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stream: fix highWaterMark integer overflow #12593

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tniessen wants to merge 4 commits into from
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stream: fix highWaterMark integer overflow #12593

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9344665
stream: fix highWaterMark integer overflow
tniessen May 10, 2017
5e110e1
Use MAX_SAFE_INTEGER instead of 2^31-1
tniessen May 10, 2017
94e6081
Add test description
tniessen May 11, 2017
a15dacd
Use floor instead of trunc
tniessen May 15, 2017
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2 changes: 1 addition & 1 deletion lib/_stream_readable.js
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Expand Up @@ -72,7 +72,7 @@ function ReadableState(options, stream) {
this.highWaterMark = (hwm || hwm === 0) ? hwm : defaultHwm;

// cast to ints.
this.highWaterMark = ~~this.highWaterMark;
this.highWaterMark = Math.trunc(this.highWaterMark);

@mscdex mscdex May 14, 2017 •
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Actually, I think we may want to use Math.floor() instead, it seems to be significantly faster (~6x at least on V8 5.8).

@mcollina mcollina May 15, 2017

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👍

@mcollina mcollina May 15, 2017

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@tniessen can you update that?

@tniessen tniessen May 15, 2017

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Done.


// A linked list is used to store data chunks instead of an array because the
// linked list can remove elements from the beginning faster than
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2 changes: 1 addition & 1 deletion lib/_stream_writable.js
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Expand Up @@ -55,7 +55,7 @@ function WritableState(options, stream) {
this.highWaterMark = (hwm || hwm === 0) ? hwm : defaultHwm;

// cast to ints.
this.highWaterMark = ~~this.highWaterMark;
this.highWaterMark = Math.trunc(this.highWaterMark);

// drain event flag.
this.needDrain = false;
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11 changes: 11 additions & 0 deletions test/parallel/test-streams-highwatermark.js
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@@ -0,0 +1,11 @@
'use strict';

require('../common');
const assert = require('assert');
const stream = require('stream');

const readable = stream.Readable({ highWaterMark: 2147483648 });

@cjihrig cjihrig May 10, 2017

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Can you move all of the 2147483648s into a variable, and add a comment on why that specific value was chosen. That should prevent anyone from changing it to a small value in the future.

@mscdex mscdex May 10, 2017

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I think a better value to test is Number.MAX_SAFE_INTEGER.

@tniessen tniessen May 10, 2017

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@mscdex Done.

assert.strictEqual(readable._readableState.highWaterMark, 2147483648);

const writable = stream.Writable({ highWaterMark: 2147483648 });
assert.strictEqual(writable._writableState.highWaterMark, 2147483648);