From 830faf74247ee225aa5c5884caaf2b55c409cbce Mon Sep 17 00:00:00 2001
From: Natsu Kagami <natsukagami@gmail.com>
Date: Wed, 2 Sep 2020 17:24:49 -0400
Subject: [PATCH] DB: No more Arcs!

---
 youmubot-db/src/lib.rs | 58 ++++++++++++++++++++++--------------------
 1 file changed, 30 insertions(+), 28 deletions(-)

diff --git a/youmubot-db/src/lib.rs b/youmubot-db/src/lib.rs
index af734f0..51c7db6 100644
--- a/youmubot-db/src/lib.rs
+++ b/youmubot-db/src/lib.rs
@@ -1,15 +1,19 @@
-use rustbreak::{deser::Yaml as Ron, FileDatabase};
+use rustbreak::{deser::Yaml, FileDatabase};
 use serde::{de::DeserializeOwned, Deserialize, Serialize};
 use serenity::{framework::standard::CommandError as Error, model::id::GuildId, prelude::*};
-use std::collections::HashMap;
-use std::{cell::Cell, path::Path, sync::Arc};
+use std::{collections::HashMap, path::Path};
+
 /// GuildMap defines the guild-map type.
 /// It is basically a HashMap from a GuildId to a data structure.
 pub type GuildMap<V> = HashMap<GuildId, V>;
 /// The generic DB type we will be using.
 pub struct DB<T>(std::marker::PhantomData<T>);
-impl<T: std::any::Any> serenity::prelude::TypeMapKey for DB<T> {
-    type Value = Arc<FileDatabase<T, Ron>>;
+
+/// A short type abbreviation for a FileDatabase.
+type Database<T> = FileDatabase<T, Yaml>;
+
+impl<T: std::any::Any + Send + Sync> serenity::prelude::TypeMapKey for DB<T> {
+    type Value = Database<T>;
 }
 
 impl<T: std::any::Any + Default + Send + Sync + Clone + Serialize + std::fmt::Debug> DB<T>
@@ -17,66 +21,64 @@ where
     for<'de> T: Deserialize<'de>,
 {
     /// Insert into a ShareMap.
-    pub fn insert_into(data: &mut ShareMap, path: impl AsRef<Path>) -> Result<(), Error> {
-        let db = FileDatabase::<T, Ron>::from_path(path, T::default())?;
-        db.load().or_else(|e| {
-            dbg!(e);
-            db.save()
-        })?;
-        data.insert::<DB<T>>(Arc::new(db));
+    pub fn insert_into(data: &mut TypeMap, path: impl AsRef<Path>) -> Result<(), Error> {
+        let db = Database::<T>::load_from_path_or_default(path)?;
+        data.insert::<DB<T>>(db);
         Ok(())
     }
 
     /// Open a previously inserted DB.
-    pub fn open(data: &ShareMap) -> DBWriteGuard<T> {
-        data.get::<Self>().expect("DB initialized").clone().into()
+    pub fn open(data: &TypeMap) -> DBWriteGuard<T> {
+        data.get::<Self>().expect("DB initialized").into()
     }
 }
 
 /// The write guard for our FileDatabase.
 /// It wraps the FileDatabase in a write-on-drop lock.
 #[derive(Debug)]
-pub struct DBWriteGuard<T>
+pub struct DBWriteGuard<'a, T>
 where
     T: Send + Sync + Clone + std::fmt::Debug + Serialize + DeserializeOwned,
 {
-    db: Arc<FileDatabase<T, Ron>>,
-    needs_save: Cell<bool>,
+    db: &'a Database<T>,
+    needs_save: bool,
 }
 
-impl<T> From<Arc<FileDatabase<T, Ron>>> for DBWriteGuard<T>
+impl<'a, T> From<&'a Database<T>> for DBWriteGuard<'a, T>
 where
     T: Send + Sync + Clone + std::fmt::Debug + Serialize + DeserializeOwned,
 {
-    fn from(v: Arc<FileDatabase<T, Ron>>) -> Self {
+    fn from(v: &'a Database<T>) -> Self {
         DBWriteGuard {
             db: v,
-            needs_save: Cell::new(false),
+            needs_save: false,
         }
     }
 }
 
-impl<T> DBWriteGuard<T>
+impl<'a, T> DBWriteGuard<'a, T>
 where
     T: Send + Sync + Clone + std::fmt::Debug + Serialize + DeserializeOwned,
 {
     /// Borrows the FileDatabase.
-    pub fn borrow(&self) -> Result<std::sync::RwLockReadGuard<T>, rustbreak::RustbreakError> {
-        (*self).db.borrow_data()
+    pub fn borrow(&'a self) -> Result<std::sync::RwLockReadGuard<T>, rustbreak::RustbreakError> {
+        self.db.borrow_data()
     }
     /// Borrows the FileDatabase for writing.
-    pub fn borrow_mut(&self) -> Result<std::sync::RwLockWriteGuard<T>, rustbreak::RustbreakError> {
-        self.needs_save.set(true);
-        (*self).db.borrow_data_mut()
+    pub fn borrow_mut(
+        &'a mut self,
+    ) -> Result<std::sync::RwLockWriteGuard<T>, rustbreak::RustbreakError> {
+        self.needs_save = true;
+        self.db.borrow_data_mut()
     }
 }
 
-impl<T> Drop for DBWriteGuard<T>
+impl<'a, T> Drop for DBWriteGuard<'a, T>
 where
     T: Send + Sync + Clone + std::fmt::Debug + Serialize + DeserializeOwned,
 {
     fn drop(&mut self) {
-        if self.needs_save.get() {
+        if self.needs_save {
             if let Err(e) = self.db.save() {
                 dbg!(e);
             }