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97 lines
2.0 KiB
Go
97 lines
2.0 KiB
Go
package redis
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import (
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"math/rand"
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"strconv"
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"sync/atomic"
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"time"
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red "github.com/go-redis/redis"
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"github.com/tal-tech/go-zero/core/logx"
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)
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const (
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letters = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
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lockCommand = `if redis.call("GET", KEYS[1]) == ARGV[1] then
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redis.call("SET", KEYS[1], ARGV[1], "PX", ARGV[2])
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return "OK"
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else
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return redis.call("SET", KEYS[1], ARGV[1], "NX", "PX", ARGV[2])
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end`
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delCommand = `if redis.call("GET", KEYS[1]) == ARGV[1] then
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return redis.call("DEL", KEYS[1])
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else
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return 0
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end`
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randomLen = 16
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tolerance = 500 // milliseconds
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millisPerSecond = 1000
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)
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type RedisLock struct {
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store *Redis
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seconds uint32
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key string
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id string
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}
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func init() {
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rand.Seed(time.Now().UnixNano())
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}
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func NewRedisLock(store *Redis, key string) *RedisLock {
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return &RedisLock{
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store: store,
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key: key,
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id: randomStr(randomLen),
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}
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}
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func (rl *RedisLock) Acquire() (bool, error) {
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seconds := atomic.LoadUint32(&rl.seconds)
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resp, err := rl.store.Eval(lockCommand, []string{rl.key}, []string{
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rl.id, strconv.Itoa(int(seconds)*millisPerSecond + tolerance)})
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if err == red.Nil {
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return false, nil
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} else if err != nil {
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logx.Errorf("Error on acquiring lock for %s, %s", rl.key, err.Error())
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return false, err
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} else if resp == nil {
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return false, nil
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}
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reply, ok := resp.(string)
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if ok && reply == "OK" {
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return true, nil
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}
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logx.Errorf("Unknown reply when acquiring lock for %s: %v", rl.key, resp)
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return false, nil
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}
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func (rl *RedisLock) Release() (bool, error) {
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resp, err := rl.store.Eval(delCommand, []string{rl.key}, []string{rl.id})
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if err != nil {
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return false, err
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}
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reply, ok := resp.(int64)
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if !ok {
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return false, nil
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}
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return reply == 1, nil
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}
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func (rl *RedisLock) SetExpire(seconds int) {
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atomic.StoreUint32(&rl.seconds, uint32(seconds))
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}
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func randomStr(n int) string {
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b := make([]byte, n)
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for i := range b {
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b[i] = letters[rand.Intn(len(letters))]
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}
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return string(b)
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}
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