From 2d525bf2b8267cbcebd5ce3899a78684ddbeeff4 Mon Sep 17 00:00:00 2001
From: Anton Kaliaev <anton.kalyaev@gmail.com>
Date: Mon, 19 Nov 2018 16:22:17 +0400
Subject: [PATCH] mempool: add txs from Update to cache

We should add txs that come in from mempool.Update to the mempool's
cache, so that they never hit a potentially expensive check tx.

Originally posted by @ValarDragon in #2846
https://github.com/tendermint/tendermint/issues/2846#issuecomment-439216656

Refs #2855
---
 CHANGELOG_PENDING.md    |  1 +
 mempool/mempool.go      |  5 +++++
 mempool/mempool_test.go | 11 +++++++++++
 3 files changed, 17 insertions(+)

diff --git a/CHANGELOG_PENDING.md b/CHANGELOG_PENDING.md
index b499ab40c..de4930be4 100644
--- a/CHANGELOG_PENDING.md
+++ b/CHANGELOG_PENDING.md
@@ -26,5 +26,6 @@ program](https://hackerone.com/tendermint).
 ### IMPROVEMENTS:
 
 - [config] \#2877 add blocktime_iota to the config.toml (@ackratos)
+- [mempool] \#2855 add txs from Update to cache
 
 ### BUG FIXES:
diff --git a/mempool/mempool.go b/mempool/mempool.go
index 136f7abf8..6f8ee0211 100644
--- a/mempool/mempool.go
+++ b/mempool/mempool.go
@@ -545,6 +545,11 @@ func (mem *Mempool) Update(
 		mem.postCheck = postCheck
 	}
 
+	// Add committed transactions to cache (if missing).
+	for _, tx := range txs {
+		_ = mem.cache.Push(tx)
+	}
+
 	// Remove committed transactions.
 	txsLeft := mem.removeTxs(txs)
 
diff --git a/mempool/mempool_test.go b/mempool/mempool_test.go
index d7ab82737..15bfaa25b 100644
--- a/mempool/mempool_test.go
+++ b/mempool/mempool_test.go
@@ -163,6 +163,17 @@ func TestMempoolFilters(t *testing.T) {
 	}
 }
 
+func TestMempoolUpdateAddsTxsToCache(t *testing.T) {
+	app := kvstore.NewKVStoreApplication()
+	cc := proxy.NewLocalClientCreator(app)
+	mempool := newMempoolWithApp(cc)
+	mempool.Update(1, []types.Tx{[]byte{0x01}}, nil, nil)
+	err := mempool.CheckTx([]byte{0x01}, nil)
+	if assert.Error(t, err) {
+		assert.Equal(t, ErrTxInCache, err)
+	}
+}
+
 func TestTxsAvailable(t *testing.T) {
 	app := kvstore.NewKVStoreApplication()
 	cc := proxy.NewLocalClientCreator(app)