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sync/atomic: explain how to add -1 using AddUint32 #6408

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gopherbot opened this issue Sep 17, 2013 · 7 comments
Closed

sync/atomic: explain how to add -1 using AddUint32 #6408

gopherbot opened this issue Sep 17, 2013 · 7 comments
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Documentation FrozenDueToAge
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Go1.2

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@gopherbot
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by runner.mei:

Add atomic Sub* operation to sync/atomic package.

func SubUint32(addr *uint32, new uint32) (old uint32)
func SubUint64(addr *uint64, new uint64) (old uint64)

Add and Sub is useful for stats counters
@minux
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minux commented Sep 17, 2013

Comment 1:

Sub(x) could be emulated by Add(1<<width-x), so why introducing more APIs?

@gopherbot
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Comment 2 by runner.mei:

It's not very friendly for most programmers (like me)，this is too hard

@robpike
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robpike commented Sep 17, 2013

Comment 3:

Also AddInt32(-int32(x))

@davecheney
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Comment 4:

I will add some examples to the package to show how Sub can be implemented.

Labels changed: added priority-later, go1.2maybe, documentation, removed priority-triage.

Owner changed to @davecheney.

Status changed to Accepted.

@rsc
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rsc commented Sep 17, 2013

Comment 5:

SubUint32(addr, x) is AddUint32(addr, -x). This part isn't even worth a comment.
The only time this is awkward is when x is a constant and you're using an unsigned type.
I think that's a more general issue with constants, although not one I have a solution
to.
The easiest fix is to use a signed count.

@robpike
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robpike commented Oct 3, 2013

Comment 7:

This issue was closed by revision c457963.

Status changed to Fixed.

@bradfitz
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bradfitz commented Nov 3, 2013

Comment 8:

Issue #6711 has been merged into this issue.

@bradfitz bradfitz mentioned this issue Dec 8, 2014
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@rsc rsc added this to the Go1.2 milestone Apr 14, 2015
@rsc rsc removed the go1.2maybe label Apr 14, 2015
@golang golang locked and limited conversation to collaborators Jun 25, 2016
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@bradfitz @davecheney @rsc @minux @robpike @gopherbot