Cancel mining if blockchain's tip index is changed

CHANGES.md

@@ -8,8 +8,13 @@ To be released.
 
 ### Backward-incompatible interface changes
 
+ -  `BlockChain<T>.MineBlock()` is now `async` and became to throw
+    `OperationCanceledException` if `BlockChain<T>`'s tip index is changed while
+    mining.  [[#460], [#517]]
+ -  Users became able to give a cancellation token to `Block<T>.Mine()` and
+    `Hashcash.Answer()` to cancel the operation.  [[#460], [#517]]
  -  Replaced `UnexpectedlyTerminatedTxRehearsalException` with
-    `UnexpectedlyTerminatedActionException`.
+    `UnexpectedlyTerminatedActionException`.  [[#498]]
  -  The following methods became to throw
     `UnexpectedlyTerminatedActionException` with having its `InnerException`
     during actions being evaluated if any action of them throws an exception:
@@ -64,6 +69,8 @@ To be released.
 
 ### Added interfaces
 
+ -  Added `BlockChain<T>.TipChanged` event handler which invoked with argument
+    of `long` typed tip index when `BlockChain<T>.Tip` is changed.  [[#517]]
  -  Added `Swarm<T>.PrepareAsync()` method. The method should be called before
     calling `Swarm<T>.BootstrapAsync()`, `Swarm<T>.PreloadAsync()` and
     `Swarm<T>.StartAsync()`.  [[#353]]
@@ -118,6 +125,7 @@ To be released.
 [#355]: https://github.com/planetarium/libplanet/pull/355
 [#420]: https://github.com/planetarium/libplanet/pull/420
 [#450]: https://github.com/planetarium/libplanet/pull/450
+[#460]: https://github.com/planetarium/libplanet/issues/460
 [#461]: https://github.com/planetarium/libplanet/issues/461
 [#463]: https://github.com/planetarium/libplanet/issues/463
 [#467]: https://github.com/planetarium/libplanet/pull/467
@@ -132,6 +140,7 @@ To be released.
 [#509]: https://github.com/planetarium/libplanet/issues/509
 [#511]: https://github.com/planetarium/libplanet/pull/511
 [#512]: https://github.com/planetarium/libplanet/pull/512
+[#517]: https://github.com/planetarium/libplanet/pull/517
 [#519]: https://github.com/planetarium/libplanet/pull/519
 [#520]: https://github.com/planetarium/libplanet/pull/520
 [#521]: https://github.com/planetarium/libplanet/pull/521

Libplanet.Benchmarks/MineBlock.cs

@@ -1,3 +1,4 @@
+using System.Threading.Tasks;
 using BenchmarkDotNet.Attributes;
 using Libplanet.Blockchain;
 using Libplanet.Blocks;
@@ -23,9 +24,9 @@ public MineBlock()
         }
 
         [Benchmark]
-        public Block<DumbAction> MineBlockEmpty()
+        public async Task<Block<DumbAction>> MineBlockEmpty()
         {
-            return _blockChain.MineBlock(_fx.Address1);
+            return await _blockChain.MineBlock(_fx.Address1);
         }
 
         [IterationSetup(Target = "MineBlockOneTransactionNoAction")]
@@ -35,9 +36,9 @@ public void MakeOneTransactionNoAction()
         }
 
         [Benchmark]
-        public Block<DumbAction> MineBlockOneTransactionNoAction()
+        public async Task<Block<DumbAction>> MineBlockOneTransactionNoAction()
         {
-            return _blockChain.MineBlock(_fx.Address1);
+            return await _blockChain.MineBlock(_fx.Address1);
         }
 
         [IterationSetup(Target = "MineBlockTenTransactionsNoAction")]
@@ -50,9 +51,9 @@ public void MakeTenTransactionsNoAction()
         }
 
         [Benchmark]
-        public Block<DumbAction> MineBlockTenTransactionsNoAction()
+        public async Task<Block<DumbAction>> MineBlockTenTransactionsNoAction()
         {
-            return _blockChain.MineBlock(_fx.Address1);
+            return await _blockChain.MineBlock(_fx.Address1);
         }
 
         [IterationSetup(Target = "MineBlockOneTransactionWithActions")]
@@ -71,9 +72,9 @@ public void MakeOneTransactionWithActions()
         }
 
         [Benchmark]
-        public Block<DumbAction> MineBlockOneTransactionWithActions()
+        public async Task<Block<DumbAction>> MineBlockOneTransactionWithActions()
         {
-            return _blockChain.MineBlock(_fx.Address1);
+            return await _blockChain.MineBlock(_fx.Address1);
         }
 
         [IterationSetup(Target = "MineBlockTenTransactionsWithActions")]
@@ -95,9 +96,9 @@ public void MakeTenTransactionsWithActions()
         }
 
         [Benchmark]
-        public Block<DumbAction> MineBlockTenTransactionsWithActions()
+        public async Task<Block<DumbAction>> MineBlockTenTransactionsWithActions()
         {
-            return _blockChain.MineBlock(_fx.Address1);
+            return await _blockChain.MineBlock(_fx.Address1);
         }
     }
 }