locks around observable list's access
authorDamyan Ivanov <dam+mobileledger@ktnx.net>
Sun, 24 Mar 2019 17:09:41 +0000 (19:09 +0200)
committerDamyan Ivanov <dam+mobileledger@ktnx.net>
Mon, 25 Mar 2019 06:17:36 +0000 (06:17 +0000)
to help guarantee that the list is not modified by another thread while
traversing

app/src/main/java/net/ktnx/mobileledger/async/CommitAccountsTask.java
app/src/main/java/net/ktnx/mobileledger/model/Data.java
app/src/main/java/net/ktnx/mobileledger/model/MobileLedgerProfile.java
app/src/main/java/net/ktnx/mobileledger/ui/account_summary/AccountSummaryAdapter.java
app/src/main/java/net/ktnx/mobileledger/ui/activity/MainActivity.java
app/src/main/java/net/ktnx/mobileledger/ui/activity/NewTransactionActivity.java
app/src/main/java/net/ktnx/mobileledger/utils/LockHolder.java [new file with mode: 0644]
app/src/main/java/net/ktnx/mobileledger/utils/ObservableList.java

index 8f8c1da..7a6f713 100644 (file)
@@ -23,6 +23,7 @@ import android.util.Log;
 
 import net.ktnx.mobileledger.model.Data;
 import net.ktnx.mobileledger.model.LedgerAccount;
+import net.ktnx.mobileledger.utils.LockHolder;
 import net.ktnx.mobileledger.utils.MLDB;
 
 import java.util.ArrayList;
@@ -38,6 +39,7 @@ public class CommitAccountsTask
             SQLiteDatabase db = MLDB.getDatabase();
             db.beginTransaction();
             try {
+                try (LockHolder lh = params[0].accountList.lockForWriting()) {
                     for (int i = 0; i < params[0].accountList.size(); i++ ){
                         LedgerAccount acc = params[0].accountList.get(i);
                         Log.d("CAT", String.format("Setting %s to %s", acc.getName(),
@@ -48,6 +50,7 @@ public class CommitAccountsTask
 
                         acc.setHiddenByStar(acc.isHiddenByStarToBe());
                         if (!params[0].showOnlyStarred || !acc.isHiddenByStar()) newList.add(acc);
+                    }
                     db.setTransactionSuccessful();
                 }
             }
index 5965d27..d92ddef 100644 (file)
@@ -17,6 +17,7 @@
 
 package net.ktnx.mobileledger.model;
 
+import net.ktnx.mobileledger.utils.LockHolder;
 import net.ktnx.mobileledger.utils.MLDB;
 import net.ktnx.mobileledger.utils.ObservableAtomicInteger;
 import net.ktnx.mobileledger.utils.ObservableList;
@@ -41,12 +42,13 @@ public final class Data {
         profile.set(newProfile);
     }
     public static int getProfileIndex(MobileLedgerProfile profile) {
+        try(LockHolder lh = profiles.lockForReading()) {
             for (int i = 0; i < profiles.size(); i++) {
                 MobileLedgerProfile p = profiles.get(i);
                 if (p.equals(profile)) return i;
+            }
 
+            return -1;
         }
-
-        return -1;
     }
 }
index 1971ca2..9731e3e 100644 (file)
@@ -21,7 +21,9 @@ import android.database.Cursor;
 import android.database.sqlite.SQLiteDatabase;
 import android.util.Log;
 
+import net.ktnx.mobileledger.async.DbOpQueue;
 import net.ktnx.mobileledger.utils.Globals;
+import net.ktnx.mobileledger.utils.LockHolder;
 import net.ktnx.mobileledger.utils.MLDB;
 
 import java.util.ArrayList;
@@ -101,12 +103,14 @@ public final class MobileLedgerProfile {
         db.beginTransaction();
         try {
             int orderNo = 0;
+            try (LockHolder lh = Data.profiles.lockForReading()) {
                 for (int i = 0; i < Data.profiles.size(); i++) {
                     MobileLedgerProfile p = Data.profiles.get(i);
                     db.execSQL("update profiles set order_no=? where uuid=?",
                             new Object[]{orderNo, p.getUuid()});
                     p.orderNo = orderNo;
                     orderNo++;
+                }
             }
             db.setTransactionSuccessful();
         }
@@ -126,21 +130,21 @@ public final class MobileLedgerProfile {
     public String getName() {
         return name;
     }
-    public void setName(String name) {
-        this.name = name;
-    }
     public void setName(CharSequence text) {
         setName(String.valueOf(text));
     }
+    public void setName(String name) {
+        this.name = name;
+    }
     public String getUrl() {
         return url;
     }
-    public void setUrl(String url) {
-        this.url = url;
-    }
     public void setUrl(CharSequence text) {
         setUrl(String.valueOf(text));
     }
+    public void setUrl(String url) {
+        this.url = url;
+    }
     public boolean isAuthEnabled() {
         return authEnabled;
     }
@@ -150,21 +154,21 @@ public final class MobileLedgerProfile {
     public String getAuthUserName() {
         return authUserName;
     }
-    public void setAuthUserName(String authUserName) {
-        this.authUserName = authUserName;
-    }
     public void setAuthUserName(CharSequence text) {
         setAuthUserName(String.valueOf(text));
     }
+    public void setAuthUserName(String authUserName) {
+        this.authUserName = authUserName;
+    }
     public String getAuthPassword() {
         return authPassword;
     }
-    public void setAuthPassword(String authPassword) {
-        this.authPassword = authPassword;
-    }
     public void setAuthPassword(CharSequence text) {
         setAuthPassword(String.valueOf(text));
     }
+    public void setAuthPassword(String authPassword) {
+        this.authPassword = authPassword;
+    }
     public void storeInDB() {
         SQLiteDatabase db = MLDB.getDatabase();
         db.beginTransaction();
@@ -274,8 +278,7 @@ public final class MobileLedgerProfile {
     }
     public void setOption(String name, String value) {
         Log.d("profile", String.format("setting option %s=%s", name, value));
-        SQLiteDatabase db = MLDB.getDatabase();
-        db.execSQL("insert or replace into options(profile, name, value) values(?, ?, ?);",
+        DbOpQueue.add("insert or replace into options(profile, name, value) values(?, ?, ?);",
                 new String[]{uuid, name, value});
     }
     public void setLongOption(String name, long value) {
@@ -352,13 +355,13 @@ public final class MobileLedgerProfile {
 //        Log.d("profile", String.format("Profile.getThemeId() returning %d", themeId));
         return this.themeId;
     }
+    public void setThemeId(Object o) {
+        setThemeId(Integer.valueOf(String.valueOf(o)).intValue());
+    }
     public void setThemeId(int themeId) {
 //        Log.d("profile", String.format("Profile.setThemeId(%d) called", themeId));
         this.themeId = themeId;
     }
-    public void setThemeId(Object o) {
-        setThemeId(Integer.valueOf(String.valueOf(o)).intValue());
-    }
     public void markTransactionsAsNotPresent(SQLiteDatabase db) {
         db.execSQL("UPDATE transactions set keep=0 where profile=?", new String[]{uuid});
 
index 3778552..c2ec0e9 100644 (file)
@@ -31,6 +31,7 @@ import android.widget.TextView;
 import net.ktnx.mobileledger.R;
 import net.ktnx.mobileledger.model.Data;
 import net.ktnx.mobileledger.model.LedgerAccount;
+import net.ktnx.mobileledger.utils.LockHolder;
 
 import androidx.annotation.NonNull;
 import androidx.constraintlayout.widget.ConstraintLayout;
@@ -45,41 +46,43 @@ public class AccountSummaryAdapter
     }
 
     public void onBindViewHolder(@NonNull LedgerRowHolder holder, int position) {
-        if (position < Data.accounts.size()) {
-            LedgerAccount acc = Data.accounts.get(position);
-            Context ctx = holder.row.getContext();
-            Resources rm = ctx.getResources();
-
-            holder.row.setTag(acc);
-            holder.row.setVisibility(View.VISIBLE);
-            holder.vTrailer.setVisibility(View.GONE);
-            holder.tvAccountName.setText(acc.getShortName());
-            ConstraintLayout.LayoutParams lp =
-                    (ConstraintLayout.LayoutParams) holder.tvAccountName.getLayoutParams();
-            lp.setMarginStart(
-                    acc.getLevel() * rm.getDimensionPixelSize(R.dimen.thumb_row_height) / 2);
-            holder.expanderContainer
-                    .setVisibility(acc.hasSubAccounts() ? View.VISIBLE : View.INVISIBLE);
-            holder.expanderContainer.setRotation(acc.isExpanded() ? 0 : 180);
-            holder.tvAccountAmounts.setText(acc.getAmountsString());
-
-            if (acc.isHiddenByStar()) {
-                holder.tvAccountName.setTypeface(null, Typeface.ITALIC);
-                holder.tvAccountAmounts.setTypeface(null, Typeface.ITALIC);
+        try (LockHolder lh = Data.accounts.lockForReading()) {
+            if (position < Data.accounts.size()) {
+                LedgerAccount acc = Data.accounts.get(position);
+                Context ctx = holder.row.getContext();
+                Resources rm = ctx.getResources();
+
+                holder.row.setTag(acc);
+                holder.row.setVisibility(View.VISIBLE);
+                holder.vTrailer.setVisibility(View.GONE);
+                holder.tvAccountName.setText(acc.getShortName());
+                ConstraintLayout.LayoutParams lp =
+                        (ConstraintLayout.LayoutParams) holder.tvAccountName.getLayoutParams();
+                lp.setMarginStart(
+                        acc.getLevel() * rm.getDimensionPixelSize(R.dimen.thumb_row_height) / 2);
+                holder.expanderContainer
+                        .setVisibility(acc.hasSubAccounts() ? View.VISIBLE : View.INVISIBLE);
+                holder.expanderContainer.setRotation(acc.isExpanded() ? 0 : 180);
+                holder.tvAccountAmounts.setText(acc.getAmountsString());
+
+                if (acc.isHiddenByStar()) {
+                    holder.tvAccountName.setTypeface(null, Typeface.ITALIC);
+                    holder.tvAccountAmounts.setTypeface(null, Typeface.ITALIC);
+                }
+                else {
+                    holder.tvAccountName.setTypeface(null, Typeface.NORMAL);
+                    holder.tvAccountAmounts.setTypeface(null, Typeface.NORMAL);
+                }
+
+                holder.selectionCb.setVisibility(selectionActive ? View.VISIBLE : View.GONE);
+                holder.selectionCb.setChecked(!acc.isHiddenByStarToBe());
+
+                holder.row.setTag(R.id.POS, position);
             }
             else {
-                holder.tvAccountName.setTypeface(null, Typeface.NORMAL);
-                holder.tvAccountAmounts.setTypeface(null, Typeface.NORMAL);
+                holder.vTrailer.setVisibility(View.VISIBLE);
+                holder.row.setVisibility(View.GONE);
             }
-
-            holder.selectionCb.setVisibility(selectionActive ? View.VISIBLE : View.GONE);
-            holder.selectionCb.setChecked(!acc.isHiddenByStarToBe());
-
-            holder.row.setTag(R.id.POS, position);
-        }
-        else {
-            holder.vTrailer.setVisibility(View.VISIBLE);
-            holder.row.setVisibility(View.GONE);
         }
     }
 
@@ -96,12 +99,15 @@ public class AccountSummaryAdapter
         return Data.accounts.size() + 1;
     }
     public void startSelection() {
-        for (int i = 0; i < Data.accounts.size(); i++ ) {
-            LedgerAccount acc = Data.accounts.get(i);
-            acc.setHiddenByStarToBe(acc.isHiddenByStar());
+        try (LockHolder lh = Data.accounts.lockForWriting()) {
+            for (int i = 0; i < Data.accounts.size(); i++) {
+                LedgerAccount acc = Data.accounts.get(i);
+                acc.setHiddenByStarToBe(acc.isHiddenByStar());
+            }
+            this.selectionActive = true;
+            lh.downgrade();
+            notifyDataSetChanged();
         }
-        this.selectionActive = true;
-        notifyDataSetChanged();
     }
 
     public void stopSelection() {
@@ -114,20 +120,24 @@ public class AccountSummaryAdapter
     }
 
     public void selectItem(int position) {
-        LedgerAccount acc = Data.accounts.get(position);
-        acc.toggleHiddenToBe();
-        toggleChildrenOf(acc, acc.isHiddenByStarToBe(), position);
-        notifyItemChanged(position);
+        try (LockHolder lh = Data.accounts.lockForWriting()) {
+            LedgerAccount acc = Data.accounts.get(position);
+            acc.toggleHiddenToBe();
+            toggleChildrenOf(acc, acc.isHiddenByStarToBe(), position);
+            notifyItemChanged(position);
+        }
     }
     void toggleChildrenOf(LedgerAccount parent, boolean hiddenToBe, int parentPosition) {
         int i = parentPosition + 1;
-        for (int j = 0; j < Data.accounts.size(); j++) {
-            LedgerAccount acc = Data.accounts.get(j);
-            if (acc.getName().startsWith(parent.getName() + ":")) {
-                acc.setHiddenByStarToBe(hiddenToBe);
-                notifyItemChanged(i);
-                toggleChildrenOf(acc, hiddenToBe, i);
-                i++;
+        try (LockHolder lh = Data.accounts.lockForWriting()) {
+            for (int j = 0; j < Data.accounts.size(); j++) {
+                LedgerAccount acc = Data.accounts.get(j);
+                if (acc.getName().startsWith(parent.getName() + ":")) {
+                    acc.setHiddenByStarToBe(hiddenToBe);
+                    notifyItemChanged(i);
+                    toggleChildrenOf(acc, hiddenToBe, i);
+                    i++;
+                }
             }
         }
     }
index 0f668ce..cd58740 100644 (file)
@@ -50,6 +50,7 @@ import net.ktnx.mobileledger.ui.profiles.ProfilesRecyclerViewAdapter;
 import net.ktnx.mobileledger.ui.transaction_list.TransactionListFragment;
 import net.ktnx.mobileledger.ui.transaction_list.TransactionListViewModel;
 import net.ktnx.mobileledger.utils.Colors;
+import net.ktnx.mobileledger.utils.LockHolder;
 import net.ktnx.mobileledger.utils.MLDB;
 
 import java.lang.ref.WeakReference;
@@ -588,6 +589,7 @@ public class MainActivity extends ProfileThemedActivity {
 
                     // removing all child accounts from the view
                     int start = -1, count = 0;
+                    try (LockHolder lh = Data.accounts.lockForWriting()) {
                         for (int i = 0; i < Data.accounts.size(); i++) {
                             if (acc.isParentOf(Data.accounts.get(i))) {
 //                                Log.d("accounts", String.format("Found a child '%s' at position %d",
@@ -616,6 +618,7 @@ public class MainActivity extends ProfileThemedActivity {
 
                             mAccountSummaryFragment.modelAdapter
                                     .notifyItemRangeRemoved(start, count);
+                        }
                     }
                 }
                 else {
@@ -624,6 +627,7 @@ public class MainActivity extends ProfileThemedActivity {
                     animator.rotationBy(-180);
                     List<LedgerAccount> children =
                             Data.profile.get().loadVisibleChildAccountsOf(acc);
+                    try (LockHolder lh = Data.accounts.lockForWriting()) {
                         int parentPos = Data.accounts.indexOf(acc);
                         if (parentPos != -1) {
                             // may have disappeared in a concurrent refresh operation
@@ -631,6 +635,7 @@ public class MainActivity extends ProfileThemedActivity {
                             mAccountSummaryFragment.modelAdapter
                                     .notifyItemRangeInserted(parentPos + 1, children.size());
                         }
+                    }
                 }
                 break;
             case R.id.account_row_acc_amounts:
index b7770dc..5a5a352 100644 (file)
@@ -56,12 +56,12 @@ import net.ktnx.mobileledger.model.MobileLedgerProfile;
 import net.ktnx.mobileledger.ui.DatePickerFragment;
 import net.ktnx.mobileledger.ui.OnSwipeTouchListener;
 import net.ktnx.mobileledger.utils.Globals;
+import net.ktnx.mobileledger.utils.LockHolder;
 import net.ktnx.mobileledger.utils.MLDB;
 
 import java.text.ParseException;
 import java.util.ArrayList;
 import java.util.Date;
-import java.util.List;
 import java.util.Locale;
 import java.util.Objects;
 
@@ -492,20 +492,22 @@ public class NewTransactionActivity extends ProfileThemedActivity
             String profileUUID = c.getString(0);
             int transactionId = c.getInt(1);
             LedgerTransaction tr;
+            try(LockHolder lh = Data.profiles.lockForReading()) {
                 MobileLedgerProfile profile = null;
                 for (int i = 0; i < Data.profiles.size(); i++) {
                     MobileLedgerProfile p = Data.profiles.get(i);
                     if (p.getUuid().equals(profileUUID)) {
                         profile = p;
                         break;
+                    }
                 }
-            }
                 if (profile == null) throw new RuntimeException(String.format(
                         "Unable to find profile %s, which is supposed to contain " +
                         "transaction %d with description %s", profileUUID, transactionId,
                         description));
 
                 tr = profile.loadTransaction(transactionId);
+            }
             int i = 0;
             table = findViewById(R.id.new_transaction_accounts_table);
             ArrayList<LedgerTransactionAccount> accounts = tr.getAccounts();
diff --git a/app/src/main/java/net/ktnx/mobileledger/utils/LockHolder.java b/app/src/main/java/net/ktnx/mobileledger/utils/LockHolder.java
new file mode 100644 (file)
index 0000000..f0c976d
--- /dev/null
@@ -0,0 +1,46 @@
+/*
+ * Copyright © 2019 Damyan Ivanov.
+ * This file is part of MoLe.
+ * MoLe is free software: you can distribute it and/or modify it
+ * under the term of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your opinion), any later version.
+ *
+ * MoLe is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License terms for details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with MoLe. If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package net.ktnx.mobileledger.utils;
+
+import java.io.Closeable;
+import java.util.concurrent.locks.Lock;
+
+public class LockHolder implements Closeable {
+    private Lock rLock, wLock;
+    LockHolder(Lock rLock) {
+        this.rLock = rLock;
+        this.wLock = null;
+    }
+    public LockHolder(Lock rLock, Lock wLock) {
+        this.rLock = rLock;
+        this.wLock = wLock;
+    }
+    @Override
+    public void close() {
+        if (wLock != null) wLock.unlock();
+        if (rLock != null) rLock.unlock();
+    }
+    public void downgrade() {
+        if (rLock == null) throw new IllegalStateException("no locks are held");
+
+        if (wLock == null) return;
+
+        wLock.unlock();
+        wLock = null;
+    }
+}
index 9e44fae..eac0237 100644 (file)
@@ -27,6 +27,7 @@ import java.util.List;
 import java.util.ListIterator;
 import java.util.Observable;
 import java.util.Spliterator;
+import java.util.concurrent.locks.ReentrantReadWriteLock;
 import java.util.function.Consumer;
 import java.util.function.Predicate;
 import java.util.function.UnaryOperator;
@@ -38,6 +39,7 @@ import androidx.annotation.RequiresApi;
 
 public class ObservableList<T> extends Observable implements List<T> {
     private List<T> list;
+    private ReentrantReadWriteLock lock = new ReentrantReadWriteLock();
     public ObservableList(List<T> list) {
         this.list = list;
     }
@@ -50,149 +52,243 @@ public class ObservableList<T> extends Observable implements List<T> {
         notifyObservers(index);
     }
     public int size() {
-        return list.size();
+        try (LockHolder lh = lockForReading()) {
+            return list.size();
+        }
     }
     public boolean isEmpty() {
-        return list.isEmpty();
+        try (LockHolder lh = lockForReading()) {
+            return list.isEmpty();
+        }
     }
     public boolean contains(@Nullable Object o) {
-        return list.contains(o);
+        try (LockHolder lh = lockForReading()) {
+            return list.contains(o);
+        }
     }
     @NonNull
     public Iterator<T> iterator() {
-        return list.iterator();
+        throw new RuntimeException("Iterators break encapsulation and ignore locking");
+//        return list.iterator();
     }
     public Object[] toArray() {
-        return list.toArray();
+        try (LockHolder lh = lockForReading()) {
+            return list.toArray();
+        }
     }
     public <T1> T1[] toArray(@Nullable T1[] a) {
-        return list.toArray(a);
+        try (LockHolder lh = lockForReading()) {
+            return list.toArray(a);
+        }
     }
     public boolean add(T t) {
-        boolean result = list.add(t);
-        if (result) forceNotify();
-        return result;
+        try (LockHolder lh = lockForWriting()) {
+            boolean result = list.add(t);
+            lh.downgrade();
+            if (result) forceNotify();
+            return result;
+        }
     }
     public boolean remove(@Nullable Object o) {
-        boolean result = list.remove(o);
-        if (result) forceNotify();
-        return result;
+        try (LockHolder lh = lockForWriting()) {
+            boolean result = list.remove(o);
+            lh.downgrade();
+            if (result) forceNotify();
+            return result;
+        }
     }
     public T removeQuietly(int index) {
         return list.remove(index);
     }
     public boolean containsAll(@NonNull Collection<?> c) {
-        return list.containsAll(c);
+        try (LockHolder lh = lockForReading()) {
+            return list.containsAll(c);
+        }
     }
     public boolean addAll(@NonNull Collection<? extends T> c) {
-        boolean result = list.addAll(c);
-        if (result) forceNotify();
-        return result;
+        try (LockHolder lh = lockForWriting()) {
+            boolean result = list.addAll(c);
+            lh.downgrade();
+            if (result) forceNotify();
+            return result;
+        }
     }
     public boolean addAll(int index, @NonNull Collection<? extends T> c) {
-        boolean result = list.addAll(index, c);
-        if (result) forceNotify();
-        return result;
+        try (LockHolder lh = lockForWriting()) {
+            boolean result = list.addAll(index, c);
+            lh.downgrade();
+            if (result) forceNotify();
+            return result;
+        }
     }
     public boolean addAllQuietly(int index, Collection<? extends T> c) {
         return list.addAll(index, c);
     }
     public boolean removeAll(@NonNull Collection<?> c) {
-        boolean result = list.removeAll(c);
-        if (result) forceNotify();
-        return result;
+        try (LockHolder lh = lockForWriting()) {
+            boolean result = list.removeAll(c);
+            lh.downgrade();
+            if (result) forceNotify();
+            return result;
+        }
     }
     public boolean retainAll(@NonNull Collection<?> c) {
-        boolean result = list.retainAll(c);
-        if (result) forceNotify();
-        return result;
+        try (LockHolder lh = lockForWriting()) {
+            boolean result = list.retainAll(c);
+            lh.downgrade();
+            if (result) forceNotify();
+            return result;
+        }
     }
     @RequiresApi(api = Build.VERSION_CODES.N)
     public void replaceAll(@NonNull UnaryOperator<T> operator) {
-        list.replaceAll(operator);
-        forceNotify();
+        try (LockHolder lh = lockForWriting()) {
+            list.replaceAll(operator);
+            lh.downgrade();
+            forceNotify();
+        }
     }
     @RequiresApi(api = Build.VERSION_CODES.N)
     public void sort(@Nullable Comparator<? super T> c) {
-        list.sort(c);
-        forceNotify();
+        try (LockHolder lh = lockForWriting()) {
+            lock.writeLock().lock();
+            list.sort(c);
+            lh.downgrade();
+            forceNotify();
+        }
     }
     public void clear() {
-        boolean wasEmpty = list.isEmpty();
-        list.clear();
-        if (!wasEmpty) forceNotify();
+        try (LockHolder lh = lockForWriting()) {
+            boolean wasEmpty = list.isEmpty();
+            list.clear();
+            lh.downgrade();
+            if (!wasEmpty) forceNotify();
+        }
     }
     public T get(int index) {
-        return list.get(index);
+        try (LockHolder lh = lockForReading()) {
+            return list.get(index);
+        }
     }
     public T set(int index, T element) {
-        T result = list.set(index, element);
-        forceNotify();
-        return result;
+        try (LockHolder lh = lockForWriting()) {
+            T result = list.set(index, element);
+            lh.downgrade();
+            forceNotify();
+            return result;
+        }
     }
     public void add(int index, T element) {
-        list.add(index, element);
-        forceNotify();
+        try (LockHolder lh = lockForWriting()) {
+            list.add(index, element);
+            lh.downgrade();
+            forceNotify();
+        }
     }
     public T remove(int index) {
-        T result = list.remove(index);
-        forceNotify();
-        return result;
+        try (LockHolder lh = lockForWriting()) {
+            T result = list.remove(index);
+            lh.downgrade();
+            forceNotify();
+            return result;
+        }
     }
     public int indexOf(@Nullable Object o) {
-        return list.indexOf(o);
+        try (LockHolder lh = lockForReading()) {
+            return list.indexOf(o);
+        }
     }
     public int lastIndexOf(@Nullable Object o) {
-        return list.lastIndexOf(o);
+        try (LockHolder lh = lockForReading()) {
+            return list.lastIndexOf(o);
+        }
     }
     public ListIterator<T> listIterator() {
+        if (!lock.isWriteLockedByCurrentThread()) throw new RuntimeException(
+                "Iterators break encapsulation and ignore locking. Write-lock first");
         return list.listIterator();
     }
     public ListIterator<T> listIterator(int index) {
+        if (!lock.isWriteLockedByCurrentThread()) throw new RuntimeException(
+                "Iterators break encapsulation and ignore locking. Write-lock first");
         return list.listIterator(index);
     }
     public List<T> subList(int fromIndex, int toIndex) {
-        return list.subList(fromIndex, toIndex);
+        try (LockHolder lh = lockForReading()) {
+            return list.subList(fromIndex, toIndex);
+        }
     }
     @RequiresApi(api = Build.VERSION_CODES.N)
     public Spliterator<T> spliterator() {
+        if (!lock.isWriteLockedByCurrentThread()) throw new RuntimeException(
+                "Iterators break encapsulation and ignore locking. Write-lock first");
         return list.spliterator();
     }
     @RequiresApi(api = Build.VERSION_CODES.N)
     public boolean removeIf(Predicate<? super T> filter) {
-        boolean result = list.removeIf(filter);
-        if (result) forceNotify();
-        return result;
+        try (LockHolder lh = lockForWriting()) {
+            boolean result = list.removeIf(filter);
+            lh.downgrade();
+            if (result) forceNotify();
+            return result;
+        }
     }
     @RequiresApi(api = Build.VERSION_CODES.N)
     public Stream<T> stream() {
+        if (!lock.isWriteLockedByCurrentThread()) throw new RuntimeException(
+                "Iterators break encapsulation and ignore locking. Write-lock first");
         return list.stream();
     }
     @RequiresApi(api = Build.VERSION_CODES.N)
     public Stream<T> parallelStream() {
+        if (!lock.isWriteLockedByCurrentThread()) throw new RuntimeException(
+                "Iterators break encapsulation and ignore locking. Write-lock first");
         return list.parallelStream();
     }
     @RequiresApi(api = Build.VERSION_CODES.N)
     public void forEach(Consumer<? super T> action) {
-        list.forEach(action);
+        try (LockHolder lh = lockForReading()) {
+            list.forEach(action);
+        }
     }
     public List<T> getList() {
+        if (!lock.isWriteLockedByCurrentThread()) throw new RuntimeException(
+                "Direct list access breaks encapsulation and ignore locking. Write-lock first");
         return list;
     }
     public void setList(List<T> aList) {
-        list = aList;
-        forceNotify();
+        try (LockHolder lh = lockForWriting()) {
+            list = aList;
+            lh.downgrade();
+            forceNotify();
+        }
     }
     public void triggerItemChangedNotification(T item) {
-        int index = list.indexOf(item);
-        if (index == -1) {
-            Log.d("ObList", "??? not sending notifications for item not found in the list");
-            return;
+        try (LockHolder lh = lockForReading()) {
+            int index = list.indexOf(item);
+            if (index == -1) {
+                Log.d("ObList", "??? not sending notifications for item not found in the list");
+                return;
+            }
+            Log.d("ObList", "Notifying item change observers");
+            triggerItemChangedNotification(index);
         }
-        Log.d("ObList", "Notifying item change observers");
-        triggerItemChangedNotification(index);
     }
     public void triggerItemChangedNotification(int index) {
         forceNotify(index);
     }
+    public LockHolder lockForWriting() {
+        ReentrantReadWriteLock.WriteLock wLock = lock.writeLock();
+        wLock.lock();
+
+        ReentrantReadWriteLock.ReadLock rLock = lock.readLock();
+        rLock.lock();
+
+        return new LockHolder(rLock, wLock);
+    }
+    public LockHolder lockForReading() {
+        ReentrantReadWriteLock.ReadLock rLock = lock.readLock();
+        rLock.lock();
+        return new LockHolder(rLock);
+    }
 }
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