Adds read-only mode.

src/ZoneTree/Collections/BTree/BTree.cs

@@ -24,16 +24,18 @@ public partial class BTree<TKey, TValue>
     volatile LeafNode LastLeafNode;
 
     public readonly IRefComparer<TKey> Comparer;
-    
+
     volatile int _length;
 
     public int Length => _length;
-    
+
     public readonly BTreeLockMode LockMode;
 
     public IIncrementalIdProvider OpIndexProvider { get; }
 
-    public bool IsReadOnly { get; set; }
+    volatile bool _isReadOnly;
+    
+    public bool IsReadOnly { get => _isReadOnly; set => _isReadOnly = value; }
 
     public BTree(
         IRefComparer<TKey> comparer,
@@ -62,7 +64,7 @@ public partial class BTree<TKey, TValue>
     ILocker GetNodeLocker() => LockMode switch
     {
         BTreeLockMode.TopLevelMonitor or
-        BTreeLockMode.TopLevelReaderWriter or 
+        BTreeLockMode.TopLevelReaderWriter or
         BTreeLockMode.NoLock => new NoLock(),
 
         BTreeLockMode.NodeLevelMonitor => new MonitorLock(),
@@ -129,7 +131,7 @@ public partial class BTree<TKey, TValue>
         var iterator = GetFrozenLeafNode(key).GetFrozenIterator();
         return iterator.SeekFirstKeyGreaterOrEqual(Comparer, in key);
     }
-        
+
     public NodeIterator GetFirstIterator()
     {
         try
@@ -166,7 +168,7 @@ public partial class BTree<TKey, TValue>
         return LastLeafNode.GetFrozenIterator();
     }
 
-    public void SetNextOpIndex(long nextId) 
+    public void SetNextOpIndex(long nextId)
         => OpIndexProvider.SetNextId(nextId);
 
     public long GetLastOpIndex()

src/ZoneTree/Core/ZoneTree.cs

@@ -1,8 +1,8 @@
 #undef TRACE_MERGE
 
 using System.Collections.Concurrent;
-using System.Diagnostics;
 using Tenray.ZoneTree.Collections;
+using Tenray.ZoneTree.Exceptions;
 using Tenray.ZoneTree.Segments;
 using Tenray.ZoneTree.Segments.Disk;
 
@@ -95,6 +95,10 @@ public sealed class ZoneTree<TKey, TValue> : IZoneTree<TKey, TValue>, IZoneTreeM
 
     public event ZoneTreeIsDisposing<TKey, TValue> OnZoneTreeIsDisposing;
 
+    volatile bool _isReadOnly;
+
+    public bool IsReadOnly { get => _isReadOnly; set => _isReadOnly = value; }
+
     public ZoneTree(ZoneTreeOptions<TKey, TValue> options)
     {
         options.WriteAheadLogProvider.InitCategory(SegmentWalCategory);
@@ -207,6 +211,9 @@ public sealed class ZoneTree<TKey, TValue> : IZoneTree<TKey, TValue>, IZoneTreeM
 
     public bool TryAtomicAdd(in TKey key, in TValue value)
     {
+        if (IsReadOnly)
+            throw new ZoneTreeIsReadOnlyException();
+
         if (key == null)
             throw new ArgumentNullException(nameof(key));
         lock (AtomicUpdateLock)
@@ -220,6 +227,8 @@ public sealed class ZoneTree<TKey, TValue> : IZoneTree<TKey, TValue>, IZoneTreeM
 
     public bool TryAtomicUpdate(in TKey key, in TValue value)
     {
+        if (IsReadOnly)
+            throw new ZoneTreeIsReadOnlyException();
         if (key == null)
             throw new ArgumentNullException(nameof(key));
         lock (AtomicUpdateLock)
@@ -233,6 +242,8 @@ public sealed class ZoneTree<TKey, TValue> : IZoneTree<TKey, TValue>, IZoneTreeM
 
     public bool TryAtomicAddOrUpdate(in TKey key, in TValue valueToAdd, Func<TValue, TValue> valueToUpdateGetter)
     {
+        if (IsReadOnly)
+            throw new ZoneTreeIsReadOnlyException();
         if (key == null)
             throw new ArgumentNullException(nameof(key));
         AddOrUpdateResult status;
@@ -276,6 +287,8 @@ public sealed class ZoneTree<TKey, TValue> : IZoneTree<TKey, TValue>, IZoneTreeM
 
     public void AtomicUpsert(in TKey key, in TValue value)
     {
+        if (IsReadOnly)
+            throw new ZoneTreeIsReadOnlyException();
         lock (AtomicUpdateLock)
         {
             Upsert(in key, in value);
@@ -284,6 +297,8 @@ public sealed class ZoneTree<TKey, TValue> : IZoneTree<TKey, TValue>, IZoneTreeM
 
     public void Upsert(in TKey key, in TValue value)
     {
+        if (IsReadOnly)
+            throw new ZoneTreeIsReadOnlyException();
         if (key == null)
             throw new ArgumentNullException(nameof(key));
         while (true)
@@ -305,6 +320,8 @@ public sealed class ZoneTree<TKey, TValue> : IZoneTree<TKey, TValue>, IZoneTreeM
 
     public bool TryDelete(in TKey key)
     {
+        if (IsReadOnly)
+            throw new ZoneTreeIsReadOnlyException();
         if (key == null)
             throw new ArgumentNullException(nameof(key));
         if (!ContainsKey(key))
@@ -315,6 +332,8 @@ public sealed class ZoneTree<TKey, TValue> : IZoneTree<TKey, TValue>, IZoneTreeM
 
     public void ForceDelete(in TKey key)
     {
+        if (IsReadOnly)
+            throw new ZoneTreeIsReadOnlyException();
         if (key == null)
             throw new ArgumentNullException(nameof(key));
         while (true)

src/ZoneTree/Exceptions/BTreeIsReadOnlyException.cs

@@ -6,4 +6,4 @@ public class BTreeIsReadOnlyException : ZoneTreeException
         : base("Can't write to read-only BTree.")
     {
     }
-}
+}

src/ZoneTree/Exceptions/ZoneTreeIsReadOnlyException.cs

@@ -0,0 +1,9 @@
+namespace Tenray.ZoneTree.Exceptions;
+
+public class ZoneTreeIsReadOnlyException : ZoneTreeException
+{
+    public ZoneTreeIsReadOnlyException()
+        : base("Can't write to read-only ZoneTree.")
+    {
+    }
+}

src/ZoneTree/ITransactionalZoneTree.cs

@@ -206,4 +206,9 @@ public interface ITransactionalZoneTree<TKey, TValue> : IDisposable
     /// </summary>
     /// <param name="key">Key</param>
     void DeleteAutoCommit(in TKey key);
+
+    /// <summary>
+    /// Enables read-only mode.
+    /// </summary>
+    public bool IsReadOnly { get; set; }
 }

src/ZoneTree/IZoneTree.cs

@@ -161,4 +161,9 @@ public interface IZoneTree<TKey, TValue> : IDisposable
     /// Returns maintenance object belongs to this ZoneTree.
     /// </summary>
     IZoneTreeMaintenance<TKey, TValue> Maintenance { get; }
+
+    /// <summary>
+    /// Enables read-only mode.
+    /// </summary>
+    public bool IsReadOnly { get; set; }
 }

src/ZoneTree/Transactional/OptimisticZoneTree.cs

@@ -21,6 +21,12 @@ public sealed class OptimisticZoneTree<TKey, TValue> :
 
     public IReadOnlyList<long> UncommittedTransactionIds => TransactionLog.UncommittedTransactionIds;
 
+    public bool IsReadOnly
+    {
+        get => ZoneTree.IsReadOnly;
+        set => ZoneTree.IsReadOnly = value;
+    }
+
     public OptimisticZoneTree(
         ZoneTreeOptions<TKey, TValue> options,
         ITransactionLog<TKey, TValue> transactionLog,
@@ -381,6 +387,8 @@ public sealed class OptimisticZoneTree<TKey, TValue> :
 
     public void UpsertAutoCommit(in TKey key, in TValue oldVal)
     {
+        if (IsReadOnly)
+            throw new ZoneTreeIsReadOnlyException();
         lock (this)
         {
             var transactionId = BeginTransaction();
@@ -406,6 +414,8 @@ public sealed class OptimisticZoneTree<TKey, TValue> :
 
     public void DeleteAutoCommit(in TKey key)
     {
+        if (IsReadOnly)
+            throw new ZoneTreeIsReadOnlyException();
         lock (this)
         {
             var transactionId = BeginTransaction();
@@ -498,6 +508,8 @@ public sealed class OptimisticZoneTree<TKey, TValue> :
 
     public TransactionResult<bool> UpsertNoThrow(long transactionId, in TKey key, in TValue value)
     {
+        if (IsReadOnly)
+            throw new ZoneTreeIsReadOnlyException();
         lock (this)
         {
             var transaction = GetOrCreateTransactionNoAbortThrow(transactionId);
@@ -528,11 +540,13 @@ public sealed class OptimisticZoneTree<TKey, TValue> :
             TransactionLog.AddOrUpdateReadWriteStamp(key, in readWriteStamp);
             ZoneTree.Upsert(in key, in value);
             return TransactionResult<bool>.Success(!hasOldValue);
-        }        
+        }
     }
 
     public TransactionResult DeleteNoThrow(long transactionId, in TKey key)
     {
+        if (IsReadOnly)
+            throw new ZoneTreeIsReadOnlyException();
         lock (this)
         {
             var transaction = GetOrCreateTransactionNoAbortThrow(transactionId);