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string.go
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/
string.go
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package main
import (
"encoding/binary"
"github.com/jmhodges/levigo"
)
// Keys stored in LevelDB for strings
//
// MetadataKey | key = StringLengthValue | string length uint32
//
// For each key:
// StringKey | key = value
func Set(args [][]byte, wb *levigo.WriteBatch) interface{} {
err := set(args[0], args[1], wb)
if err != nil {
return err
}
return ReplyOK
}
func Get(args [][]byte, wb *levigo.WriteBatch) interface{} {
res, err := DB.Get(DefaultReadOptions, stringKey(args[0]))
if err != nil {
return err
}
return res
}
func DelString(key []byte, wb *levigo.WriteBatch) {
wb.Delete(stringKey(key))
}
func setStringLen(key []byte, length int, wb *levigo.WriteBatch) {
meta := make([]byte, 5)
meta[0] = StringLengthValue
binary.BigEndian.PutUint32(meta[1:], uint32(length))
wb.Put(key, meta)
}
func stringKey(k []byte) []byte {
key := make([]byte, 5+len(k))
key[0] = StringKey
binary.BigEndian.PutUint32(key[1:], uint32(len(k)))
copy(key[5:], k)
return key
}
func set(k []byte, v []byte, wb *levigo.WriteBatch) error {
mk := metaKey(k)
res, err := DB.Get(DefaultReadOptions, mk)
if err != nil {
return err
}
// If there is a non-string key here, let's delete it first
if len(res) > 0 && res[0] != StringLengthValue {
del(k, res[0], wb)
}
setStringLen(mk, len(v), wb)
wb.Put(stringKey(k), v)
return nil
}
// APPEND
func Append(args [][]byte, wb *levigo.WriteBatch) interface{} {
k := args[0]
appendVal := args[1]
res, err := DB.Get(DefaultReadOptions, stringKey(k))
if err != nil {
return err
}
concat := append(res, appendVal...)
err = set(k, concat, wb)
if err != nil {
return err
}
return len(concat)
}
// BITCOUNT
// BITOP
// DECR
// DECRBY
// GETBIT
// GETRANGE
// GETSET
// INCR
// INCRBY
// INCRBYFLOAT
// MGET
// MSET
// MSETNX
// PSETEX
// SETBIT
// SETEX
// SETNX
// SETRANGE
// STRLEN