From 73548fef14f3bf978f54696b598d8ba2b024f25f Mon Sep 17 00:00:00 2001
From: qianbin <cola.tin.com@gmail.com>
Date: Tue, 25 Feb 2020 01:04:02 +0800
Subject: [PATCH 1/2] leveldb: optimize pickCompaction

using binary search to find next table
---
 leveldb/session_compaction.go | 20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/leveldb/session_compaction.go b/leveldb/session_compaction.go
index 4c1d336b..41032ede 100644
--- a/leveldb/session_compaction.go
+++ b/leveldb/session_compaction.go
@@ -7,6 +7,7 @@
 package leveldb
 
 import (
+	"sort"
 	"sync/atomic"
 
 	"github.com/syndtr/goleveldb/leveldb/iterator"
@@ -62,10 +63,21 @@ func (s *session) pickCompaction() *compaction {
 		sourceLevel = v.cLevel
 		cptr := s.getCompPtr(sourceLevel)
 		tables := v.levels[sourceLevel]
-		for _, t := range tables {
-			if cptr == nil || s.icmp.Compare(t.imax, cptr) > 0 {
-				t0 = append(t0, t)
-				break
+		if cptr != nil {
+			if sourceLevel == 0 {
+				for _, t := range tables {
+					if s.icmp.Compare(t.imax, cptr) > 0 {
+						t0 = append(t0, t)
+						break
+					}
+				}
+			} else {
+				n := len(tables)
+				if i := sort.Search(n, func(i int) bool {
+					return s.icmp.Compare(tables[i].imax, cptr) > 0
+				}); i < n {
+					t0 = append(t0, tables[i])
+				}
 			}
 		}
 		if len(t0) == 0 {

From 220069e961bfb1a36a6bb8dcc1dd2ffbb8819434 Mon Sep 17 00:00:00 2001
From: qianbin <cola.tin.com@gmail.com>
Date: Mon, 13 Jul 2020 10:48:23 +0800
Subject: [PATCH 2/2] leveldb: remove unnecessary code for picking L0 table

---
 leveldb/session_compaction.go | 21 ++++++---------------
 1 file changed, 6 insertions(+), 15 deletions(-)

diff --git a/leveldb/session_compaction.go b/leveldb/session_compaction.go
index 41032ede..b46a3e45 100644
--- a/leveldb/session_compaction.go
+++ b/leveldb/session_compaction.go
@@ -63,21 +63,12 @@ func (s *session) pickCompaction() *compaction {
 		sourceLevel = v.cLevel
 		cptr := s.getCompPtr(sourceLevel)
 		tables := v.levels[sourceLevel]
-		if cptr != nil {
-			if sourceLevel == 0 {
-				for _, t := range tables {
-					if s.icmp.Compare(t.imax, cptr) > 0 {
-						t0 = append(t0, t)
-						break
-					}
-				}
-			} else {
-				n := len(tables)
-				if i := sort.Search(n, func(i int) bool {
-					return s.icmp.Compare(tables[i].imax, cptr) > 0
-				}); i < n {
-					t0 = append(t0, tables[i])
-				}
+		if cptr != nil && sourceLevel > 0 {
+			n := len(tables)
+			if i := sort.Search(n, func(i int) bool {
+				return s.icmp.Compare(tables[i].imax, cptr) > 0
+			}); i < n {
+				t0 = append(t0, tables[i])
 			}
 		}
 		if len(t0) == 0 {