Fix deadlock

Use Combine instead of notifications to transfer "needs update" information. This avoids a deadlock because notifications were delivered synchronously (which is not needed in this case).
cochrane · Mar 15, 2023 · 8be0215 · 8be0215
1 parent 74da60f
commit 8be0215
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Showing 6 changed files with 17 additions and 16 deletions.
diff --git a/GLLara/GLLItemDrawer.swift b/GLLara/GLLItemDrawer.swift
@@ -80,7 +80,7 @@ class GLLItemDrawer {
     }
 
     func propertiesChanged() {
-        sceneDrawer?.notifyRedraw()
+        sceneDrawer?.needsUpdate = true
     }
 
     private func permutationTableColumn(for assignment: GLLItemChannelAssignment) -> vector_float4 {

diff --git a/GLLara/GLLNotifications.h b/GLLara/GLLNotifications.h
@@ -8,8 +8,6 @@
 
 #include <Foundation/Foundation.h>
 
-extern NSString *GLLSceneDrawerNeedsUpdateNotification;
-
 // Sent when bound textures or similar change outside of normal execution, to
 // indicate that the draw state needs to be reset for the next frame.
 extern NSString *GLLDrawStateChangedNotification;
diff --git a/GLLara/GLLNotifications.m b/GLLara/GLLNotifications.m
@@ -8,7 +8,4 @@
 
 #import <Foundation/Foundation.h>
 
-
-NSString *GLLSceneDrawerNeedsUpdateNotification = @"GLLSceneDrawerNeedsUpdateNotification";
-
 NSString *GLLDrawStateChangedNotification = @"GLLDrawStateChangedNotification";
diff --git a/GLLara/GLLSceneDrawer.swift b/GLLara/GLLSceneDrawer.swift
@@ -8,8 +8,9 @@
 
 import Cocoa
 import CoreData
+import Combine
 
-@objc class GLLSceneDrawer: NSObject {
+@objc class GLLSceneDrawer: NSObject, ObservableObject {
 
     @objc init(document: GLLDocument) {
         self.document = document
@@ -40,11 +41,11 @@ import CoreData
                     }
                 }
             }
-            self.notifyRedraw()
+            self.needsUpdate = true
         }
 
         drawStateNotificationObserver = NotificationCenter.default.addObserver(forName: Notification.Name.GLLDrawStateChanged, object: nil, queue: OperationQueue.main) { [weak self] notification in
-            self?.notifyRedraw()
+            self?.needsUpdate = true
         }
 
         // Load existing items
@@ -78,7 +79,7 @@ import CoreData
     @objc var selectedBones: [GLLItemBone] {
         set {
             skeletonDrawer.selectedBones = newValue
-            notifyRedraw()
+            needsUpdate = true
         }
         get {
             return skeletonDrawer.selectedBones
@@ -95,9 +96,7 @@ import CoreData
         skeletonDrawer.draw(into: commandEncoder)
     }
 
-    func notifyRedraw() {
-        NotificationCenter.default.post(name: NSNotification.Name.GLLSceneDrawerNeedsUpdate, object: self)
-    }
+    @Published var needsUpdate = false
 
     private var itemDrawers: [GLLItemDrawer] = []
     private let skeletonDrawer: GLLSkeletonDrawer

diff --git a/GLLara/GLLView.swift b/GLLara/GLLView.swift
@@ -9,6 +9,7 @@
 import Cocoa
 import MetalKit
 import GameController
+import Combine
 
 @objc class GLLView: MTKView {
 
@@ -27,9 +28,6 @@ import GameController
         notificationObservers.append(NotificationCenter.default.addObserver(forName: UserDefaults.didChangeNotification, object: nil, queue: OperationQueue.main) { [weak self] notification in
             self?.showSelection = UserDefaults.standard.bool(forKey: GLLPrefShowSkeleton)
         })
-        notificationObservers.append(NotificationCenter.default.addObserver(forName: NSNotification.Name.GLLSceneDrawerNeedsUpdate, object: nil, queue: OperationQueue.main) { [weak self] notification in
-            self?.unpause()
-        })
         notificationObservers.append(NotificationCenter.default.addObserver(forName: NSNotification.Name.GCControllerDidBecomeCurrent, object: nil, queue: OperationQueue.main) { [weak self] notification in
             self?.unpause()
         })
@@ -57,13 +55,20 @@ import GameController
 
     @objc func set(camera: GLLCamera, sceneDrawer: GLLSceneDrawer) {
         self.camera = camera
+        sceneDrawerUpdateRegistration?.cancel()
         self.sceneDrawer = sceneDrawer
+        sceneDrawerUpdateRegistration = sceneDrawer.$needsUpdate.sink { [weak self] value in
+            if value {
+                self?.unpause()
+            }
+        }
         self.viewDrawer = GLLViewDrawer(sceneDrawer: sceneDrawer, camera: camera, view: self)
     }
 
     var camera: GLLCamera? = nil
     @objc weak var document: GLLDocument? = nil
     var sceneDrawer: GLLSceneDrawer? = nil
+    var sceneDrawerUpdateRegistration: AnyCancellable? = nil
     @objc var viewDrawer: GLLViewDrawer? = nil
     var showSelection: Bool = false
     var keysDown = CharacterSet()

diff --git a/GLLara/GLLViewDrawer.swift b/GLLara/GLLViewDrawer.swift
@@ -290,6 +290,8 @@ import UniformTypeIdentifiers
 
     private func draw(commandBuffer: MTLCommandBuffer, viewRenderPassDescriptor: MTLRenderPassDescriptor, surface: Surface, includeUI: Bool = true, screenScale: Double = 2.0) {
 
+        sceneDrawer.needsUpdate = false
+
         var viewProjection = camera.viewProjectionMatrix(forAspectRatio: Float(surface.width) / Float(surface.height))
 
         if needsUpdateLights {