From 19718ac10265ded3784dced3f6d42aeffe003d85 Mon Sep 17 00:00:00 2001
From: talelbaz <63008512+talelbaz@users.noreply.github.com>
Date: Mon, 10 May 2021 15:21:48 +0300
Subject: [PATCH] Change removeTransactionAndItsChainedTransactions to be
 non-recursive (#1696)

* Change removeTransactionAndItsChainedTransactions to be non-recursive

* Split the variables assigning.

* Change names of function and variables.

* Append the correct queue.

Co-authored-by: tal <tal@daglabs.com>
Co-authored-by: stasatdaglabs <39559713+stasatdaglabs@users.noreply.github.com>
---
 domain/miningmanager/mempool/mempool.go | 55 ++++++++++++++++---------
 1 file changed, 35 insertions(+), 20 deletions(-)

diff --git a/domain/miningmanager/mempool/mempool.go b/domain/miningmanager/mempool/mempool.go
index 9ff7c9d67..10e460302 100644
--- a/domain/miningmanager/mempool/mempool.go
+++ b/domain/miningmanager/mempool/mempool.go
@@ -406,34 +406,49 @@ func (mp *mempool) removeTransactionsFromPool(txs []*consensusexternalapi.Domain
 	return nil
 }
 
+type transactionAndOutpoint struct {
+	transaction *consensusexternalapi.DomainTransaction
+	outpoint    *consensusexternalapi.DomainOutpoint
+}
+
 // removeTransactionAndItsChainedTransactions removes a transaction and all of its chained transaction from the mempool.
-//
 // This function MUST be called with the mempool lock held (for writes).
-func (mp *mempool) removeTransactionAndItsChainedTransactions(tx *consensusexternalapi.DomainTransaction) error {
-	txID := consensushashing.TransactionID(tx)
+func (mp *mempool) removeTransactionAndItsChainedTransactions(transaction *consensusexternalapi.DomainTransaction) error {
+	transactionAndOutpointQueue := make([]*transactionAndOutpoint, 0)
+	transactionAndOutpointQueue = appendTransactionToTransactionAndOutpointQueue(transactionAndOutpointQueue, transaction)
 	// Remove any transactions which rely on this one.
-	for i := uint32(0); i < uint32(len(tx.Outputs)); i++ {
-		prevOut := consensusexternalapi.DomainOutpoint{TransactionID: *txID, Index: i}
-		if txRedeemer, exists := mp.mempoolUTXOSet.poolTransactionBySpendingOutpoint(prevOut); exists {
-			err := mp.removeTransactionAndItsChainedTransactions(txRedeemer)
-			if err != nil {
-				return err
-			}
+	for len(transactionAndOutpointQueue) > 0 {
+		txAndOutpoint := transactionAndOutpointQueue[0]
+		transactionAndOutpointQueue = transactionAndOutpointQueue[1:]
+		if txRedeemer, exists := mp.mempoolUTXOSet.poolTransactionBySpendingOutpoint(*txAndOutpoint.outpoint); exists {
+			transactionAndOutpointQueue = appendTransactionToTransactionAndOutpointQueue(transactionAndOutpointQueue, txRedeemer)
+		}
+
+		transactionID := txAndOutpoint.outpoint.TransactionID
+		if _, exists := mp.chainedTransactions[transactionID]; exists {
+			mp.removeChainTransaction(txAndOutpoint.transaction)
+		}
+		err := mp.cleanTransactionFromSets(txAndOutpoint.transaction)
+		if err != nil {
+			return err
 		}
 	}
-
-	if _, exists := mp.chainedTransactions[*txID]; exists {
-		mp.removeChainTransaction(tx)
-	}
-
-	err := mp.cleanTransactionFromSets(tx)
-	if err != nil {
-		return err
-	}
-
 	return nil
 }
 
+func appendTransactionToTransactionAndOutpointQueue(queue []*transactionAndOutpoint,
+	transaction *consensusexternalapi.DomainTransaction) []*transactionAndOutpoint {
+
+	transactionID := consensushashing.TransactionID(transaction)
+	queueWithAddedTransactionAndOutpoint := queue
+	for i := uint32(0); i < uint32(len(transaction.Outputs)); i++ {
+		previousOutpoint := consensusexternalapi.DomainOutpoint{TransactionID: *transactionID, Index: i}
+		queueWithAddedTransactionAndOutpoint = append(queueWithAddedTransactionAndOutpoint,
+			&transactionAndOutpoint{transaction: transaction, outpoint: &previousOutpoint})
+	}
+	return queueWithAddedTransactionAndOutpoint
+}
+
 // cleanTransactionFromSets removes the transaction from all mempool related transaction sets.
 // It assumes that any chained transaction is already cleaned from the mempool.
 //