初始化仓库

daemon/logrotate.go

@@ -0,0 +1,87 @@
+package daemon
+
+import (
+	"log/slog"
+	"os"
+	"path/filepath"
+	"sync"
+)
+
+// RotatingWriter is a thread-safe io.Writer that appends to a log file
+// and rotates it when the file exceeds maxSize. One backup (.1) is kept,
+// so the maximum disk usage is ≈ 2 × maxSize.
+type RotatingWriter struct {
+	mu      sync.Mutex
+	file    *os.File
+	path    string
+	maxSize int64
+	curSize int64
+}
+
+func NewRotatingWriter(path string, maxSize int64) (*RotatingWriter, error) {
+	if err := os.MkdirAll(filepath.Dir(path), 0755); err != nil {
+		return nil, err
+	}
+	f, err := os.OpenFile(path, os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0644)
+	if err != nil {
+		return nil, err
+	}
+	info, err := f.Stat()
+	if err != nil {
+		f.Close()
+		return nil, err
+	}
+	return &RotatingWriter{
+		file:    f,
+		path:    path,
+		maxSize: maxSize,
+		curSize: info.Size(),
+	}, nil
+}
+
+func (w *RotatingWriter) Write(p []byte) (int, error) {
+	w.mu.Lock()
+	defer w.mu.Unlock()
+
+	if w.file == nil {
+		return 0, os.ErrClosed
+	}
+
+	n, err := w.file.Write(p)
+	w.curSize += int64(n)
+
+	if w.curSize > w.maxSize {
+		w.rotate()
+	}
+	return n, err
+}
+
+func (w *RotatingWriter) rotate() {
+	w.file.Close()
+
+	backup := w.path + ".1"
+	os.Remove(backup)
+	if err := os.Rename(w.path, backup); err != nil {
+		slog.Warn("logrotate: rename failed", "error", err, "path", w.path, "backup", backup)
+	}
+
+	f, err := os.OpenFile(w.path, os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0644)
+	if err != nil {
+		// If we cannot open the new log file, w.file will be nil.
+		// Write() checks for nil and returns os.ErrClosed instead of panicking.
+		w.file = nil
+		w.curSize = 0
+		return
+	}
+	w.file = f
+	w.curSize = 0
+}
+
+func (w *RotatingWriter) Close() error {
+	w.mu.Lock()
+	defer w.mu.Unlock()
+	if w.file != nil {
+		return w.file.Close()
+	}
+	return nil
+}