add ltrim_front and ltrim_back command, imitation ssdb's qtrim_front and qtrim_back commands

ledis/t_list.go

@@ -9,6 +9,7 @@ import (
 
 	"github.com/siddontang/go/hack"
 	"github.com/siddontang/go/log"
+	"github.com/siddontang/go/num"
 	"github.com/siddontang/ledisdb/store"
 )
 
@@ -215,6 +216,61 @@ func (db *DB) lpop(key []byte, whereSeq int32) ([]byte, error) {
 	return value, err
 }
 
+func (db *DB) ltrim(key []byte, trimSize, whereSeq int32) (int32, error) {
+	if err := checkKeySize(key); err != nil {
+		return 0, err
+	}
+
+	if trimSize == 0 {
+		return 0, nil
+	}
+
+	t := db.listBatch
+	t.Lock()
+	defer t.Unlock()
+
+	var headSeq int32
+	var tailSeq int32
+	var size int32
+	var err error
+
+	metaKey := db.lEncodeMetaKey(key)
+	headSeq, tailSeq, size, err = db.lGetMeta(nil, metaKey)
+	if err != nil {
+		return 0, err
+	} else if size == 0 {
+		return 0, nil
+	}
+
+	var (
+		trimStartSeq int32
+		trimEndSeq   int32
+	)
+
+	if whereSeq == listHeadSeq {
+		trimStartSeq = headSeq
+		trimEndSeq = num.MinInt32(trimStartSeq+trimSize-1, tailSeq)
+		headSeq = trimEndSeq + 1
+	} else {
+		trimEndSeq = tailSeq
+		trimStartSeq = num.MaxInt32(trimEndSeq-trimSize+1, headSeq)
+		tailSeq = trimStartSeq - 1
+	}
+
+	for trimSeq := trimStartSeq; trimSeq <= trimEndSeq; trimSeq++ {
+		itemKey := db.lEncodeListKey(key, trimSeq)
+		t.Delete(itemKey)
+	}
+
+	size = db.lSetMeta(metaKey, headSeq, tailSeq)
+	if size == 0 {
+		db.rmExpire(t, ListType, key)
+	}
+
+	err = t.Commit()
+	return trimEndSeq - trimStartSeq + 1, err
+}
+
 //	ps : here just focus on deleting the list data,
 //		 any other likes expire is ignore.
 func (db *DB) lDelete(t *batch, key []byte) int64 {
@@ -352,6 +408,14 @@ func (db *DB) LPop(key []byte) ([]byte, error) {
 	return db.lpop(key, listHeadSeq)
 }
 
+func (db *DB) LTrimFront(key []byte, trimSize int32) (int32, error) {
+	return db.ltrim(key, trimSize, listHeadSeq)
+}
+
+func (db *DB) LTrimBack(key []byte, trimSize int32) (int32, error) {
+	return db.ltrim(key, trimSize, listTailSeq)
+}
+
 func (db *DB) LPush(key []byte, args ...[]byte) (int64, error) {
 	return db.lpush(key, listHeadSeq, args...)
 }

server/cmd_list.go

@@ -292,6 +292,52 @@ func lkeyexistsCommand(c *client) error {
 	return nil
 }
 
+func lTrimFrontCommand(c *client) error {
+	args := c.args
+	if len(args) != 2 {
+		return ErrCmdParams
+	}
+
+	var trimSize int32
+	var err error
+
+	trimSize, err = ledis.StrInt32(args[1], nil)
+	if err != nil || trimSize < 0 {
+		return ErrValue
+	}
+
+	if n, err := c.db.LTrimFront(args[0], trimSize); err != nil {
+		return err
+	} else {
+		c.resp.writeInteger(int64(n))
+	}
+
+	return nil
+}
+
+func lTrimBackCommand(c *client) error {
+	args := c.args
+	if len(args) != 2 {
+		return ErrCmdParams
+	}
+
+	var trimSize int32
+	var err error
+
+	trimSize, err = ledis.StrInt32(args[1], nil)
+	if err != nil || trimSize < 0 {
+		return ErrValue
+	}
+
+	if n, err := c.db.LTrimBack(args[0], trimSize); err != nil {
+		return err
+	} else {
+		c.resp.writeInteger(int64(n))
+	}
+
+	return nil
+}
+
 func init() {
 	register("blpop", blpopCommand)
 	register("brpop", brpopCommand)
@@ -312,4 +358,7 @@ func init() {
 	register("lttl", lttlCommand)
 	register("lpersist", lpersistCommand)
 	register("lkeyexists", lkeyexistsCommand)
+
+	register("ltrim_front", lTrimFrontCommand)
+	register("ltrim_back", lTrimBackCommand)
 }

server/cmd_list_test.go

@@ -297,6 +297,72 @@ func TestPop(t *testing.T) {
 
 }
 
+func TestTrim(t *testing.T) {
+	c := getTestConn()
+	defer c.Close()
+
+	key := []byte("d")
+	if n, err := goredis.Int(c.Do("rpush", key, 1, 2, 3, 4, 5, 6)); err != nil {
+		t.Fatal(err)
+	} else if n != 6 {
+		t.Fatal(n)
+	}
+
+	if n, err := goredis.Int(c.Do("ltrim_front", key, 2)); err != nil {
+		t.Fatal(err)
+	} else if n != 2 {
+		t.Fatal(n)
+	}
+
+	if n, err := goredis.Int(c.Do("llen", key)); err != nil {
+		t.Fatal(err)
+	} else if n != 4 {
+		t.Fatal(n)
+	}
+
+	if n, err := goredis.Int(c.Do("ltrim_back", key, 2)); err != nil {
+		t.Fatal(err)
+	} else if n != 2 {
+		t.Fatal(n)
+	}
+
+	if n, err := goredis.Int(c.Do("llen", key)); err != nil {
+		t.Fatal(err)
+	} else if n != 2 {
+		t.Fatal(n)
+	}
+
+	if n, err := goredis.Int(c.Do("ltrim_front", key, 5)); err != nil {
+		t.Fatal(err)
+	} else if n != 2 {
+		t.Fatal(n)
+	}
+
+	if n, err := goredis.Int(c.Do("llen", key)); err != nil {
+		t.Fatal(err)
+	} else if n != 0 {
+		t.Fatal(n)
+	}
+
+	if n, err := goredis.Int(c.Do("rpush", key, 1, 2)); err != nil {
+		t.Fatal(err)
+	} else if n != 2 {
+		t.Fatal(n)
+	}
+
+	if n, err := goredis.Int(c.Do("ltrim_front", key, 2)); err != nil {
+		t.Fatal(err)
+	} else if n != 2 {
+		t.Fatal(n)
+	}
+
+	if n, err := goredis.Int(c.Do("llen", key)); err != nil {
+		t.Fatal(err)
+	} else if n != 0 {
+		t.Fatal(n)
+	}
+}
+
 func TestListErrorParams(t *testing.T) {
 	c := getTestConn()
 	defer c.Close()
@@ -353,4 +419,11 @@ func TestListErrorParams(t *testing.T) {
 		t.Fatal("invalid err of %v", err)
 	}
 
+	if _, err := c.Do("ltrim_front", "test_ltrimfront", "-1"); err == nil {
+		t.Fatal("invalid err of %v", err)
+	}
+
+	if _, err := c.Do("ltrim_back", "test_ltrimback", "a"); err == nil {
+		t.Fatal("invalid err of %v", err)
+	}
 }