Method appendLogRecord

engine/db.go:184–229

appendLogRecord Append data to a file

(logRecord *data2.LogRecord)

// appendLogRecord Append data to a file
func (db *DB) appendLogRecord(logRecord *data2.LogRecord) (*data2.LogRecordPst, error) {
	// Check whether the active data file exists
	// Initializes the data file if empty
	if db.activeFile == nil {
		if err := db.setActiveDataFile(); err != nil {
			return nil, err
		}
	}

	// Write data coding
	encRecord, size := data2.EncodeLogRecord(logRecord)
	if db.activeFile.WriteOff+size > db.options.DataFileSize {
		// Persisting data files to ensure that existing data is persisted to disk
		if err := db.activeFile.Sync(); err != nil {
			return nil, err
		}

		// Converts the current 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 {
			return nil, err
		}
	}

	writeOff := db.activeFile.WriteOff
	if err := db.activeFile.Write(encRecord); err != nil {
		return nil, err
	}

	// Determines whether to initialize based on user configuration
	if db.options.SyncWrite {
		if err := db.activeFile.Sync(); err != nil {
			return nil, err
		}
	}

	// Build in-memory index information
	pst := &data2.LogRecordPst{
		Fid:    db.activeFile.FileID,
		Offset: writeOff,
	}
	return pst, nil

}

// Set the current active file
// Hold a mutex before accessing this method