From 708f35e5c1155f75b3fa2808d460720c44193532 Mon Sep 17 00:00:00 2001
From: Anton Kaliaev <anton.kalyaev@gmail.com>
Date: Tue, 22 May 2018 17:05:54 +0400
Subject: [PATCH] do not look for height in older files if we've seen height -
 1

Refs #1600
---
 CHANGELOG.md     | 1 +
 consensus/wal.go | 7 +++++++
 2 files changed, 8 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 599c66073..bf3059374 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,7 @@ IMPROVEMENTS:
 
 - [consensus] consensus reactor now receives events from a separate event bus,
   which is not dependant on external RPC load
+- [consensus/wal] do not look for height in older files if we've seen height - 1
 
 ## 0.19.5
 
diff --git a/consensus/wal.go b/consensus/wal.go
index c00fec614..80cb8fc3c 100644
--- a/consensus/wal.go
+++ b/consensus/wal.go
@@ -151,6 +151,7 @@ type WALSearchOptions struct {
 // CONTRACT: caller must close group reader.
 func (wal *baseWAL) SearchForEndHeight(height int64, options *WALSearchOptions) (gr *auto.GroupReader, found bool, err error) {
 	var msg *TimedWALMessage
+	lastHeightFound := int64(-1)
 
 	// NOTE: starting from the last file in the group because we're usually
 	// searching for the last height. See replay.go
@@ -166,6 +167,11 @@ func (wal *baseWAL) SearchForEndHeight(height int64, options *WALSearchOptions)
 		for {
 			msg, err = dec.Decode()
 			if err == io.EOF {
+				// OPTIMISATION: no need to look for height in older files if we've seen h < height
+				if lastHeightFound > 0 && lastHeightFound < height {
+					gr.Close()
+					return nil, false, nil
+				}
 				// check next file
 				break
 			}
@@ -179,6 +185,7 @@ func (wal *baseWAL) SearchForEndHeight(height int64, options *WALSearchOptions)
 			}
 
 			if m, ok := msg.Msg.(EndHeightMessage); ok {
+				lastHeightFound = m.Height
 				if m.Height == height { // found
 					wal.Logger.Debug("Found", "height", height, "index", index)
 					return gr, true, nil