mempool: fix cache_size==0. closes #1761

CHANGELOG.md

@@ -6,7 +6,8 @@
 
 BUG FIXES
 
-[consensus] Fix #1754 where we don't make blocks when `create_empty_blocks=false`
+- [consensus] Fix #1754 where we don't make blocks when `create_empty_blocks=false`
+- [mempool] Fix #1761 where we don't process txs if `cache_size=0`
 
 ## 0.20.0
 

mempool/mempool.go

@@ -478,6 +478,11 @@ func (cache *txCache) Push(tx types.Tx) bool {
 	cache.mtx.Lock()
 	defer cache.mtx.Unlock()
 
+	// if cache size is 0, do nothing
+	if cache.size == 0 {
+		return true
+	}
+
 	if _, exists := cache.map_[string(tx)]; exists {
 		return false
 	}