Determine CHANNEL_SIZE from environment

[mschauer]

Fixes #169 in the way proposed by @JobJob .

[JobJob]

This is really good, but you're not based off master! Can you fix it up? prob easiest just to do it manually, or you can do this:

git format-patch -1 4eda8253161600e053fc4dbe3970980bf503b9b0 #sha of your commit
git checkout master
git pull
git branch channelsize2
git checkout channelsize2
patch -p1 < 0001-Determine-CHANNEL_SIZE-from-environment.patch

[mschauer]

Ah, I started off with git checkout master without a fetch. Fixed here.

[JobJob]

Ace!

[JobJob]

Nice touch 😄
maybe we should also add "by setting ENV[\"REACTIVE_CHANNEL_SIZE\"] = ... before using Reactive" ?

[mschauer]

Hm..., that won't be enough because of pre-compilation freezing the value into the constant.

[JobJob]

oh shit, you're right... maybe we need to change CHANNEL_SIZE to be a Ref ?

[JobJob]

As in

const CHANNEL_SIZE = Ref(1024)
CHANNEL_SIZE[] = parse(Int, get(ENV, "REACTIVE_CHANNEL_SIZE", "1024"))

or something

[JobJob]

maybe haskey(ENV, "REACTIVE_CHANNEL_SIZE") && (CHANNEL_SIZE[] = parse(Int, ENV["REACTIVE_CHANNEL_SIZE"])) is better (less repetition of 1024)

edit: missed a )

[mschauer]

What is the advantage of

const CHANNEL_SIZE = Ref(parse(Int, get(ENV, "REACTIVE_CHANNEL_SIZE", "1024")))

over

CHANNEL_SIZE = parse(Int, get(ENV, "REACTIVE_CHANNEL_SIZE", "1024"))

?

[JobJob]

Because then we can set the Ref in the __init__() function. And it will be updated based on the current value of ENV["REACTIVE_CHANNEL_SIZE"] on using Reactive

[JobJob]

I just tried out const CHANNEL_SIZE = Ref(1024)
and in __init__()

    haskey(ENV, "REACTIVE_CHANNEL_SIZE") && 
        (CHANNEL_SIZE[] = parse(Int, ENV["REACTIVE_CHANNEL_SIZE"]))
    runner_task[] = @async run()

plus changing lines ~226, ~257 from CHANNEL_SIZE to CHANNEL_SIZE[] and it seems to respect my ENV["REACTIVE_CHANNEL_SIZE"]

[JobJob]

Oh, I missed that your CHANNEL_SIZE above is not const. The const is an advantage for static compilation, and because non-const globals can be slow.

[mschauer]

Ah, I get it, const x = Ref makes sure that Julia can infer Int because only the value but not the type can change. JuliaLang/julia#13817 (comment)

[JobJob]

Nice, didn't realise ENV converts to strings auto-magically.

[JobJob]

Awesome. Thanks very much!