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redislock.go
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/
redislock.go
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package redislock
import (
"encoding/base64"
"errors"
"github.com/go-redis/redis"
"math/rand"
"sync"
"time"
)
const (
DefaultRetry = 5
DefaultInterval = 100 * time.Millisecond
DefaultExpire = 5 * time.Second
DefaultExpireUnsame = 600 * time.Second
)
var ErrFailed = errors.New("failed to acquire lock")
type RedisLock struct {
Expiry time.Duration
Retry int
RetryInterval time.Duration
lockKey string
lockValue string
sameLock bool
mutex sync.Mutex
}
func NewRedisLock(lk string, sameLock bool) *RedisLock {
if sameLock {
return &RedisLock{lockKey: lk, Expiry: DefaultExpire, Retry: DefaultRetry, RetryInterval: DefaultInterval}
} else {
return &RedisLock{lockKey: lk, Expiry: DefaultExpireUnsame, Retry: 1, RetryInterval: 0}
}
}
func NewRedisLockWithParam(lk string, expire time.Duration, retry int, interval time.Duration, sameLock bool) *RedisLock {
return &RedisLock{lockKey: lk, Expiry: expire, Retry: retry, RetryInterval: interval}
}
func (rl *RedisLock) Lock(rds *redis.Client) error {
if rl.sameLock {
rl.mutex.Lock()
err := rl.lock(rds)
if err != nil {
rl.mutex.Unlock()
}
return err
} else {
err := rl.lock(rds)
return err
}
}
func (rl *RedisLock) lock(rds *redis.Client) error {
if rl.sameLock {
b := make([]byte, 16)
_, err := rand.Read(b)
if err != nil {
return err
}
rl.lockValue = base64.StdEncoding.EncodeToString(b)
} else {
rl.lockValue = ""
}
for i := 0; i < rl.Retry; i++ {
ok, err := rds.SetNX(rl.lockKey, rl.lockValue, rl.Expiry).Result()
if err != nil {
return err
}
if ok {
return nil
}
if i < rl.Retry-1 {
time.Sleep(rl.RetryInterval)
}
}
return ErrFailed
}
const delScript = `
if redis.call("get", KEYS[1]) == ARGV[1] then
return redis.call("del", KEYS[1])
else
return 0
end`
func (rl *RedisLock) UnLock(rds *redis.Client) error {
if rl.sameLock {
_, err := rds.Eval(delScript, []string{rl.lockKey}, rl.lockValue).Result()
rl.mutex.Unlock()
return err
} else {
_, err := rds.Del(rl.lockKey).Result()
return err
}
}