From edc46b5362df2b43dc442fb729de8f6e1c54ede9 Mon Sep 17 00:00:00 2001
From: jiangyangdong <jiangyangdong@yunzhisheng.cn>
Date: Thu, 26 Nov 2015 15:04:21 +0800
Subject: [PATCH] add ltrim command

---
 ledis/t_list.go      | 58 +++++++++++++++++++++++++++++
 ledis/t_list_test.go | 88 ++++++++++++++++++++++++++++++++++++++++++++
 server/cmd_list.go   | 29 +++++++++++++++
 3 files changed, 175 insertions(+)

diff --git a/ledis/t_list.go b/ledis/t_list.go
index faf6d39..24ec6d2 100644
--- a/ledis/t_list.go
+++ b/ledis/t_list.go
@@ -216,6 +216,60 @@ func (db *DB) lpop(key []byte, whereSeq int32) ([]byte, error) {
 	return value, err
 }
 
+func (db *DB) ltrim2(key []byte, startP, stopP int64) (err error) {
+	if err := checkKeySize(key); err != nil {
+		return err
+	}
+
+	t := db.listBatch
+	t.Lock()
+	defer t.Unlock()
+
+	var headSeq int32
+	var llen int32
+	start := int32(startP)
+	stop := int32(stopP)
+
+	ek := db.lEncodeMetaKey(key)
+	if headSeq, _, llen, err = db.lGetMeta(nil, ek); err != nil {
+		return err
+	} else {
+		if start < 0 {
+			start = llen + start
+		}
+		if stop < 0 {
+			stop = llen + stop
+		}
+		if start >= llen || start > stop {
+			db.lDelete(t, key)
+			db.rmExpire(t, ListType, key)
+			return t.Commit()
+		}
+
+		if start < 0 {
+			start = 0
+		}
+		if stop >= llen {
+			stop = llen - 1
+		}
+	}
+
+	if start > 0 {
+		for i := int32(0); i < start; i++ {
+			t.Delete(db.lEncodeListKey(key, headSeq+i))
+		}
+	}
+	if stop < int32(llen-1) {
+		for i := int32(stop + 1); i < llen; i++ {
+			t.Delete(db.lEncodeListKey(key, headSeq+i))
+		}
+	}
+
+	db.lSetMeta(ek, headSeq+start, headSeq+stop)
+
+	return t.Commit()
+}
+
 func (db *DB) ltrim(key []byte, trimSize, whereSeq int32) (int32, error) {
 	if err := checkKeySize(key); err != nil {
 		return 0, err
@@ -408,6 +462,10 @@ func (db *DB) LPop(key []byte) ([]byte, error) {
 	return db.lpop(key, listHeadSeq)
 }
 
+func (db *DB) LTrim(key []byte, start, stop int64) error {
+	return db.ltrim2(key, start, stop)
+}
+
 func (db *DB) LTrimFront(key []byte, trimSize int32) (int32, error) {
 	return db.ltrim(key, trimSize, listHeadSeq)
 }
diff --git a/ledis/t_list_test.go b/ledis/t_list_test.go
index b21118a..32d960d 100644
--- a/ledis/t_list_test.go
+++ b/ledis/t_list_test.go
@@ -2,6 +2,7 @@ package ledis
 
 import (
 	"fmt"
+	"strconv"
 	"sync"
 	"testing"
 	"time"
@@ -29,6 +30,93 @@ func TestListCodec(t *testing.T) {
 	}
 }
 
+func TestListTrim(t *testing.T) {
+	db := getTestDB()
+
+	key := []byte("test_list_trim")
+
+	init := func() {
+		db.LClear(key)
+		for i := 0; i < 100; i++ {
+			n, err := db.RPush(key, []byte(strconv.Itoa(i)))
+			if err != nil {
+				t.Fatal(err)
+			}
+			if n != int64(i+1) {
+				t.Fatal("length wrong")
+			}
+		}
+	}
+
+	init()
+
+	err := db.LTrim(key, 0, 99)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if l, _ := db.LLen(key); l != int64(100) {
+		t.Fatal("wrong len:", l)
+	}
+
+	err = db.LTrim(key, 0, 50)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if l, _ := db.LLen(key); l != int64(51) {
+		t.Fatal("wrong len:", l)
+	}
+	for i := int32(0); i < 51; i++ {
+		v, err := db.LIndex(key, i)
+		if err != nil {
+			t.Fatal(err)
+		}
+		if string(v) != strconv.Itoa(int(i)) {
+			t.Fatal("wrong value")
+		}
+	}
+
+	err = db.LTrim(key, 11, 30)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if l, _ := db.LLen(key); l != int64(30-11+1) {
+		t.Fatal("wrong len:", l)
+	}
+	for i := int32(11); i < 31; i++ {
+		v, err := db.LIndex(key, i-11)
+		if err != nil {
+			t.Fatal(err)
+		}
+		if string(v) != strconv.Itoa(int(i)) {
+			t.Fatal("wrong value")
+		}
+	}
+
+	err = db.LTrim(key, 0, -1)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if l, _ := db.LLen(key); l != int64(30-11+1) {
+		t.Fatal("wrong len:", l)
+	}
+
+	init()
+	err = db.LTrim(key, -3, -3)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if l, _ := db.LLen(key); l != int64(1) {
+		t.Fatal("wrong len:", l)
+	}
+	v, err := db.LIndex(key, 0)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if string(v) != "97" {
+		t.Fatal("wrong value", string(v))
+	}
+}
+
 func TestDBList(t *testing.T) {
 	db := getTestDB()
 
diff --git a/server/cmd_list.go b/server/cmd_list.go
index 0f23094..e7523f3 100644
--- a/server/cmd_list.go
+++ b/server/cmd_list.go
@@ -292,6 +292,34 @@ func lkeyexistsCommand(c *client) error {
 	return nil
 }
 
+func lTrimCommand(c *client) error {
+	args := c.args
+	if len(args) != 3 {
+		return ErrCmdParams
+	}
+
+	var start int32
+	var stop int32
+	var err error
+
+	start, err = ledis.StrInt64(args[1], nil)
+	if err != nil {
+		return ErrValue
+	}
+	stop, err = ledis.StrInt64(args[2], nil)
+	if err != nil {
+		return ErrValue
+	}
+
+	if err := c.db.LTrim(args[0], start, stop); err != nil {
+		return err
+	} else {
+		c.resp.writeStatus(OK)
+	}
+
+	return nil
+}
+
 func lTrimFrontCommand(c *client) error {
 	args := c.args
 	if len(args) != 2 {
@@ -361,4 +389,5 @@ func init() {
 
 	register("ltrim_front", lTrimFrontCommand)
 	register("ltrim_back", lTrimBackCommand)
+	register("ltrim", lTrimCommand)
 }