feat(app): add internal components batch 1

internal/app/diagnostics.go

@@ -0,0 +1,120 @@
+package app
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
+	"strconv"
+	"sync"
+	"time"
+)
+
+const diagnosticLogBytes = 5 * 1024 * 1024
+const diagnosticLogBackups = 2
+
+type diagnosticEvent struct {
+	HTTPStatus         int       `json:"httpStatus,omitempty"`
+	RequestedQuality   int       `json:"requestedQuality,omitempty"`
+	Time               time.Time `json:"time"`
+	Level              string    `json:"level"`
+	Event              string    `json:"event"`
+	Source             string    `json:"source,omitempty"`
+	DramaID            string    `json:"dramaId,omitempty"`
+	DramaTitle         string    `json:"dramaTitle,omitempty"`
+	Episode            int       `json:"episode,omitempty"`
+	Run                uint64    `json:"run,omitempty"`
+	StartSeconds       float64   `json:"startSeconds,omitempty"`
+	Host               string    `json:"host,omitempty"`
+	OffsetBytes        int64     `json:"offsetBytes,omitempty"`
+	TotalBytes         int64     `json:"totalBytes,omitempty"`
+	Attempt            int       `json:"attempt,omitempty"`
+	Quality            int       `json:"quality,omitempty"`
+	AvailableQualities []int     `json:"availableQualities,omitempty"`
+	Message            string    `json:"message"`
+}
+
+type diagnosticLog struct {
+	mu          sync.Mutex
+	path        string
+	limit       int64
+	warningOnce sync.Once
+}
+
+func newDiagnosticLog(directory string) *diagnosticLog {
+	return &diagnosticLog{path: filepath.Join(directory, "logs", "app.log"), limit: diagnosticLogBytes}
+}
+
+func (log *diagnosticLog) write(event diagnosticEvent) error {
+	event.Time = time.Now()
+	if event.Level == "" {
+		event.Level = "error"
+	}
+	data, err := json.Marshal(event)
+	if err != nil {
+		return err
+	}
+	data = append(data, '\n')
+	log.mu.Lock()
+	defer log.mu.Unlock()
+	if int64(len(data)) > log.limit {
+		return errors.New("单条诊断日志过大")
+	}
+	if err := os.MkdirAll(filepath.Dir(log.path), 0700); err != nil {
+		return err
+	}
+	info, err := os.Stat(log.path)
+	if err != nil && !errors.Is(err, os.ErrNotExist) {
+		return err
+	}
+	if info != nil && info.Size()+int64(len(data)) > log.limit {
+		if err := log.rotate(); err != nil {
+			return err
+		}
+	}
+	file, err := os.OpenFile(log.path, os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0600)
+	if err != nil {
+		return err
+	}
+	_, writeErr := file.Write(data)
+	return errors.Join(writeErr, file.Close())
+}
+
+func (log *diagnosticLog) rotate() error {
+	oldest := log.path + "." + strconv.Itoa(diagnosticLogBackups)
+	if err := os.Remove(oldest); err != nil && !errors.Is(err, os.ErrNotExist) {
+		return err
+	}
+	for index := diagnosticLogBackups; index > 0; index-- {
+		previous := log.path
+		if index > 1 {
+			previous += "." + strconv.Itoa(index-1)
+		}
+		if err := os.Rename(previous, log.path+"."+strconv.Itoa(index)); err != nil && !errors.Is(err, os.ErrNotExist) {
+			return err
+		}
+	}
+	return nil
+}
+
+func (downloader *Downloader) recordDiagnostic(event diagnosticEvent) {
+	if downloader == nil || downloader.diagnostics == nil {
+		return
+	}
+	event.Message = truncate(redactErrorString(event.Message), 4096)
+	event.DramaTitle = truncate(redactErrorString(event.DramaTitle), 256)
+	if err := downloader.diagnostics.write(event); err != nil {
+		downloader.diagnostics.warningOnce.Do(func() {
+			fmt.Fprintf(os.Stderr, "诊断日志保存失败：%v\n", publicError(err))
+		})
+	}
+}
+
+func (downloader *Downloader) recordTaskFailure(event string, task Task, start float64, err error) {
+	if err == nil {
+		return
+	}
+	downloader.recordDiagnostic(diagnosticEvent{Event: event, Source: firstNonEmpty(task.Chapter.Source, sourceFromDramaID(task.DramaID)),
+		DramaID: task.DramaID, DramaTitle: task.DramaTitle, Episode: task.Index, StartSeconds: start, Message: err.Error()})
+}