package dbg

import (
	"container/list"
	"errors"
	"sync"
)

type Queue struct {
	list     list.List
	mutex    sync.Mutex
	maxCount int
}

func NewQueue(maxSize int) *Queue {
	resp := new(Queue)
	resp.maxCount = maxSize
	return resp
}

func (me *Queue) PutNoWait(d interface{}) error {
	me.mutex.Lock()
	defer me.mutex.Unlock()
	if me.list.Len() >= me.maxCount {
		return errors.New("queue full")
	}
	me.list.PushBack(d)
	return nil
}

func (me *Queue) GetNoWait() (interface{}, error) {
	me.mutex.Lock()
	defer me.mutex.Unlock()
	if me.list.Len() == 0 {
		return nil, errors.New("not data")
	}
	e := me.list.Front()
	me.list.Remove(e)
	return e.Value, nil
}

func (me *Queue) Size() int {
	me.mutex.Lock()
	defer me.mutex.Unlock()
	return me.list.Len()
}