Migrate ML Downloader to DataStore by emilypgoogle · Pull Request #8418 · firebase/firebase-android-sdk

emilypgoogle · 2026-07-14T23:04:02Z

Following previous PRs, updates ML Model Downloader's Shared Preference utility class to use DataStore instead. This includes removing synchronized on a lot of methods since this is handled by our DataStore wrapper innately. Additionally, added helper methods for several keys with duplicate code.

gemini-code-assist · 2026-07-14T23:04:06Z

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github-actions · 2026-07-14T23:47:11Z

📝 PRs merging into main branch

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milaGGL · 2026-07-16T13:49:24Z

/gemini review

gemini-code-assist

Code Review

This pull request migrates SharedPreferencesUtil from Android's SharedPreferences to Jetpack DataStore-backed JavaDataStorage. The review feedback highlights several performance and consistency issues arising from the migration. Specifically, the reviewer recommends retrieving all preferences in a single snapshot using dataStore.getAllSync() to avoid multiple sequential, non-atomic blocking reads in getCustomModelDetails and getDownloadingCustomModelDetails. Additionally, they suggest compiling regex patterns outside of loops and optimizing getCustomModelStatsCollectionFlag to avoid redundant sequential blocking calls.

gemini-code-assist · 2026-07-16T13:51:10Z

+  public CustomModel getCustomModelDetails(@NonNull String modelName) {
+    String modelHash = dataStore.getSync(localModelHashKey(modelName), null);

    if (modelHash == null || modelHash.isEmpty()) {
      // no model downloaded - check if model is being downloaded.
      return getDownloadingCustomModelDetails(modelName);
    }

-    String filePath =
-        getSharedPreferences()
-            .getString(String.format(LOCAL_MODEL_FILE_PATH_PATTERN, persistenceKey, modelName), "");
+    String filePath = dataStore.getSync(localModelFilePathKey(modelName), "");

-    long fileSize =
-        getSharedPreferences()
-            .getLong(String.format(LOCAL_MODEL_FILE_SIZE_PATTERN, persistenceKey, modelName), 0);
+    long fileSize = dataStore.getSync(localModelFileSizeKey(modelName), 0L);

    // if no-zero - local model is present and new model being downloaded
-    long id =
-        getSharedPreferences()
-            .getLong(String.format(DOWNLOADING_MODEL_ID_PATTERN, persistenceKey, modelName), 0);
+    long id = dataStore.getSync(downloadingModelIdKey(modelName), 0L);


Calling dataStore.getSync(...) multiple times sequentially performs multiple blocking flow collections, which is inefficient. Furthermore, because these reads are not atomic, a concurrent write could modify the preferences between reads, leading to an inconsistent CustomModel state.

We can retrieve all preferences in a single consistent snapshot using dataStore.getAllSync() and extract the values from the map.

Suggested change

public CustomModel getCustomModelDetails(@NonNull String modelName) {

String modelHash = dataStore.getSync(localModelHashKey(modelName), null);

if (modelHash == null || modelHash.isEmpty()) {

// no model downloaded - check if model is being downloaded.

return getDownloadingCustomModelDetails(modelName);

}

String filePath =

getSharedPreferences()

.getString(String.format(LOCAL_MODEL_FILE_PATH_PATTERN, persistenceKey, modelName), "");

String filePath = dataStore.getSync(localModelFilePathKey(modelName), "");

long fileSize =

getSharedPreferences()

.getLong(String.format(LOCAL_MODEL_FILE_SIZE_PATTERN, persistenceKey, modelName), 0);

long fileSize = dataStore.getSync(localModelFileSizeKey(modelName), 0L);

// if no-zero - local model is present and new model being downloaded

long id =

getSharedPreferences()

.getLong(String.format(DOWNLOADING_MODEL_ID_PATTERN, persistenceKey, modelName), 0);

long id = dataStore.getSync(downloadingModelIdKey(modelName), 0L);

public CustomModel getCustomModelDetails(@NonNull String modelName) {

Map<Preferences.Key<?>, Object> allPrefs = dataStore.getAllSync();

String modelHash = (String) allPrefs.get(localModelHashKey(modelName));

if (modelHash == null || modelHash.isEmpty()) {

// no model downloaded - check if model is being downloaded.

return getDownloadingCustomModelDetails(modelName);

}

String filePath = (String) allPrefs.getOrDefault(localModelFilePathKey(modelName), "");

long fileSize = (Long) allPrefs.getOrDefault(localModelFileSizeKey(modelName), 0L);

// if no-zero - local model is present and new model being downloaded

long id = (Long) allPrefs.getOrDefault(downloadingModelIdKey(modelName), 0L);

gemini-code-assist · 2026-07-16T13:51:11Z

+  public CustomModel getDownloadingCustomModelDetails(@NonNull String modelName) {
+    String modelHash = dataStore.getSync(downloadingModelHashKey(modelName), null);

    if (modelHash == null || modelHash.isEmpty()) {
      // no model hash means no download in progress
      return null;
    }

-    long fileSize =
-        getSharedPreferences()
-            .getLong(String.format(DOWNLOADING_MODEL_SIZE_PATTERN, persistenceKey, modelName), 0);
+    long fileSize = dataStore.getSync(downloadingModelSizeKey(modelName), 0L);

-    long id =
-        getSharedPreferences()
-            .getLong(String.format(DOWNLOADING_MODEL_ID_PATTERN, persistenceKey, modelName), 0);
+    long id = dataStore.getSync(downloadingModelIdKey(modelName), 0L);


Calling dataStore.getSync(...) multiple times sequentially performs multiple blocking flow collections, which is inefficient. Furthermore, because these reads are not atomic, a concurrent write could modify the preferences between reads, leading to an inconsistent CustomModel state.

We can retrieve all preferences in a single consistent snapshot using dataStore.getAllSync() and extract the values from the map.

Suggested change

public CustomModel getDownloadingCustomModelDetails(@NonNull String modelName) {

String modelHash = dataStore.getSync(downloadingModelHashKey(modelName), null);

if (modelHash == null || modelHash.isEmpty()) {

// no model hash means no download in progress

return null;

}

long fileSize =

getSharedPreferences()

.getLong(String.format(DOWNLOADING_MODEL_SIZE_PATTERN, persistenceKey, modelName), 0);

long fileSize = dataStore.getSync(downloadingModelSizeKey(modelName), 0L);

long id =

getSharedPreferences()

.getLong(String.format(DOWNLOADING_MODEL_ID_PATTERN, persistenceKey, modelName), 0);

long id = dataStore.getSync(downloadingModelIdKey(modelName), 0L);

public CustomModel getDownloadingCustomModelDetails(@NonNull String modelName) {

Map<Preferences.Key<?>, Object> allPrefs = dataStore.getAllSync();

String modelHash = (String) allPrefs.get(downloadingModelHashKey(modelName));

if (modelHash == null || modelHash.isEmpty()) {

// no model hash means no download in progress

return null;

}

long fileSize = (Long) allPrefs.getOrDefault(downloadingModelSizeKey(modelName), 0L);

long id = (Long) allPrefs.getOrDefault(downloadingModelIdKey(modelName), 0L);

gemini-code-assist · 2026-07-16T13:51:11Z

+  public Set<CustomModel> listDownloadedModels() {
    Set<CustomModel> customModels = new HashSet<>();
-    Set<String> keySet = getSharedPreferences().getAll().keySet();
+    Set<Preferences.Key<?>> keySet = dataStore.getAllSync().keySet();

-    for (String key : keySet) {
+    for (Preferences.Key<?> key : keySet) {
+      String keyName = key.getName();
      // if a local file path is present - get model details.
-      Matcher matcher = Pattern.compile(LOCAL_MODEL_FILE_PATH_MATCHER).matcher(key);
+      Matcher matcher = Pattern.compile(LOCAL_MODEL_FILE_PATH_MATCHER).matcher(keyName);


Compiling the Pattern inside the loop for every key is inefficient. Additionally, calling getCustomModelDetails(modelName) inside the loop performs multiple sequential blocking reads (dataStore.getSync(...)) for each model. For $N$ models, this results in $4N$ blocking flow collections, which can significantly degrade performance.

We can optimize this by compiling the pattern once outside the loop, and retrieving all preferences in a single consistent snapshot using dataStore.getAllSync().

public Set<CustomModel> listDownloadedModels() { Set<CustomModel> customModels = new HashSet<>(); Map<Preferences.Key<?>, Object> allPrefs = dataStore.getAllSync(); Pattern pathPattern = Pattern.compile(LOCAL_MODEL_FILE_PATH_MATCHER); for (Preferences.Key<?> key : allPrefs.keySet()) { String keyName = key.getName(); // if a local file path is present - get model details. Matcher matcher = pathPattern.matcher(keyName);

gemini-code-assist · 2026-07-16T13:51:11Z

+  public boolean getCustomModelStatsCollectionFlag() {
+    if (dataStore.contains(eventLoggingEnabledKey())) {
+      return dataStore.getSync(eventLoggingEnabledKey(), true);
    }


Calling dataStore.contains(...) followed by dataStore.getSync(...) results in two sequential blocking reads. We can optimize this to a single read by calling getSync with a default value of null and checking if the result is non-null.

Suggested change

public boolean getCustomModelStatsCollectionFlag() {

if (dataStore.contains(eventLoggingEnabledKey())) {

return dataStore.getSync(eventLoggingEnabledKey(), true);

}

public boolean getCustomModelStatsCollectionFlag() {

Boolean enabled = dataStore.getSync(eventLoggingEnabledKey(), null);

if (enabled != null) {

return enabled;

}

Migrate ML Downloader to DataStore

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Migrate ML Downloader to DataStore#8418

Migrate ML Downloader to DataStore#8418
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