Change processing of network TRANSACTION_SIGNATURES message.

Previously Controller would loop through the transaction signatures,
discard those already known, and then requesting the full transaction
via peer.getResponse(). This would tie up a networking thread for some
time and also potentially cause repository deadlocks, although the latter
could have been fixed another way.

However, the code after peer.getResponse() was identical to the code
processing an incoming TRANSACTION message. Now instead of requesting
and waiting for then processing each transaction, Controller simply
sends the peer a GET_TRANSACTION for each unknown transaction signature.

As the peer responds with corresponding TRANSACTION messages, these can
be processed individually with shorter period of locking.

src/main/java/org/qortal/controller/Controller.java

@@ -1028,6 +1028,9 @@ public class Controller extends Thread {
 		} catch (DataException e) {
 			LOGGER.error(String.format("Repository issue while processing transaction %s from peer %s", Base58.encode(transactionData.getSignature()), peer), e);
 		}
+
+		// Broadcast transaction signature because it's new to us
+		Network.getInstance().broadcast(broadcastPeer -> broadcastPeer == peer ? null : new TransactionSignaturesMessage(Arrays.asList(transactionData.getSignature())));
 	}
 
 	private void onNetworkGetBlockSummariesMessage(Peer peer, Message message) {
@@ -1149,7 +1152,6 @@ public class Controller extends Thread {
 	private void onNetworkTransactionSignaturesMessage(Peer peer, Message message) {
 		TransactionSignaturesMessage transactionSignaturesMessage = (TransactionSignaturesMessage) message;
 		List<byte[]> signatures = transactionSignaturesMessage.getSignatures();
-		List<byte[]> newSignatures = new ArrayList<>();
 
 		try (final Repository repository = RepositoryManager.getRepository()) {
 			for (byte[] signature : signatures) {
@@ -1165,62 +1167,14 @@ public class Controller extends Thread {
 
 				// Fetch actual transaction data from peer
 				Message getTransactionMessage = new GetTransactionMessage(signature);
-				Message responseMessage = peer.getResponse(getTransactionMessage);
+				if (!peer.sendMessage(getTransactionMessage)) {
-				if (!(responseMessage instanceof TransactionMessage)) {
+					peer.disconnect("failed to request transaction");
-					// Maybe peer no longer has this transaction
-					LOGGER.trace(() -> String.format("Peer %s didn't send transaction %s", peer, Base58.encode(signature)));
-					continue;
-				}
-
-				// Check isInterrupted() here and exit fast
-				if (Thread.currentThread().isInterrupted())
 					return;
-
-				TransactionMessage transactionMessage = (TransactionMessage) responseMessage;
-				TransactionData transactionData = transactionMessage.getTransactionData();
-				Transaction transaction = Transaction.fromData(repository, transactionData);
-
-				// Check signature
-				if (!transaction.isSignatureValid()) {
-					LOGGER.trace(() -> String.format("Ignoring %s transaction %s with invalid signature from peer %s", transactionData.getType().name(), Base58.encode(transactionData.getSignature()), peer));
-					continue;
-				}
-
-				ValidationResult validationResult = transaction.importAsUnconfirmed();
-
-				if (validationResult == ValidationResult.TRANSACTION_ALREADY_EXISTS) {
-					LOGGER.trace(() -> String.format("Ignoring existing transaction %s from peer %s", Base58.encode(transactionData.getSignature()), peer));
-					continue;
 				}
-
-				if (validationResult == ValidationResult.NO_BLOCKCHAIN_LOCK) {
-					LOGGER.trace(() -> String.format("Couldn't lock blockchain to import unconfirmed transaction %s from peer %s", Base58.encode(transactionData.getSignature()), peer));
-					// Some other thread (e.g. Synchronizer) might have blockchain lock for a while so might as well give up for now
-					break;
-				}
-
-				if (validationResult != ValidationResult.OK) {
-					LOGGER.trace(() -> String.format("Ignoring invalid (%s) %s transaction %s from peer %s", validationResult.name(), transactionData.getType().name(), Base58.encode(transactionData.getSignature()), peer));
-					continue;
-				}
-
-				LOGGER.debug(() -> String.format("Imported %s transaction %s from peer %s", transactionData.getType().name(), Base58.encode(transactionData.getSignature()), peer));
-
-				// We could collate signatures that are new to us and broadcast them to our peers too
-				newSignatures.add(signature);
 			}
 		} catch (DataException e) {
 			LOGGER.error(String.format("Repository issue while processing unconfirmed transactions from peer %s", peer), e);
-		} catch (InterruptedException e) {
-			// Shutdown
-			return;
 		}
-
-		if (newSignatures.isEmpty())
-			return;
-
-		// Broadcast signatures that are new to us
-		Network.getInstance().broadcast(broadcastPeer -> broadcastPeer == peer ? null : new TransactionSignaturesMessage(newSignatures));
 	}
 
 	private void onNetworkGetArbitraryDataMessage(Peer peer, Message message) {