readline: key interval delay for \r & \n #8109

princejwesley · 2016-08-15T12:23:48Z

Checklist

make -j4 test (UNIX), or vcbuild test nosign (Windows) passes
tests and/or benchmarks are included
commit message follows commit guidelines

Affected core subsystem(s)

readline

Description of change

Emit two line events when there is a delay between
CR('\r') and LF('\n')

cjihrig · 2016-08-15T14:16:50Z

test/parallel/test-readline-interface.js

@@ -199,6 +199,27 @@ function isWarned(emitter) {
  assert.equal(callCount, expectedLines.length);
  rli.close();

+  // Emit two line events where there is a delay
+  //   between \r and \n
+  (() => {


Can you drop this style and just wrap this portion of the test in curly braces. That will provide the block scope you want.

Fishrock123 · 2016-08-15T14:17:36Z

@princejwesley Could you give an example as to how to induce the problem this fixes?

\r\n (\n after \r) is a grapheme iirc aka one character

Fishrock123 · 2016-08-15T14:20:29Z

CI: https://ci.nodejs.org/job/node-test-pull-request/3673/

princejwesley · 2016-08-15T14:52:20Z

@Fishrock123

This is how I reproduced in macOS. Run the below snippet and hit enter/return for (\r) and ctrl + j for (\n). You can try with repl too.

const readline = require('readline');

const rli = new readline.Interface({
    input: process.stdin,
    output: process.stdout,
    terminal: true
});
let count = 0;
rli.on('line', function(line) {
    count++;
    console.log(`line event triggered ${count}`);
});

Edit: \r\n - two characters. Here is the interesting history behind it

jasnell · 2016-08-15T15:47:42Z

It may be better to make the delay period configurable

mscdex · 2016-08-15T16:28:39Z

I think if we're going to add a delay, it should definitely be configurable (with some sensible default but allowing to opt out altogether -- perhaps with a 0 value).

princejwesley · 2016-08-15T18:05:44Z

@mscdex Delay is introduced to differentiate whether its a system that emits \r\n for a single newline or a user or both. Setting delay as zero will nullify this fix.

In nutshell, this PR tries to figure out whether \n is an individual event or the tail of \r(emitted by the system for newline).

Current experience,

~ 🙈 node
> // I hit enter - that emits CR(\r)
> // now I hit `ctrl + j ` to emit LF(\n) - no newline

mscdex · 2016-08-15T18:19:09Z

@princejwesley I understand, but I think it would be useful to be able to explicitly tell readline what to check for instead of trying to guess by adding a delay, whether that's setting 0 for the delay or setting some other option/flag.

princejwesley · 2016-08-15T18:47:46Z

@mscdex I'll update the PR with configurable option. Shall I use crLfDelay or any better name?

mscdex · 2016-08-15T21:58:56Z

lib/readline.js

  }
  return rl;
 };


-function Interface(input, output, completer, terminal) {
+function Interface(input, output, completer, terminal,
+    crLfDelay = kCRLFDelayInMillis) {


IMHO this should line up with the input parameter.

mscdex · 2016-08-15T22:02:04Z

@princejwesley I don't really have a preference on the name. Although personally I think if it starts with 'CRLF', that prefix would look better lowercased (crlf) instead of mixed cased (crLf).

princejwesley · 2016-08-16T04:13:26Z

@mscdex Updated. CI: https://ci.nodejs.org/job/node-test-pull-request/3686/

jasnell · 2016-08-16T15:08:12Z

doc/api/readline.md

@@ -358,6 +358,9 @@ added: v0.1.98
    only if `terminal` is set to `true` by the user or by an internal `output`
    check, otherwise the history caching mechanism is not initialized at all.
  * `prompt` - the prompt string to use. Default: `'> '`
+  * `crlfDelay` {number} If the delay between `\r` and `\n` exceeds
+    `crlfDelay`, both `\r` and `\n` will be treated as separate end-of-line


Suggestion: s/exceeds crlfDelay/exceeds crlfDelay milliseconds

also... should there be a maximum delay? And how does one turn off the delay entirely? In other APIs, we've used setting the value explicitly to 0 or null or Infinity to turn it off.

I am not sure about the maximum delay but minimum delay should not be zero. the reason is subsequent events(\r followed by \n) may have latency greater than or equal to 1ms. It will obviously break windows system.
What do you suggest ? 10ms as minimum delay?

That should work.

I am afraid to put 10ms (seems low because of context switches and other factors). Now I set [100, 2000] as range. It will go few more rounds to come up with better range 😄

princejwesley · 2016-08-17T18:57:57Z

CI: https://ci.nodejs.org/job/node-test-pull-request/3712/

princejwesley · 2016-08-20T18:45:04Z

Another attempt, CI: https://ci.nodejs.org/job/node-test-pull-request/3766/

yorkie · 2016-08-20T18:56:30Z

test/parallel/test-readline-interface.js

+  rli = new readline.Interface({ input: fi, output: fi, crlfDelay: 1 << 30});
+  assert.strictEqual(rli.crlfDelay, 2000);
+  rli.close();
+}


To 3 separate scopes?

@yorkie done

Emit two line events when there is a delay between CR('\r') and LF('\n')

yorkie · 2016-08-21T08:54:55Z

test/parallel/test-readline-interface.js

+      callCount++;
+    });
+    fi.emit('data', '\r');
+    setTimeout(() => {


Wrap this function with common.mustCall?

yorkie · 2016-08-24T08:14:59Z

LGTM :)

princejwesley · 2016-08-26T03:25:09Z

CI: https://ci.nodejs.org/job/node-test-pull-request/3840/

princejwesley · 2016-08-26T17:47:24Z

@jasnell @Fishrock123 @mscdex PTAL

jasnell · 2016-08-26T17:56:52Z

LGTM

mscdex · 2016-08-26T20:58:36Z

LGTM

princejwesley · 2016-08-28T13:57:41Z

Trying again for green build: https://ci.nodejs.org/job/node-test-pull-request/3865/

jasnell · 2016-08-30T21:03:51Z

build bot failure on the last CI run... trying one final time for green: https://ci.nodejs.org/job/node-test-pull-request/3897/

princejwesley · 2016-08-31T00:49:41Z

@jasnell failed again 😞

jasnell · 2016-08-31T16:44:17Z

@nodejs/build @jbergstroem ... can someone take a look to see what's happening with the arm build bot on this?

princejwesley · 2016-09-02T05:21:09Z

ping @nodejs/build

princejwesley · 2016-09-05T14:23:19Z

@jasnell I see full of red & unstable CI jobs. I'll trigger build after few days to get green build

jbergstroem · 2016-09-05T16:06:39Z

We've fixed the arm issues; disk-related. Please try again!

princejwesley · 2016-09-05T16:09:33Z

CI: https://ci.nodejs.org/job/node-test-pull-request/3943/
Another attempt: https://ci.nodejs.org/job/node-test-pull-request/3955/

Last CI run: https://ci.nodejs.org/job/node-test-pull-request/3959/ (unstable)
Trying again: https://ci.nodejs.org/job/node-test-pull-request/3960/

princejwesley · 2016-09-08T13:27:14Z

@jbergstroem last two build attempts - unstable. can you take a look?

jbergstroem · 2016-09-08T13:45:14Z

@princejwesley 3959,3960 looked good though! Flaky is fine -- it means a test is known to fail.

Emit two line events when there is a delay between CR('\r') and LF('\n'). Introduced a new option `crlfDelay`. If the delay between \r and \n exceeds `crlfDelay` milliseconds, both \r and \n will be treated as separate end-of-line input. Default to 100 milliseconds. `crlfDelay` will be coerced to [100, 2000] range. PR-URL: #8109 Reviewed-By: Yorkie Liu <yorkiefixer@gmail.com> Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Brian White <mscdex@mscdex.net>

princejwesley · 2016-09-08T15:16:36Z

Landed in a634554

Emit two line events when there is a delay between CR('\r') and LF('\n'). Introduced a new option `crlfDelay`. If the delay between \r and \n exceeds `crlfDelay` milliseconds, both \r and \n will be treated as separate end-of-line input. Default to 100 milliseconds. `crlfDelay` will be coerced to [100, 2000] range. PR-URL: #8109 Reviewed-By: Yorkie Liu <yorkiefixer@gmail.com> Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Brian White <mscdex@mscdex.net>

nodejs-github-bot added the readline Issues and PRs related to the built-in readline module. label Aug 15, 2016

cjihrig reviewed Aug 15, 2016
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mscdex reviewed Aug 15, 2016
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princejwesley force-pushed the readline-lf branch from b85b036 to 587646a Compare August 16, 2016 04:10

Trott added the semver-minor PRs that contain new features and should be released in the next minor version. label Aug 16, 2016

jasnell reviewed Aug 16, 2016
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yorkie reviewed Aug 20, 2016
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princejwesley added 6 commits August 21, 2016 13:53

readline: key interval delay for \r & \n

0fb6ffb

Emit two line events when there is a delay between CR('\r') and LF('\n')

Braces for block scope

eb49af7

Configurable delay option

a13083d

option name & alignment fix

f5cf531

Coerce to Min/max range

515627c

scoped tests

3b1b84e

princejwesley force-pushed the readline-lf branch from 8d1d416 to 3b1b84e Compare August 21, 2016 08:36

yorkie reviewed Aug 21, 2016
View reviewed changes

wrap function with mustCall

9ed8f55

princejwesley closed this Sep 8, 2016

Azard mentioned this pull request Jun 6, 2017

readline: remove max limit of crlfDelay #13497

Closed

4 tasks

vsemozhetbyt mentioned this pull request Oct 8, 2017

readline: crlfDelay and fs streams #16077

Closed

readline: key interval delay for \r & \n #8109

readline: key interval delay for \r & \n #8109

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princejwesley commented Aug 15, 2016

Checklist

Affected core subsystem(s)

Description of change

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Fishrock123 commented Aug 15, 2016

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yorkie commented Aug 24, 2016

princejwesley commented Aug 26, 2016

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jasnell commented Aug 26, 2016

mscdex commented Aug 26, 2016

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jasnell commented Aug 30, 2016

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jasnell commented Aug 31, 2016

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