partitions.go
func (c *partitionConsumer) MarkOffset(offset int64, metadata string) {
	c.mu.Lock()
	if next := offset + 1; next > c.state.Info.Offset {
		c.state.Info.Offset = next
		c.state.Info.Metadata = metadata
		c.state.Dirty = true
	}
	c.mu.Unlock()
}
func (c *partitionConsumer) MarkOffset(offset int64, metadata string) {
	c.mu.Lock()
	if next := offset + 1; next > c.state.Info.Offset {
		c.state.Info.Offset = next
		c.state.Info.Metadata = metadata
		c.state.Dirty = true
	}
	c.mu.Unlock()
}
// MarkOffset implements PartitionConsumer