[android] Fixes 'drawRenderNode called on a context with no surface' crash (#33655)

Author: 0xZOne

shell/platform/android/io/flutter/embedding/android/FlutterActivityAndFragmentDelegate.java

@@ -844,24 +844,10 @@ void onTrimMemory(int level) {
         flutterEngine.getDartExecutor().notifyLowMemoryWarning();
         flutterEngine.getSystemChannel().sendMemoryPressureWarning();
       }
+      flutterEngine.getRenderer().onTrimMemory(level);
     }
   }
 
-  /**
-   * Invoke this from {@link android.app.Activity#onLowMemory()}.
-   *
-   * <p>A {@code Fragment} host must have its containing {@code Activity} forward this call so that
-   * the {@code Fragment} can then invoke this method.
-   *
-   * <p>This method sends a "memory pressure warning" message to Flutter over the "system channel".
-   */
-  void onLowMemory() {
-    Log.v(TAG, "Forwarding onLowMemory() to FlutterEngine.");
-    ensureAlive();
-    flutterEngine.getDartExecutor().notifyLowMemoryWarning();
-    flutterEngine.getSystemChannel().sendMemoryPressureWarning();
-  }
-
   /**
    * Ensures that this delegate has not been {@link #release()}'ed.
    *

shell/platform/android/io/flutter/embedding/android/FlutterFragment.java

@@ -980,19 +980,6 @@ public void onTrimMemory(int level) {
     }
   }
 
-  /**
-   * Callback invoked when memory is low.
-   *
-   * <p>This implementation forwards a memory pressure warning to the running Flutter app.
-   */
-  @Override
-  public void onLowMemory() {
-    super.onLowMemory();
-    if (stillAttachedForEvent("onLowMemory")) {
-      delegate.onLowMemory();
-    }
-  }
-
   /**
    * {@link FlutterActivityAndFragmentDelegate.Host} method that is used by {@link
    * FlutterActivityAndFragmentDelegate} to obtain Flutter shell arguments when initializing

shell/platform/android/io/flutter/embedding/engine/renderer/FlutterRenderer.java

@@ -12,12 +12,17 @@
 import android.view.Surface;
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
+import androidx.annotation.VisibleForTesting;
 import io.flutter.Log;
 import io.flutter.embedding.engine.FlutterJNI;
 import io.flutter.view.TextureRegistry;
+import java.lang.ref.WeakReference;
 import java.nio.ByteBuffer;
 import java.util.ArrayList;
+import java.util.HashSet;
+import java.util.Iterator;
 import java.util.List;
+import java.util.Set;
 import java.util.concurrent.atomic.AtomicLong;
 
 /**
@@ -42,6 +47,10 @@ public class FlutterRenderer implements TextureRegistry {
   private boolean isDisplayingFlutterUi = false;
   private Handler handler = new Handler();
 
+  @NonNull
+  private final Set<WeakReference<TextureRegistry.OnTrimMemoryListener>> onTrimMemoryListeners =
+      new HashSet<>();
+
   @NonNull
   private final FlutterUiDisplayListener flutterUiDisplayListener =
       new FlutterUiDisplayListener() {
@@ -89,6 +98,39 @@ public void removeIsDisplayingFlutterUiListener(@NonNull FlutterUiDisplayListene
     flutterJNI.removeIsDisplayingFlutterUiListener(listener);
   }
 
+  private void clearDeadListeners() {
+    final Iterator<WeakReference<OnTrimMemoryListener>> iterator = onTrimMemoryListeners.iterator();
+    while (iterator.hasNext()) {
+      WeakReference<OnTrimMemoryListener> listenerRef = iterator.next();
+      final OnTrimMemoryListener listener = listenerRef.get();
+      if (listener == null) {
+        iterator.remove();
+      }
+    }
+  }
+
+  /** Adds a listener that is invoked when a memory pressure warning was forward. */
+  @VisibleForTesting
+  /* package */ void addOnTrimMemoryListener(@NonNull OnTrimMemoryListener listener) {
+    // Purge dead listener to avoid accumulating.
+    clearDeadListeners();
+    onTrimMemoryListeners.add(new WeakReference<>(listener));
+  }
+
+  /**
+   * Removes a {@link OnTrimMemoryListener} that was added with {@link
+   * #addOnTrimMemoryListener(OnTrimMemoryListener)}.
+   */
+  @VisibleForTesting
+  /* package */ void removeOnTrimMemoryListener(@NonNull OnTrimMemoryListener listener) {
+    for (WeakReference<OnTrimMemoryListener> listenerRef : onTrimMemoryListeners) {
+      if (listenerRef.get() == listener) {
+        onTrimMemoryListeners.remove(listenerRef);
+        break;
+      }
+    }
+  }
+
   // ------ START TextureRegistry IMPLEMENTATION -----
   /**
    * Creates and returns a new {@link SurfaceTexture} managed by the Flutter engine that is also
@@ -112,20 +154,38 @@ public SurfaceTextureEntry registerSurfaceTexture(@NonNull SurfaceTexture surfac
         new SurfaceTextureRegistryEntry(nextTextureId.getAndIncrement(), surfaceTexture);
     Log.v(TAG, "New SurfaceTexture ID: " + entry.id());
     registerTexture(entry.id(), entry.textureWrapper());
+    addOnTrimMemoryListener(entry);
     return entry;
   }
 
-  final class SurfaceTextureRegistryEntry implements TextureRegistry.SurfaceTextureEntry {
+  @Override
+  public void onTrimMemory(int level) {
+    final Iterator<WeakReference<OnTrimMemoryListener>> iterator = onTrimMemoryListeners.iterator();
+    while (iterator.hasNext()) {
+      WeakReference<OnTrimMemoryListener> listenerRef = iterator.next();
+      final OnTrimMemoryListener listener = listenerRef.get();
+      if (listener != null) {
+        listener.onTrimMemory(level);
+      } else {
+        // Purge cleared refs to avoid accumulating a lot of dead listener
+        iterator.remove();
+      }
+    }
+  }
+
+  final class SurfaceTextureRegistryEntry
+      implements TextureRegistry.SurfaceTextureEntry, TextureRegistry.OnTrimMemoryListener {
     private final long id;
     @NonNull private final SurfaceTextureWrapper textureWrapper;
     private boolean released;
-    @Nullable private OnFrameConsumedListener listener;
+    @Nullable private OnTrimMemoryListener trimMemoryListener;
+    @Nullable private OnFrameConsumedListener frameConsumedListener;
     private final Runnable onFrameConsumed =
         new Runnable() {
           @Override
           public void run() {
-            if (listener != null) {
-              listener.onFrameConsumed();
+            if (frameConsumedListener != null) {
+              frameConsumedListener.onFrameConsumed();
             }
           }
         };
@@ -149,6 +209,13 @@ public void run() {
       }
     }
 
+    @Override
+    public void onTrimMemory(int level) {
+      if (trimMemoryListener != null) {
+        trimMemoryListener.onTrimMemory(level);
+      }
+    }
+
     private SurfaceTexture.OnFrameAvailableListener onFrameListener =
         new SurfaceTexture.OnFrameAvailableListener() {
           @Override
@@ -164,6 +231,10 @@ public void onFrameAvailable(@NonNull SurfaceTexture texture) {
           }
         };
 
+    private void removeListener() {
+      removeOnTrimMemoryListener(this);
+    }
+
     @NonNull
     public SurfaceTextureWrapper textureWrapper() {
       return textureWrapper;
@@ -188,6 +259,7 @@ public void release() {
       Log.v(TAG, "Releasing a SurfaceTexture (" + id + ").");
       textureWrapper.release();
       unregisterTexture(id);
+      removeListener();
       released = true;
     }
 
@@ -206,7 +278,12 @@ protected void finalize() throws Throwable {
 
     @Override
     public void setOnFrameConsumedListener(@Nullable OnFrameConsumedListener listener) {
-      this.listener = listener;
+      frameConsumedListener = listener;
+    }
+
+    @Override
+    public void setOnTrimMemoryListener(@Nullable OnTrimMemoryListener listener) {
+      trimMemoryListener = listener;
     }
   }
 

shell/platform/android/io/flutter/plugin/platform/PlatformViewWrapper.java

@@ -4,6 +4,8 @@
 
 package io.flutter.plugin.platform;
 
+import static android.content.ComponentCallbacks2.TRIM_MEMORY_COMPLETE;
+
 import android.annotation.SuppressLint;
 import android.annotation.TargetApi;
 import android.content.Context;
@@ -56,7 +58,7 @@ class PlatformViewWrapper extends FrameLayout {
   @Nullable @VisibleForTesting ViewTreeObserver.OnGlobalFocusChangeListener activeFocusListener;
   private final AtomicLong pendingFramesCount = new AtomicLong(0L);
 
-  private final TextureRegistry.OnFrameConsumedListener listener =
+  private final TextureRegistry.OnFrameConsumedListener frameConsumedListener =
       new TextureRegistry.OnFrameConsumedListener() {
         @Override
         public void onFrameConsumed() {
@@ -66,12 +68,40 @@ public void onFrameConsumed() {
         }
       };
 
+  private boolean shouldRecreateSurfaceForLowMemory = false;
+  private final TextureRegistry.OnTrimMemoryListener trimMemoryListener =
+      new TextureRegistry.OnTrimMemoryListener() {
+        @Override
+        public void onTrimMemory(int level) {
+          // When a memory pressure warning is received and the level equal {@code
+          // ComponentCallbacks2.TRIM_MEMORY_COMPLETE}, the Android system releases the underlying
+          // surface. If we continue to use the surface (e.g., call lockHardwareCanvas), a crash
+          // occurs, and we found that this crash appeared on Android10 and above.
+          // See https://github.com/flutter/flutter/issues/103870 for more details.
+          //
+          // Here our workaround is to recreate the surface before using it.
+          if (level == TRIM_MEMORY_COMPLETE && Build.VERSION.SDK_INT >= 29) {
+            shouldRecreateSurfaceForLowMemory = true;
+          }
+        }
+      };
+
   private void onFrameProduced() {
     if (Build.VERSION.SDK_INT == 29) {
       pendingFramesCount.incrementAndGet();
     }
   }
 
+  private void recreateSurfaceIfNeeded() {
+    if (shouldRecreateSurfaceForLowMemory) {
+      if (surface != null) {
+        surface.release();
+      }
+      surface = createSurface(tx);
+      shouldRecreateSurfaceForLowMemory = false;
+    }
+  }
+
   private boolean shouldDrawToSurfaceNow() {
     if (Build.VERSION.SDK_INT == 29) {
       return pendingFramesCount.get() <= 0L;
@@ -87,7 +117,8 @@ public PlatformViewWrapper(@NonNull Context context) {
   public PlatformViewWrapper(
       @NonNull Context context, @NonNull TextureRegistry.SurfaceTextureEntry textureEntry) {
     this(context);
-    textureEntry.setOnFrameConsumedListener(listener);
+    textureEntry.setOnFrameConsumedListener(frameConsumedListener);
+    textureEntry.setOnTrimMemoryListener(trimMemoryListener);
     setTexture(textureEntry.surfaceTexture());
   }
 
@@ -249,6 +280,10 @@ public void draw(Canvas canvas) {
       // If there are still frames that are not consumed, we will draw them next time.
       invalidate();
     } else {
+      // We try to recreate the surface before using it to avoid the crash:
+      // https://github.com/flutter/flutter/issues/103870
+      recreateSurfaceIfNeeded();
+
       // Override the canvas that this subtree of views will use to draw.
       final Canvas surfaceCanvas = surface.lockHardwareCanvas();
       try {

shell/platform/android/io/flutter/view/TextureRegistry.java

@@ -31,6 +31,13 @@ public interface TextureRegistry {
   @NonNull
   SurfaceTextureEntry registerSurfaceTexture(@NonNull SurfaceTexture surfaceTexture);
 
+  /**
+   * Callback invoked when memory is low.
+   *
+   * <p>Invoke this from {@link android.app.Activity#onTrimMemory(int)}.
+   */
+  default void onTrimMemory(int level) {}
+
   /** A registry entry for a managed SurfaceTexture. */
   interface SurfaceTextureEntry {
     /** @return The managed SurfaceTexture. */
@@ -45,6 +52,9 @@ interface SurfaceTextureEntry {
 
     /** Set a listener that will be notified when the most recent image has been consumed. */
     default void setOnFrameConsumedListener(@Nullable OnFrameConsumedListener listener) {}
+
+    /** Set a listener that will be notified when a memory pressure warning was forward. */
+    default void setOnTrimMemoryListener(@Nullable OnTrimMemoryListener listener) {}
   }
 
   /** Listener invoked when the most recent image has been consumed. */
@@ -55,4 +65,10 @@ interface OnFrameConsumedListener {
      */
     void onFrameConsumed();
   }
+
+  /** Listener invoked when a memory pressure warning was forward. */
+  interface OnTrimMemoryListener {
+    /** This method will be invoked when a memory pressure warning was forward. */
+    void onTrimMemory(int level);
+  }
 }

shell/platform/android/test/io/flutter/embedding/android/FlutterActivityAndFragmentDelegateTest.java

@@ -863,23 +863,6 @@ public void itNotifiesDartExecutorAndSendsMessageOverSystemChannelWhenToldToTrim
     verify(mockFlutterEngine.getSystemChannel(), times(6)).sendMemoryPressureWarning();
   }
 
-  @Test
-  public void itNotifiesDartExecutorAndSendsMessageOverSystemChannelWhenInformedOfLowMemory() {
-    // Create the real object that we're testing.
-    FlutterActivityAndFragmentDelegate delegate = new FlutterActivityAndFragmentDelegate(mockHost);
-
-    // --- Execute the behavior under test ---
-    // The FlutterEngine is set up in onAttach().
-    delegate.onAttach(ctx);
-
-    // Emulate the host and call the method that we expect to be forwarded.
-    delegate.onLowMemory();
-
-    // Verify that the call was forwarded to the engine.
-    verify(mockFlutterEngine.getDartExecutor(), times(1)).notifyLowMemoryWarning();
-    verify(mockFlutterEngine.getSystemChannel(), times(1)).sendMemoryPressureWarning();
-  }
-
   @Test
   public void itDestroysItsOwnEngineIfHostRequestsIt() {
     // ---- Test setup ----