Update CopyOnWrite readme, fixes (#420)

* Update README.md for CopyOnWrite

* Sign output

* Ensure CloneFile support called only once

Author: AndyGerlicher

README.md

@@ -29,6 +29,12 @@ Supports utility projects that do not compile an assembly.
 
 Supports staging artifacts from build outputs.
 
+### [Microsoft.Build.CopyOnWrite](src/CopyOnWrite)
+[![NuGet](https://img.shields.io/nuget/v/Microsoft.Build.CopyOnWrite.svg)](https://www.nuget.org/packages/Microsoft.Build.CopyOnWrite)
+ [![NuGet](https://img.shields.io/nuget/dt/Microsoft.Build.CopyOnWrite.svg)](https://www.nuget.org/packages/Microsoft.Build.CopyOnWrite)
+
+Enables Copy on Write for faster file copies.
+
 ## How can I use these SDKs?
 
 When using an MSBuild Project SDK obtained via NuGet (such as the SDKs in this repo) a specific version **must** be specified.

src/CopyOnWrite/Copy.cs

@@ -1000,7 +1000,7 @@ private bool TryCopyOnWrite(string source, string dest)
             return true;
         }
 
-        private static readonly ConcurrentDictionary<string, bool> _reFsDrives = new(StringComparer.OrdinalIgnoreCase);
+        private static readonly ConcurrentDictionary<string, Lazy<bool>> _reFsDrives = new(StringComparer.OrdinalIgnoreCase);
 
         /// <summary>
         /// Check for CopyOnWrite support. Result is cached by drive root.
@@ -1024,16 +1024,16 @@ private bool IsCopyOnWriteSupported(string source, string dest)
             }
 
             return _reFsDrives.GetOrAdd(
-                source,
-                (key) =>
+                sourceDrive,
+                (key) => new Lazy<bool>(() =>
                 {
                     var supportsCloneFile = _cow.CopyOnWriteLinkSupportedInDirectoryTree(key);
                     Log.LogMessage(MessageImportance.Low,
                         supportsCloneFile
-                            ? $"Drive {sourceDrive} has support for CloneFile. All copies will attempt to use CloneFile."
-                            : $"Drive {sourceDrive} does not have support for CloneFile. File.Copy will be used.");
+                            ? $"Drive {key} has support for CloneFile. All copies will attempt to use CloneFile."
+                            : $"Drive {key} does not have support for CloneFile. File.Copy will be used.");
                     return supportsCloneFile;
-                });
+                })).Value;
         }
         #endregion
     }

src/CopyOnWrite/Microsoft.Build.CopyOnWrite.csproj

@@ -19,7 +19,9 @@
     </None>
     <None Include=".editorconfig" />
   </ItemGroup>
-
+  <ItemGroup>
+    <FilesToSign Include="$(TargetPath)" Authenticode="Microsoft400" StrongName="StrongName" />
+  </ItemGroup>
   <ItemGroup>
     <PackageReference Include="CopyOnWrite" GeneratePathProperty="True" PrivateAssets="All" />
 	  <PackageReference Include="Microsoft.Build.Tasks.Core" PrivateAssets="all" ExcludeAssets="Runtime">

src/CopyOnWrite/README.md

@@ -1,4 +1,6 @@
 # Microsoft.Build.CopyOnWrite
+[![NuGet](https://img.shields.io/nuget/v/Microsoft.Build.CopyOnWrite.svg)](https://www.nuget.org/packages/Microsoft.Build.CopyOnWrite)
+ [![NuGet](https://img.shields.io/nuget/dt/Microsoft.Build.CopyOnWrite.svg)](https://www.nuget.org/packages/Microsoft.Build.CopyOnWrite)
 
 The `Microsoft.Build.CopyOnWrite` MSBuild SDK overrides the native MSBuild Copy task to add support for ReFS CloneFile (Copy on Write). It is designed to be as backwards compatible as possible and should directly replace all usages of Copy in MSBuild.