Plug in and enable mempool address indexing

Although the address indexer for the memory pool was a part of its
struct, it was not enabled in the daemon. The framework to enable it
by default has been completed and the mempool should now correctly
index transactions by address.

mempool.go

@@ -957,6 +957,9 @@ func (mp *txMemPool) removeTransaction(tx *dcrutil.Tx, removeRedeemers bool) {
 		delete(mp.pool, *txHash)
 		mp.lastUpdated = time.Now()
 	}
+
+	// Remove the transaction and its addresses from the address index.
+	mp.pruneTxFromAddrIndex(tx)
 }
 
 // RemoveTransaction removes the passed transaction from the mempool. If
@@ -1052,7 +1055,7 @@ func (mp *txMemPool) indexScriptAddressToTx(pkVersion uint16, pkScript []byte,
 	_, addresses, _, err := txscript.ExtractPkScriptAddrs(pkVersion, pkScript,
 		activeNetParams.Params)
 	if err != nil {
-		txmpLog.Errorf("Unable to extract encoded addresses from script "+
+		txmpLog.Tracef("Unable to extract encoded addresses from script "+
 			"for addrindex: %v", err)
 		return err
 	}
@@ -1067,6 +1070,76 @@ func (mp *txMemPool) indexScriptAddressToTx(pkVersion uint16, pkScript []byte,
 	return nil
 }
 
+// pruneTxFromAddrIndex deletes references to the transaction in the address
+// index by searching first for the address from an output and second for the
+// transaction itself.
+//
+// This function MUST be called with the mempool lock held (for writes).
+func (mp *txMemPool) pruneTxFromAddrIndex(tx *dcrutil.Tx) {
+	txHash := tx.Sha()
+
+	for _, txOut := range tx.MsgTx().TxOut {
+		_, addresses, _, err := txscript.ExtractPkScriptAddrs(txOut.Version,
+			txOut.PkScript, activeNetParams.Params)
+		if err != nil {
+			// If we couldn't extract addresses, skip this output.
+			continue
+		}
+
+		for _, addr := range addresses {
+			if mp.addrindex[addr.EncodeAddress()] != nil {
+				// First remove all references to the transaction hash.
+				for thisTxHash := range mp.addrindex[addr.EncodeAddress()] {
+					if thisTxHash == *txHash {
+						delete(mp.addrindex[addr.EncodeAddress()], thisTxHash)
+					}
+				}
+
+				// Then, if the address has no transactions referenced,
+				// remove it too.
+				if len(mp.addrindex[addr.EncodeAddress()]) == 0 {
+					delete(mp.addrindex, addr.EncodeAddress())
+				}
+			}
+		}
+	}
+}
+
+// findTxForAddr searches for all referenced transactions for a given address
+// that are currently stored in the mempool.
+//
+// This function is safe for concurrent access.
+func (mp *txMemPool) findTxForAddr(addr dcrutil.Address) []*dcrutil.Tx {
+	var txs []*dcrutil.Tx
+	if mp.addrindex[addr.EncodeAddress()] != nil {
+		// Lookup all relevant transactions and append them.
+		for thisTxHash := range mp.addrindex[addr.EncodeAddress()] {
+			txDesc, exists := mp.pool[thisTxHash]
+			if !exists {
+				txmpLog.Warnf("Failed to find transaction %v in mempool "+
+					"that was referenced in the mempool addrIndex",
+					thisTxHash)
+				continue
+			}
+
+			txs = append(txs, txDesc.Tx)
+		}
+	}
+
+	return txs
+}
+
+// FindTxForAddr is the exported and concurrency safe version of findTxForAddr.
+//
+// This function is safe for concurrent access.
+func (mp *txMemPool) FindTxForAddr(addr dcrutil.Address) []*dcrutil.Tx {
+	// Protect concurrent access.
+	mp.Lock()
+	defer mp.Unlock()
+
+	return mp.findTxForAddr(addr)
+}
+
 // calcInputValueAge is a helper function used to calculate the input age of
 // a transaction.  The input age for a txin is the number of confirmations
 // since the referenced txout multiplied by its output value.  The total input
@@ -1686,6 +1759,13 @@ func (mp *txMemPool) maybeAcceptTransaction(tx *dcrutil.Tx, isNew,
 		}
 	}
 
+	// Insert the address into the mempool address index.
+	for _, txOut := range tx.MsgTx().TxOut {
+		// This function returns an error, but we don't really care
+		// if the script was non-standard or otherwise malformed.
+		mp.indexScriptAddressToTx(txOut.Version, txOut.PkScript, tx)
+	}
+
 	txmpLog.Debugf("Accepted transaction %v (pool size: %v)", txHash,
 		len(mp.pool))
 

rpcserver.go

@@ -1469,6 +1469,13 @@ func handleExistsAddress(s *rpcServer, cmd interface{},
 	if err == nil && tlr != nil {
 		return true, nil
 	}
+
+	// Check the mempool as well.
+	txs := s.server.txMemPool.FindTxForAddr(addr)
+	if len(txs) > 0 {
+		return true, nil
+	}
+
 	return false, nil
 }