mirror of
https://codeberg.org/forgejo/forgejo.git
synced 2024-09-06 03:45:20 +02:00
215 lines
4.2 KiB
Go
215 lines
4.2 KiB
Go
|
// Copyright 2019 Lunny Xiao. All rights reserved.
|
||
|
// Use of this source code is governed by a MIT-style
|
||
|
// license that can be found in the LICENSE file.
|
||
|
|
||
|
package levelqueue
|
||
|
|
||
|
import (
|
||
|
"bytes"
|
||
|
"encoding/binary"
|
||
|
"sync"
|
||
|
|
||
|
"github.com/syndtr/goleveldb/leveldb"
|
||
|
)
|
||
|
|
||
|
// Queue defines a queue struct
|
||
|
type Queue struct {
|
||
|
db *leveldb.DB
|
||
|
highLock sync.Mutex
|
||
|
lowLock sync.Mutex
|
||
|
low int64
|
||
|
high int64
|
||
|
}
|
||
|
|
||
|
// Open opens a queue object or create it if not exist
|
||
|
func Open(dataDir string) (*Queue, error) {
|
||
|
db, err := leveldb.OpenFile(dataDir, nil)
|
||
|
if err != nil {
|
||
|
return nil, err
|
||
|
}
|
||
|
|
||
|
var queue = &Queue{
|
||
|
db: db,
|
||
|
}
|
||
|
queue.low, err = queue.readID(lowKey)
|
||
|
if err == leveldb.ErrNotFound {
|
||
|
queue.low = 1
|
||
|
err = db.Put(lowKey, id2bytes(1), nil)
|
||
|
}
|
||
|
if err != nil {
|
||
|
return nil, err
|
||
|
}
|
||
|
|
||
|
queue.high, err = queue.readID(highKey)
|
||
|
if err == leveldb.ErrNotFound {
|
||
|
err = db.Put(highKey, id2bytes(0), nil)
|
||
|
}
|
||
|
if err != nil {
|
||
|
return nil, err
|
||
|
}
|
||
|
|
||
|
return queue, nil
|
||
|
}
|
||
|
|
||
|
func (queue *Queue) readID(key []byte) (int64, error) {
|
||
|
bs, err := queue.db.Get(key, nil)
|
||
|
if err != nil {
|
||
|
return 0, err
|
||
|
}
|
||
|
return bytes2id(bs)
|
||
|
}
|
||
|
|
||
|
var (
|
||
|
lowKey = []byte("low")
|
||
|
highKey = []byte("high")
|
||
|
)
|
||
|
|
||
|
func (queue *Queue) highincrement() (int64, error) {
|
||
|
id := queue.high + 1
|
||
|
queue.high = id
|
||
|
err := queue.db.Put(highKey, id2bytes(queue.high), nil)
|
||
|
if err != nil {
|
||
|
queue.high = queue.high - 1
|
||
|
return 0, err
|
||
|
}
|
||
|
return id, nil
|
||
|
}
|
||
|
|
||
|
func (queue *Queue) highdecrement() (int64, error) {
|
||
|
queue.high = queue.high - 1
|
||
|
err := queue.db.Put(highKey, id2bytes(queue.high), nil)
|
||
|
if err != nil {
|
||
|
queue.high = queue.high + 1
|
||
|
return 0, err
|
||
|
}
|
||
|
return queue.high, nil
|
||
|
}
|
||
|
|
||
|
func (queue *Queue) lowincrement() (int64, error) {
|
||
|
queue.low = queue.low + 1
|
||
|
err := queue.db.Put(lowKey, id2bytes(queue.low), nil)
|
||
|
if err != nil {
|
||
|
queue.low = queue.low - 1
|
||
|
return 0, err
|
||
|
}
|
||
|
return queue.low, nil
|
||
|
}
|
||
|
|
||
|
func (queue *Queue) lowdecrement() (int64, error) {
|
||
|
queue.low = queue.low - 1
|
||
|
err := queue.db.Put(lowKey, id2bytes(queue.low), nil)
|
||
|
if err != nil {
|
||
|
queue.low = queue.low + 1
|
||
|
return 0, err
|
||
|
}
|
||
|
return queue.low, nil
|
||
|
}
|
||
|
|
||
|
// Len returns the length of the queue
|
||
|
func (queue *Queue) Len() int64 {
|
||
|
queue.lowLock.Lock()
|
||
|
queue.highLock.Lock()
|
||
|
l := queue.high - queue.low + 1
|
||
|
queue.highLock.Unlock()
|
||
|
queue.lowLock.Unlock()
|
||
|
return l
|
||
|
}
|
||
|
|
||
|
func id2bytes(id int64) []byte {
|
||
|
var buf = make([]byte, 8)
|
||
|
binary.PutVarint(buf, id)
|
||
|
return buf
|
||
|
}
|
||
|
|
||
|
func bytes2id(b []byte) (int64, error) {
|
||
|
return binary.ReadVarint(bytes.NewReader(b))
|
||
|
}
|
||
|
|
||
|
// RPush pushes a data from right of queue
|
||
|
func (queue *Queue) RPush(data []byte) error {
|
||
|
queue.highLock.Lock()
|
||
|
id, err := queue.highincrement()
|
||
|
if err != nil {
|
||
|
queue.highLock.Unlock()
|
||
|
return err
|
||
|
}
|
||
|
err = queue.db.Put(id2bytes(id), data, nil)
|
||
|
queue.highLock.Unlock()
|
||
|
return err
|
||
|
}
|
||
|
|
||
|
// LPush pushes a data from left of queue
|
||
|
func (queue *Queue) LPush(data []byte) error {
|
||
|
queue.highLock.Lock()
|
||
|
id, err := queue.lowdecrement()
|
||
|
if err != nil {
|
||
|
queue.highLock.Unlock()
|
||
|
return err
|
||
|
}
|
||
|
err = queue.db.Put(id2bytes(id), data, nil)
|
||
|
queue.highLock.Unlock()
|
||
|
return err
|
||
|
}
|
||
|
|
||
|
// RPop pop a data from right of queue
|
||
|
func (queue *Queue) RPop() ([]byte, error) {
|
||
|
queue.highLock.Lock()
|
||
|
currentID := queue.high
|
||
|
|
||
|
res, err := queue.db.Get(id2bytes(currentID), nil)
|
||
|
if err != nil {
|
||
|
queue.highLock.Unlock()
|
||
|
if err == leveldb.ErrNotFound {
|
||
|
return nil, ErrNotFound
|
||
|
}
|
||
|
return nil, err
|
||
|
}
|
||
|
|
||
|
_, err = queue.highdecrement()
|
||
|
if err != nil {
|
||
|
queue.highLock.Unlock()
|
||
|
return nil, err
|
||
|
}
|
||
|
|
||
|
err = queue.db.Delete(id2bytes(currentID), nil)
|
||
|
queue.highLock.Unlock()
|
||
|
if err != nil {
|
||
|
return nil, err
|
||
|
}
|
||
|
return res, nil
|
||
|
}
|
||
|
|
||
|
// LPop pop a data from left of queue
|
||
|
func (queue *Queue) LPop() ([]byte, error) {
|
||
|
queue.lowLock.Lock()
|
||
|
currentID := queue.low
|
||
|
|
||
|
res, err := queue.db.Get(id2bytes(currentID), nil)
|
||
|
if err != nil {
|
||
|
queue.lowLock.Unlock()
|
||
|
if err == leveldb.ErrNotFound {
|
||
|
return nil, ErrNotFound
|
||
|
}
|
||
|
return nil, err
|
||
|
}
|
||
|
|
||
|
_, err = queue.lowincrement()
|
||
|
if err != nil {
|
||
|
return nil, err
|
||
|
}
|
||
|
|
||
|
err = queue.db.Delete(id2bytes(currentID), nil)
|
||
|
queue.lowLock.Unlock()
|
||
|
if err != nil {
|
||
|
return nil, err
|
||
|
}
|
||
|
return res, nil
|
||
|
}
|
||
|
|
||
|
// Close closes the queue
|
||
|
func (queue *Queue) Close() error {
|
||
|
err := queue.db.Close()
|
||
|
queue.db = nil
|
||
|
return err
|
||
|
}
|