Avoid unnecessary closures/delegates in Process (#50496)

Author: stephentoub

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

@@ -33,7 +33,7 @@ public void Kill(bool entireProcessTree)
 
         private bool IsSelfOrDescendantOf(Process processOfInterest)
         {
-            if (SafePredicateTest(() => Equals(processOfInterest)))
+            if (Equals(processOfInterest))
                 return true;
 
             Process[] allProcesses = GetProcesses();
@@ -47,7 +47,7 @@ private bool IsSelfOrDescendantOf(Process processOfInterest)
                 {
                     foreach (Process candidate in current.GetChildProcesses(allProcesses))
                     {
-                        if (SafePredicateTest(() => processOfInterest.Equals(candidate)))
+                        if (processOfInterest.Equals(candidate))
                             return true;
 
                         descendantProcesses.Enqueue(candidate);
@@ -82,7 +82,7 @@ private IReadOnlyList<Process> GetChildProcesses(Process[]? processes = null)
 
                 try
                 {
-                    if (SafePredicateTest(() => IsParentOf(possibleChildProcess)))
+                    if (IsParentOf(possibleChildProcess))
                     {
                         childProcesses.Add(possibleChildProcess);
                         dispose = false;
@@ -98,19 +98,10 @@ private IReadOnlyList<Process> GetChildProcesses(Process[]? processes = null)
             return childProcesses;
         }
 
-        private bool SafePredicateTest(Func<bool> predicate)
-        {
-            try
-            {
-                return predicate();
-            }
-            catch (Exception e) when (e is InvalidOperationException || e is Win32Exception)
-            {
-                // InvalidOperationException signifies conditions such as the process already being dead.
-                // Win32Exception signifies issues such as insufficient permissions to get details on the process.
-                // In either case, the predicate couldn't be applied so return the fallback result.
-                return false;
-            }
-        }
+        private static bool IsProcessInvalidException(Exception e) =>
+            // InvalidOperationException signifies conditions such as the process already being dead.
+            // Win32Exception signifies issues such as insufficient permissions to get details on the process.
+            // In either case, the predicate couldn't be applied so return the fallback result.
+            e is InvalidOperationException || e is Win32Exception;
     }
 }

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

@@ -308,11 +308,29 @@ private ProcessPriorityClass PriorityClassCore
         }
 
         /// <summary>Checks whether the argument is a direct child of this process.</summary>
-        private bool IsParentOf(Process possibleChildProcess) =>
-            Id == possibleChildProcess.ParentProcessId;
+        private bool IsParentOf(Process possibleChildProcess)
+        {
+            try
+            {
+                return Id == possibleChildProcess.ParentProcessId;
+            }
+            catch (Exception e) when (IsProcessInvalidException(e))
+            {
+                return false;
+            }
+        }
 
-        private bool Equals(Process process) =>
-            Id == process.Id;
+        private bool Equals(Process process)
+        {
+            try
+            {
+                return Id == process.Id;
+            }
+            catch (Exception e) when (IsProcessInvalidException(e))
+            {
+                return false;
+            }
+        }
 
         partial void ThrowIfExited(bool refresh)
         {

src/libraries/System.Diagnostics.Process/src/System/Diagnostics/Process.Win32.cs

@@ -330,9 +330,17 @@ private bool WaitForInputIdleCore(int milliseconds)
         /// <remarks>
         /// A child process is a process which has this process's id as its parent process id and which started after this process did.
         /// </remarks>
-        private bool IsParentOf(Process possibleChild) =>
-            StartTime < possibleChild.StartTime
-            && Id == possibleChild.ParentProcessId;
+        private bool IsParentOf(Process possibleChild)
+        {
+            try
+            {
+                return StartTime < possibleChild.StartTime && Id == possibleChild.ParentProcessId;
+            }
+            catch (Exception e) when (IsProcessInvalidException(e))
+            {
+                return false;
+            }
+        }
 
         /// <summary>
         /// Get the process's parent process id.
@@ -353,9 +361,17 @@ private unsafe int ParentProcessId
             }
         }
 
-        private bool Equals(Process process) =>
-            Id == process.Id
-            && StartTime == process.StartTime;
+        private bool Equals(Process process)
+        {
+            try
+            {
+                return Id == process.Id && StartTime == process.StartTime;
+            }
+            catch (Exception e) when (IsProcessInvalidException(e))
+            {
+                return false;
+            }
+        }
 
         private List<Exception>? KillTree()
         {
@@ -389,7 +405,7 @@ private bool Equals(Process process) =>
                 (exceptions ??= new List<Exception>()).Add(e);
             }
 
-            List<(Process Process, SafeProcessHandle Handle)> children = GetProcessHandlePairs(p => SafePredicateTest(() => IsParentOf(p)));
+            List<(Process Process, SafeProcessHandle Handle)> children = GetProcessHandlePairs((thisProcess, otherProcess) => thisProcess.IsParentOf(otherProcess));
             try
             {
                 foreach ((Process Process, SafeProcessHandle Handle) child in children)
@@ -413,7 +429,7 @@ private bool Equals(Process process) =>
             return exceptions;
         }
 
-        private List<(Process Process, SafeProcessHandle Handle)> GetProcessHandlePairs(Func<Process, bool> predicate)
+        private List<(Process Process, SafeProcessHandle Handle)> GetProcessHandlePairs(Func<Process, Process, bool> predicate)
         {
             var results = new List<(Process Process, SafeProcessHandle Handle)>();
 
@@ -422,7 +438,7 @@ private bool Equals(Process process) =>
                 SafeProcessHandle h = SafeGetHandle(p);
                 if (!h.IsInvalid)
                 {
-                    if (predicate(p))
+                    if (predicate(this, p))
                     {
                         results.Add((p, h));
                     }