Only notify about main BlockchainProcessor shutdown (#8819)

Author: benaadams

src/Nethermind/Nethermind.Consensus/Processing/BlockchainProcessor.cs

@@ -61,6 +61,7 @@ public sealed class BlockchainProcessor : IBlockchainProcessor, IBlockProcessing
 
     private bool _recoveryComplete = false;
     private int _queueCount;
+    private bool _disposed;
 
     private readonly ProcessingStats _stats;
 
@@ -101,9 +102,6 @@ public BlockchainProcessor(
         _stateReader = stateReader ?? throw new ArgumentNullException(nameof(stateReader));
         _options = options;
 
-        _blockTree.NewBestSuggestedBlock += OnNewBestBlock;
-        _blockTree.NewHeadBlock += OnNewHeadBlock;
-
         _stats = new ProcessingStats(stateReader, _logger);
         _loopCancellationSource = new CancellationTokenSource();
     }
@@ -179,13 +177,34 @@ public async ValueTask Enqueue(Block block, ProcessingOptions processingOptions)
 
     public void Start()
     {
+        ObjectDisposedException.ThrowIf(_disposed, this);
+        if (_processorTask is not null) ThrowAlreadyStarted();
+
+        _blockTree.NewBestSuggestedBlock += OnNewBestBlock;
+        _blockTree.NewHeadBlock += OnNewHeadBlock;
+
         _loopCancellationSource ??= new CancellationTokenSource();
         _recoveryTask = RunRecovery();
         _processorTask = RunProcessing();
+
+        if (_logger.IsInfo) _logger.Info($"{nameof(BlockchainProcessor)} started.");
+
+        [StackTraceHidden, DoesNotReturn]
+        static void ThrowAlreadyStarted() => throw new InvalidOperationException($"{nameof(BlockchainProcessor)} already started");
     }
 
     public async Task StopAsync(bool processRemainingBlocks = false)
     {
+        if (_disposed) return;
+        _disposed = true;
+
+        bool isStarted = _processorTask is not null;
+        if (isStarted)
+        {
+            _blockTree.NewBestSuggestedBlock -= OnNewBestBlock;
+            _blockTree.NewHeadBlock -= OnNewHeadBlock;
+        }
+
         _recoveryComplete = true;
         if (processRemainingBlocks)
         {
@@ -201,7 +220,7 @@ public async Task StopAsync(bool processRemainingBlocks = false)
         }
 
         await Task.WhenAll(_recoveryTask ?? Task.CompletedTask, _processorTask ?? Task.CompletedTask);
-        if (_logger.IsInfo) _logger.Info("Blockchain Processor shutdown complete.. please wait for all components to close");
+        if (isStarted && _logger.IsInfo) _logger.Info($"{nameof(BlockchainProcessor)} shutdown complete.");
     }
 
     private async Task RunRecovery()
@@ -800,8 +819,6 @@ void ThrowUnknownUncleHash(Block suggestedBlock, int i)
 
     public async ValueTask DisposeAsync()
     {
-        _blockTree.NewBestSuggestedBlock -= OnNewBestBlock;
-        _blockTree.NewHeadBlock -= OnNewHeadBlock;
         await StopAsync(processRemainingBlocks: false);
     }