howood/imagereductor

package caches

import (
    "context"
    "fmt"
    "time"

    log "github.com/howood/imagereductor/infrastructure/logger"
    "github.com/patrickmn/go-cache"
)

const (
    // NumInstance is number of instance
    NumInstance = 5
    // PurgeExpiredTime is time to purge cache
    PurgeExpiredTime = 10
)

var gocacheConnectionMap map[int]*cache.Cache

func init() {
    gocacheConnectionMap = make(map[int]*cache.Cache, 0)
    for i := 0; i < NumInstance; i++ {
        gocacheConnectionMap[i] = cache.New(60*time.Minute, PurgeExpiredTime*time.Minute)
    }
}

// GoCacheClient struct
type GoCacheClient struct {
    ctx context.Context
}

// NewGoCacheClient creates a new GoCacheClient
func NewGoCacheClient(ctx context.Context) *GoCacheClient {
    ret := &GoCacheClient{ctx: ctx}
    return ret
}

// Get gets from cache
func (cc *GoCacheClient) Get(key string) (interface{}, bool) {
    return cc.getInstance(key).Get(key)
}

// Set puts to cache
func (cc *GoCacheClient) Set(key string, value interface{}, ttl time.Duration) error {
    cc.getInstance(key).Set(key, value, ttl)
    return nil
}

// Del deletes from cache
func (cc *GoCacheClient) Del(key string) error {
    cc.getInstance(key).Delete(key)
    return nil
}

// DelBulk bulk deletes from cache
func (cc *GoCacheClient) DelBulk(key string) error {
    cc.getInstance(key).Delete(key)
    return nil
}

// CloseConnect close connection
func (cc *GoCacheClient) CloseConnect() error {
    return nil
}

func (cc *GoCacheClient) getInstance(key string) *cache.Cache {
    // djb2 algorithm
    i, hash := 0, uint32(5381)
    for _, c := range key {
        hash = ((hash << 5) + hash) + uint32(c)
    }
    i = int(hash) % NumInstance
    log.Info(cc.ctx, fmt.Sprintf("get_instance: %d", i))
    return gocacheConnectionMap[i]
}