The Readable and Writable classes will nextTick certain things
if in sync mode. The sync flag gets unset after a call to _read
or _write. However, most of these behaviors should also be
deferred until nextTick if no reads have been made (for example,
the automatic '_read up to hwm' behavior on Readable.push(chunk))
Set the sync flag to true in the constructor, so that it will not
trigger an immediate 'readable' event, call to _read, before the
user has had a chance to set a _read method implementation.
It seems like a good idea on the face of it, but lowWaterMarks are
actually not useful, and in practice should always be set to zero.
It would be worthwhile for writers if we actually did some kind of
writev() type of thing, but actually this just delays calling write()
and the overhead of doing a bunch of Buffer copies is not worth the
slight benefit of calling write() fewer times.
This is more backwards-compatible with stream1 streams like `fs.WriteStream`
which would allow a callback function to be passed in as the only argument.
Closes#4719.
We detect for non-string and non-buffer values in onread and
turn the stream into an "objectMode" stream.
If we are in "objectMode" mode then howMuchToRead will
always return 1, state.length will always have 1 appended
to it when there is a new item and fromList always takes
the first value from the list.
This means that for object streams, the n in read(n) is
ignored and read() will always return a single value
Fixed a bug with unpipe where the pipe would break because
the flowing state was not reset to false.
Fixed a bug with sync cb(null, null) in _read which would
forget to end the readable stream
There was previously an assert() in there, but this part of the code is
so high-volume that the added cost made a measurable dent in http_simple.
Just checking inline is fine, though, and prevents a lot of potential
hazards.
isaacs
Nathan Rajlich
Raynos