Method Merge

engine/merge.go:21–160

Merge Clear the invalid data and generate the hint index file

()

// Merge Clear the invalid data and generate the hint index file
func (db *DB) Merge() error {
	// If the database is empty, it is returned directly
	if db.activeFile == nil {
		return nil
	}
	db.lock.Lock()
	// If the merge is in progress, return directly
	if db.isMerging {
		db.lock.Unlock()
		return _const.ErrMergeIsProgress
	}
	db.isMerging = true
	defer func() {
		db.isMerging = false
	}()

	// Persist the currently active file
	if err := db.activeFile.Sync(); err != nil {
		db.lock.Unlock()
		return err
	}

	// Converts the currently active file to the old data file
	db.olderFiles[db.activeFile.FileID] = db.activeFile
	// Open a new active file
	if err := db.setActiveDataFile(); err != nil {
		db.lock.Unlock()
		return nil
	}

	// Records files that have not participated in the merge recently
	noMergeFileId := db.activeFile.FileID

	// Retrieve all files that need to be merged
	var mergeFiles []*data2.DataFile
	for _, files := range db.olderFiles {
		mergeFiles = append(mergeFiles, files)
	}
	db.lock.Unlock()

	// Sort merge files from smallest to largest
	sort.Slice(mergeFiles, func(i, j int) bool {
		return mergeFiles[i].FileID < mergeFiles[j].FileID
	})

	mergePath := db.getMergePath()
	// If the directory exists, it has been merged and needs to be deleted
	if _, err := os.Stat(mergePath); err == nil {
		if err := os.RemoveAll(mergePath); err != nil {
			return err
		}
	}
	// Creating a merge Directory
	if err := os.MkdirAll(mergePath, os.ModePerm); err != nil {
		return err
	}

	// Open a temporary new instance and modify the configuration item