Canonical namespace explicitly stored

CHANGES.md

@@ -20,6 +20,8 @@ To be released.
  -  `BaseIndex.ContainsKey()` method became `abstract`.  [[#390]]
  -  `BlockDownloadState.TotalBlockCount` and `BlockDownloadState.ReceivedBlockCount`
     became to `Int64` type.  [[#396], [#399]]
+ -  Added `IStore.GetCanonicalNamespace()` method.  [[#426]]
+ -  Added `IStore.SetCanonicalNamespace()` method.  [[#426]]
 
 ### Added interfaces
 
@@ -125,6 +127,7 @@ To be released.
 [#417]: https://github.com/planetarium/libplanet/pull/417
 [#418]: https://github.com/planetarium/libplanet/pull/418
 [#424]: https://github.com/planetarium/libplanet/pull/424
+[#426]: https://github.com/planetarium/libplanet/pull/426
 [LiteDB #1268]: https://github.com/mbdavid/LiteDB/issues/1268
 
 

Libplanet.Tests/Blockchain/BlockChainTest.cs

@@ -114,6 +114,25 @@ public void CanFindBlockByIndex()
             Assert.Equal(anotherBlock, _blockChain[1]);
         }
 
+        [Fact]
+        public void CanonicalId()
+        {
+            var x = _blockChain;
+            x.MineBlock(_fx.Address1);
+            x.MineBlock(_fx.Address1);
+            Assert.Equal(x.Id.ToString(), _fx.Store.GetCanonicalNamespace());
+            var y = x.Fork(x.Tip.Hash);
+            y.MineBlock(_fx.Address1);
+            Assert.Equal(x.Id.ToString(), _fx.Store.GetCanonicalNamespace());
+
+            var z = new BlockChain<DumbAction>(
+                new BlockPolicy<DumbAction>(new MinerReward(1)),
+                _fx.Store
+            );
+
+            Assert.Equal(x.Id, z.Id);
+        }
+
         [Fact]
         public void Enumerate()
         {
@@ -1212,34 +1231,6 @@ public void MakeTransaction()
             Assert.Equal(actions, transaction.Actions);
         }
 
-        [Fact]
-        public void GetCanonicalChain()
-        {
-            Assert.Null(BlockChain<DumbAction>.GetCanonicalChain(_fx.Store));
-
-            Block<DumbAction> block1 = TestUtils.MineGenesis<DumbAction>();
-            Block<DumbAction> block2 = TestUtils.MineNext(block1);
-            Block<DumbAction> block3 = TestUtils.MineNext(block2);
-            Guid id1 = Guid.NewGuid();
-            Guid id2 = Guid.NewGuid();
-
-            foreach (Block<DumbAction> b in new[] { block1 })
-            {
-                _fx.Store.AppendIndex(id1.ToString(), b.Hash);
-                _fx.Store.PutBlock(b);
-            }
-
-            Assert.Equal(id1, BlockChain<DumbAction>.GetCanonicalChain(_fx.Store));
-
-            foreach (Block<DumbAction> b in new[] { block2, block3 })
-            {
-                _fx.Store.AppendIndex(id2.ToString(), b.Hash);
-                _fx.Store.PutBlock(b);
-            }
-
-            Assert.Equal(id2, BlockChain<DumbAction>.GetCanonicalChain(_fx.Store));
-        }
-
         [Fact]
         public void MineBlockWithBlockAction()
         {

Libplanet.Tests/Store/StoreTest.cs

@@ -65,6 +65,17 @@ public void DeleteNamespace()
             Assert.Equal(0, Fx.Store.GetTxNonce(Fx.StoreNamespace, Fx.Transaction1.Signer));
         }
 
+        [Fact]
+        public void CanonicalNamespace()
+        {
+            Assert.Null(Fx.Store.GetCanonicalNamespace());
+            Assert.Throws<ArgumentNullException>(() => Fx.Store.SetCanonicalNamespace(null));
+            Fx.Store.SetCanonicalNamespace("foo");
+            Assert.Equal("foo", Fx.Store.GetCanonicalNamespace());
+            Fx.Store.SetCanonicalNamespace("bar");
+            Assert.Equal("bar", Fx.Store.GetCanonicalNamespace());
+        }
+
         [Fact]
         public void ListAddresses()
         {

Libplanet.Tests/Store/StoreTracker.cs

@@ -227,5 +227,17 @@ public void UnstageTransactionIds(ISet<TxId> txids)
             _logs.Add((nameof(UnstageTransactionIds), txids, null));
             _store.UnstageTransactionIds(txids);
         }
+
+        public string GetCanonicalNamespace()
+        {
+            _logs.Add((nameof(GetCanonicalNamespace), null, null));
+            return _store.GetCanonicalNamespace();
+        }
+
+        public void SetCanonicalNamespace(string @namespace)
+        {
+            _logs.Add((nameof(SetCanonicalNamespace), @namespace, null));
+            _store.SetCanonicalNamespace(@namespace);
+        }
     }
 }

Libplanet/Blockchain/BlockChain.cs

@@ -29,7 +29,20 @@ public class BlockChain<T> : IReadOnlyList<Block<T>>
         private readonly object _txLock;
 
         public BlockChain(IBlockPolicy<T> policy, IStore store)
-            : this(policy, store, GetCanonicalChain(store) ?? Guid.NewGuid())
+            : this(
+                policy,
+                store,
+                store.GetCanonicalNamespace()
+            )
+        {
+        }
+
+        internal BlockChain(IBlockPolicy<T> policy, IStore store, string @namespace)
+            : this(
+                policy,
+                store,
+                @namespace is null ? Guid.NewGuid() : Guid.Parse(@namespace)
+            )
         {
         }
 
@@ -43,6 +56,11 @@ internal BlockChain(IBlockPolicy<T> policy, IStore store, Guid id)
 
             _rwlock = new ReaderWriterLockSlim(LockRecursionPolicy.SupportsRecursion);
             _txLock = new object();
+
+            if (Store.GetCanonicalNamespace() is null)
+            {
+                Store.SetCanonicalNamespace(Id.ToString());
+            }
         }
 
         ~BlockChain()
@@ -522,24 +540,6 @@ public Transaction<T> MakeTransaction(
             }
         }
 
-        // FIXME it should be separated into separate class (like IConsensus).
-        internal static Guid? GetCanonicalChain(IStore store)
-        {
-            string @namespace = store
-                .ListNamespaces()
-                .OrderByDescending(store.CountIndex)
-                .FirstOrDefault();
-
-            if (@namespace is null)
-            {
-                return null;
-            }
-            else
-            {
-                return new Guid(@namespace);
-            }
-        }
-
         internal void Append(
             Block<T> block,
             DateTimeOffset currentTime,
@@ -1009,6 +1009,7 @@ t.PreviousHash is HashDigest<SHA256> tp &&
 
                 Guid obsoleteId = Id;
                 Id = other.Id;
+                Store.SetCanonicalNamespace(Id.ToString());
                 Blocks = new BlockSet<T>(Store);
                 Transactions = new TransactionSet<T>(Store);
                 Store.DeleteNamespace(obsoleteId.ToString());

Libplanet/Store/BaseStore.cs

@@ -15,6 +15,12 @@ public abstract class BaseStore : IStore
         /// <inheritdoc />
         public abstract IEnumerable<string> ListNamespaces();
 
+        /// <inheritdoc />
+        public abstract string GetCanonicalNamespace();
+
+        /// <inheritdoc />
+        public abstract void SetCanonicalNamespace(string @namespace);
+
         public abstract long CountIndex(string @namespace);
 
         public abstract IEnumerable<HashDigest<SHA256>> IterateIndex(

Libplanet/Store/FileStore.cs

@@ -133,6 +133,11 @@ public string GetIndexPath(string @namespace)
             );
         }
 
+        public string GetCanonicalNamespacePath()
+        {
+            return Path.Combine(_path, "canon.txt");
+        }
+
         public string GetStateReferencePath(string @namespace)
         {
             return Path.Combine(
@@ -182,6 +187,38 @@ public override IEnumerable<string> ListNamespaces()
             }
         }
 
+        /// <inheritdoc />
+        public override string GetCanonicalNamespace()
+        {
+            var file = new FileInfo(GetCanonicalNamespacePath());
+            try
+            {
+                using (StreamReader reader = file.OpenText())
+                {
+                    return reader.ReadToEnd();
+                }
+            }
+            catch (FileNotFoundException)
+            {
+                return null;
+            }
+        }
+
+        /// <inheritdoc />
+        public override void SetCanonicalNamespace(string @namespace)
+        {
+            if (@namespace is null)
+            {
+                throw new ArgumentNullException(nameof(@namespace));
+            }
+
+            var file = new FileInfo(GetCanonicalNamespacePath());
+            using (StreamWriter writer = file.CreateText())
+            {
+                writer.Write(@namespace);
+            }
+        }
+
         /// <inheritdoc/>
         public override void DeleteNamespace(string @namespace)
         {

Libplanet/Store/IStore.cs

@@ -17,6 +17,20 @@ public interface IStore
         /// <returns>Existing namespaces.</returns>
         IEnumerable<string> ListNamespaces();
 
+        /// <summary>
+        /// Gets the current canonical namespace.
+        /// </summary>
+        /// <returns>The current canonical namespace.  Maybe <c>null</c>.</returns>
+        string GetCanonicalNamespace();
+
+        /// <summary>
+        /// Set canonical namespace.
+        /// </summary>
+        /// <param name="namespace">A new canonical namespace.  Cannot be <c>null</c>.</param>
+        /// <exception cref="ArgumentNullException">Thrown when <paramref name="namespace"/> is
+        /// <c>null</c>.</exception>
+        void SetCanonicalNamespace(string @namespace);
+
         long CountIndex(string @namespace);
 
         /// <summary>

Libplanet/Store/LiteDBStore.cs

@@ -112,6 +112,30 @@ public override void DeleteNamespace(string @namespace)
             _db.DropCollection(StateRefId(@namespace));
         }
 
+        /// <inheritdoc />
+        public override string GetCanonicalNamespace()
+        {
+            LiteCollection<BsonDocument> collection = _db.GetCollection<BsonDocument>("canon");
+            var docId = new BsonValue("canon");
+            BsonDocument doc = collection.FindById(docId);
+            return doc is null
+                ? null
+                : (doc.TryGetValue("ns", out BsonValue ns) ? ns.AsString : null);
+        }
+
+        /// <inheritdoc />
+        public override void SetCanonicalNamespace(string @namespace)
+        {
+            if (@namespace is null)
+            {
+                throw new ArgumentNullException(nameof(@namespace));
+            }
+
+            LiteCollection<BsonDocument> collection = _db.GetCollection<BsonDocument>("canon");
+            var docId = new BsonValue("canon");
+            collection.Upsert(docId, new BsonDocument() { ["ns"] = new BsonValue(@namespace) });
+        }
+
         /// <inheritdoc/>
         public override long CountIndex(string @namespace)
         {