vfs/meta.go

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/*
* Copyright (c) 2015 Alex Yatskov <alex@foosoft.net>
* Author: Alex Yatskov <alex@foosoft.net>
*
* Permission is hereby granted, free of charge, to any person obtaining a copy of
* this software and associated documentation files (the "Software"), to deal in
* the Software without restriction, including without limitation the rights to
* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
* the Software, and to permit persons to whom the Software is furnished to do so,
* subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
* FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
* IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
package main
import (
"encoding/json"
"io/ioutil"
"os"
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"strings"
)
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//
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// verMeta
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//
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type verMeta struct {
Deleted []string `json:"deleted"`
path string
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dirty bool
}
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func newVerMeta(path string) (*verMeta, error) {
meta := &verMeta{path: path}
if err := meta.load(); err != nil {
return nil, err
}
return meta, nil
}
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func (m *verMeta) filter(nodes verNodeMap) {
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for _, delPath := range m.Deleted {
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for name, node := range nodes {
if strings.HasPrefix(node.path, delPath) {
delete(nodes, name)
}
}
}
}
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func (m *verMeta) removeNode(path string) {
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m.Deleted = append(m.Deleted, path)
m.dirty = true
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}
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func (m *verMeta) createNode(path string) {
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m.dirty = true
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}
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func (m *verMeta) modifyNode(path string) {
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m.dirty = true
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}
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func (m *verMeta) load() error {
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m.dirty = false
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if _, err := os.Stat(m.path); os.IsNotExist(err) {
return nil
}
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bytes, err := ioutil.ReadFile(m.path)
if err != nil {
return err
}
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if err := json.Unmarshal(bytes, &m); err != nil {
return err
}
return nil
}
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func (m *verMeta) save() error {
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if !m.dirty {
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return nil
}
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js, err := json.Marshal(m)
if err != nil {
return err
}
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return ioutil.WriteFile(m.path, js, 0644)
}