mirror of https://github.com/certusone/dc4bc.git
82 lines
1.2 KiB
Go
82 lines
1.2 KiB
Go
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package storage
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import (
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"bufio"
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"encoding/json"
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"io"
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"os"
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"sync"
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)
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var _ Storage = (*FileStorage)(nil)
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type FileStorage struct {
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sync.Mutex
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file *os.File
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reader *bufio.Reader
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}
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func InitFileStorage(filename string) (*FileStorage, error) {
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var (
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fs FileStorage
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err error
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)
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if fs.file, err = os.OpenFile(filename, os.O_APPEND|os.O_CREATE|os.O_RDWR, 0644); err != nil {
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return nil, err
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}
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fs.reader = bufio.NewReader(fs.file)
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return &fs, nil
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}
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func (fs *FileStorage) Post(m Message) error {
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fs.Lock()
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defer fs.Unlock()
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data, err := json.Marshal(m)
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if err != nil {
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return err
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}
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data = append(data, '\n')
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_, err = fs.file.Write(data)
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return err
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}
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func (fs *FileStorage) GetMessages(offset int) ([]Message, error) {
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fs.Lock()
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defer fs.Unlock()
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var (
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msgs []Message
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err error
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row []byte
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data Message
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)
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if _, err = fs.file.Seek(0, 0); err != nil {
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return nil, err
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}
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for {
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row, err = fs.reader.ReadBytes('\n')
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if err != nil {
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break
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}
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if offset > 0 {
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offset--
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continue
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}
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if err = json.Unmarshal(row, &data); err != nil {
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return nil, err
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}
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msgs = append(msgs, data)
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}
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if err != io.EOF {
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return nil, err
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}
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return msgs, nil
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}
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func (fs *FileStorage) Close() error {
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return fs.file.Close()
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}
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