rotator

README

Rotator (Rotation)

Supporting bitmaps

• In-Memory
• Redis

Rotator Mode

• default: perform rotation by RotatorConfig.Freq. It's effective with all bitmaps.
  • if rotation is performed when 2022-01-02T03:04:05 and Freq is 3h, the next rotation will be 2022-01-02T06:04:05.
• truncated-time: perform rotation by truncated time and RotatorConfig.Freq. It's only effective with bitmap.Redis.
• Refer following Explanation for more information.

Explanation

• Assume we have config.FactoryConfig as following:

package main

import (
	"github.com/x0rworld/go-bloomfilter/config"
)

var cfg = config.FactoryConfig{
	FilterConfig: config.FilterConfig{
		BitmapConfig: config.BitmapConfig{Type: config.BitmapTypeRedis},
		M:            100,
		K:            2,
	},
	RedisConfig: config.RedisConfig{
		Addr:    "elasticache.us-west-2.amazonaws.com:6379",
		Timeout: 5 * time.Second,
		Key:     "bloomfilter",
	},
	RotatorConfig: config.RotatorConfig{
		Enable: true,
		Freq:   "3h",
		Mode:   config.RotatorModeTruncatedTime,
	},
}

• The current time is 2022-09-06 08:24:31.35128. (timestamp by nano is 1662452671351280000)

Then, the Redis key for bitmap will be generated and manipulated as following:

Mode	Redis Key [1]	Next Rotation will be at
default	bloomfilter_1662452671351280000	2022-09-06 11:24:31
truncated-time	bloomfilter_1662444000000000000 [2]	2022-09-06 09:00:00

• [1]: bitmap.Redis manipulates bitmap based on Redis Key.
• [2]: 1662444000000000000 is timestamp by nano, which is at 2022-09-06 06:00:00.

Note

Ideally, we assume all machines can produce the closed system time, so go-bloomfilter adopts system time for synchronization with truncated-time. However, it's not robust because we can't guarantee for the consistency of system time and this package doesn't provide the synchronization for the time yet.

Unless you handle the consistency problem with system time, please consider suitability of your project before you adopt truncated-time way if you'd like to rely on system time for synchronization.

Documentation

Overview

Package rotator is used to rotate filter by period.

Index

• type NewFilterFunc
• type Rotator
  • func NewRotator(ctx context.Context, cfg config.RotatorConfig, newFilter NewFilterFunc) (*Rotator, error)
  • func (r *Rotator) Add(data string) error
  • func (r *Rotator) Exist(data string) (bool, error)

Types

type NewFilterFunc

type NewFilterFunc func(ctx context.Context) (filter.Filter, error)

NewFilterFunc returns filter that will be performed by Rotator in handleRotating. It's the same signature with factory.FilterFactory.NewFilter.

type Rotator

type Rotator struct {
	// contains filtered or unexported fields
}

func NewRotator

func NewRotator(ctx context.Context, cfg config.RotatorConfig, newFilter NewFilterFunc) (*Rotator, error)

NewRotator returns *Rotator that rotates filter by period, all rotating filters will be generated by newFilter.

func (*Rotator) Add

func (r *Rotator) Add(data string) error

func (*Rotator) Exist

func (r *Rotator) Exist(data string) (bool, error)