feat: add optimized Wallet.getTransaction functions

core/src/main/java/org/bitcoinj/wallet/Wallet.java

@@ -3275,6 +3275,42 @@ public Set<Transaction> getTransactions(boolean includeDead) {
         }
     }
 
+    public Set<Transaction> getTransactionsOpt(boolean includeDead) {
+        lock.lock();
+        try {
+            int capacity = unspent.size() + spent.size() + pending.size() + (includeDead ? dead.size(): 0);
+            Set<Transaction> all = new HashSet<>(capacity);
+            all.addAll(unspent.values());
+            all.addAll(spent.values());
+            all.addAll(pending.values());
+            if (includeDead)
+                all.addAll(dead.values());
+            return all;
+        } finally {
+            lock.unlock();
+        }
+    }
+
+    /**
+     * Returns a list of all transactions in the wallet.
+     * @param includeDead     If true, transactions that were overridden by a double spend are included.
+     */
+    public Collection<Transaction> getTransactionList(boolean includeDead) {
+        lock.lock();
+        try {
+            int capacity = unspent.size() + spent.size() + pending.size() + (includeDead ? dead.size(): 0);
+            ArrayList<Transaction> all = new ArrayList<>(capacity);
+            all.addAll(unspent.values());
+            all.addAll(spent.values());
+            all.addAll(pending.values());
+            if (includeDead)
+                all.addAll(dead.values());
+            return all;
+        } finally {
+            lock.unlock();
+        }
+    }
+
     /**
      * Returns a set of all WalletTransactions in the wallet.
      */

core/src/test/java/org/bitcoinj/wallet/WalletBenchmarkTest.java

@@ -0,0 +1,44 @@
+package org.bitcoinj.wallet;
+
+import com.google.common.base.Stopwatch;
+import org.bitcoinj.core.Transaction;
+import org.junit.Test;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.Collection;
+import java.util.Set;
+
+import static org.junit.Assert.assertEquals;
+
+public class WalletBenchmarkTest {
+    @Test
+    public void getTransactionsTest() throws UnreadableWalletException, IOException {
+        Set<Transaction> set = null;
+        Collection<Transaction> list = null;
+        int count = 1;
+        try (InputStream stream = getClass().getResourceAsStream("coinjoin-testnet-big.wallet")) {
+            WalletEx coinJoinWallet = (WalletEx) new WalletProtobufSerializer().readWallet(stream);
+            Stopwatch watch = Stopwatch.createStarted();
+            for (int i = 0; i < count; ++i)
+                set = coinJoinWallet.getTransactions(true);
+            System.out.println("getTransactions = " + watch);
+        }
+        try (InputStream stream = getClass().getResourceAsStream("coinjoin-testnet-big.wallet")) {
+            WalletEx coinJoinWallet = (WalletEx) new WalletProtobufSerializer().readWallet(stream);
+            Stopwatch watch = Stopwatch.createStarted();
+            for (int i = 0; i < count; ++i)
+               set = coinJoinWallet.getTransactionsOpt(true);
+            System.out.println("getTransactions(optimized) = " + watch);
+        }
+        try (InputStream stream = getClass().getResourceAsStream("coinjoin-testnet-big.wallet")) {
+            WalletEx coinJoinWallet = (WalletEx) new WalletProtobufSerializer().readWallet(stream);
+            Stopwatch watch = Stopwatch.createStarted();
+            for (int i = 0; i < count; ++i)
+                list = coinJoinWallet.getTransactionList(true);
+            System.out.println("getTransactionList = " + watch);
+        }
+        assertEquals(set.size(), list.size());
+    }
+
+}