Add support for tmp savefiles, fix multiple handles for savefiles, clean up

OpenDreamRuntime/DreamManager.cs

@@ -98,7 +98,7 @@ public void Update() {
             _procScheduler.Process();
             UpdateStat();
             _dreamMapManager.UpdateTiles();
-
+            DreamObjectSavefile.FlushAllUpdates();
             WorldInstance.SetVariableValue("cpu", WorldInstance.GetVariable("tick_usage"));
         }
 

OpenDreamRuntime/EntryPoint.cs

@@ -72,8 +72,8 @@ public override void PostInit() {
 
         protected override void Dispose(bool disposing) {
             // Write every savefile to disk
-            foreach (var savefile in DreamObjectSavefile.Savefiles) {
-                savefile.Flush();
+            foreach (var savefile in DreamObjectSavefile.Savefiles.ToArray()) { //ToArray() to avoid modifying the collection while iterating over it
+                savefile.Close();
             }
 
             _dreamManager.Shutdown();

OpenDreamRuntime/Objects/Types/DreamObjectSavefile.cs

@@ -1,4 +1,5 @@
-using System.Text.Json;
+using System.IO;
+using System.Text.Json;
 using OpenDreamRuntime.Procs;
 using OpenDreamRuntime.Resources;
 using OpenDreamShared.Dream;
@@ -9,42 +10,74 @@ public sealed class DreamObjectSavefile : DreamObject {
     public sealed class SavefileDirectory : Dictionary<string, DreamValue> { }
 
     public static readonly List<DreamObjectSavefile> Savefiles = new();
+    //basically a global database of savefile contents, which each savefile datum points to - this preserves state between savefiles and reduces memory usage
+    private static readonly Dictionary<string, Dictionary<string, SavefileDirectory>> SavefileDirectories = new();
+    private static readonly HashSet<DreamObjectSavefile> _savefilesToFlush = new();
 
     public override bool ShouldCallNew => false;
 
     public DreamResource Resource;
-    public Dictionary<string, SavefileDirectory> Directories;
+    public Dictionary<string, SavefileDirectory> Directories => SavefileDirectories[Resource.ResourcePath ?? ""];
     public SavefileDirectory CurrentDir => Directories[_currentDirPath];
 
     private string _currentDirPath = "/";
 
+    //Temporary savefiles should be deleted when the DreamObjectSavefile is deleted. Temporary savefiles can be created by creating a new savefile datum with a null filename or an entry in the world's resource cache
+    private bool _isTemporary = false;
+
+    private static ISawmill? _sawmill = null;
+    /// <summary>
+    /// Flushes all savefiles that have been marked as needing flushing. Basically just used to call Flush() between ticks instead of on every write.
+    /// </summary>
+    public static void FlushAllUpdates() {
+        _sawmill ??= Logger.GetSawmill("opendream.res");
+        foreach (DreamObjectSavefile savefile in _savefilesToFlush) {
+            try {
+                savefile.Flush();
+            } catch (Exception e) {
+                _sawmill.Error($"Error flushing savefile {savefile.Resource.ResourcePath}: {e}");
+            }
+        }
+        _savefilesToFlush.Clear();
+    }
+
     public DreamObjectSavefile(DreamObjectDefinition objectDefinition) : base(objectDefinition) {
 
     }
 
     public override void Initialize(DreamProcArguments args) {
         base.Initialize(args);
 
-        string filename = args.GetArgument(0).GetValueAsString();
+        args.GetArgument(0).TryGetValueAsString(out string? filename);
         DreamValue timeout = args.GetArgument(1); //TODO: timeout
 
+        if (string.IsNullOrEmpty(filename)) {
+            _isTemporary = true;
+            filename = Path.GetTempPath() + "tmp_opendream_savefile_" + System.DateTime.Now.Ticks.ToString();
+        }
+
         Resource = DreamResourceManager.LoadResource(filename);
 
-        string? data = Resource.ReadAsString();
-        if (!string.IsNullOrEmpty(data)) {
-            Directories = JsonSerializer.Deserialize<Dictionary<string, SavefileDirectory>>(data);
-        } else {
-            Directories = new() {
-                { "/", new SavefileDirectory() }
-            };
+        if(!SavefileDirectories.ContainsKey(filename)) {
+            //if the savefile hasn't already been loaded, load it or create it
+            string? data = Resource.ReadAsString();
+
+            if (!string.IsNullOrEmpty(data)) {
+                SavefileDirectories.Add(filename, JsonSerializer.Deserialize<Dictionary<string, SavefileDirectory>>(data));
+            } else {
+                 SavefileDirectories.Add(filename, new() {
+                    { "/", new SavefileDirectory() }
+                });
+                //create the file immediately
+                Flush();
+            }
         }
 
         Savefiles.Add(this);
     }
 
     protected override void HandleDeletion() {
-        Savefiles.Remove(this);
-
+        Close();
         base.HandleDeletion();
     }
 
@@ -53,6 +86,25 @@ public void Flush() {
         Resource.Output(new DreamValue(JsonSerializer.Serialize(Directories)));
     }
 
+    public void Close() {
+        Flush();
+        if (_isTemporary && Resource.ResourcePath != null) {
+            File.Delete(Resource.ResourcePath);
+        }
+        //check to see if the file is still in use by another savefile datum
+        if(Resource.ResourcePath != null) {
+            bool fineToDelete = true;
+            foreach (var savefile in Savefiles)
+                if (savefile != this && savefile.Resource.ResourcePath == Resource.ResourcePath) {
+                    fineToDelete = false;
+                    break;
+                }
+            if (fineToDelete)
+                SavefileDirectories.Remove(Resource.ResourcePath);
+        }
+        Savefiles.Remove(this);
+    }
+
     protected override bool TryGetVar(string varName, out DreamValue value) {
         switch (varName) {
             case "cd":
@@ -102,7 +154,7 @@ public override DreamValue OperatorIndex(DreamValue index) {
             throw new Exception($"Invalid savefile index {index}");
 
         if (CurrentDir.TryGetValue(entryName, out DreamValue entry)) {
-            return entry;
+            return entry; //TODO: This should be something like value.DMProc("Read", new DreamProcArguments(this)) for DreamObjects and a copy for everything else
         } else {
             return DreamValue.Null;
         }
@@ -112,7 +164,8 @@ public override void OperatorIndexAssign(DreamValue index, DreamValue value) {
         if (!index.TryGetValueAsString(out string? entryName))
             throw new Exception($"Invalid savefile index {index}");
 
-        CurrentDir[entryName] = value;
+        CurrentDir[entryName] = value; //TODO: This should be something like value.DMProc("Write", new DreamProcArguments(this)) for DreamObjects and a copy for everything else
+        _savefilesToFlush.Add(this); //mark this as needing flushing
     }
 
     private void ChangeDirectory(string path) {