rebuild the temp collection if cached files don't persist

LightlessSync/PlayerData/Pairs/PairHandlerAdapter.cs

@@ -77,6 +77,8 @@ internal sealed class PairHandlerAdapter : DisposableMediatorSubscriberBase, IPa
     private CancellationTokenSource? _downloadCancellationTokenSource = new();
     private bool _forceApplyMods = false;
     private bool _forceFullReapply;
+    private Dictionary<(string GamePath, string? Hash), string>? _lastAppliedModdedPaths;
+    private bool _needsCollectionRebuild;
     private bool _isVisible;
     private Guid _penumbraCollection;
     private readonly object _collectionGate = new();
@@ -349,12 +351,14 @@ internal sealed class PairHandlerAdapter : DisposableMediatorSubscriberBase, IPa
     private void ResetPenumbraCollection(bool releaseFromPenumbra = true, string? reason = null)
     {
         Guid toRelease = Guid.Empty;
+        bool hadCollection = false;
         lock (_collectionGate)
         {
             if (_penumbraCollection != Guid.Empty)
             {
                 toRelease = _penumbraCollection;
                 _penumbraCollection = Guid.Empty;
+                hadCollection = true;
             }
         }
 
@@ -362,6 +366,13 @@ internal sealed class PairHandlerAdapter : DisposableMediatorSubscriberBase, IPa
         if (cached.HasValue && cached.Value != Guid.Empty)
         {
             toRelease = cached.Value;
+            hadCollection = true;
+        }
+
+        if (hadCollection)
+        {
+            _needsCollectionRebuild = true;
+            _forceFullReapply = true;
         }
 
         if (!releaseFromPenumbra || toRelease == Guid.Empty || !_ipcManager.Penumbra.APIAvailable)
@@ -600,6 +611,25 @@ internal sealed class PairHandlerAdapter : DisposableMediatorSubscriberBase, IPa
         return data;
     }
 
+    private bool HasValidCachedModdedPaths()
+    {
+        if (_lastAppliedModdedPaths is null || _lastAppliedModdedPaths.Count == 0)
+        {
+            return false;
+        }
+
+        foreach (var entry in _lastAppliedModdedPaths)
+        {
+            if (string.IsNullOrEmpty(entry.Value) || !File.Exists(entry.Value))
+            {
+                Logger.LogDebug("Cached file path {path} missing for {handler}, forcing recalculation", entry.Value ?? "empty", GetLogIdentifier());
+                return false;
+            }
+        }
+
+        return true;
+    }
+
     private bool CanApplyNow()
     {
         return !_dalamudUtil.IsInCombat
@@ -844,6 +874,8 @@ internal sealed class PairHandlerAdapter : DisposableMediatorSubscriberBase, IPa
         {
             PlayerName = null;
             _cachedData = null;
+            _lastAppliedModdedPaths = null;
+            _needsCollectionRebuild = false;
             Logger.LogDebug("Disposing {name} complete", name);
         }
     }
@@ -1012,73 +1044,103 @@ internal sealed class PairHandlerAdapter : DisposableMediatorSubscriberBase, IPa
 
         var updateModdedPaths = updatedData.Values.Any(v => v.Any(p => p == PlayerChanges.ModFiles));
         var updateManip = updatedData.Values.Any(v => v.Any(p => p == PlayerChanges.ModManip));
+        var needsCollectionRebuild = _needsCollectionRebuild;
+        var reuseCachedModdedPaths = !updateModdedPaths && needsCollectionRebuild && _lastAppliedModdedPaths is not null;
+        updateModdedPaths = updateModdedPaths || needsCollectionRebuild;
+        updateManip = updateManip || needsCollectionRebuild;
+        Dictionary<(string GamePath, string? Hash), string>? cachedModdedPaths = null;
+        if (reuseCachedModdedPaths)
+        {
+            if (HasValidCachedModdedPaths())
+            {
+                cachedModdedPaths = _lastAppliedModdedPaths;
+            }
+            else
+            {
+                Logger.LogDebug("{handler}: Cached files missing, recalculating mappings", GetLogIdentifier());
+                _lastAppliedModdedPaths = null;
+            }
+        }
 
         _downloadCancellationTokenSource = _downloadCancellationTokenSource?.CancelRecreate() ?? new CancellationTokenSource();
         var downloadToken = _downloadCancellationTokenSource.Token;
-        _ = DownloadAndApplyCharacterAsync(applicationBase, charaData, updatedData, updateModdedPaths, updateManip, downloadToken).ConfigureAwait(false);
+        _ = DownloadAndApplyCharacterAsync(applicationBase, charaData, updatedData, updateModdedPaths, updateManip, cachedModdedPaths, downloadToken).ConfigureAwait(false);
     }
 
     private Task? _pairDownloadTask;
 
     private async Task DownloadAndApplyCharacterAsync(Guid applicationBase, CharacterData charaData, Dictionary<ObjectKind, HashSet<PlayerChanges>> updatedData,
-        bool updateModdedPaths, bool updateManip, CancellationToken downloadToken)
+        bool updateModdedPaths, bool updateManip, Dictionary<(string GamePath, string? Hash), string>? cachedModdedPaths, CancellationToken downloadToken)
     {
         await using var concurrencyLease = await _pairProcessingLimiter.AcquireAsync(downloadToken).ConfigureAwait(false);
-        Dictionary<(string GamePath, string? Hash), string> moddedPaths = [];
         bool skipDownscaleForPair = ShouldSkipDownscale();
         var user = GetPrimaryUserData();
+        Dictionary<(string GamePath, string? Hash), string> moddedPaths;
 
         if (updateModdedPaths)
         {
-            int attempts = 0;
+            if (cachedModdedPaths is not null)
-            List<FileReplacementData> toDownloadReplacements = TryCalculateModdedDictionary(applicationBase, charaData, out moddedPaths, downloadToken);
-
-            while (toDownloadReplacements.Count > 0 && attempts++ <= 10 && !downloadToken.IsCancellationRequested)
             {
-                if (_pairDownloadTask != null && !_pairDownloadTask.IsCompleted)
+                moddedPaths = new Dictionary<(string GamePath, string? Hash), string>(cachedModdedPaths, cachedModdedPaths.Comparer);
+            }
+            else
+            {
+                int attempts = 0;
+                List<FileReplacementData> toDownloadReplacements = TryCalculateModdedDictionary(applicationBase, charaData, out moddedPaths, downloadToken);
+
+                while (toDownloadReplacements.Count > 0 && attempts++ <= 10 && !downloadToken.IsCancellationRequested)
                 {
-                    Logger.LogDebug("[BASE-{appBase}] Finishing prior running download task for player {name}, {kind}", applicationBase, PlayerName, updatedData);
+                    if (_pairDownloadTask != null && !_pairDownloadTask.IsCompleted)
+                    {
+                        Logger.LogDebug("[BASE-{appBase}] Finishing prior running download task for player {name}, {kind}", applicationBase, PlayerName, updatedData);
+                        await _pairDownloadTask.ConfigureAwait(false);
+                    }
+
+                    Logger.LogDebug("[BASE-{appBase}] Downloading missing files for player {name}, {kind}", applicationBase, PlayerName, updatedData);
+
+                    Mediator.Publish(new EventMessage(new Event(PlayerName, user, nameof(PairHandlerAdapter), EventSeverity.Informational,
+                        $"Starting download for {toDownloadReplacements.Count} files")));
+                    var toDownloadFiles = await _downloadManager.InitiateDownloadList(_charaHandler!, toDownloadReplacements, downloadToken).ConfigureAwait(false);
+
+                    if (!_playerPerformanceService.ComputeAndAutoPauseOnVRAMUsageThresholds(this, charaData, toDownloadFiles))
+                    {
+                        _downloadManager.ClearDownload();
+                        return;
+                    }
+
+                    var handlerForDownload = _charaHandler;
+                    _pairDownloadTask = Task.Run(async () => await _downloadManager.DownloadFiles(handlerForDownload, toDownloadReplacements, downloadToken, skipDownscaleForPair).ConfigureAwait(false));
+
                     await _pairDownloadTask.ConfigureAwait(false);
+
+                    if (downloadToken.IsCancellationRequested)
+                    {
+                        Logger.LogTrace("[BASE-{appBase}] Detected cancellation", applicationBase);
+                        return;
+                    }
+
+                    toDownloadReplacements = TryCalculateModdedDictionary(applicationBase, charaData, out moddedPaths, downloadToken);
+
+                    if (toDownloadReplacements.TrueForAll(c => _downloadManager.ForbiddenTransfers.Exists(f => string.Equals(f.Hash, c.Hash, StringComparison.Ordinal))))
+                    {
+                        break;
+                    }
+
+                    await Task.Delay(TimeSpan.FromSeconds(2), downloadToken).ConfigureAwait(false);
                 }
 
-                Logger.LogDebug("[BASE-{appBase}] Downloading missing files for player {name}, {kind}", applicationBase, PlayerName, updatedData);
+                if (!await _playerPerformanceService.CheckBothThresholds(this, charaData).ConfigureAwait(false))
-
-                Mediator.Publish(new EventMessage(new Event(PlayerName, user, nameof(PairHandlerAdapter), EventSeverity.Informational,
-                    $"Starting download for {toDownloadReplacements.Count} files")));
-                var toDownloadFiles = await _downloadManager.InitiateDownloadList(_charaHandler!, toDownloadReplacements, downloadToken).ConfigureAwait(false);
-
-                if (!_playerPerformanceService.ComputeAndAutoPauseOnVRAMUsageThresholds(this, charaData, toDownloadFiles))
                 {
-                    _downloadManager.ClearDownload();
                     return;
                 }
-
-                var handlerForDownload = _charaHandler;
-                _pairDownloadTask = Task.Run(async () => await _downloadManager.DownloadFiles(handlerForDownload, toDownloadReplacements, downloadToken, skipDownscaleForPair).ConfigureAwait(false));
-
-                await _pairDownloadTask.ConfigureAwait(false);
-
-                if (downloadToken.IsCancellationRequested)
-                {
-                    Logger.LogTrace("[BASE-{appBase}] Detected cancellation", applicationBase);
-                    return;
-                }
-
-                toDownloadReplacements = TryCalculateModdedDictionary(applicationBase, charaData, out moddedPaths, downloadToken);
-
-                if (toDownloadReplacements.TrueForAll(c => _downloadManager.ForbiddenTransfers.Exists(f => string.Equals(f.Hash, c.Hash, StringComparison.Ordinal))))
-                {
-                    break;
-                }
-
-                await Task.Delay(TimeSpan.FromSeconds(2), downloadToken).ConfigureAwait(false);
-            }
-
-            if (!await _playerPerformanceService.CheckBothThresholds(this, charaData).ConfigureAwait(false))
-            {
-                return;
             }
         }
+        else
+        {
+            moddedPaths = cachedModdedPaths is not null
+                ? new Dictionary<(string GamePath, string? Hash), string>(cachedModdedPaths, cachedModdedPaths.Comparer)
+                : [];
+        }
 
         downloadToken.ThrowIfCancellationRequested();
 
@@ -1162,6 +1224,7 @@ internal sealed class PairHandlerAdapter : DisposableMediatorSubscriberBase, IPa
 
                 await _ipcManager.Penumbra.SetTemporaryModsAsync(Logger, _applicationId, penumbraCollection,
                     moddedPaths.ToDictionary(k => k.Key.GamePath, k => k.Value, StringComparer.Ordinal)).ConfigureAwait(false);
+                _lastAppliedModdedPaths = new Dictionary<(string GamePath, string? Hash), string>(moddedPaths, moddedPaths.Comparer);
                 LastAppliedDataBytes = -1;
                 foreach (var path in moddedPaths.Values.Distinct(StringComparer.OrdinalIgnoreCase).Select(v => new FileInfo(v)).Where(p => p.Exists))
                 {
@@ -1187,6 +1250,7 @@ internal sealed class PairHandlerAdapter : DisposableMediatorSubscriberBase, IPa
             _cachedData = charaData;
             _pairStateCache.Store(Ident, charaData);
             _forceFullReapply = false;
+            _needsCollectionRebuild = false;
             if (LastAppliedApproximateVRAMBytes < 0 || LastAppliedApproximateEffectiveVRAMBytes < 0)
             {
                 _playerPerformanceService.ComputeAndAutoPauseOnVRAMUsageThresholds(this, charaData, new List<DownloadFileTransfer>());