Disable cache on non-v8 versions of Node

[EdwardDrapkin]

Recently I was playing around with ChakraCore's implementation of Node (https://github.com/nodejs/node-chakracore) and noticed that v8-compile-cache fails since process.version.v8 is not set. I did some experimentation and it seems that running the cache in Chakra causes segmentation faults on version 8.3 and nightlies, so I just made sure that the cache only initializes for v8. I'm not even sure if, philosophically, a package called v8-compiler-cache should enable a cache for other implementations of Node, but I will do my best to watch Chakra's development and get another PR to enable the cache if support comes.

[jdalton]

Yes, please 😋

As more tools adopt v8-compile-cache you're essentially blocking other engines, like chakracore, from running. @zertosh could you review this?

[zertosh]

Looking

[jdalton]

Rock! On the current stable release I see chakracore erroring out in the getCacheDir() function because process.versions.v8 is undefined and path.join chokes on non-string values in
path.join(os.tmpdir(), dirname, process.versions.v8).

I believe this PR will resolve the issue since it just bypasses the entire thing.

Update:

Too fast 🚤 🎉

[zertosh]

Just published v8-compile-cache@1.1.1... sorry about the delay - totally missed this PR

[jdalton]

NP!

I'll ping back after investigating to see if other engines produce the buffer. As with chakracore I think the buffer was being produced it's just they don't have a v8 version, since it's not v8, so the directory was the bug point. If it turns out they do work I'll prep a PR for a more generic cache folder naming scheme or one that crawls all versions data.

[zertosh]

Oh wait, process.versions.v8 missing is the problem itself? Let me see if chakracore supports produceCachedData - if so, then push another update with just a fix to path.join.

[zertosh]

chakracore doesn't support cached data, but a027ea3 leaves the possibility open to use it if it ever works

[jdalton]

Nice! If you want to test in chakra core here is my appveyor.yml for reference.