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minio/xl-v1-metadata.go

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3.3 KiB

/*
* Minio Cloud Storage, (C) 2016 Minio, Inc.
*
* 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 main
import (
"encoding/json"
"errors"
"io"
"strconv"
"time"
)
// error type when key is not found.
var errMetadataKeyNotExist = errors.New("Key not found in fileMetadata.")
// This code is built on similar ideas of http.Header.
// Ref - https://golang.org/pkg/net/http/#Header
// A fileMetadata represents a metadata header mapping
// keys to sets of values.
type fileMetadata map[string][]string
// Add adds the key, value pair to the header.
// It appends to any existing values associated with key.
func (f fileMetadata) Add(key, value string) {
f[key] = append(f[key], value)
}
// Set sets the header entries associated with key to
// the single element value. It replaces any existing
// values associated with key.
func (f fileMetadata) Set(key, value string) {
f[key] = []string{value}
}
// Get gets the first value associated with the given key.
// If there are no values associated with the key, Get returns "".
// Get is a convenience method. For more complex queries,
// access the map directly.
func (f fileMetadata) Get(key string) []string {
if f == nil {
return nil
}
v, ok := f[key]
if !ok {
return nil
}
return v
}
// Write writes a metadata in wire format.
func (f fileMetadata) Write(writer io.Writer) error {
metadataBytes, err := json.Marshal(f)
if err != nil {
return err
}
_, err = writer.Write(metadataBytes)
return err
}
// Get file size.
func (f fileMetadata) GetSize() (int64, error) {
sizes := f.Get("file.size")
if sizes == nil {
return 0, errMetadataKeyNotExist
}
sizeStr := sizes[0]
return strconv.ParseInt(sizeStr, 10, 64)
}
// Set file size.
func (f fileMetadata) SetSize(size int64) {
f.Set("file.size", strconv.FormatInt(size, 10))
}
// Get file Modification time.
func (f fileMetadata) GetModTime() (time.Time, error) {
timeStrs := f.Get("file.modTime")
if timeStrs == nil {
return time.Time{}, errMetadataKeyNotExist
}
return time.Parse(timeFormatAMZ, timeStrs[0])
}
// Set file Modification time.
func (f fileMetadata) SetModTime(modTime time.Time) {
f.Set("file.modTime", modTime.Format(timeFormatAMZ))
}
// Get file version.
func (f fileMetadata) GetFileVersion() (int64, error) {
version := f.Get("file.version")
if version == nil {
return 0, errMetadataKeyNotExist
}
return strconv.ParseInt(version[0], 10, 64)
}
// Set file version.
func (f fileMetadata) SetFileVersion(fileVersion int64) {
f.Set("file.version", strconv.FormatInt(fileVersion, 10))
}
// fileMetadataDecode - file metadata decode.
func fileMetadataDecode(reader io.Reader) (fileMetadata, error) {
metadata := make(fileMetadata)
decoder := json.NewDecoder(reader)
// Unmarshalling failed, file possibly corrupted.
if err := decoder.Decode(&metadata); err != nil {
return nil, err
}
return metadata, nil
}