X-Git-Url: https://git.giacomolli.uk/onechat/blobdiff_plain/522d7fd117285e4e4ce3ea5ec9b5a1722521b681..9301f77a5709fe7daea3a71f8dd072c6cd7df4fe:/syncer.go

diff --git a/syncer.go b/syncer.go
index 3da6d7a..297405b 100644
--- a/syncer.go
+++ b/syncer.go
@@ -10,22 +10,6 @@ import (
 	"golang.org/x/sys/unix"
 )
 
-// openSyncer returns the syncer of the file system that holds dir. It syncs
-// with syncfs, which writes back only that file system.
-func openSyncer(dir string) (*Syncer, error) {
-	file, err := os.Open(dir)
-	if err != nil {
-		return nil, fmt.Errorf("open chat directory: %w", err)
-	}
-
-	s := newSyncer(func() error {
-		return unix.Syncfs(int(file.Fd()))
-	})
-	s.file = file
-
-	return s, nil
-}
-
 // Syncer makes the writes of a chat durable by group commit. Each write goes to
 // the operating system at once, so a crash of the process loses nothing. After
 // each write, Written starts a background sync of the file system of the chat,
@@ -48,59 +32,39 @@ type Syncer struct {
 	workers sync.WaitGroup
 }
 
-// Written tells the syncer that a write went to the operating system, and
-// starts a sync when none runs.
-func (s *Syncer) Written() {
-	s.mutex.Lock()
-	defer s.mutex.Unlock()
-
-	s.written++
-	s.start()
-}
-
-// Flush returns when every write before the call is durable.
-func (s *Syncer) Flush(ctx context.Context) error {
-	s.mutex.Lock()
-
-	target := s.written
-	s.mutex.Unlock()
-
-	for {
-		s.mutex.Lock()
+// openSyncer returns the syncer of the file system that holds dir. It syncs
+// with syncfs, which writes back only that file system.
+func openSyncer(dir string) (*Syncer, error) {
+	file, err := os.Open(dir)
+	if err != nil {
+		return nil, fmt.Errorf("open chat directory: %w", err)
+	}
 
-		reached := s.durable >= target
-		failure := s.failure
-		done := s.done
-		s.mutex.Unlock()
+	s := newSyncer(func() error {
+		return unix.Syncfs(int(file.Fd()))
+	})
 
-		if reached {
-			return nil
-		}
+	s.file = file
 
-		if failure != nil {
-			return failure
-		}
+	return s, nil
+}
 
-		select {
-		case <-done:
-		case <-ctx.Done():
-			return ctx.Err()
-		}
+// newSyncer returns a syncer that makes the writes durable with sync.
+func newSyncer(sync func() error) *Syncer {
+	return &Syncer{
+		sync: sync,
+		done: make(chan struct{}),
 	}
 }
 
-// Close makes every write durable, waits for the syncs, and closes the
-// directory.
-func (s *Syncer) Close() error {
-	err := s.Flush(context.Background())
-	s.workers.Wait()
-
-	if s.file != nil {
-		err = errors.Join(err, s.file.Close())
-		s.file = nil
-	}
+// Written tells the syncer that a write went to the operating system, and
+// starts a sync when none runs.
+func (s *Syncer) Written() {
+	s.mutex.Lock()
+	defer s.mutex.Unlock()
 
-	return err
+	s.written++
+	s.start()
 }
 
 // start starts a sync of the writes so far when none runs and a write is not
@@ -139,10 +103,47 @@ func (s *Syncer) run(target uint64) {
 	s.start()
 }
 
-// newSyncer returns a syncer that makes the writes durable with sync.
-func newSyncer(sync func() error) *Syncer {
-	return &Syncer{
-		sync: sync,
-		done: make(chan struct{}),
+// Close makes every write durable, waits for the syncs, and closes the
+// directory.
+func (s *Syncer) Close() error {
+	err := s.Flush(context.Background())
+	s.workers.Wait()
+
+	if s.file != nil {
+		err = errors.Join(err, s.file.Close())
+		s.file = nil
+	}
+
+	return err
+}
+
+// Flush returns when every write before the call is durable.
+func (s *Syncer) Flush(ctx context.Context) error {
+	s.mutex.Lock()
+
+	target := s.written
+	s.mutex.Unlock()
+
+	for {
+		s.mutex.Lock()
+
+		reached := s.durable >= target
+		failure := s.failure
+		done := s.done
+		s.mutex.Unlock()
+
+		if reached {
+			return nil
+		}
+
+		if failure != nil {
+			return fmt.Errorf("flush durable writes: %w", failure)
+		}
+
+		select {
+		case <-done:
+		case <-ctx.Done():
+			return ctx.Err()
+		}
 	}
 }