asset count diagnostic

crates/bevy_asset/Cargo.toml

@@ -19,6 +19,7 @@ filesystem_watcher = ["notify"]
 [dependencies]
 # bevy
 bevy_app = { path = "../bevy_app", version = "0.4.0" }
+bevy_diagnostic = { path = "../bevy_diagnostic", version = "0.4.0" }
 bevy_ecs = { path = "../bevy_ecs", version = "0.4.0" }
 bevy_reflect = { path = "../bevy_reflect", version = "0.4.0", features = ["bevy"] }
 bevy_tasks = { path = "../bevy_tasks", version = "0.4.0" }

crates/bevy_asset/src/diagnostic/asset_count_diagnostics_plugin.rs

@@ -0,0 +1,35 @@
+use crate::{Asset, Assets};
+use bevy_app::prelude::*;
+use bevy_diagnostic::{Diagnostic, DiagnosticId, Diagnostics};
+use bevy_ecs::{IntoSystem, Res, ResMut};
+
+/// Adds "asset count" diagnostic to an App
+#[derive(Default)]
+pub struct AssetCountDiagnosticsPlugin<T: Asset> {
+    marker: std::marker::PhantomData<T>,
+}
+
+impl<T: Asset> Plugin for AssetCountDiagnosticsPlugin<T> {
+    fn build(&self, app: &mut AppBuilder) {
+        app.add_startup_system(Self::setup_system.system())
+            .add_system(Self::diagnostic_system.system());
+    }
+}
+
+impl<T: Asset> AssetCountDiagnosticsPlugin<T> {
+    pub fn diagnostic_id() -> DiagnosticId {
+        DiagnosticId(T::TYPE_UUID)
+    }
+
+    pub fn setup_system(mut diagnostics: ResMut<Diagnostics>) {
+        diagnostics.add(Diagnostic::new(
+            Self::diagnostic_id(),
+            &format!("asset_count {}", std::any::type_name::<T>()),
+            20,
+        ));
+    }
+
+    pub fn diagnostic_system(mut diagnostics: ResMut<Diagnostics>, assets: Res<Assets<T>>) {
+        diagnostics.add_measurement(Self::diagnostic_id(), assets.len() as f64);
+    }
+}

crates/bevy_asset/src/diagnostic/mod.rs

@@ -0,0 +1,2 @@
+mod asset_count_diagnostics_plugin;
+pub use asset_count_diagnostics_plugin::AssetCountDiagnosticsPlugin;

crates/bevy_asset/src/lib.rs

@@ -1,5 +1,6 @@
 mod asset_server;
 mod assets;
+pub mod diagnostic;
 #[cfg(all(
     feature = "filesystem_watcher",
     all(not(target_arch = "wasm32"), not(target_os = "android"))

examples/diagnostics/log_diagnostics.rs

@@ -15,5 +15,7 @@ fn main() {
         // .add_plugin(bevy::wgpu::diagnostic::WgpuResourceDiagnosticsPlugin::default())
         // Uncomment this to add an entity count diagnostics:
         // .add_plugin(bevy::diagnostic::EntityCountDiagnosticsPlugin::default())
+        // Uncomment this to add an asset count diagnostics:
+        // .add_plugin(bevy::asset::diagnostic::AssetCountDiagnosticsPlugin::<Texture>::default())
         .run();
 }