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package buffer
import (
"bytes"
"encoding/binary"
"encoding/gob"
"io/ioutil"
"os"
"sync"
)
// Pool provides a way to Allocate and Release Buffer objects
// Pools mut be concurrent-safe for calls to Get() and Put().
type Pool interface {
Get() (Buffer, error) // Allocate a Buffer
Put(buf Buffer) error // Release or Reuse a Buffer
}
type pool struct {
pool sync.Pool
}
// NewPool returns a Pool(), 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 NewPool(New func() Buffer) Pool {
return &pool{
pool: sync.Pool{
New: func() interface{} {
return New()
},
},
}
}
func (p *pool) Get() (Buffer, error) {
return p.pool.Get().(Buffer), nil
}
func (p *pool) Put(buf Buffer) error {
buf.Reset()
p.pool.Put(buf)
return nil
}
type memPool struct {
N int64
Pool
}
// NewMemPool returns a Pool, 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 NewMemPool(N int64) Pool {
return &memPool{
N: N,
Pool: NewPool(func() Buffer {
return New(N)
}),
}
}
func (m *memPool) MarshalBinary() ([]byte, error) {
buf := bytes.NewBuffer(nil)
err := binary.Write(buf, binary.LittleEndian, m.N)
return buf.Bytes(), err
}
func (m *memPool) UnmarshalBinary(data []byte) error {
buf := bytes.NewReader(data)
err := binary.Read(buf, binary.LittleEndian, &m.N)
m.Pool = NewPool(func() Buffer {
return New(m.N)
})
return err
}
type filePool struct {
N int64
Directory string
}
// NewFilePool returns a Pool, 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 NewFilePool(N int64, dir string) Pool {
return &filePool{N: N, Directory: dir}
}
func (p *filePool) Get() (Buffer, error) {
file, err := ioutil.TempFile(p.Directory, "buffer")
if err != nil {
return nil, err
}
return NewFile(p.N, file), nil
}
func (p *filePool) Put(buf Buffer) (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(&memPool{})
gob.Register(&filePool{})
}
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