lib: Cache the output of is_sandboxed

src/lib.rs

@@ -12,13 +12,16 @@ compile_error!("You can't enable both async-std & tokio features at once");
 /// Alias for a [`Result`] with the error type `ashpd::Error`.
 pub type Result<T> = std::result::Result<T, Error>;
 
+static IS_SANDBOXED: OnceCell<bool> = OnceCell::new();
+
 /// Interact with the user's desktop such as taking a screenshot, setting a
 /// background or querying the user's location.
 pub mod desktop;
 /// Interact with the documents store or transfer files across apps.
 pub mod documents;
 mod error;
 mod window_identifier;
+
 pub use self::window_identifier::WindowIdentifier;
 mod app_id;
 pub use self::app_id::AppID;
@@ -32,20 +35,27 @@ mod proxy;
 pub mod flatpak;
 mod helpers;
 pub use enumflags2;
+use once_cell::sync::OnceCell;
 pub use url;
 pub use zbus::{self, zvariant};
 
 /// Check whether the application is running inside a sandbox.
 ///
 /// The function checks whether the file `/.flatpak-info` exists, or if the app
 /// is running as a snap, or if the environment variable `GTK_USE_PORTAL` is set
-/// to `1`.
+/// to `1`. As the return value of this function will not change during the
+/// runtime of a program; it is cached for future calls.
 pub async fn is_sandboxed() -> bool {
-    crate::helpers::is_flatpak().await
+    if let Some(cached_value) = IS_SANDBOXED.get() {
+        return *cached_value;
+    }
+    let new_value = crate::helpers::is_flatpak().await
         || crate::helpers::is_snap().await
         || std::env::var("GTK_USE_PORTAL")
             .map(|v| v == "1")
-            .unwrap_or(false)
+            .unwrap_or(false);
+    IS_SANDBOXED.set(new_value).unwrap(); // Safe to unwrap here
+    new_value
 }
 
 pub use self::error::{Error, PortalError};