From f4cf1073d4feb8f8d717269b86c473d4b56d684f Mon Sep 17 00:00:00 2001
From: Wilmer Paulino <wilmer.paulino@gmail.com>
Date: Fri, 5 Oct 2018 02:07:55 -0700
Subject: [PATCH] chainntnfs/height_hint_cache: prevent db transactions with no
 updates

In this commit, we modify our height hint cache to no longer start a
database transaction if no outpoints/txids are provided to update the
height hints for.
---
 chainntnfs/height_hint_cache.go | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/chainntnfs/height_hint_cache.go b/chainntnfs/height_hint_cache.go
index 33dac971..cd499a6e 100644
--- a/chainntnfs/height_hint_cache.go
+++ b/chainntnfs/height_hint_cache.go
@@ -127,6 +127,10 @@ func (c *HeightHintCache) CommitSpendHint(height uint32, ops ...wire.OutPoint) e
 		return nil
 	}
 
+	if len(ops) == 0 {
+		return nil
+	}
+
 	Log.Tracef("Updating spend hint to height %d for %v", height, ops)
 
 	return c.db.Batch(func(tx *bolt.Tx) error {
@@ -197,6 +201,10 @@ func (c *HeightHintCache) PurgeSpendHint(ops ...wire.OutPoint) error {
 		return nil
 	}
 
+	if len(ops) == 0 {
+		return nil
+	}
+
 	Log.Tracef("Removing spend hints for %v", ops)
 
 	return c.db.Batch(func(tx *bolt.Tx) error {
@@ -228,6 +236,10 @@ func (c *HeightHintCache) CommitConfirmHint(height uint32, txids ...chainhash.Ha
 		return nil
 	}
 
+	if len(txids) == 0 {
+		return nil
+	}
+
 	Log.Tracef("Updating confirm hints to height %d for %v", height, txids)
 
 	return c.db.Batch(func(tx *bolt.Tx) error {
@@ -299,6 +311,10 @@ func (c *HeightHintCache) PurgeConfirmHint(txids ...chainhash.Hash) error {
 		return nil
 	}
 
+	if len(txids) == 0 {
+		return nil
+	}
+
 	Log.Tracef("Removing confirm hints for %v", txids)
 
 	return c.db.Batch(func(tx *bolt.Tx) error {