write 返回了，断电之后数据还在吗
write 返回了，一秒后断电 —— 数据还在吗？
Copy the prompt, then pick a model. It plays the interviewer and asks you through it scene by scene instead of handing you the answer.
On a phone with the app installed, the system opens the app directly. Links cannot open external apps inside WeChat — open it in a browser first.
The copied text ends with the answer key the model grades you against. Don't read it yourself first — working it out on your own is the point.
这是所有「重启之后数据没了」「日志少了最后几行」类事故的源头。
中心问题是一个很多人从没想过的：新建一个文件、写完、fsync 了，断电之后这个文件一定在吗？ 文件内容落盘了，但「这个目录下有这个文件」这条目录项呢。
最后一幕是那个著名的坑：fsync 返回错误之后重试，可能返回成功而数据从来没写进去。知道这一条的人不多，踩上的代价很大。
What this one drills
This prompt in the repo (the answer key is at the end of that file — you'll see it)
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Notes from people who did this one
How to use this
This set teaches rather than interrogates: it guides you instead of pressing until you have nothing left to say. When you're stuck it first asks which layer you're stuck at (never heard of it / know it but not why / know why but can't apply it), then decides what to give. Only after guiding you twice on the same point will it spell it out — and then it asks you to say it back in your own words.
It will keep pushing you for numbers: answer "there's some overhead" or "it's faster" and it cuts you off. A conclusion you can't put a number on is a memorised one — that's exactly what this set drills.
How to start
- Pick one, open it, copy the prompt.
- Paste it into a brand-new conversation, say nothing, and wait for its first question.
- Expect to be asked for orders of magnitude: how many nanoseconds, how many microseconds, how many times slower. Saying you don't know is fine — it notes it and moves on.
Four commands you can call out at any time
跳过move to the next scene now换个说法explain this bit again from another angle直说吧spell the answer out, then make me say it back复盘jump to the wrap-up and print the review card
Three traps
- Don't read the answer key at the end first — that "how people get it wrong" section is the answer to every question it will ask.
- Don't reach for the jargon. Saying "that's a TLB miss" is easy; saying how much cheaper it is than a page fault is the part that counts.
- When it starts praising you, point it back to the "don't praise me" rule. Guiding is not coddling.
Want a feel for the numbers? Start with random reads and the first-byte one. For production debugging: malloc, TCP stalls, context switches. Writing concurrent code: reordering and false sharing.
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