Sync Map 可能会导致 ram 和 goroutine 的增加

import (
    "context"
    "errors"
    "sync"
    "time"
)

type Collector struct {
    keyValMap *sync.Map
}

func (c *Collector) LoadOrWait(key any) (retValue any, availability int, err error) {
    value, status := c.getStatusAndValue(key)

    switch status {
    case 0:
        return nil, 0, nil
    case 1:
        return value, 1, nil
    case 2:
        ctxWithTimeout, _ := context.WithTimeout(context.Background(), 5 * time.Second)
        for {
            select {
            case <-ctxWithTimeout.Done():
                return nil, 0, errRequestTimeout
            default:
                value, resourceStatus := c.getStatusAndValue(key)
                if resourceStatus == 1 {
                    return value, 1, nil
                }
                time.Sleep(50 * time.Millisecond)
            }
        }
    }

    return nil, 0, errRequestTimeout
}

// Store ...
func (c *Collector) Store(key any, value any) {
    c.keyValMap.Store(key, value)
}

func (c *Collector) getStatusAndValue(key any) (retValue any, availability int) {
    var empty any
    result, loaded := c.keyValMap.LoadOrStore(key, empty)

    if loaded && result != empty {
        return result, 1
    }

    if loaded && result == empty {
        return empty, 2
    }

    return nil, 0
}

ctxWithTimeout, cancelFunc := context.WithTimeout(context.Background(), requestTimeout)
defer cancelFunc()