package pool

import "sync"

const _MAX_RECYCLING_CAP = 4 << 10

// BytesSlicePool 定义 []byte 复用池的类型
type BytesSlicePool struct {
	maxRecyclingCap int // 最大回收容量

	pool *sync.Pool // 复用池
}

// NewBytesSlicePool 创建一个 []byte 复用池
func NewBytesSlicePool(sliceCap int, maxRecyclingCap ...int) *BytesSlicePool {
	_maxRecyclingCap := _MAX_RECYCLING_CAP
	if len(maxRecyclingCap) > 0 {
		_maxRecyclingCap = maxRecyclingCap[0]
	}

	return &BytesSlicePool{
		maxRecyclingCap: _maxRecyclingCap,
		pool: &sync.Pool{
			New: func() any {
				buf := make([]byte, 0, sliceCap)
				return &buf
			},
		},
	}
}

// Alloc 分配一个 []byte 对象
func (own *BytesSlicePool) Alloc() []byte {
	obj := own.pool.Get().(*[]byte)
	return *obj
}

// Dealloc 释放当前 []byte 对象
func (own *BytesSlicePool) Dealloc(obj []byte) {
	// 为了减少峰值分配，只向池返回较小的缓冲区
	if cap(obj) <= own.maxRecyclingCap {
		obj = (obj)[:0]
		own.pool.Put(&obj)
	}
}