Remove concept of stateful transaction signers.

core/src/main/java/org/bitcoinj/signers/CustomTransactionSigner.java

@@ -40,7 +40,7 @@ import static com.google.common.base.Preconditions.checkNotNull;
  * some local API or something else.
  * </p>
  */
-public abstract class CustomTransactionSigner extends StatelessTransactionSigner {
+public abstract class CustomTransactionSigner implements TransactionSigner {
     private static final Logger log = LoggerFactory.getLogger(CustomTransactionSigner.class);
 
     @Override

core/src/main/java/org/bitcoinj/signers/LocalTransactionSigner.java

@@ -42,7 +42,7 @@ import org.slf4j.LoggerFactory;
  * the same derivation path.</p>
  * <p>This signer always uses {@link Transaction.SigHash#ALL} signing mode.</p>
  */
-public class LocalTransactionSigner extends StatelessTransactionSigner {
+public class LocalTransactionSigner implements TransactionSigner {
     private static final Logger log = LoggerFactory.getLogger(LocalTransactionSigner.class);
 
     /**

core/src/main/java/org/bitcoinj/signers/MissingSigResolutionSigner.java

@@ -34,7 +34,7 @@ import org.slf4j.LoggerFactory;
  * In MissingSigsMode.THROW mode this signer will throw an exception. It would be MissingSignatureException
  * for P2SH or MissingPrivateKeyException for other transaction types.
  */
-public class MissingSigResolutionSigner extends StatelessTransactionSigner {
+public class MissingSigResolutionSigner implements TransactionSigner {
     private static final Logger log = LoggerFactory.getLogger(MissingSigResolutionSigner.class);
 
     public Wallet.MissingSigsMode missingSigsMode = Wallet.MissingSigsMode.USE_DUMMY_SIG;

core/src/main/java/org/bitcoinj/signers/StatelessTransactionSigner.java

@@ -1,31 +0,0 @@
-/*
- * Copyright 2014 Kosta Korenkov
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *    http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package org.bitcoinj.signers;
-
-/**
- * A signer that doesn't have any state to be serialized.
- */
-public abstract class StatelessTransactionSigner implements TransactionSigner {
-    @Override
-    public void deserialize(byte[] data) {
-    }
-
-    @Override
-    public byte[] serialize() {
-        return new byte[0];
-    }
-}

core/src/main/java/org/bitcoinj/signers/TransactionSigner.java

@@ -67,16 +67,6 @@ public interface TransactionSigner {
      */
     boolean isReady();
 
-    /**
-     * Returns byte array of data representing state of this signer. It's used to serialize/deserialize this signer
-     */
-    byte[] serialize();
-
-    /**
-     * Uses given byte array of data to reconstruct internal state of this signer
-     */
-    void deserialize(byte[] data);
-
     /**
      * Signs given transaction's inputs.
      * Returns true if signer is compatible with given transaction (can do something meaningful with it).

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

@@ -241,7 +241,7 @@ public class Wallet extends BaseTaggableObject
     private final HashMap<String, WalletExtension> extensions;
 
     // Objects that perform transaction signing. Applied subsequently one after another
-    @GuardedBy("lock") private List<TransactionSigner> signers;
+    @GuardedBy("lock") private volatile List<TransactionSigner> signers;
 
     // If this is set then the wallet selects spendable candidate outputs from a UTXO provider.
     @Nullable private volatile UTXOProvider vUTXOProvider;

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

@@ -32,8 +32,6 @@ import org.bitcoinj.crypto.KeyCrypter;
 import org.bitcoinj.crypto.KeyCrypterScrypt;
 import org.bitcoinj.script.Script;
 import org.bitcoinj.script.ScriptException;
-import org.bitcoinj.signers.LocalTransactionSigner;
-import org.bitcoinj.signers.TransactionSigner;
 import org.bitcoinj.utils.ExchangeRate;
 import org.bitcoinj.utils.Fiat;
 import org.bitcoinj.wallet.Protos.Wallet.EncryptionType;
@@ -235,16 +233,6 @@ public class WalletProtobufSerializer {
             walletBuilder.addTags(tag);
         }
 
-        for (TransactionSigner signer : wallet.getTransactionSigners()) {
-            // do not serialize LocalTransactionSigner as it's being added implicitly
-            if (signer instanceof LocalTransactionSigner)
-                continue;
-            Protos.TransactionSigner.Builder protoSigner = Protos.TransactionSigner.newBuilder();
-            protoSigner.setClassName(signer.getClass().getName());
-            protoSigner.setData(ByteString.copyFrom(signer.serialize()));
-            walletBuilder.addTransactionSigners(protoSigner);
-        }
-
         // Populate the wallet version.
         walletBuilder.setVersion(wallet.getVersion());
 
@@ -567,18 +555,6 @@ public class WalletProtobufSerializer {
             wallet.setTag(tag.getTag(), tag.getData());
         }
 
-        for (Protos.TransactionSigner signerProto : walletProto.getTransactionSignersList()) {
-            try {
-                Class signerClass = Class.forName(signerProto.getClassName());
-                TransactionSigner signer = (TransactionSigner)signerClass.newInstance();
-                signer.deserialize(signerProto.getData().toByteArray());
-                wallet.addTransactionSigner(signer);
-            } catch (Exception e) {
-                throw new UnreadableWalletException("Unable to deserialize TransactionSigner instance: " +
-                        signerProto.getClassName(), e);
-            }
-        }
-
         if (walletProto.hasVersion()) {
             wallet.setVersion(walletProto.getVersion());
         }

core/src/main/proto/wallet.proto

@@ -332,16 +332,6 @@ message Tag {
     required bytes data = 2;
 }
 
-/**
- * Data required to reconstruct TransactionSigner.
- */
-message TransactionSigner {
-	// fully qualified class name of TransactionSigner implementation
-	required string class_name = 1;
-	// arbitrary data required for signer to function
-	optional bytes data = 2;
-}
-
 /** A bitcoin wallet */
 message Wallet {
   /**
@@ -395,8 +385,7 @@ message Wallet {
 
   repeated Tag tags = 16;
 
-  // transaction signers added to the wallet
+  // (field number 17 was used by transaction_signers)
-  repeated TransactionSigner transaction_signers = 17;
 
   // Next tag: 18
 }

core/src/test/java/org/bitcoinj/testing/NopTransactionSigner.java

@@ -34,17 +34,6 @@ public class NopTransactionSigner implements TransactionSigner {
         return isReady;
     }
 
-    @Override
-    public byte[] serialize() {
-        return isReady ? new byte[]{1} : new byte[]{0};
-    }
-
-    @Override
-    public void deserialize(byte[] data) {
-        if (data.length > 0)
-            isReady = data[0] == 1;
-    }
-
     @Override
     public boolean signInputs(ProposedTransaction t, KeyBag keyBag) {
         return false;

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

@@ -42,7 +42,6 @@ import org.bitcoinj.script.Script;
 import org.bitcoinj.script.ScriptBuilder;
 import org.bitcoinj.script.ScriptChunk;
 import org.bitcoinj.script.ScriptPattern;
-import org.bitcoinj.signers.StatelessTransactionSigner;
 import org.bitcoinj.signers.TransactionSigner;
 import org.bitcoinj.store.BlockStoreException;
 import org.bitcoinj.store.MemoryBlockStore;
@@ -3319,16 +3318,6 @@ public class WalletTest extends TestWithWallet {
         wallet.addTransactionSigner(new NopTransactionSigner(false));
     }
 
-    @Test
-    public void transactionSignersShouldBeSerializedAlongWithWallet() throws Exception {
-        TransactionSigner signer = new NopTransactionSigner(true);
-        wallet.addTransactionSigner(signer);
-        assertEquals(2, wallet.getTransactionSigners().size());
-        wallet = roundTrip(wallet);
-        assertEquals(2, wallet.getTransactionSigners().size());
-        assertTrue(wallet.getTransactionSigners().get(1).isReady());
-    }
-
     @Test
     public void watchingMarriedWallet() throws Exception {
         DeterministicKey watchKey = wallet.getWatchingKey();
@@ -3340,7 +3329,7 @@ public class WalletTest extends TestWithWallet {
         final DeterministicKeyChain keyChain = new DeterministicKeyChain(new SecureRandom());
         DeterministicKey partnerKey = DeterministicKey.deserializeB58(null, keyChain.getWatchingKey().serializePubB58(UNITTEST), UNITTEST);
 
-        TransactionSigner signer = new StatelessTransactionSigner() {
+        TransactionSigner signer = new TransactionSigner() {
             @Override
             public boolean isReady() {
                 return true;