Do not use invalid cache

[yovanoc]

Describe the bug

• Node.js version: 13.3
• OS & version: MacOS Catalina

Actual behavior

I get GotError: Unexpected token in JSON at position 0 in ... when I add responseType: "json" .
But this happens 2 times out of 5 .. and If I remove the responseType and log the body, all is good..

PS: right before this error there is this warning every time: (node:34140) [DEP0005] DeprecationWarning: Buffer() is deprecated due to security and usability issues. Please use the Buffer.alloc(), Buffer.allocUnsafe(), or Buffer.from() methods instead.

Expected behavior

Should be able to parse JSON, I think got tries to parse before getting full response or something like that

Code to reproduce

const body = await got
    .get(link, {
      cache,
      retry: 4
    })
    .json();

or

const { body } = await got
    .get(link, {
      cache,
      retry: 4,
      responseType: 'json'
    });

Checklist

• I have read the documentation.
• I have tried my code with the latest version of Node.js and Got.

[szmarczak]

What's the link? If it's a custom server, please attach some code. What's the cache options?

[yovanoc]

Can we exchange by email for links? It's a private project?

[szmarczak]

That won't be neccessary I think. If you open the link in your browser, what's the first character of the body?

What's the cache options?

Also if you provided the full stack trace, that'd be awesome.

[yovanoc]

The first character is the {.

Here's the cache:

const cache = new KeyvFile({
  filename: join(appDataPath, "cache.json"), // the file path to store the data
  expiredCheckDelay: 10 * 24 * 3600 * 1000, // ms, check and remove expired data in each ms
  writeDelay: 120, // ms, batch write to disk in a specific duration, enhance write performance.
  encode: JSON.stringify, // serialize function
  decode: JSON.parse // deserialize function
});

And I will try to provide you a bigger stacktrace, thanks

[szmarczak]

Thanks, I'll now investigate.

[szmarczak]

right before this error there is this warning every time

This is actually weird as Got never does Buffer(...). It does Buffer.from(...)...

[szmarczak]

If you can provide HTTP headers, that'd awesome as well (you may leave out some of them if they are sensitive).

[yovanoc]

Response headers? Because I don't pass any for the request

[szmarczak]

yup

[yovanoc]

{
  'content-type': 'application/json',
  'last-modified': 'Wed, 27 Nov 2019 01:56:55 GMT',
  'content-encoding': 'gzip',
  vary: 'Accept-Encoding',
  age: '44979'
}

[yovanoc]

@szmarczak I've done more tests. If I simply remove the cache, all is working perfectly. AND I've tried to do a setInterval to request once a second the .json (with the cache) and 1/2 times the data is completely invalid (weird ascii characters), and give the JSON.parse error.
So I think now the cache must have an issue

[szmarczak]

Could you provide the full error stacktrace?

[yovanoc]

SyntaxError: Unexpected token  in JSON at position 0
    at JSON.parse (<anonymous>)
    at parseBody (/Users/devchris/Documents/code/nodejs/project/node_modules/got/dist/source/as-promise.js:12:47)
    at /Users/devchris/Documents/code/nodejs/project/node_modules/got/dist/source/as-promise.js:130:47
    at processTicksAndRejections (internal/process/task_queues.js:97:5)

How can I get more? Isn't good for you? And I checked: 1/2 times the key is removed in the cache file, so the next time he made the request, it's working, then error, and he removes, etc..

[szmarczak]

Unfortunately I cannot reproduce this one. If you want to you can email me here:

sz.marczak@gmail.com

I'll be more than happy to help.

[szmarczak]

It seems that it's a zero-width space character: JSON.parse('​') gives the same result. Could you try .text() instead of .json() and log these bodies? Are they the same?

[yovanoc]

Just sent to you an email, thanks

[szmarczak]

Replied back

[szmarczak]

Culprit: kornelski/http-cache-semantics#26

[szmarczak]

http-cache-semantics works properly. The second response doesn't include any validation header so headers shouldn't be merged.

Instead, it should make a new request or return the new response without merging anything.

I'll move this into #875