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db.go
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db.go
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package sticky
import (
"bytes"
"errors"
"fmt"
"io"
"os"
"strings"
)
// FileDB is a evet database based of one file.
type FileDB struct {
File string
}
// Reader opens the file and returns its reader.
func (db FileDB) Reader() (io.ReadCloser, error) {
f, err := os.Open(db.File)
if err != nil {
if errors.Is(err, os.ErrNotExist) {
return io.NopCloser(strings.NewReader("")), nil
}
return nil, fmt.Errorf("open database file: %w", err)
}
return f, nil
}
// Append adds data to the file with a newline.
func (db FileDB) Append(bs []byte) error {
if bytes.Contains(bs, []byte("\n")) {
return errors.New("event contains a newline")
}
f, err := os.OpenFile(db.File, os.O_APPEND|os.O_WRONLY|os.O_CREATE, 0600)
if err != nil {
return fmt.Errorf("open db file: %w", err)
}
defer func() {
wErr := f.Close()
if err != nil {
err = wErr
}
}()
if _, err := fmt.Fprintf(f, "%s\n", bs); err != nil {
return fmt.Errorf("writing event to file: %q: %w", bs, err)
}
return nil
}
// MemoryDB stores Events in memory.
//
// Usefull for testing.
type MemoryDB struct {
Content string
}
// NewMemoryDB initializes a MemoryDB
func NewMemoryDB(content string) *MemoryDB {
return &MemoryDB{content}
}
// Reader reads the content.
func (db *MemoryDB) Reader() (io.ReadCloser, error) {
return io.NopCloser(strings.NewReader(db.Content)), nil
}
// Append adds a new event.
func (db *MemoryDB) Append(bs []byte) error {
db.Content += fmt.Sprintf("%s\n", bs)
return nil
}