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buffer: replace SlowBuffer with Buffer.allocUnsafeSlow(size) #5833

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@jasnell jasnell commented Mar 21, 2016

Pull Request check-list

  • Does make -j8 test (UNIX) or vcbuild test nosign (Windows) pass with
    this change (including linting)?
  • Is the commit message formatted according to [CONTRIBUTING.md][0]?
  • If this change fixes a bug (or a performance problem), is a regression
    test (or a benchmark) included?
  • Is a documentation update included (if this change modifies
    existing APIs, or introduces new ones)?

Affected core subsystem(s)

buffer

Description of change

  • Adds Buffer.allocUnsafeSlow() as a replacement for SlowBuffer
  • Soft-deprecate SlowBuffer

Essentially, this aligns the functionality of SlowBuffer with the new constructor API

Refs: #5799

/cc @ChALkeR @trevnorris

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@jasnell jasnell commented Mar 21, 2016

semver-major because of the docs-only deprecation.


When calling `Buffer.allocUnsafe()`, the segment of allocated memory is
*uninitialized* (it is not zeroed-out). While this design makes the allocation
of memory quite fast, the allocated segment of memory might contain old data
that is potentially sensitive. Using a `Buffer` created by
`Buffer.allocUnsafe(size)` without *completely* overwriting the memory can
allow this old data to be leaked when the `Buffer` memory is read.
`Buffer.allocUnsafe()` without *completely* overwriting the memory can allow

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There are two spaces in «the memory» for some reason.

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@ChALkeR ChALkeR commented Mar 21, 2016

Hm. Overall looks good, but I'm not sure on the exact syntax.

It seems to me that Buffer.allocUnsafe(10, true) is not very clear to someone who does not use (or see) it often. Pehaps adding an options argument would be better? E.g. Buffer.allocUnsafe(10, {pooled: false})?

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@jasnell jasnell commented Mar 21, 2016

The object would make sense if we'd ever expect there to be additional possible options. I don't think that's the case. Also, part of the point for adding it as a second parameter was to avoid making things unnecessarily complex for this case (as opposed to adding a new function, etc). I know it's less obvious what is happening, but I think it's appropriate here. But that's just me. What do you think @trevnorris ?

@jasnell jasnell modified the milestone: 6.0.0 Mar 22, 2016
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@trevnorris trevnorris commented Mar 22, 2016

Could also have Buffer.allocUnsafe(n, kUnpooled) as a bitwise flag. :P

Without writing any benchmarks, I think passing in the extra object isn't going to add much if any noticeable overhead. Though after watching the Buffer API evolve over the last several years I can't foresee needing to pass any other options. Possibly use the boolean, but also strict check that the argument is a boolean instead of coercing it.

@@ -118,12 +118,12 @@ Buffer.alloc = function(size, fill, encoding) {
* Equivalent to Buffer(num), by default creates a non-zero-filled Buffer
* instance. If `--zero-fill-buffers` is set, will zero-fill the buffer.
**/
Buffer.allocUnsafe = function(size) {
Buffer.allocUnsafe = function(size, unpooled) {

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something like:

if (unpooled !== undefined && typeof unpooled !== 'boolean')
  throw new TypeError('unpooled must be a boolean');
@jasnell jasnell force-pushed the jasnell:dep-slow-buffer branch Mar 22, 2016
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@jasnell jasnell commented Mar 22, 2016

@trevnorris ... added the additional type check.

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@trevnorris trevnorris commented Mar 23, 2016

Thanks. I'm cool with the new API, but would also like other's opinions.

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@jasnell jasnell commented Mar 23, 2016

@nodejs/ctc ... please weigh in :-)

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@jasnell jasnell commented Mar 24, 2016

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@Fishrock123 Fishrock123 commented Mar 29, 2016

I think I'd prefer the bitwise flag idea.

Pros:

  • more explicit
  • extensible if we need other booleans in the future

Cons:

  • bitwise flag

I'm not so for adding [, true] to the buffer apis, it's not very easy to tell what that is. Also, I can't imagine many people are actually using SlowBuffer.

@ChALkeR could you test npm to try to see who might be using this?

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@jasnell jasnell commented Mar 30, 2016

A bitwise flag sounds like a good compromise on this. I can't imagine that we'd actually add any more flags to this but you never know.

@jasnell jasnell force-pushed the jasnell:dep-slow-buffer branch 2 times, most recently Apr 1, 2016
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@jasnell jasnell commented Apr 1, 2016

@Fishrock123 @trevnorris ... switched to using a Bitwise field. PTAL

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@ChALkeR ChALkeR commented Apr 1, 2016

This approach looks better to me =).

@Fishrock123

@ChALkeR could you test npm to try to see who might be using this?

Using SlowBuffer or Buffer.allocUnsafe? The former won't be affected by this, and the latter isn't used yet because it just recently landed to master.

SlowBuffer( usage: https://gist.github.com/ChALkeR/43f3376f46b3d71e1e62ef37f643fb06

Note that this doesn't include on purpose pure instanceof SlowBuffer (which is broken btw) and SlowBuffer method redifinitions (there were some, copied in various modules, they mostly add some methods from Buffer to SlowBuffer for older Node.js versions).

Note: mocha has its own SlowBuffer that is not related to Node.js SlowBuffer, ignore that match. It affects many lines in the grep result.

@jasnell jasnell force-pushed the jasnell:dep-slow-buffer branch 2 times, most recently Apr 2, 2016
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@jasnell jasnell commented Apr 2, 2016

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@jasnell jasnell commented Apr 3, 2016

@jasnell jasnell changed the title buffer: replace SlowBuffer with Buffer.allocUnsafe(size, true) buffer: replace SlowBuffer with Buffer.allocUnsafe(size, Buffer.F_UNPOOLED) Apr 3, 2016
if (typeof size !== 'number')
throw new TypeError('"size" argument must be a number');
return allocate(size);
return ((allocflags & Buffer.F_UNPOOLED) === Buffer.F_UNPOOLED) ?
createBuffer(size) : allocate(size);

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It looks like this is missing the

    if (size > 0)
      flags[kNoZeroFill] = 1;

in the createBuffer case.

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Good catch.

@jasnell jasnell force-pushed the jasnell:dep-slow-buffer branch Apr 3, 2016
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@jasnell jasnell commented Apr 3, 2016

@ChALkeR ... updated! PTAL

jasnell added a commit that referenced this pull request Apr 15, 2016
PR-URL: #5833
Reviewed-By: Сковорода Никита Андреевич <chalkerx@gmail.com>
Reviewed-By: Trevor Norris <trev.norris@gmail.com>
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>
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@jasnell jasnell commented Apr 15, 2016

Landed in 6275249, 3fe204c, and a0579c0

@jasnell jasnell closed this Apr 15, 2016
@ChALkeR ChALkeR mentioned this pull request Apr 19, 2016
joelostrowski added a commit to joelostrowski/node that referenced this pull request Apr 25, 2016
Aligns the functionality of SlowBuffer with the new Buffer
constructor API. Next step is to docs-only deprecate
SlowBuffer.

Replace the internal uses of SlowBuffer with
`Buffer.allocUnsafeSlow(size)`

PR-URL: nodejs#5833
Reviewed-By: Сковорода Никита Андреевич <chalkerx@gmail.com>
Reviewed-By: Trevor Norris <trev.norris@gmail.com>
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>
joelostrowski added a commit to joelostrowski/node that referenced this pull request Apr 25, 2016
With the addition of `Buffer.allocUnsafeSlow(size)`
`SlowBuffer` can be deprecated... but docs-only for now.

PR-URL: nodejs#5833
Reviewed-By: Сковорода Никита Андреевич <chalkerx@gmail.com>
Reviewed-By: Trevor Norris <trev.norris@gmail.com>
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>
joelostrowski added a commit to joelostrowski/node that referenced this pull request Apr 25, 2016
PR-URL: nodejs#5833
Reviewed-By: Сковорода Никита Андреевич <chalkerx@gmail.com>
Reviewed-By: Trevor Norris <trev.norris@gmail.com>
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>
jasnell added a commit that referenced this pull request Apr 26, 2016
Aligns the functionality of SlowBuffer with the new Buffer
constructor API. Next step is to docs-only deprecate
SlowBuffer.

Replace the internal uses of SlowBuffer with
`Buffer.allocUnsafeSlow(size)`

PR-URL: #5833
Reviewed-By: Сковорода Никита Андреевич <chalkerx@gmail.com>
Reviewed-By: Trevor Norris <trev.norris@gmail.com>
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>
jasnell added a commit that referenced this pull request Apr 26, 2016
With the addition of `Buffer.allocUnsafeSlow(size)`
`SlowBuffer` can be deprecated... but docs-only for now.

PR-URL: #5833
Reviewed-By: Сковорода Никита Андреевич <chalkerx@gmail.com>
Reviewed-By: Trevor Norris <trev.norris@gmail.com>
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>
jasnell added a commit that referenced this pull request Apr 26, 2016
PR-URL: #5833
Reviewed-By: Сковорода Никита Андреевич <chalkerx@gmail.com>
Reviewed-By: Trevor Norris <trev.norris@gmail.com>
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>
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@ChALkeR ChALkeR commented May 5, 2016

Note that this change wasn't backported to 5.x, unlike all the other new Buffer API methods, which were backported in #5763.

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@ChALkeR ChALkeR commented Jun 5, 2016

@jasnell Backport to v5.x in #7169.

ChALkeR added a commit to ChALkeR/io.js that referenced this pull request Jul 8, 2016
This backports the new `Buffer.alloc()`, `Buffer.allocUnsafe()`,
`Buffer.from()`, and `Buffer.allocUnsafeSlow()` APIs for v4.

Some backported tests are disabled, but those are not related to the
new API.

Note that `Buffer.from(arrayBuffer[, byteOffset [, length]])` is not
supported in v4.x, only `Buffer.from(arrayBuffer)` is.

Refs: nodejs#4682
Refs: nodejs#5833
Refs: nodejs#7475
PR-URL: nodejs#7562
Reviewed-By: Trevor Norris <trev.norris@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Nikolai Vavilov <vvnicholas@gmail.com>
MylesBorins pushed a commit that referenced this pull request Jul 8, 2016
This backports the new `Buffer.alloc()`, `Buffer.allocUnsafe()`,
`Buffer.from()`, and `Buffer.allocUnsafeSlow()` APIs for v4.

Some backported tests are disabled, but those are not related to the
new API.

Note that `Buffer.from(arrayBuffer[, byteOffset [, length]])` is not
supported in v4.x, only `Buffer.from(arrayBuffer)` is.

Refs: #4682
Refs: #5833
Refs: #7475
PR-URL: #7562
Reviewed-By: Trevor Norris <trev.norris@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Nikolai Vavilov <vvnicholas@gmail.com>
MylesBorins pushed a commit that referenced this pull request Jul 11, 2016
This backports the new `Buffer.alloc()`, `Buffer.allocUnsafe()`,
`Buffer.from()`, and `Buffer.allocUnsafeSlow()` APIs for v4.

Some backported tests are disabled, but those are not related to the
new API.

Note that `Buffer.from(arrayBuffer[, byteOffset [, length]])` is not
supported in v4.x, only `Buffer.from(arrayBuffer)` is.

Refs: #4682
Refs: #5833
Refs: #7475
PR-URL: #7562
Reviewed-By: Trevor Norris <trev.norris@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Nikolai Vavilov <vvnicholas@gmail.com>
MylesBorins pushed a commit that referenced this pull request Jul 12, 2016
This backports the new `Buffer.alloc()`, `Buffer.allocUnsafe()`,
`Buffer.from()`, and `Buffer.allocUnsafeSlow()` APIs for v4.

Some backported tests are disabled, but those are not related to the
new API.

Note that `Buffer.from(arrayBuffer[, byteOffset [, length]])` is not
supported in v4.x, only `Buffer.from(arrayBuffer)` is.

Refs: #4682
Refs: #5833
Refs: #7475
PR-URL: #7562
Reviewed-By: Trevor Norris <trev.norris@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Nikolai Vavilov <vvnicholas@gmail.com>
MylesBorins pushed a commit that referenced this pull request Jul 14, 2016
This backports the new `Buffer.alloc()`, `Buffer.allocUnsafe()`,
`Buffer.from()`, and `Buffer.allocUnsafeSlow()` APIs for v4.

Some backported tests are disabled, but those are not related to the
new API.

Note that `Buffer.from(arrayBuffer[, byteOffset [, length]])` is not
supported in v4.x, only `Buffer.from(arrayBuffer)` is.

Refs: #4682
Refs: #5833
Refs: #7475
PR-URL: #7562
Reviewed-By: Trevor Norris <trev.norris@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Nikolai Vavilov <vvnicholas@gmail.com>
MylesBorins pushed a commit that referenced this pull request Jul 14, 2016
This backports the new `Buffer.alloc()`, `Buffer.allocUnsafe()`,
`Buffer.from()`, and `Buffer.allocUnsafeSlow()` APIs for v4.

Some backported tests are disabled, but those are not related to the
new API.

Note that `Buffer.from(arrayBuffer[, byteOffset [, length]])` is not
supported in v4.x, only `Buffer.from(arrayBuffer)` is.

Refs: #4682
Refs: #5833
Refs: #7475
PR-URL: #7562
Reviewed-By: Trevor Norris <trev.norris@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Nikolai Vavilov <vvnicholas@gmail.com>
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