Replace IMemoryMappedFileAccessor with null implementation

src/Cli/func/Actions/HostActions/NullMemoryMappedFileAccessor.cs

@@ -0,0 +1,41 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the MIT License. See License.txt in the project root for license information.
+
+using System.IO.MemoryMappedFiles;
+using Microsoft.Azure.WebJobs.Script.Workers.SharedMemoryDataTransfer;
+using Microsoft.Extensions.Logging;
+
+namespace Azure.Functions.Cli.Actions.HostActions;
+
+/// <summary>
+/// A null implementation of MemoryMappedFileAccessor that disables shared memory functionality.
+/// This can be used for testing or in environments where shared memory is not supported or desired.
+/// </summary>
+public class NullMemoryMappedFileAccessor : MemoryMappedFileAccessor
+{
+    public NullMemoryMappedFileAccessor(ILogger<MemoryMappedFileAccessor> logger)
+        : base(logger)
+    {
+        Logger.LogDebug("Using NullMemoryMappedFileAccessor - shared memory data transfer is disabled");
+    }
+
+    public override bool TryCreate(string mapName, long size, out MemoryMappedFile mmf)
+    {
+        mmf = null;
+        Logger.LogDebug("NullMemoryMappedFileAccessor: TryCreate called for {MapName} with size {Size} - returning false", mapName, size);
+        return false;
+    }
+
+    public override bool TryOpen(string mapName, out MemoryMappedFile mmf)
+    {
+        mmf = null;
+        Logger.LogDebug("NullMemoryMappedFileAccessor: TryOpen called for {MapName} - returning false", mapName);
+        return false;
+    }
+
+    public override void Delete(string mapName, MemoryMappedFile mmf)
+    {
+        Logger.LogDebug("NullMemoryMappedFileAccessor: Delete called for {MapName} - no action taken", mapName);
+        mmf?.Dispose();
+    }
+}

src/Cli/func/Actions/HostActions/Startup.cs

@@ -12,8 +12,10 @@
 using Microsoft.Azure.WebJobs.Script.WebHost.Authentication;
 using Microsoft.Azure.WebJobs.Script.WebHost.Controllers;
 using Microsoft.Azure.WebJobs.Script.WebHost.DependencyInjection;
+using Microsoft.Azure.WebJobs.Script.Workers.SharedMemoryDataTransfer;
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.DependencyInjection.Extensions;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
 
@@ -84,6 +86,9 @@ public IServiceProvider ConfigureServices(IServiceCollection services)
 
             services.AddWebJobsScriptHost(_builderContext.Configuration);
 
+            // Replace the default MemoryMappedFileAccessor with a null implementation
+            services.Replace(ServiceDescriptor.Singleton<IMemoryMappedFileAccessor, NullMemoryMappedFileAccessor>());
+
             services.Configure<ScriptApplicationHostOptions>(o =>
             {
                 o.ScriptPath = _hostOptions.ScriptPath;