問題文
A note walks through the states that a buffer in the cache of blocks can hold, and through the handling that comes before such a buffer is put to use again. Which statement pairs those states with that handling?
選択肢
- A buffer that holds a version of a block as of a past moment waits for a checkpoint before it is taken over, and one that holds changes still to reach disk is fit for reuse as it stands, so the state that has served nothing yet is the readiest of them.
- A buffer that holds a version of a block as of a past moment is fit for reuse as it stands, and one that holds changes still to reach disk is fit for reuse in the same way, so the state that has served nothing yet is the readiest of the three.
- A buffer that holds a version of a block as of a past instant is fit for reuse as it stands, and one that holds changes still to reach disk waits for a checkpoint before it is taken over, so the state that has served nothing yet is the readiest of the three.
- A buffer that holds a version of a block as of a past moment waits for a checkpoint before it is taken over, and one that holds changes still to reach disk waits in the same way, so the state that has served something already is the readiest of the three.