fix deadlock

EDJournalWatcher/Program.cs

@@ -12,6 +12,7 @@ public class Program {
 
         while (true) {
             stream.ProcessQueues();
+            Thread.Sleep(100);
         }
     }
 

EDPlayerJournal/JournalStream.cs

@@ -4,6 +4,48 @@ using System.Threading;
 
 namespace EDPlayerJournal;
 
+public class SyncQueue<T> {
+    private Queue<T> queue = new();
+
+    public void Enqueue(T item) {
+        Monitor.Enter(queue);
+        try {
+            queue.Enqueue(item);
+        } finally {
+            Monitor.Exit(queue);
+        }
+    }
+
+    public T? TryDequeue() {
+        if (Monitor.TryEnter(queue)) {
+            T retval;
+
+            try {
+                queue.TryDequeue(out retval);
+            } finally {
+                Monitor.Exit(queue);
+            }
+
+            return retval;
+        }
+
+        return default(T);
+    }
+
+    public T Dequeue() {
+        T retval;
+
+        Monitor.Enter(queue);
+        try {
+            retval = queue.Dequeue();
+        } finally {
+            Monitor.Exit(queue);
+        }
+
+        return retval;
+    }
+}
+
 internal class FileWatcherThread : IDisposable {
     private string? fullPath;
     private StreamReader? stream;
@@ -14,38 +56,21 @@ internal class FileWatcherThread : IDisposable {
 
     public string? FullPath => fullPath;
 
-    private Mutex mutex = new();
-    private Queue<Entry> entries = new();
+    private SyncQueue<Entry> queue;
+
+    public SyncQueue<Entry> Queue => queue;
 
     public bool Finished => done;
 
-    public FileWatcherThread() {
+    public FileWatcherThread(SyncQueue<Entry> queue) {
+        this.queue = queue;
     }
 
-    public FileWatcherThread(string fullpath) {
+    public FileWatcherThread(string fullpath, SyncQueue<Entry> queue) {
+        this.queue = queue;
         Start(fullpath);
     }
 
-    public bool IsEmpty {
-        get {
-            lock (mutex) {
-                return entries.Count == 0;
-            }
-        }
-    }
-
-    public Entry Dequeue() {
-        lock (mutex) {
-            return entries.Dequeue();
-        }
-    }
-
-    public void Enqueue(Entry e) {
-        lock (mutex) {
-            entries.Enqueue(e);
-        }
-    }
-
     public void Signal() {
         wait.Set();
     }
@@ -84,7 +109,7 @@ internal class FileWatcherThread : IDisposable {
                     // TODO: error handling on wrong entries
                 }
                 if (entry != null) {
-                    Enqueue(entry);
+                    queue.Enqueue(entry);
                     if (entry.Is(Events.Shutdown)) {
                         done = true;
                         break;
@@ -95,6 +120,12 @@ internal class FileWatcherThread : IDisposable {
     }
 
     public void Close() {
+        if (thread != null) {
+            done = true;
+            Signal();
+            thread.Join();
+            thread = null;
+        }
         if (stream != null) {
             stream.Close();
             stream = null;
@@ -103,13 +134,6 @@ internal class FileWatcherThread : IDisposable {
             file.Close();
             file = null;
         }
-        if (thread != null) {
-            done = true;
-            Signal();
-            thread.Join();
-            thread = null;
-        }
-        entries.Clear();
     }
 
     void IDisposable.Dispose() {
@@ -128,6 +152,10 @@ public class JournalStream {
 
     public PlayerJournal? Journal;
 
+    private SyncQueue<Entry> queue = new();
+
+    public SyncQueue<Entry> Queue => queue;
+
     public JournalStream() {
     }
 
@@ -145,29 +173,11 @@ public class JournalStream {
             return;
         }
 
-        FileWatcherThread thread = new(path);
+        FileWatcherThread thread = new(path, queue);
         streams[path] = thread;
     }
 
-    /// <summary>
-    /// Processes all file watcher thread queues in the current thread. This must be
-    /// called from the main event loop sometimes to make sure all NewJournalEntry
-    /// delegates fire correctly.
-    /// </summary>
-    public void ProcessQueues() {
-        foreach (var stream in streams) {
-            if (stream.Value == null) {
-                continue;
-            }
-
-            if (stream.Value.IsEmpty) {
-                continue;
-            }
-
-            Entry entry = stream.Value.Dequeue();
-            NewJournalEntry?.Invoke(entry);
-        }
-
+    private void CleanupStreams() {
         var toRemove = streams
             .Where(x => (x.Value != null && x.Value.Finished) || x.Value == null)
             .Select(x => x)
@@ -180,6 +190,31 @@ public class JournalStream {
         }
     }
 
+    /// <summary>
+    /// Processes all file watcher thread queues in the current thread. This must be
+    /// called from the main event loop sometimes to make sure all NewJournalEntry
+    /// delegates fire correctly.
+    /// </summary>
+    public void ProcessQueues() {
+        Entry? entry;
+
+        while ((entry = queue.TryDequeue()) != null) {
+            NewJournalEntry?.Invoke(entry);
+        }
+
+        CleanupStreams();
+    }
+
+    public void ProcessQueuesWait() {
+        Entry? entry;
+
+        while ((entry = queue.Dequeue()) != null) {
+            NewJournalEntry?.Invoke(entry);
+        }
+
+        CleanupStreams();
+    }
+
     public void Open() {
         if (watcher != null) {
             return;
@@ -213,6 +248,9 @@ public class JournalStream {
             watcher.EnableRaisingEvents = false;
         }
         watcher = null;
+        foreach (var stream in streams) {
+            stream.Value.Close();
+        }
         streams.Clear();
     }