Make SystemInfo a Resource (#12584)

# Objective

We already collect a lot of system information on startup when possible
but we don't make this information available. With the upcoming work on
a diagnostic overlay it would be useful to be able to display this
information.

## Solution

Make the already existing SystemInfo a Resource

---

## Changelog

Added `SystemInfo` Resource

---------

Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: Afonso Lage <lage.afonso@gmail.com>

crates/bevy_diagnostic/src/lib.rs

@@ -19,7 +19,7 @@ pub use entity_count_diagnostics_plugin::EntityCountDiagnosticsPlugin;
 pub use frame_time_diagnostics_plugin::FrameTimeDiagnosticsPlugin;
 pub use log_diagnostics_plugin::LogDiagnosticsPlugin;
 #[cfg(feature = "sysinfo_plugin")]
-pub use system_information_diagnostics_plugin::SystemInformationDiagnosticsPlugin;
+pub use system_information_diagnostics_plugin::{SystemInfo, SystemInformationDiagnosticsPlugin};
 
 use bevy_app::prelude::*;
 
@@ -28,12 +28,11 @@ use bevy_app::prelude::*;
 pub struct DiagnosticsPlugin;
 
 impl Plugin for DiagnosticsPlugin {
-    fn build(&self, _app: &mut App) {
+    fn build(&self, app: &mut App) {
+        app.init_resource::<DiagnosticsStore>();
+
         #[cfg(feature = "sysinfo_plugin")]
-        _app.init_resource::<DiagnosticsStore>().add_systems(
+        app.init_resource::<system_information_diagnostics_plugin::SystemInfo>();
-            Startup,
-            system_information_diagnostics_plugin::internal::log_system_info,
-        );
     }
 }
 

crates/bevy_diagnostic/src/system_information_diagnostics_plugin.rs

@@ -1,5 +1,6 @@
 use crate::DiagnosticPath;
 use bevy_app::prelude::*;
+use bevy_ecs::system::Resource;
 
 /// Adds a System Information Diagnostic, specifically `cpu_usage` (in %) and `mem_usage` (in %)
 ///
@@ -24,10 +25,27 @@ impl Plugin for SystemInformationDiagnosticsPlugin {
 }
 
 impl SystemInformationDiagnosticsPlugin {
+    /// Total system cpu usage in %
     pub const CPU_USAGE: DiagnosticPath = DiagnosticPath::const_new("system/cpu_usage");
+    /// Total system memory usage in %
     pub const MEM_USAGE: DiagnosticPath = DiagnosticPath::const_new("system/mem_usage");
 }
 
+/// A resource that stores diagnostic information about the system.
+/// This information can be useful for debugging and profiling purposes.
+///
+/// # See also
+///
+/// [`SystemInformationDiagnosticsPlugin`] for more information.
+#[derive(Debug, Resource)]
+pub struct SystemInfo {
+    pub os: String,
+    pub kernel: String,
+    pub cpu: String,
+    pub core_count: String,
+    pub memory: String,
+}
+
 // NOTE: sysinfo fails to compile when using bevy dynamic or on iOS and does nothing on wasm
 #[cfg(all(
     any(
@@ -45,7 +63,7 @@ pub mod internal {
 
     use crate::{Diagnostic, Diagnostics, DiagnosticsStore};
 
-    use super::SystemInformationDiagnosticsPlugin;
+    use super::{SystemInfo, SystemInformationDiagnosticsPlugin};
 
     const BYTES_TO_GIB: f64 = 1.0 / 1024.0 / 1024.0 / 1024.0;
 
@@ -87,25 +105,15 @@ pub mod internal {
         });
     }
 
-    #[derive(Debug)]
+    impl Default for SystemInfo {
-    // This is required because the Debug trait doesn't detect it's used when it's only used in a print :(
+        fn default() -> Self {
-    #[allow(dead_code)]
-    struct SystemInfo {
-        os: String,
-        kernel: String,
-        cpu: String,
-        core_count: String,
-        memory: String,
-    }
-
-    pub(crate) fn log_system_info() {
             let sys = System::new_with_specifics(
                 RefreshKind::new()
                     .with_cpu(CpuRefreshKind::new())
                     .with_memory(MemoryRefreshKind::new().with_ram()),
             );
 
-        let info = SystemInfo {
+            let system_info = SystemInfo {
                 os: System::long_os_version().unwrap_or_else(|| String::from("not available")),
                 kernel: System::kernel_version().unwrap_or_else(|| String::from("not available")),
                 cpu: sys
@@ -121,7 +129,9 @@ pub mod internal {
                 memory: format!("{:.1} GiB", sys.total_memory() as f64 * BYTES_TO_GIB),
             };
 
-        info!("{:?}", info);
+            info!("{:?}", system_info);
+            system_info
+        }
     }
 }
 
@@ -143,7 +153,16 @@ pub mod internal {
         // no-op
     }
 
-    pub(crate) fn log_system_info() {
+    impl Default for super::SystemInfo {
-        // no-op
+        fn default() -> Self {
+            let unknown = "Unknown".to_string();
+            Self {
+                os: unknown.clone(),
+                kernel: unknown.clone(),
+                cpu: unknown.clone(),
+                core_count: unknown.clone(),
+                memory: unknown.clone(),
+            }
+        }
     }
 }