Introducing Environment.CpuUsage

src/libraries/System.Diagnostics.DiagnosticSource/src/System/Diagnostics/Metrics/RuntimeMetrics.cs

@@ -146,12 +146,14 @@ static RuntimeMetrics()
             unit: "{cpu}",
             description: "The number of processors available to the process.");
 
-        // TODO - Uncomment once an implementation for https://github.com/dotnet/runtime/issues/104844 is available.
-        //private static readonly ObservableCounter<double> s_processCpuTime = s_meter.CreateObservableCounter(
-        //    "dotnet.process.cpu.time",
-        //    GetCpuTime,
-        //    unit: "s",
-        //    description: "CPU time used by the process as reported by the CLR.");
+        private static readonly ObservableCounter<double>? s_processCpuTime =
+                                    OperatingSystem.IsBrowser() || OperatingSystem.IsTvOS() || (OperatingSystem.IsIOS() && !OperatingSystem.IsMacCatalyst()) ?
+                                    null :
+                                    s_meter.CreateObservableCounter(
+                                        "dotnet.process.cpu.time",
+                                        GetCpuTime,
+                                        unit: "s",
+                                        description: "CPU time used by the process.");
 
         public static bool IsEnabled()
         {
@@ -172,8 +174,8 @@ public static bool IsEnabled()
                 || s_threadPoolQueueLength.Enabled
                 || s_assembliesCount.Enabled
                 || s_exceptions.Enabled
-                || s_processCpuCount.Enabled;
-            //|| s_processCpuTime.Enabled;
+                || s_processCpuCount.Enabled
+                || (s_processCpuTime is not null && s_processCpuTime.Enabled);
         }
 
         private static IEnumerable<Measurement<long>> GetGarbageCollectionCounts()
@@ -188,17 +190,18 @@ private static IEnumerable<Measurement<long>> GetGarbageCollectionCounts()
             }
         }
 
-        // TODO - Uncomment once an implementation for https://github.com/dotnet/runtime/issues/104844 is available.
-        //private static IEnumerable<Measurement<double>> GetCpuTime()
-        //{
-        //    if (OperatingSystem.IsBrowser() || OperatingSystem.IsTvOS() || OperatingSystem.IsIOS())
-        //        yield break;
+        private static IEnumerable<Measurement<double>> GetCpuTime()
+        {
+            Debug.Assert(s_processCpuTime is not null);
+            Debug.Assert(!OperatingSystem.IsBrowser() && !OperatingSystem.IsTvOS() && !(OperatingSystem.IsIOS() && !OperatingSystem.IsMacCatalyst()));
 
-        //    ProcessCpuUsage processCpuUsage = Environment.CpuUsage;
+            #pragma warning disable CA1416 // This call site is reachable on all platforms. 'Environment.CpuUsage' is unsupported on: 'ios', 'tvos'
+            Environment.ProcessCpuUsage processCpuUsage = Environment.CpuUsage;
+            #pragma warning restore CA1416
 
-        //    yield return new(processCpuUsage.UserTime.TotalSeconds, [new KeyValuePair<string, object?>("cpu.mode", "user")]);
-        //    yield return new(processCpuUsage.PrivilegedTime.TotalSeconds, [new KeyValuePair<string, object?>("cpu.mode", "system")]);
-        //}
+            yield return new(processCpuUsage.UserTime.TotalSeconds, [new KeyValuePair<string, object?>("cpu.mode", "user")]);
+            yield return new(processCpuUsage.PrivilegedTime.TotalSeconds, [new KeyValuePair<string, object?>("cpu.mode", "system")]);
+        }
 
         private static IEnumerable<Measurement<long>> GetHeapSizes()
         {

src/libraries/System.Diagnostics.DiagnosticSource/tests/RuntimeMetricsTests.cs

@@ -112,48 +112,47 @@ public void GcCollectionsCount()
             }
         }
 
-        // TODO - Uncomment once an implementation for https://github.com/dotnet/runtime/issues/104844 is available.
-        //[Fact]
-        //public void CpuTime()
-        //{
-        //    using InstrumentRecorder<double> instrumentRecorder = new("dotnet.process.cpu.time");
-
-        //    instrumentRecorder.RecordObservableInstruments();
-
-        //    bool[] foundCpuModes = [false, false];
-
-        //    foreach (Measurement<double> measurement in instrumentRecorder.GetMeasurements().Where(m => m.Value >= 0))
-        //    {
-        //        var tags = measurement.Tags.ToArray();
-        //        var tag = tags.SingleOrDefault(k => k.Key == "cpu.mode");
-
-        //        if (tag.Key is not null)
-        //        {
-        //            Assert.True(tag.Value is string, "Expected CPU mode tag to be a string.");
-
-        //            string tagValue = (string)tag.Value;
-
-        //            switch (tagValue)
-        //            {
-        //                case "user":
-        //                    foundCpuModes[0] = true;
-        //                    break;
-        //                case "system":
-        //                    foundCpuModes[1] = true;
-        //                    break;
-        //                default:
-        //                    Assert.Fail($"Unexpected CPU mode tag value '{tagValue}'.");
-        //                    break;
-        //            }
-        //        }
-        //    }
-
-        //    for (int i = 0; i < foundCpuModes.Length; i++)
-        //    {
-        //        var mode = i == 0 ? "user" : "system";
-        //        Assert.True(foundCpuModes[i], $"Expected to find a measurement for '{mode}' CPU mode.");
-        //    }
-        //}
+        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsNotBrowser))]
+        public void CpuTime()
+        {
+           using InstrumentRecorder<double> instrumentRecorder = new("dotnet.process.cpu.time");
+
+           instrumentRecorder.RecordObservableInstruments();
+
+           bool[] foundCpuModes = [false, false];
+
+           foreach (Measurement<double> measurement in instrumentRecorder.GetMeasurements().Where(m => m.Value >= 0))
+           {
+               var tags = measurement.Tags.ToArray();
+               var tag = tags.SingleOrDefault(k => k.Key == "cpu.mode");
+
+               if (tag.Key is not null)
+               {
+                   Assert.True(tag.Value is string, "Expected CPU mode tag to be a string.");
+
+                   string tagValue = (string)tag.Value;
+
+                   switch (tagValue)
+                   {
+                       case "user":
+                           foundCpuModes[0] = true;
+                           break;
+                       case "system":
+                           foundCpuModes[1] = true;
+                           break;
+                       default:
+                           Assert.Fail($"Unexpected CPU mode tag value '{tagValue}'.");
+                           break;
+                   }
+               }
+           }
+
+           for (int i = 0; i < foundCpuModes.Length; i++)
+           {
+               var mode = i == 0 ? "user" : "system";
+               Assert.True(foundCpuModes[i], $"Expected to find a measurement for '{mode}' CPU mode.");
+           }
+        }
 
         [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsNotBrowser))]
         public void ExceptionsCount()

src/libraries/System.Diagnostics.Process/src/System/Diagnostics/Process.FreeBSD.cs

@@ -34,6 +34,11 @@ public TimeSpan TotalProcessorTime
         {
             get
             {
+                if (IsCurrentProcess)
+                {
+                    return Environment.CpuUsage.TotalTime;
+                }
+
                 EnsureState(State.HaveNonExitedId);
                 Interop.Process.proc_stats stat = Interop.Process.GetThreadInfo(_processId, 0);
                 return Process.TicksToTimeSpan(stat.userTime + stat.systemTime);
@@ -51,6 +56,11 @@ public TimeSpan UserProcessorTime
         {
             get
             {
+                if (IsCurrentProcess)
+                {
+                    return Environment.CpuUsage.UserTime;
+                }
+
                 EnsureState(State.HaveNonExitedId);
 
                 Interop.Process.proc_stats stat = Interop.Process.GetThreadInfo(_processId, 0);
@@ -66,6 +76,11 @@ public TimeSpan PrivilegedProcessorTime
         {
             get
             {
+                if (IsCurrentProcess)
+                {
+                    return Environment.CpuUsage.PrivilegedTime;
+                }
+
                 EnsureState(State.HaveNonExitedId);
 
                 Interop.Process.proc_stats stat = Interop.Process.GetThreadInfo(_processId, 0);

src/libraries/System.Diagnostics.Process/src/System/Diagnostics/Process.Linux.cs

@@ -53,10 +53,7 @@ public static Process[] GetProcessesByName(string? processName, string machineNa
         [SupportedOSPlatform("maccatalyst")]
         public TimeSpan PrivilegedProcessorTime
         {
-            get
-            {
-                return TicksToTimeSpan(GetStat().stime);
-            }
+            get => IsCurrentProcess ? Environment.CpuUsage.PrivilegedTime : TicksToTimeSpan(GetStat().stime);
         }
 
         /// <summary>Gets the time the associated process was started.</summary>
@@ -132,6 +129,11 @@ public TimeSpan TotalProcessorTime
         {
             get
             {
+                if (IsCurrentProcess)
+                {
+                    return Environment.CpuUsage.TotalTime;
+                }
+
                 Interop.procfs.ParsedStat stat = GetStat();
                 return TicksToTimeSpan(stat.utime + stat.stime);
             }
@@ -146,10 +148,7 @@ public TimeSpan TotalProcessorTime
         [SupportedOSPlatform("maccatalyst")]
         public TimeSpan UserProcessorTime
         {
-            get
-            {
-                return TicksToTimeSpan(GetStat().utime);
-            }
+            get => IsCurrentProcess ? Environment.CpuUsage.UserTime : TicksToTimeSpan(GetStat().utime);
         }
 
         partial void EnsureHandleCountPopulated()

src/libraries/System.Diagnostics.Process/src/System/Diagnostics/Process.OSX.cs

@@ -22,6 +22,11 @@ public TimeSpan PrivilegedProcessorTime
         {
             get
             {
+                if (IsCurrentProcess)
+                {
+                    return Environment.CpuUsage.PrivilegedTime;
+                }
+
                 EnsureState(State.HaveNonExitedId);
                 Interop.libproc.rusage_info_v3 info = Interop.libproc.proc_pid_rusage(_processId);
                 return MapTime(info.ri_system_time);
@@ -64,6 +69,11 @@ public TimeSpan TotalProcessorTime
         {
             get
             {
+                if (IsCurrentProcess)
+                {
+                    return Environment.CpuUsage.TotalTime;
+                }
+
                 EnsureState(State.HaveNonExitedId);
                 Interop.libproc.rusage_info_v3 info = Interop.libproc.proc_pid_rusage(_processId);
                 return MapTime(info.ri_system_time + info.ri_user_time);
@@ -81,6 +91,11 @@ public TimeSpan UserProcessorTime
         {
             get
             {
+                if (IsCurrentProcess)
+                {
+                    return Environment.CpuUsage.UserTime;
+                }
+
                 EnsureState(State.HaveNonExitedId);
                 Interop.libproc.rusage_info_v3 info = Interop.libproc.proc_pid_rusage(_processId);
                 return MapTime(info.ri_user_time);

src/libraries/System.Diagnostics.Process/src/System/Diagnostics/Process.Windows.cs

@@ -232,7 +232,7 @@ private DateTime ExitTimeCore
         [SupportedOSPlatform("maccatalyst")]
         public TimeSpan PrivilegedProcessorTime
         {
-            get { return GetProcessTimes().PrivilegedProcessorTime; }
+            get => IsCurrentProcess ? Environment.CpuUsage.PrivilegedTime : GetProcessTimes().PrivilegedProcessorTime;
         }
 
         /// <summary>Gets the time the associated process was started.</summary>
@@ -251,7 +251,7 @@ internal DateTime StartTimeCore
         [SupportedOSPlatform("maccatalyst")]
         public TimeSpan TotalProcessorTime
         {
-            get { return GetProcessTimes().TotalProcessorTime; }
+            get => IsCurrentProcess ? Environment.CpuUsage.TotalTime : GetProcessTimes().TotalProcessorTime;
         }
 
         /// <summary>
@@ -263,7 +263,7 @@ public TimeSpan TotalProcessorTime
         [SupportedOSPlatform("maccatalyst")]
         public TimeSpan UserProcessorTime
         {
-            get { return GetProcessTimes().UserProcessorTime; }
+            get => IsCurrentProcess ? Environment.CpuUsage.UserTime : GetProcessTimes().UserProcessorTime;
         }
 
         /// <summary>

src/libraries/System.Diagnostics.Process/src/System/Diagnostics/Process.cs

@@ -1106,6 +1106,8 @@ public static Process[] GetProcesses(string machineName)
             return processes;
         }
 
+        private bool IsCurrentProcess => _processId == Environment.ProcessId;
+
         /// <devdoc>
         ///    <para>
         ///       Returns a new <see cref='System.Diagnostics.Process'/>

src/libraries/System.Private.CoreLib/src/System/Environment.UnixOrBrowser.cs

@@ -5,6 +5,7 @@
 using System.IO;
 using System.Reflection;
 using System.Runtime.InteropServices;
+using System.Runtime.Versioning;
 using System.Text;
 using System.Threading;
 
@@ -69,5 +70,36 @@ private static int CheckedSysConf(Interop.Sys.SysConfName name)
             }
             return (int)result;
         }
+
+        /// <summary>
+        /// Get the CPU usage, including the process time spent running the application code, the process time spent running the operating system code,
+        /// and the total time spent running both the application and operating system code.
+        /// </summary>
+        [SupportedOSPlatform("maccatalyst")]
+        [UnsupportedOSPlatform("ios")]
+        [UnsupportedOSPlatform("tvos")]
+        [UnsupportedOSPlatform("browser")]
+        public static ProcessCpuUsage CpuUsage
+        {
+            get
+            {
+                Interop.Sys.ProcessCpuInformation cpuInfo = default;
+                Interop.Sys.GetCpuUtilization(ref cpuInfo);
+
+                ulong userTime100Nanoseconds = cpuInfo.lastRecordedUserTime / 100; // nanoseconds to 100-nanoseconds
+                if (userTime100Nanoseconds > long.MaxValue)
+                {
+                    userTime100Nanoseconds = long.MaxValue;
+                }
+
+                ulong kernelTime100Nanoseconds = cpuInfo.lastRecordedKernelTime / 100; // nanoseconds to 100-nanoseconds
+                if (kernelTime100Nanoseconds > long.MaxValue)
+                {
+                    kernelTime100Nanoseconds = long.MaxValue;
+                }
+
+                return new ProcessCpuUsage { UserTime = new TimeSpan((long)userTime100Nanoseconds), PrivilegedTime = new TimeSpan((long)kernelTime100Nanoseconds) };
+            }
+        }
     }
 }

src/libraries/System.Private.CoreLib/src/System/Environment.Windows.cs

@@ -6,6 +6,7 @@
 using System.IO;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
+using System.Runtime.Versioning;
 using System.Text;
 using Microsoft.Win32.SafeHandles;
 
@@ -358,5 +359,20 @@ private static unsafe string[] SegmentCommandLine(char* cmdLine)
 
             return arrayBuilder.ToArray();
         }
+
+        /// <summary>
+        /// Get the CPU usage, including the process time spent running the application code, the process time spent running the operating system code,
+        /// and the total time spent running both the application and operating system code.
+        /// </summary>
+        [SupportedOSPlatform("maccatalyst")]
+        [UnsupportedOSPlatform("ios")]
+        [UnsupportedOSPlatform("tvos")]
+        [UnsupportedOSPlatform("browser")]
+        public static ProcessCpuUsage CpuUsage
+        {
+            get => Interop.Kernel32.GetProcessTimes(Interop.Kernel32.GetCurrentProcess(), out _, out _, out long procKernelTime, out long procUserTime) ?
+                    new ProcessCpuUsage { UserTime = new TimeSpan(procUserTime), PrivilegedTime = new TimeSpan(procKernelTime) } :
+                    new ProcessCpuUsage { UserTime = TimeSpan.Zero, PrivilegedTime = TimeSpan.Zero };
+        }
     }
 }

src/libraries/System.Private.CoreLib/src/System/Environment.cs

@@ -10,6 +10,31 @@ namespace System
 {
     public static partial class Environment
     {
+        /// <summary>
+        /// Represents the CPU usage statistics of a process.
+        /// </summary>
+        /// <remarks>
+        /// The CPU usage statistics include information about the time spent by the process in the application code (user mode) and the operating system code (kernel mode),
+        /// as well as the total time spent by the process in both user mode and kernel mode.
+        /// </remarks>
+        public readonly struct ProcessCpuUsage
+        {
+            /// <summary>
+            /// Gets the amount of time the associated process has spent running code inside the application portion of the process (not the operating system code).
+            /// </summary>
+            public TimeSpan UserTime { get; internal init; }
+
+            /// <summary>
+            /// Gets the amount of time the process has spent running code inside the operating system code.
+            /// </summary>
+            public TimeSpan PrivilegedTime { get; internal init; }
+
+            /// <summary>
+            /// Gets the amount of time the process has spent utilizing the CPU including the process time spent in the application code and the process time spent in the operating system code.
+            /// </summary>
+            public TimeSpan TotalTime => UserTime + PrivilegedTime;
+        }
+
         public static int ProcessorCount { get; } = GetProcessorCount();
 
         /// <summary>