Implemented node system statistics

MoonlightServers.Daemon/Helpers/SystemMetrics.cs

@@ -0,0 +1,59 @@
+namespace MoonlightServers.Daemon.Helpers;
+
+/// <summary>
+/// Reads Linux system metrics directly from the <c>/proc</c> and <c>/sys</c>
+/// pseudo-filesystems
+/// </summary>
+public static partial class SystemMetrics
+{
+    public record SystemSnapshot(
+        CpuSnapshot Cpu,
+        MemoryInfo Memory,
+        IReadOnlyList<DiskInfo> Disks,
+        IReadOnlyList<NetworkInterfaceInfo> Network,
+        TimeSpan Uptime
+    );
+
+    /// <summary>
+    /// Collects a full system snapshot. The method waits <paramref name="sampleIntervalMs"/>
+    /// milliseconds between the two samples required to compute CPU and network rates.
+    /// All other reads happen in parallel during the second sampling window.
+    /// </summary>
+    /// <param name="sampleIntervalMs">
+    /// Interval between rate-measurement samples in milliseconds.
+    /// Larger values yield smoother CPU and network averages. Defaults to <c>500</c>.
+    /// </param>
+    /// <returns>A fully populated <see cref="SystemSnapshot"/>.</returns>
+    public static async Task<SystemSnapshot> ReadAllAsync(int sampleIntervalMs = 500)
+    {
+        // First samples — must complete before the delay.
+        var cpuSample1Task = ReadRawCpuStatsAsync();
+        var netSample1Task = ReadRawNetStatsAsync();
+        await Task.WhenAll(cpuSample1Task, netSample1Task);
+
+        await Task.Delay(sampleIntervalMs);
+
+        // Second samples + all independent reads run concurrently.
+        var cpuSample2Task = ReadRawCpuStatsAsync();
+        var netSample2Task = ReadRawNetStatsAsync();
+        var memTask = ReadMemoryAsync();
+        var diskTask = ReadDisksAsync();
+        var uptimeTask = ReadUptimeAsync();
+        var cpuNameTask = ReadCpuModelNameAsync();
+
+        await Task.WhenAll(cpuSample2Task, netSample2Task, memTask, diskTask, uptimeTask, cpuNameTask);
+
+        var cpu = ComputeCpuUsage(cpuNameTask.Result, cpuSample1Task.Result, cpuSample2Task.Result);
+        var network = ComputeNetworkRates(netSample1Task.Result, netSample2Task.Result, sampleIntervalMs / 1000.0);
+
+        return new SystemSnapshot(cpu, memTask.Result, diskTask.Result, network, uptimeTask.Result);
+    }
+
+    // Uptime
+    private static async Task<TimeSpan> ReadUptimeAsync()
+    {
+        var text = await File.ReadAllTextAsync("/proc/uptime");
+        var seconds = double.Parse(text.Split(' ')[0], System.Globalization.CultureInfo.InvariantCulture);
+        return TimeSpan.FromSeconds(seconds);
+    }
+}