stream: Fix readableState.awaitDrain mechanism

In 68990948fe4 (https://github.com/nodejs/node/pull/2325),
the conditions for increasing `readableState.awaitDrain` when
writing to a piping destination returns false were changed so
that they could not actually be met, effectively leaving
`readableState.awaitDrain` with a constant value of 0.

This patch changes the conditions to testing whether the
stream for which `.write()` returned false is still a piping
destination, which was likely the intention of the original
patch.

Fixes: https://github.com/nodejs/node/issues/5820
Fixes: https://github.com/nodejs/node/issues/5257
PR-URL: https://github.com/nodejs/node/pull/6023
Reviewed-By: Brian White <mscdex@mscdex.net>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

1 files changed, 3 insertions, 3 deletions

diff --git a/lib/_stream_readable.js b/lib/_stream_readable.js
index 338bf2a753..275691cbb2 100644
--- a/lib/_stream_readable.js
+++ b/lib/_stream_readable.js
@@ -538,9 +538,9 @@ Readable.prototype.pipe = function(dest, pipeOpts) {
       // If the user unpiped during `dest.write()`, it is possible
       // to get stuck in a permanently paused state if that write
       // also returned false.
-      if (state.pipesCount === 1 &&
-          state.pipes[0] === dest &&
-          src.listenerCount('data') === 1 &&
+      // => Check whether `dest` is still a piping destination.
+      if (((state.pipesCount === 1 && state.pipes === dest) ||
+           (state.pipesCount > 1 && state.pipes.indexOf(dest) !== -1)) &&
           !cleanedUp) {
         debug('false write response, pause', src._readableState.awaitDrain);
         src._readableState.awaitDrain++;