Database Macro (#408)

* db_macro

* wip: converted prcessor/key_gen to use create_db macro

* wip: converted prcessor/key_gen to use create_db macro

* wip: formatting

* fix: added no_run to doc

* fix: documentation example had extra parenths

* fix: ignore doc test entirely

* Corrections from rebasing

* Misc lint

---------

Co-authored-by: Luke Parker <lukeparker5132@gmail.com>

common/db/src/create_db.rs

@@ -0,0 +1,68 @@
+#[doc(hidden)]
+pub fn serai_db_key(
+  db_dst: &'static [u8],
+  item_dst: &'static [u8],
+  key: impl AsRef<[u8]>,
+) -> Vec<u8> {
+  let db_len = u8::try_from(db_dst.len()).unwrap();
+  let dst_len = u8::try_from(item_dst.len()).unwrap();
+  [[db_len].as_ref(), db_dst, [dst_len].as_ref(), item_dst, key.as_ref()].concat()
+}
+
+/// Creates a series of structs which provide namespacing for keys
+///
+/// # Description
+///
+/// Creates a unit struct and a default implementation for the `key`, `get`, and `set`. The macro
+/// uses a syntax similar to defining a function. Parameters are concatenated to produce a key,
+/// they must be `scale` encodable. The return type is used to auto encode and decode the database
+/// value bytes using `bincode`.
+///
+/// # Arguments
+///
+/// * `db_name` - A database name
+/// * `field_name` - An item name
+/// * `args` - Comma seperated list of key arguments
+/// * `field_type` - The return type
+///
+/// # Example
+///
+/// ```ignore
+/// create_db!(
+///   TrubutariesDb {
+///     AttemptsDb: (key_bytes: &[u8], attempt_id: u32) -> u64,
+///     ExpiredDb: (genesis: [u8; 32]) -> Vec<u8>
+///   }
+/// )
+/// ```
+#[macro_export]
+macro_rules! create_db {
+  ($db_name: ident {
+    $($field_name: ident: ($($arg: ident: $arg_type: ty),*) -> $field_type: ty),*
+  }) => {
+    $(
+      #[derive(Clone, Debug)]
+      pub struct $field_name;
+      impl $field_name {
+        pub fn key($($arg: $arg_type),*) -> Vec<u8> {
+          $crate::serai_db_key(
+            stringify!($db_name).as_bytes(),
+            stringify!($field_name).as_bytes(),
+            ($($arg),*).encode()
+          )
+        }
+        #[allow(dead_code)]
+        pub fn set(txn: &mut impl DbTxn $(, $arg: $arg_type)*, data: &impl serde::Serialize) {
+          let key = $field_name::key($($arg),*);
+          txn.put(&key, bincode::serialize(data).unwrap());
+        }
+        #[allow(dead_code)]
+        pub fn get(getter: &impl Get, $($arg: $arg_type),*) -> Option<$field_type> {
+          getter.get($field_name::key($($arg),*)).map(|data| {
+            bincode::deserialize(data.as_ref()).unwrap()
+          })
+        }
+      }
+    )*
+  };
+}

common/db/src/lib.rs

@@ -1,3 +1,6 @@
+mod create_db;
+pub use create_db::*;
+
 mod mem;
 pub use mem::*;