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restic/vendor/github.com/kurin/blazer/b2/buffer.go
2017-07-23 14:25:38 +02:00

128 lines
2.8 KiB
Go

// Copyright 2017, Google
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package b2
import (
"bytes"
"crypto/sha1"
"fmt"
"hash"
"io"
"io/ioutil"
"os"
"sync"
)
type writeBuffer interface {
io.Writer
Len() int
Reader() (io.ReadSeeker, error)
Hash() string // sha1 or whatever it is
Close() error
}
type memoryBuffer struct {
buf *bytes.Buffer
hsh hash.Hash
w io.Writer
mux sync.Mutex
}
var bufpool *sync.Pool
func init() {
bufpool = &sync.Pool{}
bufpool.New = func() interface{} { return &bytes.Buffer{} }
}
func newMemoryBuffer() *memoryBuffer {
mb := &memoryBuffer{
hsh: sha1.New(),
}
mb.buf = bufpool.Get().(*bytes.Buffer)
mb.w = io.MultiWriter(mb.hsh, mb.buf)
return mb
}
type thing struct {
rs io.ReadSeeker
t int
}
func (mb *memoryBuffer) Write(p []byte) (int, error) { return mb.w.Write(p) }
func (mb *memoryBuffer) Len() int { return mb.buf.Len() }
func (mb *memoryBuffer) Reader() (io.ReadSeeker, error) { return bytes.NewReader(mb.buf.Bytes()), nil }
func (mb *memoryBuffer) Hash() string { return fmt.Sprintf("%x", mb.hsh.Sum(nil)) }
func (mb *memoryBuffer) Close() error {
mb.mux.Lock()
defer mb.mux.Unlock()
if mb.buf == nil {
return nil
}
mb.buf.Truncate(0)
bufpool.Put(mb.buf)
mb.buf = nil
return nil
}
type fileBuffer struct {
f *os.File
hsh hash.Hash
w io.Writer
s int
}
func newFileBuffer(loc string) (*fileBuffer, error) {
f, err := ioutil.TempFile(loc, "blazer")
if err != nil {
return nil, err
}
fb := &fileBuffer{
f: f,
hsh: sha1.New(),
}
fb.w = io.MultiWriter(fb.f, fb.hsh)
return fb, nil
}
func (fb *fileBuffer) Write(p []byte) (int, error) {
n, err := fb.w.Write(p)
fb.s += n
return n, err
}
func (fb *fileBuffer) Len() int { return fb.s }
func (fb *fileBuffer) Hash() string { return fmt.Sprintf("%x", fb.hsh.Sum(nil)) }
func (fb *fileBuffer) Reader() (io.ReadSeeker, error) {
if _, err := fb.f.Seek(0, 0); err != nil {
return nil, err
}
return &fr{f: fb.f}, nil
}
func (fb *fileBuffer) Close() error {
fb.f.Close()
return os.Remove(fb.f.Name())
}
// wraps *os.File so that the http package doesn't see it as an io.Closer
type fr struct {
f *os.File
}
func (r *fr) Read(p []byte) (int, error) { return r.f.Read(p) }
func (r *fr) Seek(a int64, b int) (int64, error) { return r.f.Seek(a, b) }