Fix next header hash may be mis-set. (#5112)

NethermindEth · Jan 9, 2023 · 2c363ba · 2c363ba
1 parent ef5ebfc
commit 2c363ba
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Showing 2 changed files with 45 additions and 19 deletions.
diff --git a/src/Nethermind/Nethermind.Synchronization.Test/FastBlocks/FastHeadersSyncTests.cs b/src/Nethermind/Nethermind.Synchronization.Test/FastBlocks/FastHeadersSyncTests.cs
@@ -118,6 +118,25 @@ public async Task Finishes_when_all_downloaded()
             measuredProgress.HasEnded.Should().BeTrue();
         }
 
+        [Test]
+        public async Task Can_resume_downloading_from_parent_of_lowest_inserted_header()
+        {
+            IBlockTree blockTree = Substitute.For<IBlockTree>();
+            blockTree.LowestInsertedHeader.Returns(Build.A.BlockHeader
+                .WithNumber(500)
+                .WithTotalDifficulty(10_000_000)
+                .TestObject);
+
+            ISyncReport report = Substitute.For<ISyncReport>();
+            report.HeadersInQueue.Returns(new MeasuredProgress());
+            report.FastBlocksHeaders.Returns(new MeasuredProgress());
+
+            HeadersSyncFeed feed = new(Substitute.For<ISyncModeSelector>(), blockTree, Substitute.For<ISyncPeerPool>(), new SyncConfig { FastSync = true, FastBlocks = true, PivotNumber = "1000", PivotHash = Keccak.Zero.ToString(), PivotTotalDifficulty = "1000" }, report, LimboLogs.Instance);
+            feed.InitializeFeed();
+            var result = await feed.PrepareRequest();
+            result.EndNumber.Should().Be(499);
+        }
+
         private class ResettableHeaderSyncFeed : HeadersSyncFeed
         {
             public ResettableHeaderSyncFeed(ISyncModeSelector syncModeSelector, IBlockTree? blockTree, ISyncPeerPool? syncPeerPool, ISyncConfig? syncConfig, ISyncReport? syncReport, ILogManager? logManager, bool alwaysStartHeaderSync = false) : base(syncModeSelector, blockTree, syncPeerPool, syncConfig, syncReport, logManager, alwaysStartHeaderSync)

diff --git a/src/Nethermind/Nethermind.Synchronization/FastBlocks/FastHeadersSyncFeed.cs b/src/Nethermind/Nethermind.Synchronization/FastBlocks/FastHeadersSyncFeed.cs
@@ -183,18 +183,20 @@ public HeadersSyncFeed(
 
         public override void InitializeFeed()
         {
+            _logger.Info("Feed reinitialized");
             _pivotNumber = _syncConfig.PivotNumberParsed;
 
-            bool useSyncPivot = _blockTree.LowestInsertedHeader is null || _blockTree.LowestInsertedHeader.Number > _pivotNumber;
-            BlockHeader? lowestInserted = _blockTree.LowestInsertedHeader;
-            long startNumber = useSyncPivot ? _pivotNumber : lowestInserted.Number;
-            Keccak startHeaderHash = useSyncPivot ? _syncConfig.PivotHashParsed : lowestInserted.Hash;
-            UInt256? startTotalDifficulty = useSyncPivot ? _syncConfig.PivotTotalDifficultyParsed : lowestInserted?.TotalDifficulty;
-
-            _nextHeaderHash = startHeaderHash;
-            _nextHeaderDiff = startTotalDifficulty;
+            _lowestRequestedHeaderNumber = _pivotNumber + 1; // Because we want the pivot to be requested
+            _nextHeaderHash = _syncConfig.PivotHashParsed;
+            _nextHeaderDiff = _syncConfig.PivotTotalDifficultyParsed;
 
-            _lowestRequestedHeaderNumber = startNumber + 1;
+            // Resume logic
+            BlockHeader? lowestInserted = _blockTree.LowestInsertedHeader;
+            if (lowestInserted != null && lowestInserted!.Number < _pivotNumber)
+            {
+                SetExpectedNextHeaderToParent(lowestInserted);
+                _lowestRequestedHeaderNumber = lowestInserted.Number;
+            }
 
             base.InitializeFeed();
         }
@@ -652,19 +654,24 @@ protected virtual AddBlockResult InsertToBlockTree(BlockHeader header)
             AddBlockResult insertOutcome = _blockTree.Insert(header);
             if (insertOutcome == AddBlockResult.Added || insertOutcome == AddBlockResult.AlreadyKnown)
             {
-                ulong nextHeaderDiff = 0;
-                _nextHeaderHash = header.ParentHash!;
-                if (_expectedDifficultyOverride?.TryGetValue(header.Number, out nextHeaderDiff) == true)
-                {
-                    _nextHeaderDiff = nextHeaderDiff;
-                }
-                else
-                {
-                    _nextHeaderDiff = (header.TotalDifficulty ?? 0) - header.Difficulty;
-                }
+                SetExpectedNextHeaderToParent(header);
             }
 
             return insertOutcome;
         }
+
+        private void SetExpectedNextHeaderToParent(BlockHeader header)
+        {
+            ulong nextHeaderDiff = 0;
+            _nextHeaderHash = header.ParentHash!;
+            if (_expectedDifficultyOverride?.TryGetValue(header.Number, out nextHeaderDiff) == true)
+            {
+                _nextHeaderDiff = nextHeaderDiff;
+            }
+            else
+            {
+                _nextHeaderDiff = (header.TotalDifficulty ?? 0) - header.Difficulty;
+            }
+        }
     }
 }