Re: copy and mutableCopy
Re: copy and mutableCopy
- Subject: Re: copy and mutableCopy
- From: ChanMaxthon <email@hidden>
- Date: Mon, 28 Apr 2014 01:54:11 +0800
You know you can mmap(2) COW pages if kernel or hardware supports it right? GNUstep used COW implemented by sharing pointers (no kernel or hardware support needed) which is obvious, Apple can implement COW by using COW pages (kernel or hardware supported)
COW pages cannot be told apart from copied pages but if you trap into kernel you can see the difference.
Sent from my iPhone
> On Apr 28, 2014, at 12:54 AM, Jens Alfke <email@hidden> wrote:
>
>
>> On Apr 27, 2014, at 4:06 AM, Maxthon Chan <email@hidden> wrote:
>>
>> Immutables copied are just retained and returned, and mutableCopied are COW.
>> Mutables copied generates COW.
>
> Hmm. Got any proof of the copy-on-write behavior? I’ve never heard of that being implemented in CF/Foundation classes.
>
>> That would be the fastest way implementing that.
>
> The “would” makes it sound as though you’re just speculating. If you are, please make that more clear.
>
> —Jens
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