From 67707830ede34f700eda1f9529e6ccadfae2e68c Mon Sep 17 00:00:00 2001
From: Joakim Soderlund <joakim.soderlund@gmail.com>
Date: Fri, 22 May 2020 22:55:38 +0200
Subject: [PATCH] Move interner to its own module

---
 src/archive/interner.rs | 35 +++++++++++++++++++++++++++++++++++
 src/archive/mod.rs      |  1 +
 src/archive/story.rs    | 29 +++++++----------------------
 3 files changed, 43 insertions(+), 22 deletions(-)
 create mode 100644 src/archive/interner.rs

diff --git a/src/archive/interner.rs b/src/archive/interner.rs
new file mode 100644
index 0000000..84ca455
--- /dev/null
+++ b/src/archive/interner.rs
@@ -0,0 +1,35 @@
+//! interner module.
+
+use std::collections::HashSet;
+use std::sync::RwLock;
+
+pub struct Interner<T: 'static>(RwLock<HashSet<&'static T>>);
+
+impl<T> Interner<T>
+where
+    T: Eq + std::hash::Hash,
+{
+    pub fn new() -> Self {
+        Self(RwLock::new(HashSet::new()))
+    }
+
+    fn get(&self, value: &T) -> Option<&'static T> {
+        let store = self.0.read().unwrap();
+
+        store.get(value).map(|value| *value)
+    }
+
+    fn set(&self, value: T) -> &'static T {
+        let boxed: Box<T> = Box::new(value);
+        let leaked: &'static T = Box::leak(boxed);
+        let mut store = self.0.write().unwrap();
+
+        store.insert(leaked);
+
+        leaked
+    }
+
+    pub fn leak(&self, value: T) -> &'static T {
+        self.get(&value).unwrap_or_else(|| self.set(value))
+    }
+}
diff --git a/src/archive/mod.rs b/src/archive/mod.rs
index 1216681..0882039 100644
--- a/src/archive/mod.rs
+++ b/src/archive/mod.rs
@@ -1,6 +1,7 @@
 //! Archive module.
 
 mod fetcher;
+mod interner;
 mod parser;
 mod story;
 
diff --git a/src/archive/story.rs b/src/archive/story.rs
index 092a738..50ac36e 100644
--- a/src/archive/story.rs
+++ b/src/archive/story.rs
@@ -1,18 +1,15 @@
 //! Story meta.
 
-use std::collections::HashSet;
-use std::sync::Mutex;
-
 use chrono::prelude::*;
-
+use lazy_static::lazy_static;
 use serde::de::Error;
 use serde::{Deserialize, Deserializer};
 use serde_json::Value;
 
-use lazy_static::lazy_static;
+use super::interner::Interner;
 
 lazy_static! {
-    static ref TAGS: Mutex<HashSet<&'static Tag>> = Mutex::new(HashSet::new());
+    static ref TAGS: Interner<Tag> = Interner::new();
 }
 
 #[derive(Clone, Debug, Deserialize)]
@@ -43,7 +40,7 @@ pub struct Story {
     pub short_description: String,
     pub status: Status,
     pub submitted: bool,
-    #[serde(deserialize_with = "interned_tag")]
+    #[serde(deserialize_with = "tags_as_static")]
     pub tags: Vec<&'static Tag>,
     #[serde(deserialize_with = "null_to_text")]
     pub title: String,
@@ -200,25 +197,13 @@ where
     }
 }
 
-fn interned_tag<'de, D>(d: D) -> Result<Vec<&'static Tag>, D::Error>
+fn tags_as_static<'de, D>(d: D) -> Result<Vec<&'static Tag>, D::Error>
 where
     D: Deserializer<'de>,
 {
-    let tags = Vec::<Tag>::deserialize(d)?;
-    let mut store = TAGS.lock().unwrap();
+    let tags: Vec<Tag> = Vec::deserialize(d)?;
 
-    Ok(tags
-        .into_iter()
-        .map(|tag| match store.get(&tag) {
-            Some(tag) => tag,
-            None => {
-                let boxed: Box<Tag> = Box::new(tag);
-                let leaked: &'static Tag = Box::leak(boxed);
-                store.insert(leaked);
-                leaked
-            }
-        })
-        .collect())
+    Ok(tags.into_iter().map(|tag| TAGS.leak(tag)).collect())
 }
 
 impl<'de> Deserialize<'de> for Color {