d3267284b7
This is a first pass at something analogous to swift's diskfile. The API is probably not finalized. There are a few interfaces you have to implement for a new ObjectEngine. There's also a RegisterObjectEngine function to register a new object engine. See go/objectserver/objengine.go for information. I had to rejigger the AtomicFileWriter interface to make them friends, but this way is fine too. Change-Id: I032038b5e8a068aecdf8b29631f60ebf00cfb2ee
73 lines
1.9 KiB
Go
73 lines
1.9 KiB
Go
// Copyright (c) 2015 Rackspace
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
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// implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// +build !linux
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package objectserver
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import (
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"io/ioutil"
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"os"
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"path/filepath"
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)
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// TempFile implements an atomic file write by writing to a temp directory and then renaming into place.
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type TempFile struct {
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*os.File
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saved bool
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}
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// Abandon removes any resources associated with this file, if it hasn't already been saved.
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func (o *TempFile) Abandon() error {
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if o.saved {
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return nil
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}
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os.Remove(o.Name())
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return o.File.Close()
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}
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// Save atomically writes the file to its destination.
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func (o *TempFile) Save(dst string) error {
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defer o.File.Close()
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if err := o.File.Sync(); err != nil {
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return err
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}
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if err := os.MkdirAll(filepath.Dir(dst), 0755); err != nil {
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return err
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}
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if err := os.Rename(o.File.Name(), dst); err != nil {
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return err
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}
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o.saved = true
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return nil
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}
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// Preallocate pre-allocates space for the file.
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func (o *TempFile) Preallocate(size int64, reserve int64) {
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// TODO: this could be done for most non-linux operating systems, but it hasn't been important.
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}
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// NewAtomicFileWriter returns an AtomicFileWriter, which handles atomically writing files.
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func NewAtomicFileWriter(tempDir string, dstDir string) (AtomicFileWriter, error) {
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if err := os.MkdirAll(tempDir, 0770); err != nil {
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return nil, err
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}
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tempFile, err := ioutil.TempFile(tempDir, "")
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if err != nil {
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return nil, err
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}
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return &TempFile{File: tempFile}, nil
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}
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