Рыба проекта. Минимальная функциональность

pkg/adapters/storage/local/local.go

@@ -0,0 +1,132 @@
+package local
+
+import (
+	"errors"
+	"os"
+	"path/filepath"
+	"strings"
+	"sync"
+
+	"git.tswf.io/infra/go-synapse-backupper/pkg/domain"
+)
+
+// NewLocalSink creates a new local filesystem sink that writes into the given directory.
+func NewLocalSink(dir string) domain.Sink {
+	return &localSink{dir: dir}
+}
+
+type localSink struct {
+	dir string
+}
+
+func (sink *localSink) Begin(key string) (domain.SinkTx, error) {
+	tmpPath := filepath.Join(sink.dir, key+".tmp")
+	finalPath := filepath.Join(sink.dir, key)
+
+	file, err := os.Create(tmpPath)
+	if err != nil {
+		return nil, err
+	}
+
+	return &localSinkTx{
+		file:      file,
+		tmpPath:   tmpPath,
+		finalPath: finalPath,
+	}, nil
+}
+
+func (sink *localSink) List(prefix string) ([]string, error) {
+	entries, err := os.ReadDir(sink.dir)
+	if err != nil {
+		return nil, err
+	}
+
+	keys := make([]string, 0, len(entries))
+	for _, entry := range entries {
+		if entry.IsDir() {
+			continue
+		}
+		name := entry.Name()
+		if prefix != "" && !strings.HasPrefix(name, prefix) {
+			continue
+		}
+		keys = append(keys, name)
+	}
+
+	return keys, nil
+}
+
+func (sink *localSink) Remove(key string) error {
+	path := filepath.Join(sink.dir, key)
+	return os.Remove(path)
+}
+
+type localSinkTx struct {
+	file      *os.File
+	tmpPath   string
+	finalPath string
+	committed bool
+	aborted   bool
+	mu        sync.Mutex
+}
+
+func (transaction *localSinkTx) Write(p []byte) (int, error) {
+	transaction.mu.Lock()
+	defer transaction.mu.Unlock()
+
+	if transaction.committed || transaction.aborted {
+		return 0, errors.New("transaction already finished")
+	}
+
+	return transaction.file.Write(p)
+}
+
+func (transaction *localSinkTx) Commit() error {
+	transaction.mu.Lock()
+	defer transaction.mu.Unlock()
+
+	if transaction.committed || transaction.aborted {
+		return nil
+	}
+
+	transaction.committed = true
+
+	if err := transaction.file.Sync(); err != nil {
+		return err
+	}
+	if err := transaction.file.Close(); err != nil {
+		return err
+	}
+
+	if err := os.Rename(transaction.tmpPath, transaction.finalPath); err != nil {
+		return err
+	}
+
+	parent, err := os.Open(filepath.Dir(transaction.tmpPath))
+	if err != nil {
+		return err
+	}
+	defer parent.Close()
+
+	if err := parent.Sync(); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (transaction *localSinkTx) Abort() error {
+	transaction.mu.Lock()
+	defer transaction.mu.Unlock()
+
+	if transaction.committed || transaction.aborted {
+		return nil
+	}
+
+	transaction.aborted = true
+
+	_ = transaction.file.Close()
+	_ = os.Remove(transaction.tmpPath)
+
+	return nil
+}