fix(ANR): Moves saveRequestForLater from main thread. Adds synchroniz… (#162)

* fix(ANR): Moves saveRequestForLater from main thread. Adds synchronized to init method at LeanplumEventDataManager.

* fix unit tests.

Author: Enuviel

AndroidSDKCore/src/main/java/com/leanplum/internal/LeanplumEventDataManager.java

@@ -29,6 +29,7 @@
 import android.database.DatabaseUtils;
 import android.database.sqlite.SQLiteDatabase;
 import android.database.sqlite.SQLiteOpenHelper;
+import android.os.AsyncTask;
 
 import com.leanplum.Leanplum;
 import com.leanplum.utils.SharedPreferencesUtil;
@@ -41,6 +42,8 @@
 import java.util.Locale;
 import java.util.Map;
 import java.util.UUID;
+import java.util.concurrent.Executor;
+import java.util.concurrent.Executors;
 
 /**
  * LeanplumEventDataManager class to work with SQLite.
@@ -57,6 +60,7 @@ public class LeanplumEventDataManager {
   private static SQLiteDatabase database;
   private static LeanplumDataBaseManager databaseManager;
   private static ContentValues contentValues = new ContentValues();
+  private static final Executor sqlLiteThreadExecutor = Executors.newSingleThreadExecutor();
 
   static boolean willSendErrorLog = false;
 
@@ -65,7 +69,7 @@ public class LeanplumEventDataManager {
    *
    * @param context Current context.
    */
-  public static void init(Context context) {
+  public static synchronized void init(Context context) {
     if (database != null) {
       Log.e("Database is already initialized.");
       return;
@@ -181,6 +185,17 @@ private static void handleSQLiteError(String log, Throwable t) {
     }
   }
 
+  /**
+   * Execute async task on single thread Executer.
+   *
+   * @param task Async task to execute.
+   * @param params Params.
+   */
+  static <T> void executeAsyncTask(AsyncTask<T, ?, ?> task,
+      T... params) {
+    task.executeOnExecutor(sqlLiteThreadExecutor, params);
+  }
+
   private static class LeanplumDataBaseManager extends SQLiteOpenHelper {
     LeanplumDataBaseManager(Context context) {
       super(context, DATABASE_NAME, null, DATABASE_VERSION);

AndroidSDKCore/src/main/java/com/leanplum/internal/Request.java

@@ -230,30 +230,37 @@ private Map<String, Object> createArgsDictionary() {
     return args;
   }
 
-  private void saveRequestForLater(Map<String, Object> args) {
-    synchronized (Request.class) {
-      Context context = Leanplum.getContext();
-      SharedPreferences preferences = context.getSharedPreferences(
-          LEANPLUM, Context.MODE_PRIVATE);
-      SharedPreferences.Editor editor = preferences.edit();
-      long count = LeanplumEventDataManager.getEventsCount();
-      String uuid = preferences.getString(Constants.Defaults.UUID_KEY, null);
-      if (uuid == null || count % MAX_EVENTS_PER_API_CALL == 0) {
-        uuid = UUID.randomUUID().toString();
-        editor.putString(Constants.Defaults.UUID_KEY, uuid);
-        SharedPreferencesUtil.commitChanges(editor);
-      }
-      args.put(UUID_KEY, uuid);
-      LeanplumEventDataManager.insertEvent(JsonConverter.toJson(args));
-
-      dataBaseIndex = count;
-      // Checks if here response and/or error callback for this request. We need to add callbacks to
-      // eventCallbackManager only if here was internet connection, otherwise triggerErrorCallback
-      // will handle error callback for this event.
-      if (response != null || error != null && !Util.isConnected()) {
-        eventCallbackManager.addCallbacks(this, response, error);
+  private void saveRequestForLater(final Map<String, Object> args) {
+    final Request currentRequest = this;
+    LeanplumEventDataManager.executeAsyncTask(new AsyncTask<Void, Void, Void>() {
+      @Override
+      protected Void doInBackground(Void... params) {
+        synchronized (Request.class) {
+          Context context = Leanplum.getContext();
+          SharedPreferences preferences = context.getSharedPreferences(
+              LEANPLUM, Context.MODE_PRIVATE);
+          SharedPreferences.Editor editor = preferences.edit();
+          long count = LeanplumEventDataManager.getEventsCount();
+          String uuid = preferences.getString(Constants.Defaults.UUID_KEY, null);
+          if (uuid == null || count % MAX_EVENTS_PER_API_CALL == 0) {
+            uuid = UUID.randomUUID().toString();
+            editor.putString(Constants.Defaults.UUID_KEY, uuid);
+            SharedPreferencesUtil.commitChanges(editor);
+          }
+          args.put(UUID_KEY, uuid);
+          LeanplumEventDataManager.insertEvent(JsonConverter.toJson(args));
+
+          dataBaseIndex = count;
+          // Checks if here response and/or error callback for this request. We need to add callbacks to
+          // eventCallbackManager only if here was internet connection, otherwise triggerErrorCallback
+          // will handle error callback for this event.
+          if (response != null || error != null && !Util.isConnected()) {
+            eventCallbackManager.addCallbacks(currentRequest, response, error);
+          }
+          return null;
+        }
       }
-    }
+    });
   }
 
   public void send() {

AndroidSDKTests/src/test/java/com/leanplum/__setup/AbstractTest.java

@@ -130,6 +130,9 @@ public void before() throws Exception {
     // Mock with our executor which will run on main thread.
     ReflectionHelpers.setStaticField(Util.class, "asyncExecutor", new SynchronousExecutor());
     ReflectionHelpers.setStaticField(Util.class, "singleThreadExecutor", new SynchronousExecutor());
+    ReflectionHelpers.setStaticField(LeanplumEventDataManager.class, "sqlLiteThreadExecutor",
+        new SynchronousExecutor());
+
     ReflectionHelpers.setStaticField(LeanplumEventDataManager.class, "databaseManager", null);
     ReflectionHelpers.setStaticField(LeanplumEventDataManager.class, "database", null);
     // Get and set application context.

AndroidSDKTests/src/test/java/com/leanplum/internal/RequestTest.java

@@ -24,6 +24,7 @@
 
 import com.leanplum.Leanplum;
 import com.leanplum.__setup.LeanplumTestApp;
+import com.leanplum._whitebox.utilities.SynchronousExecutor;
 
 import junit.framework.TestCase;
 
@@ -34,6 +35,7 @@
 import org.robolectric.RobolectricTestRunner;
 import org.robolectric.RuntimeEnvironment;
 import org.robolectric.annotation.Config;
+import org.robolectric.util.ReflectionHelpers;
 
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
@@ -59,6 +61,8 @@ public void setUp() {
     Application context = RuntimeEnvironment.application;
     assertNotNull(context);
     Leanplum.setApplicationContext(context);
+    ReflectionHelpers.setStaticField(LeanplumEventDataManager.class, "sqlLiteThreadExecutor",  new SynchronousExecutor());
+    LeanplumEventDataManagerTest.setDatabaseToNull();
   }
 
   /**