Initialize async member

[Flarna]

Initialize async member otherwise it may happen that in FSEvents::asyncStart() the check async.data == this is already true and as a result uv_async_init() is not called.

Refs.: nodejs/node#34776 (comment)

[paulmillr]

thanks

[paulmillr]

@pipobscure should we port this to 2.x?

[pipobscure]

Not needed. v2.x has no cpp classes and no such checks so there is nowhere to port it to.

And this could only be an issue here in 1.x in very very rare (almost theoretical circumstances) but it’s definitely an issue worth fixing because in the rare case where the uninitialised memory happens to contain the exact memory address of the object that’s just been created this would be a problem. Normally I’d say this is a one in a trillion chance, but when you consider potential memory reuse this could be more frequent, so a definite thank you to @Flarna for the catch!

[Flarna]

It depends on the algorithm used by the heap manager how likely this is. Quite frequently pools for small objects are used and it's likely to get the same location if you do new - delete - new for the same size.
For whatever reaons node 12.18.2 caused that tests of glob-watcher mostly always failed and after this change problem was gone - at least for me.

[pipobscure]

which is precisely why I love you catching it!!!

Now we just have to migrate glob-watcher to v2.x so that we can stop having to worry about v1.x 😀

[Flarna]

Don't know if 1.x is still published and how often.
As far as I know gulp test have been removed for Mac from Node CITGM and I think they could be re-added if a 1.x package gets published.