Than don't pass them to multiple readers?
вторник, 13 августа 2013 г., 8:23:25 UTC+4 пользователь Jakeb Rosoman
написал:
>
> Aren't simple-stream's still a bit problematic if you pass them around
> like values? Because multiple readers would still interfere with each other
> wouldn't they?
>
> On Tuesday, August 13, 2013 4:05:02 AM UTC+12, Eldar wrote:
>>
>> If you want to create some function which accepts a stream and can affect
>> it's state you should be able to destroy the given stream on demand
>> e.g. when something went wrong and/or you are not interested in receiving
>> data anymore.
>> Unfortunately that's impossible with current node readable streams because
>> they:
>>
>> 1. Support multiple consumers
>> 2. Don't have common cleanup interface
>>
>> So you can't touch another's stream because someone else may use it
>> and if you could you don't know how.
>>
>> The absence of ability to pass streams as arguments is a huge flow. You can
>> build almost nothing
>> without that. Now someone may wonder: but there are so many useful modules
>> about streams in npm!?
>> Right. They all rely on `.pipe()`. For some reason all kind of blog posts,
>> tutorials and even node's
>> own documentation teach that for passing readable you can do
>> `readable.pipe(writable)`.
>> E.g. http file server could be:
>>
>> ```javascript
>> var http = require('http')
>> var fs = require('fs')
>> http.createServer(function(req, res) {
>> res.writeHead(200, {'Content-Type': 'text/plain'})
>> fs.createReadStream(req.url.slice(1)).pipe(res)
>> }).listen(3000)
>> ```
>>
>> That's a lie. Exactly for the reasons above `.pipe()` doesn't cleanup any
>> resources.
>> Everything works fine until the streaming process completes successfully.
>> But if something fails you get horrible leaks and hangs.
>> Almost every module doing stream processing have this flow. Obvious or not.
>>
>> That all is sad. We need another, simpler API. Although I believe
>> incompatible changes should be made
>> to node core that is not what I am calling about (at least not at the first
>> place).
>> But we definitely should stop to expose node streams in userland modules,
>> stop to extend "stream base classes", just stop to use it in userland.
>>
>> Now the constructive part. Tim Caswell proposed recently simple-stream
>> <https://github.com/creationix/js-git/blob/master/specs/simple-stream.md>
>> and build many things on top of it.
>>
>> Let's just peek this API as a standard and start using it.
>> Here is readable-to-simple-stream
>> <https://github.com/eldargab/stream-simple> converter which can be used for
>> dealing with node core.
>>
>> It also contains slightly more detailed version of original spec which could
>> be discussed.
>>
>> That's it.
>>
>>
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