What if Watchman CLI is missing...

[alunyov]

Here is an updated version of the GraphQLWatchmanClient.isAvailable. (as a fix for #2617)

Now, it's also checking if the watchman CLI is available.

Test plan (Tested with relay-examples:relay-publish-test (relayjs/relay-examples#89)

First of all, I've removed watchman from my machine.
Then,

• Build the compiler
• Install updated dependencies relay-examples (yarn)
• Run the compiler (yarn build)

Compiled without errors.

[alloy]

TIL about command ! ✨

How about using the exit status, though? (And made it async too, although it probably matters very little overall.)

const exec = require("util").promisify(require("child_process").exec)
undefined
> exec("command -v does-not-exist").then(() => console.log("Exists!")).catch(() => console.log("Does not exist!"))
Promise { … }
> Does not exist!
> exec("command -v ls").then(() => console.log("Exists!")).catch(() => console.log("Does not exist!"))
Promise { … }
> Exists!

[alunyov]

I just realized that this won't work on windows. I will add something else.

[alloy]

Can you clarify if using watchman without --watch is faster at yielding files than using fast-glob instead? (E.g. does watchman keep a live cached version of the results?)

The amount of faffing with ‘watch’ related options in the code is starting to confuse me a bit, so it would be nice if we could simplify that without a loss in performance.

[alunyov]

I'm not sure about the performance differences between watchman and fast-glob. But I think at this point, it's fine to keep it as it is.

We've been working recently on the new relay compiler. It's ready, but still has a lot of dependencies on internal tools. And we still are using both versions - but I think once we complete the migration, we will replace an open source version too.

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