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'use strict';
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const common = require('../common');
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const assert = require('assert');
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const Stream = require('stream');
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const Readable = Stream.Readable;
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const r = new Readable();
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const N = 256;
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let reads = 0;
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stream: There is no _read cb, there is only push
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.
12 years ago
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r._read = function(n) {
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return r.push(++reads === N ? null : Buffer.allocUnsafe(1));
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};
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r.on('end', common.mustCall(function() {}));
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const w = new Stream();
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w.writable = true;
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let buffered = 0;
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w.write = function(c) {
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buffered += c.length;
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process.nextTick(drain);
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return false;
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};
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function drain() {
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assert(buffered <= 3);
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buffered = 0;
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w.emit('drain');
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}
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w.end = common.mustCall(function() {});
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// Just for kicks, let's mess with the drain count.
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// This verifies that even if it gets negative in the
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// pipe() cleanup function, we'll still function properly.
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r.on('readable', function() {
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w.emit('drain');
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});
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r.pipe(w);
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