Adding ability to load a function from an assembly in the shared context

Author: fabiocav

src/WebJobs.Script/Description/DotNet/Compilation/DotNetCompilationResult.cs

@@ -19,6 +19,9 @@ public static DotNetCompilationResult FromStream(Stream assemblyStream, Stream p
         public static DotNetCompilationResult FromPath(string assemblyPath)
             => new PathCompilationResult(assemblyPath);
 
+        public static DotNetCompilationResult FromAssemblyName(string assemblyName)
+            => new AssemblyReferenceCompilationResult(assemblyName);
+
         public abstract Assembly Load(FunctionMetadata metadata, IFunctionMetadataResolver metadataResolver, ILogger logger);
 
         private sealed class BinaryCompilationResult : DotNetCompilationResult
@@ -85,5 +88,23 @@ public PathCompilationResult(string assemblyPath)
             public override Assembly Load(FunctionMetadata metadata, IFunctionMetadataResolver metadataResolver, ILogger logger)
                 => FunctionAssemblyLoadContext.Shared.LoadFromAssemblyPath(AssemblyPath, true);
         }
+
+        private sealed class AssemblyReferenceCompilationResult : DotNetCompilationResult
+        {
+            public AssemblyReferenceCompilationResult(string assemblyName)
+            {
+                if (string.IsNullOrWhiteSpace(assemblyName))
+                {
+                    throw new ArgumentException("Invalid assembly name string", nameof(assemblyName));
+                }
+
+                AssemblyName = assemblyName;
+            }
+
+            public string AssemblyName { get; }
+
+            public override Assembly Load(FunctionMetadata metadata, IFunctionMetadataResolver metadataResolver, ILogger logger)
+                => FunctionAssemblyLoadContext.Shared.LoadFromAssemblyName(new AssemblyName(AssemblyName));
+        }
     }
 }

src/WebJobs.Script/Description/DotNet/Compilation/Raw/RawAssemblyCompilation.cs

@@ -14,6 +14,7 @@ namespace Microsoft.Azure.WebJobs.Script.Description
 {
     public class RawAssemblyCompilation : IDotNetCompilation
     {
+        private const string AssemblyNamePrefix = "assembly:";
         private static readonly Regex _entryPointRegex = new Regex("^(?<typename>.*)\\.(?<methodname>\\S*)$", RegexOptions.Compiled);
         private readonly string _assemblyFilePath;
         private readonly string _entryPointName;
@@ -29,7 +30,17 @@ async Task<object> ICompilation.EmitAsync(CancellationToken cancellationToken)
 
         public Task<DotNetCompilationResult> EmitAsync(CancellationToken cancellationToken)
         {
-            return Task.FromResult(DotNetCompilationResult.FromPath(_assemblyFilePath));
+            DotNetCompilationResult result = null;
+            if (_assemblyFilePath != null && _assemblyFilePath.StartsWith(AssemblyNamePrefix))
+            {
+                result = DotNetCompilationResult.FromAssemblyName(_assemblyFilePath.Substring(AssemblyNamePrefix.Length));
+            }
+            else
+            {
+                result = DotNetCompilationResult.FromPath(_assemblyFilePath);
+            }
+
+            return Task.FromResult(result);
         }
 
         public ImmutableArray<Diagnostic> GetDiagnostics() => ImmutableArray<Diagnostic>.Empty;