diff --git a/lib/_stream_readable.js b/lib/_stream_readable.js index 0b5cac6b8376e3..029faaa6142d96 100644 --- a/lib/_stream_readable.js +++ b/lib/_stream_readable.js @@ -383,7 +383,10 @@ Readable.prototype.read = function(n) { // the 'readable' event and move on. if (n === 0 && state.needReadable && - (state.length >= state.highWaterMark || state.ended)) { + ((state.highWaterMark !== 0 ? + state.length >= state.highWaterMark : + state.length > 0) || + state.ended)) { debug('read: emitReadable', state.length, state.ended); if (state.length === 0 && state.ended) endReadable(this); @@ -808,6 +811,7 @@ Readable.prototype.on = function(ev, fn) { if (!state.endEmitted && !state.readableListening) { state.readableListening = state.needReadable = true; state.emittedReadable = false; + debug('on readable', state.length, state.reading); if (state.length) { emitReadable(this); } else if (!state.reading) { diff --git a/test/parallel/test-readable-single-end.js b/test/parallel/test-readable-single-end.js new file mode 100644 index 00000000000000..0969d49aa48e98 --- /dev/null +++ b/test/parallel/test-readable-single-end.js @@ -0,0 +1,16 @@ +'use strict'; + +const common = require('../common'); +const { Readable } = require('stream'); + +// This test ensures that there will not be an additional empty 'readable' +// event when stream has ended (only 1 event signalling about end) + +const r = new Readable({ + read: () => {}, +}); + +r.push(null); + +r.on('readable', common.mustCall()); +r.on('end', common.mustCall()); diff --git a/test/parallel/test-stream-readable-hwm-0.js b/test/parallel/test-stream-readable-hwm-0.js new file mode 100644 index 00000000000000..ecbc197d48208f --- /dev/null +++ b/test/parallel/test-stream-readable-hwm-0.js @@ -0,0 +1,30 @@ +'use strict'; + +const common = require('../common'); + +// This test ensures that Readable stream will call _read() for streams +// with highWaterMark === 0 upon .read(0) instead of just trying to +// emit 'readable' event. + +const assert = require('assert'); +const { Readable } = require('stream'); + +const r = new Readable({ + // must be called only once upon setting 'readable' listener + read: common.mustCall(), + highWaterMark: 0, +}); + +let pushedNull = false; +// this will trigger read(0) but must only be called after push(null) +// because the we haven't pushed any data +r.on('readable', common.mustCall(() => { + assert.strictEqual(r.read(), null); + assert.strictEqual(pushedNull, true); +})); +r.on('end', common.mustCall()); +process.nextTick(() => { + assert.strictEqual(r.read(), null); + pushedNull = true; + r.push(null); +}); diff --git a/test/pseudo-tty/test-readable-tty-keepalive.js b/test/pseudo-tty/test-readable-tty-keepalive.js new file mode 100644 index 00000000000000..4cf0b9fb2963f9 --- /dev/null +++ b/test/pseudo-tty/test-readable-tty-keepalive.js @@ -0,0 +1,29 @@ +'use strict'; + +const common = require('../common'); +const assert = require('assert'); + +// This test ensures that Node.js will not ignore tty 'readable' subscribers +// when it's the only tty subscriber and the only thing keeping event loop alive +// https://github.com/nodejs/node/issues/20503 + +process.stdin.setEncoding('utf8'); + +const expectedInput = ['foo', 'bar', null]; + +process.stdin.on('readable', common.mustCall(function() { + const data = process.stdin.read(); + assert.strictEqual(data, expectedInput.shift()); +}, 3)); // first 2 data, then end + +process.stdin.on('end', common.mustCall()); + +setTimeout(() => { + process.stdin.push('foo'); + process.nextTick(() => { + process.stdin.push('bar'); + process.nextTick(() => { + process.stdin.push(null); + }); + }); +}, 1); diff --git a/test/pseudo-tty/test-readable-tty-keepalive.out b/test/pseudo-tty/test-readable-tty-keepalive.out new file mode 100644 index 00000000000000..e69de29bb2d1d6