disconnect blocks slightly less eagerly

Author: arik-so

xcode/DirectBindingsApp/DirectBindingsApp/app-batteries/BlockchainObserver.swift

@@ -206,13 +206,20 @@ class BlockchainObserver {
 
 		while addedBlocks.isEmpty || addedBlocks.first!.previousblockhash != self.connectedBlocks.last!.hash {
 			// we must keep popping until it matches
-			let trimmedLocalTip = try await self.disconnectBlock()
-			if trimmedLocalTip.height <= currentChaintipHeight {
-				// if the trimmed block is simply gone, we cannot retrieve the current block hash hex
-				let reorgedBlockHash = try await self.getBlockHashHex(height: trimmedLocalTip.height)
-				let reorgedBlock = try await self.getBlock(hash: reorgedBlockHash)
-				addedBlocks.insert(reorgedBlock, at: 0)
+			let trimmingCandidate = self.connectedBlocks.last!
+			if trimmingCandidate.height > currentChaintipHeight {
+				// we can disconnect this block without prejudice
+				try await self.disconnectBlock()
+				continue
 			}
+			let reorgedBlockHash = try await self.getBlockHashHex(height: trimmingCandidate.height)
+			if reorgedBlockHash == trimmingCandidate.hash {
+				// this block matches the one we already have
+				break
+			}
+			let reorgedBlock = try await self.getBlock(hash: reorgedBlockHash)
+			try await self.disconnectBlock()
+			addedBlocks.insert(reorgedBlock, at: 0)
 		}
 
 		for addedBlock in addedBlocks {
@@ -229,6 +236,8 @@ class BlockchainObserver {
 
 		let poppedBlock = self.connectedBlocks.popLast()!
 
+		print("disconnecting block \(poppedBlock.height) with hex: \(poppedBlock.hash)")
+
 		if self.chainListeners.count > 0 {
 			let blockHeader = try await self.getBlockHeader(hash: poppedBlock.hash)
 			for listener in self.chainListeners {
@@ -253,7 +262,7 @@ class BlockchainObserver {
 			}
 		}
 
-		// print("connecting block \(block.height) with hex: \(block.hash)")
+		print("connecting block    \(block.height) with hex: \(block.hash)")
 
 		if self.chainListeners.count > 0 {
 			let binary = try await self.getBlockBinary(hash: block.hash)

xcode/DirectBindingsApp/DirectBindingsAppTests/test-batteries/bitcoin/BTCHashing.swift

@@ -9,19 +9,27 @@ import Foundation
 import Crypto
 
 class BTCHashing {
-    
-    public static let SHA_ZERO_HASH = [UInt8](repeating: 0, count: 32)
-    public static let RIPEMD_ZERO_HASH = [UInt8](repeating: 0, count: 20)
-    
-    private static func sha256(_ input: [UInt8]) -> [UInt8] {
-        let hash = Crypto.SHA256.hash(data: input)
-        let bytes = Array(hash)
-        assert(bytes.count == 32)
-        return bytes
-    }
-    
-    static func doubleSha256(_ input: [UInt8]) -> [UInt8] {
-        return sha256(sha256(input))
-    }
-    
+
+	public static let SHA_ZERO_HASH = [UInt8](repeating: 0, count: 32)
+	public static let RIPEMD_ZERO_HASH = [UInt8](repeating: 0, count: 20)
+
+	private static func sha256(_ input: [UInt8]) -> [UInt8] {
+		let hash = Crypto.SHA256.hash(data: input)
+		let bytes = Array(hash)
+		assert(bytes.count == 32)
+		return bytes
+	}
+
+	static func doubleSha256(_ input: [UInt8]) -> [UInt8] {
+		return sha256(sha256(input))
+	}
+
+	static func bytesToHexString(bytes: [UInt8]) -> String {
+		let format = "%02hhx" // "%02hhX" (uppercase)
+		return bytes.map {
+			String(format: format, $0)
+		}
+		.joined()
+	}
+
 }

xcode/DirectBindingsApp/DirectBindingsAppTests/test-batteries/bitcoin/BitcoinTests.swift

@@ -139,20 +139,21 @@ public class BitcoinTests: XCTestCase {
 				if self.initializationComplete {
 					self.newBlocksDetected += 1
 				}
-				print("block connected at height \(height): \(block)")
+				let blockHash = BTCHashing.bytesToHexString(bytes: BTCHashing.doubleSha256(block))
+				// print("block connected at height \(height): \(blockHash)")
 			}
 
 			func blockDisconnected(header: [UInt8]?, height: UInt32) {
 				self.blocksLost += 1
-				print("block disconnected from height \(height): \(header)")
+				// print("block disconnected from height \(height): \(header)")
 			}
 		}
 
 		var listener = Listener()
 		rpcInterface.registerListener(listener)
 
 		try await rpcInterface.preloadMonitor();
-		async let monitor = try rpcInterface.monitorBlockchain()
+		// async let monitor = try rpcInterface.monitorBlockchain()
 		listener.initializationComplete = true
 
 		let testAddress = try await rpcInterface.generateAddress()
@@ -163,7 +164,8 @@ public class BitcoinTests: XCTestCase {
 		try await rpcInterface.mineBlocks(number: 1, coinbaseDestinationAddress: outputAddress)
 
 		// sleep for six seconds
-		try await Task.sleep(nanoseconds: 6_000_000_000)
+		// try await Task.sleep(nanoseconds: 6_000_000_000)
+		try await rpcInterface.reconcileChaintips()
 		XCTAssertEqual(listener.newBlocksDetected, 2)
 		XCTAssertEqual(listener.blocksLost, 0)
 
@@ -182,13 +184,24 @@ public class BitcoinTests: XCTestCase {
 		do {
 			let testAddress = try await rpcInterface.generateAddress()
 			let chaintipHash = try await rpcInterface.getChaintipHashHex()
+			print("chaintip: \(chaintipHash)")
 			try await rpcInterface.unmineBlock(hash: chaintipHash)
 			try await rpcInterface.mineBlocks(number: 2, coinbaseDestinationAddress: testAddress)
 
 			try await rpcInterface.reconcileChaintips()
 			XCTAssertEqual(listener.newBlocksDetected, 5)
 			XCTAssertEqual(listener.blocksLost, 3)
 		}
+
+		do {
+			let chaintipHash = try await rpcInterface.getChaintipHashHex()
+			print("chaintip: \(chaintipHash)")
+			try await rpcInterface.unmineBlock(hash: chaintipHash)
+
+			try await rpcInterface.reconcileChaintips()
+			XCTAssertEqual(listener.newBlocksDetected, 5)
+			XCTAssertEqual(listener.blocksLost, 4)
+		}
 	}
 
 }