[3.1 port] Improve the performance of Environment.WorkingSet in Windows (#26522)

src/System.Private.CoreLib/shared/Interop/Windows/Kernel32/Interop.GetProcessMemoryInfo.cs

@@ -0,0 +1,30 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System;
+using System.Runtime.InteropServices;
+
+internal partial class Interop
+{
+    internal partial class Kernel32
+    {
+        [StructLayout(LayoutKind.Sequential)]
+        internal struct PROCESS_MEMORY_COUNTERS
+        {
+            public uint cb;
+            public uint PageFaultCount;
+            public UIntPtr PeakWorkingSetSize;
+            public UIntPtr WorkingSetSize;
+            public UIntPtr QuotaPeakPagedPoolUsage;
+            public UIntPtr QuotaPagedPoolUsage;
+            public UIntPtr QuotaPeakNonPagedPoolUsage;
+            public UIntPtr QuotaNonPagedPoolUsage;
+            public UIntPtr PagefileUsage;
+            public UIntPtr PeakPagefileUsage;
+        }
+
+        [DllImport(Libraries.Kernel32, EntryPoint="K32GetProcessMemoryInfo")]
+        internal static extern bool GetProcessMemoryInfo(IntPtr Process, ref PROCESS_MEMORY_COUNTERS ppsmemCounters, uint cb);
+    }
+}

src/System.Private.CoreLib/shared/System.Private.CoreLib.Shared.projitems

@@ -1047,6 +1047,7 @@
     <Compile Include="$(MSBuildThisFileDirectory)Interop\Windows\Kernel32\Interop.GetFullPathNameW.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Interop\Windows\Kernel32\Interop.GetLongPathNameW.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Interop\Windows\Kernel32\Interop.GetLogicalDrives.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)Interop\Windows\Kernel32\Interop.GetProcessMemoryInfo.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Interop\Windows\Kernel32\Interop.GetProcessTimes.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Interop\Windows\Kernel32\Interop.GetSystemDirectoryW.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Interop\Windows\Kernel32\Interop.GetSystemInfo.cs" />

src/System.Private.CoreLib/shared/System/Environment.Unix.cs

@@ -444,5 +444,24 @@ private static int CheckedSysConf(Interop.Sys.SysConfName name)
             }
             return (int)result;
         }
+
+        public static long WorkingSet
+        {
+            get
+            {
+                Type? processType = Type.GetType("System.Diagnostics.Process, System.Diagnostics.Process, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a", throwOnError: false);
+                if (processType?.GetMethod("GetCurrentProcess")?.Invoke(null, BindingFlags.DoNotWrapExceptions, null, null, null) is IDisposable currentProcess)
+                {
+                    using (currentProcess)
+                    {
+                        object? result = processType!.GetMethod("get_WorkingSet64")?.Invoke(currentProcess, BindingFlags.DoNotWrapExceptions, null, null, null);
+                        if (result is long) return (long)result;
+                    }
+                }
+
+                // Could not get the current working set.
+                return 0;
+            }
+        }
     }
 }

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

@@ -119,5 +119,20 @@ public static string SystemDirectory
                 return builder.ToString();
             }
         }
+
+        public static unsafe long WorkingSet
+        {
+            get
+            {
+                Interop.Kernel32.PROCESS_MEMORY_COUNTERS memoryCounters = default;
+                memoryCounters.cb = (uint)(sizeof(Interop.Kernel32.PROCESS_MEMORY_COUNTERS));
+
+                if (!Interop.Kernel32.GetProcessMemoryInfo(Interop.Kernel32.GetCurrentProcess(), ref memoryCounters, memoryCounters.cb))
+                {
+                    return 0;
+                }
+                return (long)memoryCounters.WorkingSetSize;
+            }
+        }
     }
 }

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

@@ -153,30 +153,6 @@ public static Version Version
             }
         }
 
-        public static long WorkingSet
-        {
-            get
-            {
-                // Use reflection to access the implementation in System.Diagnostics.Process.dll.  While far from ideal,
-                // we do this to avoid duplicating the Windows, Linux, macOS, and potentially other platform-specific implementations
-                // present in Process.  If it proves important, we could look at separating that functionality out of Process into
-                // Common files which could also be included here.
-                Type? processType = Type.GetType("System.Diagnostics.Process, System.Diagnostics.Process, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a", throwOnError: false);
-                IDisposable? currentProcess = processType?.GetMethod("GetCurrentProcess")?.Invoke(null, BindingFlags.DoNotWrapExceptions, null, null, null) as IDisposable;
-                if (currentProcess != null)
-                {
-                    using (currentProcess)
-                    {
-                        object? result = processType!.GetMethod("get_WorkingSet64")?.Invoke(currentProcess, BindingFlags.DoNotWrapExceptions, null, null, null);
-                        if (result is long) return (long)result;
-                    }
-                }
-
-                // Could not get the current working set.
-                return 0;
-            }
-        }
-
         private static bool ValidateAndConvertRegistryTarget(EnvironmentVariableTarget target)
         {
             Debug.Assert(target != EnvironmentVariableTarget.Process);