Start using a single thread executor for any database access to eliminate unnecessary thread creation

app/src/main/java/acr/browser/lightning/activity/BrowserActivity.java

@@ -173,7 +173,9 @@ public abstract class BrowserActivity extends ThemableBrowserActivity implements
     private boolean mShowTabsInDrawer;
     private int mOriginalOrientation, mBackgroundColor, mIdGenerator, mIconColor,
             mCurrentUiColor = Color.BLACK;
-    private String mSearchText, mUntitledTitle, mHomepage, mCameraPhotoPath;
+    private String mSearchText;
+    private String mUntitledTitle;
+    private String mCameraPhotoPath;
 
     // The singleton BookmarkManager
     @Inject
@@ -258,8 +260,6 @@ public abstract class BrowserActivity extends ThemableBrowserActivity implements
 
         mWebpageBitmap = ThemeUtils.getThemedBitmap(this, R.drawable.ic_webpage, mDarkTheme);
 
-        mHomepage = mPreferences.getHomepage();
-
         final TabsFragment tabsFragment = new TabsFragment();
         final int containerId = mShowTabsInDrawer ? R.id.left_drawer : R.id.tabs_toolbar_container;
         final Bundle tabsFragmentArguments = new Bundle();
@@ -1339,7 +1339,10 @@ public abstract class BrowserActivity extends ThemableBrowserActivity implements
     }
 
     void addItemToHistory(@Nullable final String title, @NonNull final String url) {
-        Runnable update = new Runnable() {
+        if (UrlUtils.isSpecialUrl(url)) {
+            return;
+        }
+        BrowserApp.getAppComponent().getHistoryDatabase().getIOThread().execute(new Runnable() {
             @Override
             public void run() {
                 try {
@@ -1352,10 +1355,7 @@ public abstract class BrowserActivity extends ThemableBrowserActivity implements
                     Log.e(Constants.TAG, "SQLiteException in updateHistory", e);
                 }
             }
-        };
-        if (!UrlUtils.isSpecialUrl(url)) {
-            new Thread(update).start();
-        }
+        });
     }
 
     /**
@@ -1406,7 +1406,7 @@ public abstract class BrowserActivity extends ThemableBrowserActivity implements
      */
     private void openHistory() {
         // use a thread so that history retrieval doesn't block the UI
-        Thread history = new Thread(new Runnable() {
+        BrowserApp.getAppComponent().getHistoryDatabase().getIOThread().execute(new Runnable() {
 
             @Override
             public void run() {
@@ -1415,7 +1415,6 @@ public abstract class BrowserActivity extends ThemableBrowserActivity implements
             }
 
         });
-        history.run();
     }
 
     /**

app/src/main/java/acr/browser/lightning/database/HistoryDatabase.java

@@ -13,6 +13,8 @@ import android.support.annotation.Nullable;
 
 import java.util.ArrayList;
 import java.util.List;
+import java.util.concurrent.Executor;
+import java.util.concurrent.Executors;
 
 import javax.inject.Inject;
 import javax.inject.Singleton;
@@ -40,6 +42,8 @@ public class HistoryDatabase extends SQLiteOpenHelper {
 
     private SQLiteDatabase mDatabase;
 
+    private Executor mIOThread = Executors.newSingleThreadExecutor();
+
     @Inject
     public HistoryDatabase(Context context) {
         super(context.getApplicationContext(), DATABASE_NAME, null, DATABASE_VERSION);
@@ -74,6 +78,10 @@ public class HistoryDatabase extends SQLiteOpenHelper {
         return mDatabase == null || !mDatabase.isOpen();
     }
 
+    public Executor getIOThread() {
+        return mIOThread;
+    }
+
     @Override
     public synchronized void close() {
         if (mDatabase != null) {

app/src/main/java/acr/browser/lightning/fragment/PrivacySettingsFragment.java

@@ -15,6 +15,7 @@ import android.support.v7.app.AlertDialog;
 import android.webkit.WebView;
 
 import acr.browser.lightning.R;
+import acr.browser.lightning.app.BrowserApp;
 import acr.browser.lightning.utils.Utils;
 import acr.browser.lightning.utils.WebUtils;
 import acr.browser.lightning.view.LightningView;
@@ -148,13 +149,15 @@ public class PrivacySettingsFragment extends LightningPreferenceFragment impleme
                         new DialogInterface.OnClickListener() {
                             @Override
                             public void onClick(DialogInterface arg0, int arg1) {
-                                Thread clear = new Thread(new Runnable() {
+                                BrowserApp.getAppComponent()
+                                        .getHistoryDatabase()
+                                        .getIOThread()
+                                        .execute(new Runnable() {
                                             @Override
                                             public void run() {
                                                 clearHistory();
                                             }
                                         });
-                                clear.start();
                             }
                         })
                 .setNegativeButton(getResources().getString(R.string.action_no), null).show();

app/src/main/java/acr/browser/lightning/view/LightningView.java

@@ -12,7 +12,6 @@ import android.graphics.Color;
 import android.graphics.ColorMatrix;
 import android.graphics.ColorMatrixColorFilter;
 import android.graphics.Paint;
-import android.net.Uri;
 import android.os.Build;
 import android.os.Handler;
 import android.os.Message;
@@ -546,20 +545,6 @@ public class LightningView {
         }
     }
 
-    /**
-     * Naive caching of the favicon according to the domain name of the URL
-     *
-     * @param icon the icon to cache
-     */
-    private void cacheFavicon(final Bitmap icon) {
-        if (icon == null) return;
-        final Uri uri = Uri.parse(getUrl());
-        if (uri.getHost() == null) {
-            return;
-        }
-        new Thread(new IconCacheTask(uri, icon)).start();
-    }
-
     @SuppressLint("NewApi")
     public synchronized void find(String text) {
         if (mWebView != null) {