Eliminate the duplicated parentTransaction field from TransactionInput/Output.

core/src/main/java/com/google/bitcoin/core/ChildMessage.java

@@ -20,13 +20,11 @@ import javax.annotation.Nullable;
 /**
  * Represents a Message type that can be contained within another Message.  ChildMessages that have a cached
  * backing byte array need to invalidate their parent's caches as well as their own if they are modified.
- *
- * @author git
  */
 public abstract class ChildMessage extends Message {
     private static final long serialVersionUID = -7657113383624517931L;
 
-    @Nullable private Message parent;
+    @Nullable protected Message parent;
 
     protected ChildMessage() {
     }

core/src/main/java/com/google/bitcoin/core/TransactionInput.java

@@ -58,13 +58,11 @@ public class TransactionInput extends ChildMessage implements Serializable {
     /** Value of the output connected to the input, if known. This field does not participate in equals()/hashCode(). */
     @Nullable
     private final Coin value;
-    // A pointer to the transaction that owns this input.
-    private final Transaction parentTransaction;
 
     /**
      * Creates an input that connects to nothing - used only in creation of coinbase transactions.
      */
-    public TransactionInput(NetworkParameters params, Transaction parentTransaction, byte[] scriptBytes) {
+    public TransactionInput(NetworkParameters params, @Nullable Transaction parentTransaction, byte[] scriptBytes) {
         this(params, parentTransaction, scriptBytes, new TransactionOutPoint(params, NO_SEQUENCE, (Transaction) null));
     }
 
@@ -79,8 +77,8 @@ public class TransactionInput extends ChildMessage implements Serializable {
         this.scriptBytes = scriptBytes;
         this.outpoint = outpoint;
         this.sequence = NO_SEQUENCE;
-        this.parentTransaction = parentTransaction;
         this.value = value;
+        setParent(parentTransaction);
         length = 40 + (scriptBytes == null ? 1 : VarInt.sizeOf(scriptBytes.length) + scriptBytes.length);
     }
 
@@ -90,10 +88,10 @@ public class TransactionInput extends ChildMessage implements Serializable {
     TransactionInput(NetworkParameters params, Transaction parentTransaction, TransactionOutput output) {
         super(params);
         long outputIndex = output.getIndex();
-        outpoint = new TransactionOutPoint(params, outputIndex, output.parentTransaction);
+        outpoint = new TransactionOutPoint(params, outputIndex, output.getParentTransaction());
         scriptBytes = EMPTY_ARRAY;
         sequence = NO_SEQUENCE;
-        this.parentTransaction = parentTransaction;
+        setParent(parentTransaction);
         this.value = output.getValue();
         length = 41;
     }
@@ -104,7 +102,7 @@ public class TransactionInput extends ChildMessage implements Serializable {
     public TransactionInput(NetworkParameters params, Transaction parentTransaction,
                             byte[] payload, int offset) throws ProtocolException {
         super(params, payload, offset);
-        this.parentTransaction = parentTransaction;
+        setParent(checkNotNull(parentTransaction));
         this.value = null;
     }
 
@@ -124,7 +122,6 @@ public class TransactionInput extends ChildMessage implements Serializable {
                             boolean parseLazy, boolean parseRetain)
             throws ProtocolException {
         super(params, payload, offset, parentTransaction, parseLazy, parseRetain, UNKNOWN_LENGTH);
-        this.parentTransaction = parentTransaction;
         this.value = null;
     }
 
@@ -261,7 +258,7 @@ public class TransactionInput extends ChildMessage implements Serializable {
      * @return The Transaction that owns this input.
      */
     public Transaction getParentTransaction() {
-        return parentTransaction;
+        return (Transaction) parent;
     }
 
     /**
@@ -344,13 +341,13 @@ public class TransactionInput extends ChildMessage implements Serializable {
         checkElementIndex((int) outpoint.getIndex(), transaction.getOutputs().size(), "Corrupt transaction");
         TransactionOutput out = transaction.getOutput((int) outpoint.getIndex());
         if (!out.isAvailableForSpending()) {
-            if (out.parentTransaction.equals(outpoint.fromTx)) {
+            if (getParentTransaction().equals(outpoint.fromTx)) {
                 // Already connected.
                 return ConnectionResult.SUCCESS;
             } else if (mode == ConnectMode.DISCONNECT_ON_CONFLICT) {
                 out.markAsUnspent();
             } else if (mode == ConnectMode.ABORT_ON_CONFLICT) {
-                outpoint.fromTx = checkNotNull(out.parentTransaction);
+                outpoint.fromTx = out.getParentTransaction();
                 return TransactionInput.ConnectionResult.ALREADY_SPENT;
             }
         }
@@ -360,7 +357,7 @@ public class TransactionInput extends ChildMessage implements Serializable {
 
     /** Internal use only: connects this TransactionInput to the given output (updates pointers and spent flags) */
     public void connect(TransactionOutput out) {
-        outpoint.fromTx = checkNotNull(out.parentTransaction);
+        outpoint.fromTx = out.getParentTransaction();
         out.markAsSpent(this);
     }
 
@@ -421,15 +418,15 @@ public class TransactionInput extends ChildMessage implements Serializable {
      * @throws VerificationException If the outpoint doesn't match the given output.
      */
     public void verify(TransactionOutput output) throws VerificationException {
-        if (output.parentTransaction != null) {
+        if (output.parent != null) {
-            if (!getOutpoint().getHash().equals(output.parentTransaction.getHash()))
+            if (!getOutpoint().getHash().equals(output.getParentTransaction().getHash()))
                 throw new VerificationException("This input does not refer to the tx containing the output.");
             if (getOutpoint().getIndex() != output.getIndex())
                 throw new VerificationException("This input refers to a different output on the given tx.");
         }
         Script pubKey = output.getScriptPubKey();
-        int myIndex = parentTransaction.getInputs().indexOf(this);
+        int myIndex = getParentTransaction().getInputs().indexOf(this);
-        getScriptSig().correctlySpends(parentTransaction, myIndex, pubKey, true);
+        getScriptSig().correctlySpends(getParentTransaction(), myIndex, pubKey, true);
     }
 
     /**
@@ -458,7 +455,7 @@ public class TransactionInput extends ChildMessage implements Serializable {
         if (!outpoint.equals(input.outpoint)) return false;
         if (!Arrays.equals(scriptBytes, input.scriptBytes)) return false;
         if (scriptSig != null ? !scriptSig.equals(input.scriptSig) : input.scriptSig != null) return false;
-        if (parentTransaction != input.parentTransaction) return false;
+        if (parent != input.parent) return false;
 
         return true;
     }

core/src/main/java/com/google/bitcoin/core/TransactionOutput.java

@@ -59,8 +59,6 @@ public class TransactionOutput extends ChildMessage implements Serializable {
     private boolean availableForSpending;
     @Nullable private TransactionInput spentBy;
 
-    // A reference to the transaction which holds this output, if any.
-    @Nullable Transaction parentTransaction;
     private transient int scriptLen;
 
     /**
@@ -69,7 +67,7 @@ public class TransactionOutput extends ChildMessage implements Serializable {
     public TransactionOutput(NetworkParameters params, @Nullable Transaction parent, byte[] payload,
                              int offset) throws ProtocolException {
         super(params, payload, offset);
-        parentTransaction = parent;
+        setParent(parent);
         availableForSpending = true;
     }
 
@@ -88,7 +86,6 @@ public class TransactionOutput extends ChildMessage implements Serializable {
     public TransactionOutput(NetworkParameters params, @Nullable Transaction parent, byte[] payload, int offset,
                              boolean parseLazy, boolean parseRetain) throws ProtocolException {
         super(params, payload, offset, parent, parseLazy, parseRetain, UNKNOWN_LENGTH);
-        parentTransaction = parent;
         availableForSpending = true;
     }
 
@@ -118,7 +115,7 @@ public class TransactionOutput extends ChildMessage implements Serializable {
         checkArgument(value.compareTo(NetworkParameters.MAX_MONEY) < 0, "Values larger than MAX_MONEY not allowed");
         this.value = value.value;
         this.scriptBytes = scriptBytes;
-        parentTransaction = parent;
+        setParent(parent);
         availableForSpending = true;
         length = 8 + VarInt.sizeOf(scriptBytes.length) + scriptBytes.length;
     }
@@ -218,14 +215,16 @@ public class TransactionOutput extends ChildMessage implements Serializable {
         this.value = value.value;
     }
 
-    int getIndex() {
+    /**
-        checkNotNull(parentTransaction, "This output is not attached to a parent transaction.");
+     * Gets the index of this output in the parent transaction, or throws if this output is free standing. Iterates
-        for (int i = 0; i < parentTransaction.getOutputs().size(); i++) {
+     * over the parents list to discover this.
-            if (parentTransaction.getOutputs().get(i) == this)
+     */
+    public int getIndex() {
+        for (int i = 0; i < getParentTransaction().getOutputs().size(); i++) {
+            if (getParentTransaction().getOutputs().get(i) == this)
                 return i;
         }
-        // Should never happen.
+        throw new IllegalStateException("Output linked to wrong parent transaction?");
-        throw new RuntimeException("Output linked to wrong parent transaction?");
     }
 
     /**
@@ -270,8 +269,8 @@ public class TransactionOutput extends ChildMessage implements Serializable {
         checkState(availableForSpending);
         availableForSpending = false;
         spentBy = input;
-        if (parentTransaction != null)
+        if (parent != null)
-            log.info("Marked {}:{} as spent by {}", parentTransaction.getHash(), getIndex(), input);
+            log.info("Marked {}:{} as spent by {}", getParentTransaction().getHash(), getIndex(), input);
         else
             log.info("Marked floating output as spent by {}", input);
     }
@@ -280,8 +279,8 @@ public class TransactionOutput extends ChildMessage implements Serializable {
      * Resets the spent pointer / availableForSpending flag to null.
      */
     public void markAsUnspent() {
-        if (parentTransaction != null)
+        if (parent != null)
-            log.info("Un-marked {}:{} as spent by {}", parentTransaction.getHash(), getIndex(), spentBy);
+            log.info("Un-marked {}:{} as spent by {}", getParentTransaction().getHash(), getIndex(), spentBy);
         else
             log.info("Un-marked floating output as spent by {}", spentBy);
         availableForSpending = true;
@@ -388,7 +387,7 @@ public class TransactionOutput extends ChildMessage implements Serializable {
      * Returns the transaction that owns this output, or throws NullPointerException if unowned.
      */
     public Transaction getParentTransaction() {
-        return checkNotNull(parentTransaction, "Free-standing TransactionOutput");
+        return checkNotNull((Transaction) parent, "Free-standing TransactionOutput");
     }
 
     /**
@@ -423,14 +422,13 @@ public class TransactionOutput extends ChildMessage implements Serializable {
 
         if (!Arrays.equals(scriptBytes, other.scriptBytes)) return false;
         if (value != other.value) return false;
-        if (parentTransaction != null && parentTransaction != other.parentTransaction) return false;
+        if (parent != null && parent != other.parent) return false;
 
         return true;
     }
 
     @Override
     public int hashCode() {
-        int result = 31 * (int) value + (scriptBytes != null ? Arrays.hashCode(scriptBytes) : 0);
+        return 31 * (int) value + (scriptBytes != null ? Arrays.hashCode(scriptBytes) : 0);
-        return result;
     }
 }