Hi,
I really do not think this is production ready.
1. Simple async code.
Simple example:
// m1.js
const label = 'Hi world';
setInterval(() => console.log('From m1:', label), 1000);
exports.label = label;
// m2.js
const dload = require('../index');
const mo = dload.new();
mo.fs = require('fs');
mo.path = require('path');
mo.co = require('zco');
mo.m1 = require('./m1.js');
mo.co(function * (co_next) {
let label = mo.m1.label;
console.log('Old label:', label);
setInterval(() => {
dload.reload(mo.path.join(__dirname, './m1.js'));
label = mo.m1.label;
console.log('New label:', label);
}, 1200);
})();
Run m2, then change the label manually a few times and save. All sorts of
stuff in there:
>From m1: Hello world
>From m1: Hi worlds
>From m1: Hi world
>From m1: Hello world
New label: Bye bye
>From m1: Hi worlds
>From m1: Hi world
>From m1: Hello world
>From m1: Hi world
>From m1: Hi world
>From m1: Hello worlds
>From m1: Hello world
>From m1: Hello world
>From m1: Hi world
>From m1: Hi world
>From m1: Hello world
>From m1: Hi world
>From m1: Hi worlds
>From m1: Hello world
>From m1: Hello world
>From m1: Hi worlds
>From m1: Hi world
>From m1: Hello world
>From m1: Bye bye
I know there's the _release handler, but what if my interval is not in my
code, but in some library my original module required? I would be totally
scared to run this in production and try reloading things when all kinds of
resources are attached out there. E.g. I sometimes keep anything db-related
in a separate repository. And that stuff touches say Redis, MongoDB and
RabbitMQ. I know I will have to write manual _releasse code. But if I miss
just one thing, it's not good. And if I let my colleagues use that? They
don't even know what to release! OTOH if the server is killed, I _know_
everything is shut down. And further, even with that, let's say there's a
long-running task out there. Even if you do _release, you might not be able
to interrupt it properly so your resource-consuming task will keep running,
_and_ you'll load a new copy of the same thing.
In this state, I'm not sure if I would even use it to hot-reload
configuration variables (static, sync code), let alone async modules.
2. I guess it's early, but the docs and the API should be better. On the
first read it was not clear to me what exactly I need to do. Especially
since you rewrite modules in the same code where you try to explain dload.
I would kick out that example and write something like this:
# Usage
const dload = require('dload');
const mo = dload.new();
mo.myHotModule = require('./my-hot-module');
// ... do some change to myHotModule, save the file
dload.reload(<path>);
// mo.myHotModule is reloaded.
Even your module name itself (dload) is confusing and not reflecting what
it is for.
3. Use cases
It's not clear to me what is the usecase of this. You want to be able to
load a module, use it, then _rewrite_ it from your own code, and then
reload the changes?
If I were to think of some use cases, I would say something like
auto-reload is needed. Kind of like nodemon or supervisor, but reloading
just those files. You'd give a list of files to watch, and then your server
would not restart, only those modules would.
Or maybe you have some sandbox code, like for a live, web ide, but in that
case I would never let that sandbox code in my main thread - because a
simple setInterval(() => console.log()) will kill my main thread and not
even let me reload the module. I'd rather spawn the sandbox code in a new
process in such cases.
Such as it is, I would not use this module. If I need code reload, a simple
restart is usually tollerant. And if my code is critical and I need online
redeploy, I would use simple container tech for this, because that was it's
purpose in the first place.
Please take the above as constructive critique. I love the idea, I just
think you're not there yet (for me).
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