Fix Null User State Issue

• Fixes a relatively rare crash (#503) caused by a race condition where a sync state variable was accessed before it was initialized
• Resolved by synchronizing the accessor method

Author: Nightsd01

OneSignalSDK/onesignal/src/main/java/com/onesignal/UserStateEmailSynchronizer.java

@@ -57,7 +57,7 @@ void setEmail(String email, String emailAuthHash) {
         JSONObject syncValues = getUserStateForModification().syncValues;
 
         boolean noChange = email.equals(syncValues.optString("identifier")) &&
-                               syncValues.optString("email_auth_hash").equals(emailAuthHash == null ? "" : emailAuthHash);
+                syncValues.optString("email_auth_hash").equals(emailAuthHash == null ? "" : emailAuthHash);
         if (noChange) {
             OneSignal.fireEmailUpdateSuccess();
             return;
@@ -115,7 +115,7 @@ void logoutEmail() {
         OneSignal.saveEmailId("");
 
         resetCurrentState();
-        toSyncUserState.syncValues.remove("identifier");
+        getToSyncUserState().syncValues.remove("identifier");
         toSyncUserState.syncValues.remove("email_auth_hash");
         toSyncUserState.syncValues.remove("device_player_id");
         toSyncUserState.persistState();

OneSignalSDK/onesignal/src/main/java/com/onesignal/UserStatePushSynchronizer.java

@@ -32,16 +32,16 @@ void onSuccess(String responseStr) {
                         if (lastGetTagsResponse.has("tags")) {
                             synchronized(syncLock) {
                                 JSONObject dependDiff = generateJsonDiff(currentUserState.syncValues.optJSONObject("tags"),
-                                        toSyncUserState.syncValues.optJSONObject("tags"),
+                                        getToSyncUserState().syncValues.optJSONObject("tags"),
                                         null, null);
 
                                 currentUserState.syncValues.put("tags", lastGetTagsResponse.optJSONObject("tags"));
                                 currentUserState.persistState();
 
                                 // Allow server side tags to overwrite local tags expect for any pending changes
                                 //  that haven't been successfully posted.
-                                toSyncUserState.mergeTags(lastGetTagsResponse, dependDiff);
-                                toSyncUserState.persistState();
+                                getToSyncUserState().mergeTags(lastGetTagsResponse, dependDiff);
+                                getToSyncUserState().persistState();
                             }
                         }
                     } catch (JSONException e) {

OneSignalSDK/onesignal/src/main/java/com/onesignal/UserStateSynchronizer.java

@@ -111,7 +111,7 @@ protected JSONObject generateJsonDiff(JSONObject cur, JSONObject changedTo, JSON
         }
     }
 
-    protected UserState getToSyncUserState() {
+    protected synchronized UserState getToSyncUserState() {
         if (toSyncUserState == null)
             toSyncUserState = newUserState("TOSYNC_STATE", true);
 
@@ -122,8 +122,7 @@ void initUserState() {
         if (currentUserState == null)
             currentUserState = newUserState("CURRENT_STATE", true);
 
-        if (toSyncUserState == null)
-            toSyncUserState = newUserState("TOSYNC_STATE", true);
+        getToSyncUserState();
     }
 
     abstract protected UserState newUserState(String inPersistKey, boolean load);
@@ -151,7 +150,7 @@ private boolean isSessionCall() {
     }
 
     private boolean syncEmailLogout() {
-        return toSyncUserState.dependValues.optBoolean("logoutEmail", false);
+        return getToSyncUserState().dependValues.optBoolean("logoutEmail", false);
     }
 
     synchronized void syncUserState(boolean fromSyncService) {
@@ -171,14 +170,14 @@ private void internalSyncUserState(boolean fromSyncService) {
         final boolean isSessionCall = isSessionCall();
         JSONObject jsonBody, dependDiff;
         synchronized (syncLock) {
-            jsonBody = currentUserState.generateJsonDiff(toSyncUserState, isSessionCall);
-            dependDiff = generateJsonDiff(currentUserState.dependValues, toSyncUserState.dependValues, null, null);
+            jsonBody = currentUserState.generateJsonDiff(getToSyncUserState(), isSessionCall);
+            dependDiff = generateJsonDiff(currentUserState.dependValues, getToSyncUserState().dependValues, null, null);
 
             if (jsonBody == null) {
                 currentUserState.persistStateAfterSync(dependDiff, null);
                 return;
             }
-            toSyncUserState.persistState();
+            getToSyncUserState().persistState();
         }
 
         if (!isSessionCall || fromSyncService)
@@ -228,7 +227,7 @@ void onSuccess(String response) {
     }
 
     private void logoutEmailSyncSuccess() {
-        toSyncUserState.dependValues.remove("logoutEmail");
+        getToSyncUserState().dependValues.remove("logoutEmail");
         toSyncUserState.dependValues.remove("email_auth_hash");
         toSyncUserState.syncValues.remove("parent_player_id");
         toSyncUserState.persistState();
@@ -326,7 +325,7 @@ private void handleNetworkFailure() {
         if (jsonBody != null)
             fireEventsForUpdateFailure(jsonBody);
 
-        if (toSyncUserState.dependValues.optBoolean("logoutEmail", false))
+        if (getToSyncUserState().dependValues.optBoolean("logoutEmail", false))
             OneSignal.handleFailedEmailLogout();
     }