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package buffer
import (
"bytes"
"encoding/binary"
"encoding/gob"
"io/ioutil"
"os"
"sync"
)
// PoolAt provides a way to Allocate and Release BufferAt objects
// PoolAt's mut be concurrent-safe for calls to Get() and Put().
type PoolAt interface {
Get() (BufferAt, error) // Allocate a BufferAt
Put(buf BufferAt) error // Release or Reuse a BufferAt
}
type poolAt struct {
poolAt sync.Pool
}
// NewPoolAt returns a PoolAt(), it's backed by a sync.Pool so its safe for concurrent use.
// Get() and Put() errors will always be nil.
// It will not work with gob.
func NewPoolAt(New func() BufferAt) PoolAt {
return &poolAt{
poolAt: sync.Pool{
New: func() interface{} {
return New()
},
},
}
}
func (p *poolAt) Get() (BufferAt, error) {
return p.poolAt.Get().(BufferAt), nil
}
func (p *poolAt) Put(buf BufferAt) error {
buf.Reset()
p.poolAt.Put(buf)
return nil
}
type memPoolAt struct {
N int64
PoolAt
}
// NewMemPoolAt returns a PoolAt, Get() returns an in memory buffer of max size N.
// Put() returns the buffer to the pool after resetting it.
// Get() and Put() errors will always be nil.
func NewMemPoolAt(N int64) PoolAt {
return &memPoolAt{
N: N,
PoolAt: NewPoolAt(func() BufferAt {
return New(N)
}),
}
}
func (m *memPoolAt) MarshalBinary() ([]byte, error) {
buf := bytes.NewBuffer(nil)
err := binary.Write(buf, binary.LittleEndian, m.N)
return buf.Bytes(), err
}
func (m *memPoolAt) UnmarshalBinary(data []byte) error {
buf := bytes.NewReader(data)
err := binary.Read(buf, binary.LittleEndian, &m.N)
m.PoolAt = NewPoolAt(func() BufferAt {
return New(m.N)
})
return err
}
type filePoolAt struct {
N int64
Directory string
}
// NewFilePoolAt returns a PoolAt, Get() returns a file-based buffer of max size N.
// Put() closes and deletes the underlying file for the buffer.
// Get() may return an error if it fails to create a file for the buffer.
// Put() may return an error if it fails to delete the file.
func NewFilePoolAt(N int64, dir string) PoolAt {
return &filePoolAt{N: N, Directory: dir}
}
func (p *filePoolAt) Get() (BufferAt, error) {
file, err := ioutil.TempFile(p.Directory, "buffer")
if err != nil {
return nil, err
}
return NewFile(p.N, file), nil
}
func (p *filePoolAt) Put(buf BufferAt) (err error) {
buf.Reset()
if fileBuf, ok := buf.(*fileBuffer); ok {
fileBuf.file.Close()
err = os.Remove(fileBuf.file.Name())
}
return err
}
func init() {
gob.Register(&memPoolAt{})
gob.Register(&filePoolAt{})
}
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