait TrevmBuilder<'a, Ext, Db: Database + DatabaseCommit> {
     /// Builds the [`Trevm`].
     fn build_trevm(self) -> EvmNeedsCfg<'a, Ext, Db>;