refactor: move accesslog to logging/accesslog

internal/logging/accesslog/file_logger.go

@@ -0,0 +1,68 @@
+package accesslog
+
+import (
+	"fmt"
+	"os"
+	pathPkg "path"
+	"sync"
+
+	"github.com/yusing/go-proxy/internal/logging"
+	"github.com/yusing/go-proxy/internal/utils"
+)
+
+type File struct {
+	*os.File
+	sync.Mutex
+
+	// os.File.Name() may not equal to key of `openedFiles`.
+	// Store it for later delete from `openedFiles`.
+	path string
+
+	refCount *utils.RefCount
+}
+
+var (
+	openedFiles   = make(map[string]*File)
+	openedFilesMu sync.Mutex
+)
+
+func newFileIO(path string) (AccessLogIO, error) {
+	openedFilesMu.Lock()
+
+	var file *File
+	path = pathPkg.Clean(path)
+	if opened, ok := openedFiles[path]; ok {
+		opened.refCount.Add()
+		file = opened
+	} else {
+		f, err := os.OpenFile(path, os.O_APPEND|os.O_CREATE|os.O_RDWR, 0o644)
+		if err != nil {
+			openedFilesMu.Unlock()
+			return nil, fmt.Errorf("access log open error: %w", err)
+		}
+		file = &File{File: f, path: path, refCount: utils.NewRefCounter()}
+		openedFiles[path] = file
+		go file.closeOnZero()
+	}
+
+	openedFilesMu.Unlock()
+	return file, nil
+}
+
+func (f *File) Close() error {
+	f.refCount.Sub()
+	return nil
+}
+
+func (f *File) closeOnZero() {
+	defer logging.Debug().
+		Str("path", f.path).
+		Msg("access log closed")
+
+	<-f.refCount.Zero()
+
+	openedFilesMu.Lock()
+	delete(openedFiles, f.path)
+	openedFilesMu.Unlock()
+	f.File.Close()
+}