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streams: Replace _read callback with push() #4878
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A primary motivation of this is to make the onread function more inline-friendly, but also to make it more easy to explore not having onread at all, in favor of always using push() to signal the end of reading.
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Oops, some tests are failing, don't land this yet :) |
This makes it so that `stream.push(chunk)` is the only way to signal the
end of reading, removing the confusing disparity between the
callback-style _read method, and the fact that most real-world streams
do not have a 1:1 corollation between the "please give me data" event,
and the actual arrival of a chunk of data.
It is still possible, of course, to implement a `CallbackReadable` on
top of this. Simply provide a method like this as the callback:
function readCallback(er, chunk) {
if (er)
stream.emit('error', er);
else
stream.push(chunk);
}
However, *only* fs streams actually would behave in this way, so it
makes not a lot of sense to make TCP, TLS, HTTP, and all the rest have
to bend into this uncomfortable paradigm.
The first example uses Readable, and shows the use of readable.unshift(). The second uses the Transform class, showing that it's much simpler in this case.
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Fixed tests. Was a dumb debuggery typo. The system works! |
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LGTM. This definitely simplifies the API which is one of the major things I was desiring 🍻 |
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Landed on master. Thanks! |
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This looks nice, and matches another idea of mine, though I didn't think about making _read completely sync which solves some issues. 👍 I guess now the conceptual API is that any number of push's will eventually be followed by a _read, and that no further _read's will be called until after at least one push (of any size). Also, you missed a callback in the example for |
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Also, this splits up several readable methods so that they're more inline-friendly, implements
Readable.unshift(chunk)(the mirror ofReadable.push(chunk)) and adds a parser example to the docs.