Added option to limit query threads

app/src/main/java/eu/faircode/email/DB.java

@@ -106,8 +106,6 @@ public abstract class DB extends RoomDatabase {
     public abstract DaoLog log();
 
     private static DB sInstance;
-    private static final ExecutorService executor =
-            Helper.getBackgroundExecutor(2, "query"); // AndroidX default thread count: 4
 
     private static final String DB_NAME = "fairemail";
     private static final int DB_CHECKPOINT = 1000; // requery/sqlite-android default
@@ -261,6 +259,11 @@ public abstract class DB extends RoomDatabase {
             Log.e(ex);
         }
 
+        SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context);
+        int threads = prefs.getInt("query_threads", 4); // AndroidX default thread count: 4
+        Log.i("Query threads=" + threads);
+        ExecutorService executor = Helper.getBackgroundExecutor(threads, "query");
+
         return Room
                 .databaseBuilder(context, DB.class, DB_NAME)
                 .openHelperFactory(new RequerySQLiteOpenHelperFactory())

app/src/main/java/eu/faircode/email/FragmentOptionsMisc.java

@@ -76,6 +76,7 @@ public class FragmentOptionsMisc extends FragmentBase implements SharedPreferenc
     private SwitchCompat swUpdates;
     private SwitchCompat swExperiments;
     private TextView tvExperimentsHint;
+    private SwitchCompat swQueries;
     private SwitchCompat swCrashReports;
     private TextView tvUuid;
     private SwitchCompat swDebug;
@@ -98,7 +99,7 @@ public class FragmentOptionsMisc extends FragmentBase implements SharedPreferenc
 
     private final static String[] RESET_OPTIONS = new String[]{
             "shortcuts", "fts", "english", "watchdog", "updates",
-            "experiments", "crash_reports", "debug", "auth_sasl", "cleanup_attachments"
+            "experiments", "query_threads", "crash_reports", "debug", "auth_sasl", "cleanup_attachments"
     };
 
     private final static String[] RESET_QUESTIONS = new String[]{
@@ -131,6 +132,7 @@ public class FragmentOptionsMisc extends FragmentBase implements SharedPreferenc
         swUpdates = view.findViewById(R.id.swUpdates);
         swExperiments = view.findViewById(R.id.swExperiments);
         tvExperimentsHint = view.findViewById(R.id.tvExperimentsHint);
+        swQueries = view.findViewById(R.id.swQueries);
         swCrashReports = view.findViewById(R.id.swCrashReports);
         tvUuid = view.findViewById(R.id.tvUuid);
         swDebug = view.findViewById(R.id.swDebug);
@@ -259,6 +261,14 @@ public class FragmentOptionsMisc extends FragmentBase implements SharedPreferenc
             }
         });
 
+        swQueries.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
+            @Override
+            public void onCheckedChanged(CompoundButton compoundButton, boolean checked) {
+                prefs.edit().putInt("query_threads", checked ? 2 : 4).commit(); // apply won't work here
+                restart();
+            }
+        });
+
         swCrashReports.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
             @Override
             public void onCheckedChanged(CompoundButton compoundButton, boolean checked) {
@@ -536,6 +546,7 @@ public class FragmentOptionsMisc extends FragmentBase implements SharedPreferenc
                 Helper.isPlayStoreInstall() || !Helper.hasValidFingerprint(getContext())
                         ? View.GONE : View.VISIBLE);
         swExperiments.setChecked(prefs.getBoolean("experiments", false));
+        swQueries.setChecked(prefs.getInt("query_threads", 4) < 4);
         swCrashReports.setChecked(prefs.getBoolean("crash_reports", false));
         tvUuid.setText(prefs.getString("uuid", null));
         swDebug.setChecked(prefs.getBoolean("debug", false));

app/src/main/res/layout/fragment_options_misc.xml

@@ -183,6 +183,29 @@
             app:layout_constraintStart_toStartOf="parent"
             app:layout_constraintTop_toBottomOf="@id/swExperiments" />
 
+        <androidx.appcompat.widget.SwitchCompat
+            android:id="@+id/swQueries"
+            android:layout_width="0dp"
+            android:layout_height="wrap_content"
+            android:layout_marginTop="12dp"
+            android:text="@string/title_advanced_query_threads"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toBottomOf="@id/tvExperimentsHint"
+            app:switchPadding="12dp" />
+
+        <eu.faircode.email.FixedTextView
+            android:id="@+id/tvQueriesHint"
+            android:layout_width="0dp"
+            android:layout_height="wrap_content"
+            android:layout_marginEnd="48dp"
+            android:text="@string/title_advanced_english_hint"
+            android:textAppearance="@style/TextAppearance.AppCompat.Small"
+            android:textStyle="italic"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toBottomOf="@id/swQueries" />
+
         <androidx.appcompat.widget.SwitchCompat
             android:id="@+id/swCrashReports"
             android:layout_width="0dp"
@@ -191,7 +214,7 @@
             android:text="@string/title_advanced_crash_reports"
             app:layout_constraintEnd_toEndOf="parent"
             app:layout_constraintStart_toStartOf="parent"
-            app:layout_constraintTop_toBottomOf="@id/tvExperimentsHint"
+            app:layout_constraintTop_toBottomOf="@id/tvQueriesHint"
             app:switchPadding="12dp" />
 
         <eu.faircode.email.FixedTextView

app/src/main/res/values/strings.xml

@@ -466,6 +466,7 @@
     <string name="title_advanced_optimize">Automatically optimize</string>
     <string name="title_advanced_updates">Check for updates</string>
     <string name="title_advanced_experiments">Try experimental features</string>
+    <string name="title_advanced_query_threads">Limit parallel database reads</string>
     <string name="title_advanced_crash_reports">Send error reports</string>
     <string name="title_advanced_debug">Debug mode</string>
     <string name="title_advanced_cleanup_attachments">Delete attachments of old messages</string>