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pool.go
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pool.go
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package leveledbytebufferpool
import (
"math/bits"
"sync"
"github.com/VictoriaMetrics/VictoriaMetrics/lib/bytesutil"
)
// pools contains pools for byte slices of various capacities.
//
// pools[0] is for capacities from 0 to 8
// pools[1] is for capacities from 9 to 16
// pools[2] is for capacities from 17 to 32
// ...
// pools[n] is for capacities from 2^(n+2)+1 to 2^(n+3)
//
// Limit the maximum capacity to 2^18, since there are no performance benefits
// in caching byte slices with bigger capacities.
var pools [17]sync.Pool
// Get returns byte buffer with the given capacity.
func Get(capacity int) *bytesutil.ByteBuffer {
id, capacityNeeded := getPoolIDAndCapacity(capacity)
for i := 0; i < 2; i++ {
if id < 0 || id >= len(pools) {
break
}
if v := pools[id].Get(); v != nil {
return v.(*bytesutil.ByteBuffer)
}
id++
}
return &bytesutil.ByteBuffer{
B: make([]byte, 0, capacityNeeded),
}
}
// Put returns bb to the pool.
func Put(bb *bytesutil.ByteBuffer) {
capacity := cap(bb.B)
id, poolCapacity := getPoolIDAndCapacity(capacity)
if capacity <= poolCapacity {
bb.Reset()
pools[id].Put(bb)
}
}
func getPoolIDAndCapacity(size int) (int, int) {
size--
if size < 0 {
size = 0
}
size >>= 3
id := bits.Len(uint(size))
if id >= len(pools) {
id = len(pools) - 1
}
return id, (1 << (id + 3))
}