Various optimizations and cleanups. "in" removed from GpuUInt128 to avoid defensive copies from IL.

PerfectNumbers.Core/HeuristicFailureLog.cs

@@ -0,0 +1,98 @@
+using System.Collections.Concurrent;
+using System.Globalization;
+using System.Text;
+
+namespace PerfectNumbers.Core
+{
+    internal static class HeuristicFailureLog
+    {
+        private const string LogFileName = "prime-order-heuristic-fallbacks.log";
+        private const int FlushThreshold = 4096;
+        private const int MaxBufferedEntries = 16;
+        private static readonly ThreadLocal<StringBuilder?> s_threadBuilder = new(() => StringBuilderPool.Rent(), trackAllValues: true);
+        private static readonly ThreadLocal<int> s_threadEntryCount = new(() => 0, trackAllValues: true);
+        private static readonly object s_fileLock = new();
+        private static readonly string s_logPath = Path.Combine(AppContext.BaseDirectory, LogFileName);
+        private static readonly UTF8Encoding s_utf8NoBom = new(false);
+
+        static HeuristicFailureLog()
+        {
+            AppDomain.CurrentDomain.ProcessExit += static (_, _) => FlushAll(force: true);
+        }
+
+        public static void Record(ulong prime, ulong? candidateOrder, HeuristicFailureReason reason)
+        {
+            string primeText = prime.ToString(CultureInfo.InvariantCulture);
+            string? candidateText = candidateOrder.HasValue ? candidateOrder.Value.ToString(CultureInfo.InvariantCulture) : null;
+            RecordInternal(primeText, candidateText, reason);
+        }
+
+        public static void Record(UInt128 prime, UInt128? candidateOrder, HeuristicFailureReason reason)
+        {
+            string primeText = prime.ToString(CultureInfo.InvariantCulture);
+            string? candidateText = candidateOrder.HasValue ? candidateOrder.Value.ToString(CultureInfo.InvariantCulture) : null;
+            RecordInternal(primeText, candidateText, reason);
+        }
+
+        private static void RecordInternal(string primeText, string? candidateText, HeuristicFailureReason reason)
+        {
+            StringBuilder? existing = s_threadBuilder.Value;
+            StringBuilder builder = existing ?? StringBuilderPool.Rent();
+            int count = s_threadEntryCount.Value + 1;
+            bool forceFlush = count >= MaxBufferedEntries;
+            builder.Append(DateTime.UtcNow.ToString("o", CultureInfo.InvariantCulture));
+            builder.Append(" | prime=");
+            builder.Append(primeText);
+            builder.Append(" | reason=");
+            builder.Append(reason);
+            if (candidateText is not null)
+            {
+                builder.Append(" | candidateOrder=");
+                builder.Append(candidateText);
+            }
+
+            builder.AppendLine();
+            FlushBuilderIfNeeded(builder, forceFlush);
+            if (builder.Length == 0)
+            {
+                count = 0;
+            }
+
+            s_threadEntryCount.Value = count;
+            s_threadBuilder.Value = builder;
+        }
+
+        private static void FlushAll(bool force)
+        {
+            foreach (StringBuilder? builder in s_threadBuilder.Values)
+            {
+                if (builder is not null)
+                {
+                    FlushBuilderIfNeeded(builder, force);
+                }
+            }
+        }
+
+        private static void FlushBuilderIfNeeded(StringBuilder builder, bool force)
+        {
+            if (builder.Length == 0)
+            {
+                return;
+            }
+
+            if (!force && builder.Length < FlushThreshold)
+            {
+                return;
+            }
+
+            string text = builder.ToString();
+            builder.Clear();
+            lock (s_fileLock)
+            {
+                using FileStream stream = new FileStream(s_logPath, FileMode.Append, FileAccess.Write, FileShare.ReadWrite);
+                using StreamWriter writer = new StreamWriter(stream, s_utf8NoBom);
+                writer.Write(text);
+            }
+        }
+    }
+}