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fix: app freeze (ANR) when we check if a model has been downloaded (isModelDownloaded) #807

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Merged
merged 4 commits into from
Sep 17, 2025
Merged

fix: app freeze (ANR) when we check if a model has been downloaded (isModelDownloaded) #807

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8c488d6
fix-anr-when-checking-if-model-downloaded
Sep 11, 2025
f6d555a
Merge pull request #1 from helloimfrog/fix-anr-when-checking-if-model…
helloimfrog Sep 11, 2025
023f83e
update lints
Sep 12, 2025
eef271d
Merge pull request #2 from helloimfrog/fix-anr-when-checking-if-model…
helloimfrog Sep 12, 2025
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116 changes: 71 additions & 45 deletions ...gle_mlkit_commons/android/src/main/java/com/google_mlkit_commons/GenericModelManager.java
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Original file line number Diff line number Diff line change
@@ -1,17 +1,9 @@
package com.google_mlkit_commons;

import com.google.android.gms.tasks.Task;
import com.google.android.gms.tasks.Tasks;
import com.google.mlkit.common.model.DownloadConditions;
import com.google.mlkit.common.model.RemoteModel;
import com.google.mlkit.common.model.RemoteModelManager;

import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;

import io.flutter.plugin.common.MethodCall;
import io.flutter.plugin.common.MethodChannel;

Expand All @@ -20,13 +12,22 @@ public class GenericModelManager {
private static final String DELETE = "delete";
private static final String CHECK = "check";

public RemoteModelManager remoteModelManager = RemoteModelManager.getInstance();
public interface CheckModelIsDownloadedCallback {
void onCheckResult(Boolean isDownloaded);

void onError(Exception e);
}

//To avoid downloading models in the main thread as they are around 20MB and may crash the app.
private final ExecutorService executorService = Executors.newCachedThreadPool();
public RemoteModelManager remoteModelManager = RemoteModelManager.getInstance();

public void manageModel(final RemoteModel model, final MethodCall call, final MethodChannel.Result result) {
String task = call.argument("task");

if (task == null) {
result.notImplemented();
return;
}

switch (task) {
case DOWNLOAD:
boolean isWifiReqRequired = call.argument("wifi");
Expand All @@ -41,52 +42,77 @@ public void manageModel(final RemoteModel model, final MethodCall call, final Me
deleteModel(model, result);
break;
case CHECK:
Boolean downloaded = isModelDownloaded(model);
if (downloaded != null) result.success(downloaded);
else result.error("error", null, null);
isModelDownloaded(
model,
new CheckModelIsDownloadedCallback() {
@Override
public void onCheckResult(Boolean isDownloaded) {
result.success(isDownloaded);
}

@Override
public void onError(Exception e) {
result.error("error", e.toString(), null);
}
}
);
break;
default:
result.notImplemented();
}
}

public void downloadModel(RemoteModel remoteModel, DownloadConditions downloadConditions, final MethodChannel.Result result) {
if (isModelDownloaded(remoteModel)) {
result.success("success");
return;
}
remoteModelManager.download(remoteModel, downloadConditions).addOnSuccessListener(aVoid -> result.success("success")).addOnFailureListener(e -> result.error("error", e.toString(), null));
}
isModelDownloaded(
remoteModel,
new CheckModelIsDownloadedCallback() {
@Override
public void onCheckResult(Boolean isDownloaded) {
if (isDownloaded) {
result.success("success");
return;
}

public void deleteModel(RemoteModel remoteModel, final MethodChannel.Result result) {
if (!isModelDownloaded(remoteModel)) {
result.success("success");
return;
}
remoteModelManager.deleteDownloadedModel(remoteModel).addOnSuccessListener(aVoid -> result.success("success")).addOnFailureListener(e -> result.error("error", e.toString(), null));
}
remoteModelManager.download(remoteModel, downloadConditions)
.addOnSuccessListener(aVoid -> result.success("success"))
.addOnFailureListener(e -> result.error("error", e.toString(), null));
}

public Boolean isModelDownloaded(RemoteModel model) {
IsModelDownloaded myCallable = new IsModelDownloaded(remoteModelManager.isModelDownloaded(model));
Future<Boolean> taskResult = executorService.submit(myCallable);
try {
return taskResult.get();
} catch (InterruptedException | ExecutionException e) {
e.printStackTrace();
}
return null;
@Override
public void onError(Exception e) {
result.error("error", e.toString(), null);
}
}
);
}
}

class IsModelDownloaded implements Callable<Boolean> {
final Task<Boolean> booleanTask;
public void deleteModel(RemoteModel remoteModel, final MethodChannel.Result result) {
isModelDownloaded(remoteModel, new CheckModelIsDownloadedCallback() {
@Override
public void onCheckResult(Boolean isDownloaded) {
if (!isDownloaded) {
result.success("success");
return;
}
remoteModelManager.deleteDownloadedModel(remoteModel)
.addOnSuccessListener(aVoid -> result.success("success"))
.addOnFailureListener(e -> result.error("error", e.toString(), null));
}

public IsModelDownloaded(Task<Boolean> booleanTask) {
this.booleanTask = booleanTask;
@Override
public void onError(Exception e) {
result.error("error", e.toString(), null);
}
});
}

@Override
public Boolean call() throws Exception {
return Tasks.await(booleanTask);
public void isModelDownloaded(RemoteModel model, CheckModelIsDownloadedCallback callback) {
try {
remoteModelManager.isModelDownloaded(model)
.addOnFailureListener(callback::onError)
.addOnSuccessListener(callback::onCheckResult);
} catch (Exception e) {
callback.onError(e);
}
}
}
}
32 changes: 27 additions & 5 deletions .../android/src/main/java/com/google_mlkit_digital_ink_recognition/DigitalInkRecognizer.java
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Original file line number Diff line number Diff line change
Expand Up @@ -54,11 +54,33 @@ private void handleDetection(MethodCall call, final MethodChannel.Result result)
DigitalInkRecognitionModel model = getModel(tag, result);
if (model == null)
return;
if (!genericModelManager.isModelDownloaded(model)) {
result.error("Model Error", "Model has not been downloaded yet ", null);
return;
}

genericModelManager.isModelDownloaded(
model,
new GenericModelManager.CheckModelIsDownloadedCallback() {
@Override
public void onCheckResult(Boolean isDownloaded) {
if (!isDownloaded) {
result.error("Model Error", "Model has not been downloaded yet ", null);
return;
}

handleInkDetectionIfModelDownloaded(call, result, model);
}

@Override
public void onError(Exception e) {
result.error("Model download check failed", e.toString(), e);
}
}
);
}

private void handleInkDetectionIfModelDownloaded(
MethodCall call,
final MethodChannel.Result result,
DigitalInkRecognitionModel model
) {
String id = call.argument("id");
com.google.mlkit.vision.digitalink.DigitalInkRecognizer recognizer = instances.get(id);
if (recognizer == null) {
Expand Down Expand Up @@ -164,4 +186,4 @@ private DigitalInkRecognitionModel getModel(String tag, final MethodChannel.Resu
}
return DigitalInkRecognitionModel.builder(modelIdentifier).build();
}
}
}
65 changes: 41 additions & 24 deletions ...ge_labeling/android/src/main/java/com/google_mlkit_image_labeling/ImageLabelDetector.java
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Original file line number Diff line number Diff line change
Expand Up @@ -79,12 +79,43 @@ private void handleDetection(MethodCall call, final MethodChannel.Result result)
CustomImageLabelerOptions labelerOptions = getLocalOptions(options);
imageLabeler = ImageLabeling.getClient(labelerOptions);
} else if (type.equals("remote")) {
CustomImageLabelerOptions labelerOptions = getRemoteOptions(options);
if (labelerOptions == null) {
result.error("Error Model has not been downloaded yet", "Model has not been downloaded yet", "Model has not been downloaded yet");
return;
}
imageLabeler = ImageLabeling.getClient(labelerOptions);
float confidenceThreshold = (float) (double) options.get("confidenceThreshold");
int maxCount = (int) options.get("maxCount");
String name = (String) options.get("modelName");

FirebaseModelSource firebaseModelSource = new FirebaseModelSource.Builder(name).build();
CustomRemoteModel remoteModel = new CustomRemoteModel.Builder(firebaseModelSource).build();

genericModelManager.isModelDownloaded(
remoteModel,
new GenericModelManager.CheckModelIsDownloadedCallback() {
@Override
public void onCheckResult(Boolean isDownloaded) {
if (!isDownloaded) {
result.error("Error Model has not been downloaded yet", "Model has not been downloaded yet", "Model has not been downloaded yet");
return;
}

startImageLabelDetector(
ImageLabeling.getClient(
new CustomImageLabelerOptions.Builder(remoteModel)
.setConfidenceThreshold(confidenceThreshold)
.setMaxResultCount(maxCount)
.build()
),
inputImage,
result
);
}

@Override
public void onError(Exception e) {
result.error("Model download check failed", e.getMessage(), e);
}
}
);

return;
} else {
String error = "Invalid model type: " + type;
result.error(type, error, error);
Expand All @@ -93,6 +124,10 @@ private void handleDetection(MethodCall call, final MethodChannel.Result result)
instances.put(id, imageLabeler);
}

startImageLabelDetector(imageLabeler, inputImage, result);
}

private void startImageLabelDetector(ImageLabeler imageLabeler, InputImage inputImage, MethodChannel.Result result) {
imageLabeler.process(inputImage)
.addOnSuccessListener(imageLabels -> {
List<Map<String, Object>> labels = new ArrayList<>(imageLabels.size());
Expand Down Expand Up @@ -131,24 +166,6 @@ private CustomImageLabelerOptions getLocalOptions(Map<String, Object> labelerOpt
.build();
}

//Options for labeler to work with custom model.
private CustomImageLabelerOptions getRemoteOptions(Map<String, Object> labelerOptions) {
float confidenceThreshold = (float) (double) labelerOptions.get("confidenceThreshold");
int maxCount = (int) labelerOptions.get("maxCount");
String name = (String) labelerOptions.get("modelName");

FirebaseModelSource firebaseModelSource = new FirebaseModelSource.Builder(name).build();
CustomRemoteModel remoteModel = new CustomRemoteModel.Builder(firebaseModelSource).build();
if (!genericModelManager.isModelDownloaded(remoteModel)) {
return null;
}

return new CustomImageLabelerOptions.Builder(remoteModel)
.setConfidenceThreshold(confidenceThreshold)
.setMaxResultCount(maxCount)
.build();
}

private void closeDetector(MethodCall call) {
String id = call.argument("id");
ImageLabeler imageLabeler = instances.get(id);
Expand Down
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