fix support for language switch

update document

src/ext/json.rs

@@ -1,4 +1,7 @@
 use json::JsonValue;
+use std::ops::Deref;
+use std::sync::RwLockReadGuard;
+use std::sync::RwLockWriteGuard;
 
 pub trait ToJson {
     fn to_json(&self) -> Option<JsonValue>;
@@ -28,6 +31,27 @@ impl<T: ToJson> ToJson for &T {
     }
 }
 
+impl<T: ToJson> ToJson for Option<T> {
+    fn to_json(&self) -> Option<JsonValue> {
+        match self {
+            Some(d) => { d.to_json() }
+            None => { None }
+        }
+    }
+}
+
+impl<T: ToJson> ToJson for RwLockReadGuard<'_, T> {
+    fn to_json(&self) -> Option<JsonValue> {
+        self.deref().to_json()
+    }
+}
+
+impl<T: ToJson> ToJson for RwLockWriteGuard<'_, T> {
+    fn to_json(&self) -> Option<JsonValue> {
+        self.deref().to_json()
+    }
+}
+
 pub trait FromJson where Self: Sized {
     type Err;
     fn from_json<T: ToJson>(v: T) -> Result<Self, Self::Err>;

src/ext/mod.rs

@@ -4,5 +4,6 @@ pub mod flagset;
 pub mod json;
 #[cfg(any(feature = "exif", feature = "avdict", feature = "ugoira"))]
 pub mod rawhandle;
+pub mod rw_lock;
 pub mod try_err;
 pub mod use_or_not;

src/ext/rw_lock.rs

@@ -0,0 +1,35 @@
+use spin_on::spin_on;
+use std::sync::RwLock;
+use std::sync::RwLockReadGuard;
+use std::sync::RwLockWriteGuard;
+use std::time::Duration;
+
+pub trait GetRwLock {
+    type Target;
+    fn get_ref(&self) -> RwLockReadGuard<Self::Target>;
+    fn get_mut(&self) -> RwLockWriteGuard<Self::Target>;
+}
+
+impl<T: Sized> GetRwLock for RwLock<T> {
+    type Target = T;
+    fn get_ref<'a>(&'a self) -> RwLockReadGuard<'a, Self::Target> {
+        loop {
+            match self.try_read() {
+                Ok(f) => { return f; }
+                Err(_) => {
+                    spin_on(tokio::time::sleep(Duration::new(0, 1_000_000)));
+                }
+            }
+        }
+    }
+    fn get_mut<'a>(&'a self) -> RwLockWriteGuard<'a, Self::Target> {
+        loop {
+            match self.try_write() {
+                Ok(f) => { return f; }
+                Err(_) => {
+                    spin_on(tokio::time::sleep(Duration::new(0, 1_000_000)));
+                }
+            }
+        }
+    }
+}