The stall is exposed in the test, though the test itself asserts before
it stalls.
The test is constructed to replicate the stalling state of a complex
Passthrough usecase since I was not able to reliable trigger the stall.
Some of the preconditions for triggering the stall are:
* rs.length >= rs.highWaterMark
* !rs.needReadable
* _transform() handler that can return empty transforms
* multiple sync write() calls
Combined this can trigger a case where rs.reading is not cleared when
further progress requires this. The fix is to always clear rs.reading.
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.
The refactor in b43e544140 to use
stream.push() in Transform inadvertently caused it to immediately
consume all the written data, regardless of whether or not the readable
side was being consumed.
Only pull data through the _transform() process when the readable side
is being consumed.
Fix#4667
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
This also slightly changes the semantics, in that a 'readable'
event may be triggered by the first write() call, even if a
user has not yet called read().
This happens because the Transform _write() handler is calling
read(0) to start the flow of data. Technically, the new behavior
is more 'correct', since it is more in line with the semantics
of the 'readable' event in other streams.
Gil Pedersen
isaacs
Raynos