Optimized transaction importing by using a temporary cache of unconfirmed transactions.

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

@@ -47,6 +47,9 @@ public class TransactionImporter extends Thread {
     /** Map of recent invalid unconfirmed transactions. Key is base58 transaction signature, value is do-not-request expiry timestamp. */
     private final Map<String, Long> invalidUnconfirmedTransactions = Collections.synchronizedMap(new HashMap<>());
 
+    /** Cached list of unconfirmed transactions, used when counting per creator. This is replaced regularly */
+    public static List<TransactionData> unconfirmedTransactionsCache = null;
+
 
     public static synchronized TransactionImporter getInstance() {
         if (instance == null) {
@@ -254,6 +257,12 @@ public class TransactionImporter extends Thread {
         int processedCount = 0;
         try (final Repository repository = RepositoryManager.getRepository()) {
 
+            // Use a single copy of the unconfirmed transactions list for each cycle, to speed up constant lookups
+            // when counting unconfirmed transactions by creator.
+            List<TransactionData> unconfirmedTransactions = repository.getTransactionRepository().getUnconfirmedTransactions();
+            unconfirmedTransactions.removeIf(t -> t.getType() == Transaction.TransactionType.CHAT);
+            unconfirmedTransactionsCache = unconfirmedTransactions;
+
             // Import transactions with valid signatures
             try {
                 for (int i = 0; i < sigValidTransactions.size(); ++i) {
@@ -317,6 +326,9 @@ public class TransactionImporter extends Thread {
             } finally {
                 LOGGER.debug("Finished importing {} incoming transaction{}", processedCount, (processedCount == 1 ? "" : "s"));
                 blockchainLock.unlock();
+
+                // Clear the unconfirmed transaction cache so new data can be populated in the next cycle
+                unconfirmedTransactionsCache = null;
             }
         } catch (DataException e) {
             LOGGER.error("Repository issue while importing incoming transactions", e);

src/main/java/org/qortal/transaction/Transaction.java

@@ -13,6 +13,7 @@ import org.qortal.account.PublicKeyAccount;
 import org.qortal.asset.Asset;
 import org.qortal.block.BlockChain;
 import org.qortal.controller.Controller;
+import org.qortal.controller.TransactionImporter;
 import org.qortal.crypto.Crypto;
 import org.qortal.data.block.BlockData;
 import org.qortal.data.group.GroupApprovalData;
@@ -617,7 +618,10 @@ public abstract class Transaction {
 	}
 
 	private int countUnconfirmedByCreator(PublicKeyAccount creator) throws DataException {
-		List<TransactionData> unconfirmedTransactions = repository.getTransactionRepository().getUnconfirmedTransactions();
+		List<TransactionData> unconfirmedTransactions = TransactionImporter.getInstance().unconfirmedTransactionsCache;
+		if (unconfirmedTransactions == null) {
+			unconfirmedTransactions = repository.getTransactionRepository().getUnconfirmedTransactions();
+		}
 
 		// We exclude CHAT transactions as they never get included into blocks and
 		// have spam/DoS prevention by requiring proof of work