object.get sometimes returns an empty DAGNode

[haadcode]

Sometimes, when doing object.get, the result is an empty DAGNode, ie. res.toJSON().Data --> empty buffer). The hash involved is probably this QmdfTbBqBPQ7VNxZEYEj14VmRuZBkqFbiwReogJgS1zR1n seeing it around a lot.

This has been around since 0.1x.x and is still present in 0.14.1.

[dignifiedquire]

This is a bug in js-ipfs-repo. Node streams are not working properly for fs-blob-store when reading and writing a lot.

[dignifiedquire]

This is an example on how this can be fixed https://gist.github.com/dignifiedquire/b98e2f1caf6c549c0e04895c88e8ca3d

[daviddias]

@dignifiedquire could you make a diff instead of a gist? (and better, a PR)

[dignifiedquire]

@diasdavid no I can not, as this is just a hack. If you look closely it stops using the abstract-blob-store interface and so would immediately stop working in the browser. As far as I can tell this can not be fixed as long as we use abstract-blob-store with node-streams to read and write files.

[daviddias]

Got it, what I meant was that it is hard to check what changed when there is no diff. Yes, changing from stream to sync write is not the solution.

[haadcode]

changing from stream to sync write is not the solution

https://gist.github.com/dignifiedquire/b98e2f1caf6c549c0e04895c88e8ca3d#file-datastore-js-L61

I think the problem here was, iirc discussion with @dignifiedquire, that fs.createReadStream in abstract-blob-store was not working as expected. So, his fix was to change the fs layer to use .writeFile (async) instead of streams.

[daviddias]

This should be fixed once #403 is done

[dignifiedquire]

#403 was merged and should fix this, please reopen if this is still an issue

[daviddias]

@haadcode please verify :)