Asynchronous GeometryTile deletion (#2051)

Co-authored-by: Tim Sylvester <tim@wetdogweather.com>

platform/android/MapboxGLAndroidSDK/src/cpp/map_renderer.cpp

@@ -60,7 +60,7 @@ ActorRef<Renderer> MapRenderer::actor() const {
     return *rendererRef;
 }
 
-void MapRenderer::schedule(std::function<void()> scheduled) {
+void MapRenderer::schedule(std::function<void()>&& scheduled) {
     try {
         // Create a runnable
         android::UniqueEnv _env = android::AttachEnv();
@@ -84,6 +84,23 @@ void MapRenderer::schedule(std::function<void()> scheduled) {
     }
 }
 
+std::size_t MapRenderer::waitForEmpty(Milliseconds timeout) {
+    try {
+        android::UniqueEnv _env = android::AttachEnv();
+        static auto& javaClass = jni::Class<MapRenderer>::Singleton(*_env);
+        static auto waitForEmpty = javaClass.GetMethod<jni::jint(jni::jlong)>(*_env, "waitForEmpty");
+        if (auto weakReference = javaPeer.get(*_env)) {
+            return weakReference.Call(*_env, waitForEmpty, static_cast<int64_t>(timeout.count()));
+        }
+        // If the peer is already cleaned up, there's nothing to wait for
+        return 0;
+    } catch (...) {
+        Log::Error(Event::Android, "MapRenderer::waitForEmpty failed");
+        jni::ThrowJavaError(*android::AttachEnv(), std::current_exception());
+        return 0;
+    }
+}
+
 void MapRenderer::requestRender() {
     try {
         android::UniqueEnv _env = android::AttachEnv();

platform/android/MapboxGLAndroidSDK/src/cpp/map_renderer.hpp

@@ -66,9 +66,13 @@ public:
 
     // From Scheduler. Schedules by using callbacks to the
     // JVM to process the mailbox on the right thread.
-    void schedule(std::function<void()> scheduled) override;
+    void schedule(std::function<void()>&& scheduled) override;
     mapbox::base::WeakPtr<Scheduler> makeWeakPtr() override { return weakFactory.makeWeakPtr(); }
 
+    // Wait for the queue to be empty
+    // A timeout of zero results in an unbounded wait
+    std::size_t waitForEmpty(Milliseconds timeout) override;
+
     void requestRender();
 
     // Snapshot - requires a RunLoop on the calling thread

platform/android/MapboxGLAndroidSDK/src/main/java/org/maplibre/android/maps/renderer/MapRenderer.java

@@ -120,6 +120,11 @@ public abstract class MapRenderer implements MapRendererScheduler {
     this.queueEvent((Runnable) runnable);
   }
 
+  /// Wait indefinitely for the queue to become empty
+  public void waitForEmpty() {
+    waitForEmpty(0);
+  }
+
   private native void nativeInitialize(MapRenderer self,
                                        float pixelRatio,
                                        String localIdeographFontFamily);

platform/android/MapboxGLAndroidSDK/src/main/java/org/maplibre/android/maps/renderer/MapRendererScheduler.java

@@ -14,4 +14,9 @@ public interface MapRendererScheduler {
   @Keep
   void queueEvent(Runnable runnable);
 
+  @Keep
+  void waitForEmpty();
+
+  @Keep
+  long waitForEmpty(long timeoutMillis);
 }

platform/android/MapboxGLAndroidSDK/src/main/java/org/maplibre/android/maps/renderer/glsurfaceview/GLSurfaceViewMapRenderer.java

@@ -116,4 +116,11 @@ public class GLSurfaceViewMapRenderer extends MapRenderer implements GLSurfaceVi
     glSurfaceView.queueEvent(runnable);
   }
 
+  /**
+   * {@inheritDoc}
+   */
+  @Override
+  public long waitForEmpty(long timeoutMillis) {
+    return glSurfaceView.waitForEmpty(timeoutMillis);
+  }
 }

platform/android/MapboxGLAndroidSDK/src/main/java/org/maplibre/android/maps/renderer/glsurfaceview/MapLibreGLSurfaceView.java

@@ -317,6 +317,16 @@ public class MapLibreGLSurfaceView extends SurfaceView implements SurfaceHolder.
     glThread.queueEvent(r);
   }
 
+  /**
+   * Wait for the queue to become empty
+   * @param timeoutMillis Timeout in milliseconds
+   * @return Number of queue items remaining
+   */
+  public long waitForEmpty(long timeoutMillis) {
+    return glThread.waitForEmpty(timeoutMillis);
+  }
+
+
   /**
    * This method is used as part of the View class and is not normally
    * called or subclassed by clients of GLSurfaceView.
@@ -1023,6 +1033,39 @@ public class MapLibreGLSurfaceView extends SurfaceView implements SurfaceHolder.
       }
     }
 
+    /**
+     * Wait for the queue to become empty
+     * @param timeoutMillis Timeout in milliseconds, zero for indefinite wait
+     * @return Number of queue items remaining
+    */
+    public int waitForEmpty(long timeoutMillis) {
+      final long startTime = System.nanoTime();
+      synchronized (glThreadManager) {
+        // Wait for the queue to be empty
+        while (!this.eventQueue.isEmpty()) {
+          if (timeoutMillis > 0) {
+            final long elapsedMillis = (System.nanoTime() - startTime) / 1000 / 1000;
+            if (elapsedMillis < timeoutMillis) {
+              try {
+                glThreadManager.wait(timeoutMillis - elapsedMillis);
+              } catch (InterruptedException ex) {
+                Thread.currentThread().interrupt();
+              }
+            } else {
+              break;
+            }
+          } else {
+            try {
+              glThreadManager.wait();
+            } catch (InterruptedException ex) {
+              Thread.currentThread().interrupt();
+            }
+          }
+        }
+        return this.eventQueue.size();
+      }
+    }
+
     // Once the thread is started, all accesses to the following member
     // variables are protected by the sGLThreadManager monitor
     private boolean shouldExit;

platform/android/MapboxGLAndroidSDK/src/main/java/org/maplibre/android/maps/renderer/textureview/TextureViewMapRenderer.java

@@ -35,6 +35,7 @@ public class TextureViewMapRenderer extends MapRenderer {
     super(context, localIdeographFontFamily);
     this.translucentSurface = translucentSurface;
     renderThread = new TextureViewRenderThread(textureView, this);
+    renderThread.setName("TextureViewRenderer");
     renderThread.start();
   }
 
@@ -86,6 +87,14 @@ public class TextureViewMapRenderer extends MapRenderer {
     renderThread.queueEvent(runnable);
   }
 
+  /**
+   * {@inheritDoc}
+   */
+  @Override
+  public long waitForEmpty(long timeoutMillis) {
+    return renderThread.waitForEmpty(timeoutMillis);
+  }
+
   /**
    * {@inheritDoc}
    */

platform/android/MapboxGLAndroidSDK/src/main/java/org/maplibre/android/maps/renderer/textureview/TextureViewRenderThread.java

@@ -135,6 +135,39 @@ class TextureViewRenderThread extends Thread implements TextureView.SurfaceTextu
     }
   }
 
+  /**
+   * Wait for the queue to be empty.
+   * @param timeoutMillis Maximum time to wait, in milliseconds
+   * @return The number of items remaining in the queue
+   */
+  @UiThread
+  int waitForEmpty(long timeoutMillis) {
+    final long startTime = System.nanoTime();
+    synchronized (lock) {
+      // Wait for the queue to be empty
+      while (!this.eventQueue.isEmpty()) {
+        if (timeoutMillis > 0) {
+          final long elapsedMillis = (System.nanoTime() - startTime) / 1000 / 1000;
+          if (elapsedMillis < timeoutMillis) {
+            try {
+              lock.wait(timeoutMillis - elapsedMillis);
+            } catch (InterruptedException ex) {
+              Thread.currentThread().interrupt();
+            }
+          } else {
+            break;
+          }
+        } else {
+          try {
+            lock.wait(0);
+          } catch (InterruptedException ex) {
+            Thread.currentThread().interrupt();
+          }
+        }
+      }
+      return this.eventQueue.size();
+    }
+  }
 
   @UiThread
   void onPause() {