Keep AcquireBytes consistent

[wenxuwan]

What would you like to be added:

When the current AcquireBytes function misses a byte slice in the pool, it will return a byte slice with a length of 0 and a cap of size, and when it hits, it will return a slice with both length and cap of size. I think consistency is more user friendly

Why is this needed:

When the current AcquireBytes function misses a byte slice in the pool, it will return a byte slice with a length of 0 and a cap of size, and when it hits, it will return a slice with both length and cap of size. I think consistency is more user friendly

[tiltwind]

@AlexStocks keep consistency is important, but I think should change the size of slice to 0 when hits in pool. Because the user can use it directly without to resize it .

s := AcquireBytes(128)
s = s[:0] // this is wretched
s = append(s , b)