State.cs

using System;
using System.Collections.Generic;
using System.Threading;
using Microsoft.Diagnostics.Tracing.Session;

namespace IoMonitor
{
    /// <summary>
    /// Shared global state for the interactive I/O monitor.
    /// </summary>
    internal static partial class Program
    {
        // Per-process historical totals and last-seen values.
        private static readonly Dictionary<int, ProcessIoHistory> _history = new();

        // ETW-aggregated byte totals per process.
        private static readonly Dictionary<int, (long read, long write)> _etwTotals = new();

        // Last ETW snapshot per process so that deltas can be derived.
        private static readonly Dictionary<int, (long read, long write)> _etwLast = new();

        // Per-process, per-drive I/O totals.
        private static readonly Dictionary<int, Dictionary<string, (long read, long write)>> _processIoByDrive = new();

        // Rolling bytes-per-second history, used for thrashing detection.
        private static readonly Dictionary<int, List<long>> _ioHistory = new();

        // Global per-file I/O statistics (trimmed to top 1000 entries).
        private static readonly Dictionary<string, (long read, long write)> _fileIoStats = new();

        // In-memory CSV batch state; flushed infrequently to reduce monitor-generated disk writes.
        private static readonly Dictionary<int, ProcessIoLogEntry> _pendingLogEntries = new();

        // Synchronizes access to shared collections and cached samples.
        private static readonly object _dataLock = new();
        private static readonly object _sampleLock = new();

        // ETW session and worker thread.
        private static TraceEventSession? _etwSession;
        private static Thread? _etwThread;

        private static bool _hasAdmin;
        private static bool _hasDebug;
        private static bool _etwActive;

        // Application lifecycle state.
        private static bool _running = true;
        private static bool _csvLoggingOn;
        private static bool _isPaused;

        // Update interval and UI configuration.
        private static int _updateMs = 1000;
        private static int _tableRows = 15;
        private const int CsvMaxRowsPerFlush = 20;
        private static readonly TimeSpan CsvWriteInterval = TimeSpan.FromSeconds(30);

        private static DateTime _lastCsvWrite = DateTime.MinValue;
        private static DateTime _programStartTime;

        // Last sampled snapshot; guarded by _dataLock.
        private static List<ProcessIoSample> _cachedSamples = new();

        // Optional drive letter filter (e.g. "C").
        private static string _driveFilter = string.Empty;
        private static List<string> _availableDriveLetters = new();
        private static DateTime _nextDriveRefresh = DateTime.MinValue;

        // Bytes per second threshold used by thrashing heuristics.
        private static long _thrashingThreshold = 50L * 1024 * 1024; // 50 MB/s

        private static bool _showAlerts = true;

        // Text-based process name filter.
        private static string _searchFilter = string.Empty;
        private static bool _inSearchMode;

        // Last effective sample interval in seconds.
        private static double _lastSampleIntervalSeconds = 1.0;

        // Single-instance guard.
        private static Mutex? _singleInstanceMutex;

        // Drive selection menu state.
        private static bool _inDriveMenu;
        private static List<string> _driveMenuItems = new();
        private static List<string> _driveMenuLetters = new();
        private static int _driveMenuIndex;

        private static bool _showClosedProcesses;

        // Active sort mode for the main table.
        private enum SortMode
        {
            TotalWrite,
            TotalRead,
            WriteDelta,
            ReadDelta,
            Handles,
            IoOps,
            WorkingSet
        }

        private static SortMode _sortMode = SortMode.TotalWrite;
    }
}