/
iterator.go
64 lines (58 loc) · 1.74 KB
/
iterator.go
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// Copyright 2019 sch00lb0y.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// See the License for the specific language governing permissions and
// limitations under the License.
package aran
import (
"encoding/binary"
"os"
"github.com/sirupsen/logrus"
)
// simple forward iterator
type iterator struct {
currentOffset int
metaOffset int
fp *os.File
}
func newIterator(fp *os.File, metaOffset int) *iterator {
fp.Seek(0, 0)
return &iterator{currentOffset: 0, metaOffset: metaOffset, fp: fp}
}
func (t *iterator) has() bool {
has := t.currentOffset != t.metaOffset
if has == false {
t.fp.Close()
}
return has
}
// kl, vl, key, val
func (t *iterator) next() ([]byte, []byte, []byte, []byte) {
buf := make([]byte, 8)
n, err := t.fp.Read(buf)
if err != nil {
logrus.Fatalf("iterator: failed during reading key and value length %s", err.Error())
}
if n != 8 {
logrus.Fatalf("iterator: failed to read key and value length expected 8 but got %d", n)
}
kl := binary.BigEndian.Uint32(buf[0:4])
vl := binary.BigEndian.Uint32(buf[4:8])
bufval := make([]byte, kl+vl)
n, err = t.fp.Read(bufval)
if err != nil {
logrus.Fatalf("iterator: failed during reading key and value %s", err.Error())
}
if n != int(kl+vl) {
logrus.Fatalf("iterator: failed to read key and value expected %d but got %d", kl+vl, n)
}
t.currentOffset += 8 + int(kl) + int(vl)
return buf[0:4], buf[4:8], bufval[0:kl], bufval[kl : kl+vl]
}