Remove all cross-process deduping and simplify

We cannot actually prevent reporting across processes because ultimately that causes VS to drop diagnostics which it seems to expect to match across multiple processes (analyzer, compiler).

By making the analyzer properly detect direct dependencies only, we potentially eliminate most duplication which typically would come from transitive dependencies (except for development dependencies, say, which I'd say are the exception other than the norm).

samples/dotnet/SponsorLink/DiagnosticsManager.cs

@@ -4,13 +4,9 @@
 using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.Collections.Immutable;
-using System.Diagnostics;
 using System.Globalization;
 using System.IO;
-using System.IO.MemoryMappedFiles;
 using System.Linq;
-using System.Runtime.InteropServices;
-using System.Threading;
 using Humanizer;
 using Humanizer.Localisation;
 using Microsoft.CodeAnalysis;
@@ -44,32 +40,6 @@ class DiagnosticsManager
     ConcurrentDictionary<string, Diagnostic> Diagnostics
         => AppDomainDictionary.Get<ConcurrentDictionary<string, Diagnostic>>(appDomainDiagnosticsKey.ToString());
 
-    /// <summary>
-    /// Attemps to remove a diagnostic for the given product.
-    /// </summary>
-    /// <param name="product">The product diagnostic that might have been pushed previously.</param>
-    /// <returns>The removed diagnostic, or <see langword="null" /> if none was previously pushed.</returns>
-    public void ReportOnce(Action<Diagnostic> report, string product = Funding.Product)
-    {
-        if (Diagnostics.TryRemove(product, out var diagnostic) &&
-            GetStatus(diagnostic) != SponsorStatus.Grace)
-        {
-            // Ensure only one such diagnostic is reported per product for the entire process, 
-            // so that we can avoid polluting the error list with duplicates across multiple projects.
-            var id = string.Concat(SessionId, product, diagnostic.Id);
-            using var mutex = new Mutex(false, "mutex" + id);
-            mutex.WaitOne();
-            using var mmf = CreateOrOpenMemoryMappedFile(product, 1);
-            using var accessor = mmf.CreateViewAccessor();
-            if (accessor.ReadByte(0) == 0)
-            {
-                accessor.Write(0, (byte)1);
-                report(diagnostic);
-                Tracing.Trace($"👈{diagnostic.Severity.ToString().ToLowerInvariant()}:{Process.GetCurrentProcess().Id}:{Process.GetCurrentProcess().ProcessName}:{product}:{diagnostic.Id}");
-            }
-        }
-    }
-
     /// <summary>
     /// Gets the status of the given product based on a previously stored diagnostic. 
     /// To ensure the value is always set before returning, use <see cref="GetOrSetStatus"/>.
@@ -100,6 +70,34 @@ public SponsorStatus GetOrSetStatus(ImmutableArray<AdditionalText> manifests, An
     public SponsorStatus GetOrSetStatus(Func<AnalyzerOptions?> options)
         => GetOrSetStatus(() => options().GetSponsorAdditionalFiles(), () => options()?.AnalyzerConfigOptionsProvider.GlobalOptions);
 
+    /// <summary>
+    /// Attemps to remove a diagnostic for the given product.
+    /// </summary>
+    /// <param name="product">The product diagnostic that might have been pushed previously.</param>
+    /// <returns>The removed diagnostic, or <see langword="null" /> if none was previously pushed.</returns>
+    public Diagnostic? Pop(string product = Funding.Product)
+    {
+        if (Diagnostics.TryRemove(product, out var diagnostic) &&
+            GetStatus(diagnostic) != SponsorStatus.Grace)
+        {
+            return diagnostic;
+        }
+
+        return null;
+    }
+
+    /// <summary>
+    /// Pushes a diagnostic for the given product. 
+    /// </summary>
+    /// <returns>The same diagnostic that was pushed, for chained invocations.</returns>
+    Diagnostic Push(Diagnostic diagnostic, string product = Funding.Product)
+    {
+        // We only expect to get one warning per sponsorable+product 
+        // combination, and first one to set wins.
+        Diagnostics.TryAdd(product, diagnostic);
+        return diagnostic;
+    }
+
     SponsorStatus GetOrSetStatus(Func<ImmutableArray<AdditionalText>> getAdditionalFiles, Func<AnalyzerConfigOptions?> getGlobalOptions)
     {
         if (GetStatus() is { } status)
@@ -166,29 +164,6 @@ SponsorStatus GetOrSetStatus(Func<ImmutableArray<AdditionalText>> getAdditionalF
         }
     }
 
-    /// <summary>
-    /// Pushes a diagnostic for the given product. 
-    /// </summary>
-    /// <returns>The same diagnostic that was pushed, for chained invocations.</returns>
-    Diagnostic Push(Diagnostic diagnostic, string product = Funding.Product)
-    {
-        // We only expect to get one warning per sponsorable+product 
-        // combination, and first one to set wins.
-        if (Diagnostics.TryAdd(product, diagnostic))
-        {
-            // Reset the process-wide flag for this diagnostic.
-            var id = string.Concat(SessionId, product, diagnostic.Id);
-            using var mutex = new Mutex(false, "mutex" + id);
-            mutex.WaitOne();
-            using var mmf = CreateOrOpenMemoryMappedFile(id, 1);
-            using var accessor = mmf.CreateViewAccessor();
-            accessor.Write(0, (byte)0);
-            Tracing.Trace($"👉{diagnostic.Severity.ToString().ToLowerInvariant()}:{Process.GetCurrentProcess().Id}:{Process.GetCurrentProcess().ProcessName}:{product}:{diagnostic.Id}");
-        }
-
-        return diagnostic;
-    }
-
     SponsorStatus? GetStatus(Diagnostic? diagnostic) => diagnostic?.Properties.TryGetValue(nameof(SponsorStatus), out var value) == true
         ? value switch
         {
@@ -201,19 +176,6 @@ Diagnostic Push(Diagnostic diagnostic, string product = Funding.Product)
         }
         : null;
 
-    static MemoryMappedFile CreateOrOpenMemoryMappedFile(string mapName, int capacity)
-    {
-        if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
-            return MemoryMappedFile.CreateOrOpen(mapName, capacity);
-
-        // On *nix, use a file-based memory-mapped file
-        var filePath = $"/tmp/{mapName}";
-        using (var fs = new FileStream(filePath, FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.ReadWrite))
-            fs.Write(new byte[capacity], 0, capacity);
-
-        return MemoryMappedFile.CreateFromFile(filePath, FileMode.OpenOrCreate);
-    }
-
     internal static DiagnosticDescriptor CreateSponsor(string[] sponsorable, string prefix) => new(
             $"{prefix}100",
             Resources.Sponsor_Title,

samples/dotnet/SponsorLink/SponsorLinkAnalyzer.cs

@@ -41,7 +41,16 @@ public override void Initialize(AnalysisContext context)
                 // so it's expected to NOT get a diagnostic back. Also, we don't want to report 
                 // multiple diagnostics for each project in a solution that uses the same product.
                 ctx.RegisterCompilationEndAction(ctx =>
-                    Diagnostics.ReportOnce(diagnostic => ctx.ReportDiagnostic(diagnostic)));
+                {
+                    var prop = Funding.PackageId.Replace('.', '_');
+                    // Only report if the package is directly referenced in the project. See SL_CollectDependencies in buildTransitive\Devlooped.Sponsors.targets
+                    if (ctx.Options.AnalyzerConfigOptionsProvider.GlobalOptions.TryGetValue("build_property." + prop, out var package) &&
+                        package?.Length > 0 &&
+                        Diagnostics.Pop() is { } diagnostic)
+                    {
+                        ctx.ReportDiagnostic(diagnostic);
+                    }
+                });
             }
         });
 #pragma warning restore RS1013 // Start action has no registered non-end actions