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limiter.go
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limiter.go
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package kit
import (
"context"
"crypto/tls"
"fmt"
"runtime"
"time"
"github.com/go-redis/redis/v8"
"github.com/neoxelox/errors"
"github.com/neoxelox/kit/util"
)
const (
_LIMITER_REDIS_DSN = "%s:%d"
)
var (
KeyLimiter Key = KeyBase + "limiter:"
)
var (
ErrLimiterGeneric = errors.New("limiter failed")
ErrLimiterTimedOut = errors.New("limiter timed out")
)
var (
_LIMITER_DEFAULT_CONFIG = LimiterConfig{
CacheMinConns: util.Pointer(1),
CacheMaxConns: util.Pointer(max(8, 4*runtime.GOMAXPROCS(-1))),
CacheMaxConnIdleTime: util.Pointer(30 * time.Minute),
CacheMaxConnLifeTime: util.Pointer(1 * time.Hour),
CacheReadTimeout: util.Pointer(30 * time.Second),
CacheWriteTimeout: util.Pointer(30 * time.Second),
CacheDialTimeout: util.Pointer(30 * time.Second),
}
)
type LimiterConfig struct {
CacheHost string
CachePort int
CacheSSLMode bool
CachePassword string
CacheMinConns *int
CacheMaxConns *int
CacheMaxConnIdleTime *time.Duration
CacheMaxConnLifeTime *time.Duration
CacheReadTimeout *time.Duration
CacheWriteTimeout *time.Duration
CacheDialTimeout *time.Duration
}
type Limiter struct {
config LimiterConfig
observer *Observer
client *redis.Client
}
func NewLimiter(observer *Observer, config LimiterConfig) *Limiter {
util.Merge(&config, _LIMITER_DEFAULT_CONFIG)
redis.SetLogger(_newRedisLogger(observer))
dsn := fmt.Sprintf(_LIMITER_REDIS_DSN, config.CacheHost, config.CachePort)
var ssl *tls.Config
if config.CacheSSLMode {
ssl = &tls.Config{
MinVersion: tls.VersionTLS12,
}
}
redisConfig := &redis.Options{
Addr: dsn,
TLSConfig: ssl,
Password: config.CachePassword,
MinIdleConns: *config.CacheMinConns,
PoolSize: *config.CacheMaxConns,
IdleTimeout: *config.CacheMaxConnIdleTime,
MaxConnAge: *config.CacheMaxConnLifeTime,
ReadTimeout: *config.CacheReadTimeout,
WriteTimeout: *config.CacheWriteTimeout,
DialTimeout: *config.CacheDialTimeout,
PoolTimeout: *config.CacheDialTimeout,
}
return &Limiter{
config: config,
observer: observer,
client: redis.NewClient(redisConfig),
}
}
func (self *Limiter) Limit(ctx context.Context, key string, limit int, period time.Duration) (int, error) {
key = string(KeyLimiter) + key
pipeline := self.client.TxPipeline()
increment := pipeline.Incr(ctx, key)
pipeline.Expire(ctx, key, period)
_, err := pipeline.Exec(ctx)
if err != nil {
return -1, ErrLimiterGeneric.Raise().Cause(err)
}
rate, err := increment.Result()
if err != nil {
return -1, ErrLimiterGeneric.Raise().Cause(err)
}
if rate > int64(limit) {
return -1, nil
}
return int(int64(limit) - rate), nil
}
func (self *Limiter) Close(ctx context.Context) error {
err := util.Deadline(ctx, func(exceeded <-chan struct{}) error {
self.observer.Info(ctx, "Closing limiter")
err := self.client.Close()
if err != nil {
return ErrLimiterGeneric.Raise().Cause(err)
}
self.observer.Info(ctx, "Closed limiter")
return nil
})
if err != nil {
if util.ErrDeadlineExceeded.Is(err) {
return ErrLimiterTimedOut.Raise().Cause(err)
}
return err
}
return nil
}