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Re: Accessing buffers in NSData/NSMutableData under garbage collection
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Re: Accessing buffers in NSData/NSMutableData under garbage collection


  • Subject: Re: Accessing buffers in NSData/NSMutableData under garbage collection
  • From: Chris Suter <email@hidden>
  • Date: Wed, 20 Feb 2008 10:59:53 +1100


On 20/02/2008, at 10:35 AM, Quincey Morris wrote:


On Feb 19, 2008, at 14:42, Chris Suter wrote:

The only solution that I can see is viable is the one I proposed— use autoreleased memory for these kinds of temporary objects.

OK, I'll fess up and admit I don't know what this means. At what point does the lifetime of such an object end?

It's exactly the same as how it used to work in the non GC world. In the old world -[NSString UTF8String] would have created an auto- released object (that you don't get to access) and when it gets released (i.e. when the associated auto-release pool gets released) the memory pointed to by --[NSString UTF8String] gets released. The problem with it is that it relies on you releasing an auto-release pool periodically (or equivalent) which is fine for the main thread but it's a pain to ask the user to do that for secondary threads—so maybe it's not the best solution after all. :-)


Thinking about it now, maybe a better way is if you can flag return values to the compiler so that the compiler ensures that the return value is left on the stack or in a register for the lifetime of the callers stack frame. But then that has its own issues—you can't reclaim the memory until the function returns.

Hmm, it's a tricky one to solve. Thankfully I don't have to solve it and I'm not using GC.

- Chris

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References: 
 >Accessing buffers in NSData/NSMutableData under garbage collection (From: Rick Hoge <email@hidden>)
 >Re: Accessing buffers in NSData/NSMutableData under garbage collection (From: Adam P Jenkins <email@hidden>)
 >Re: Accessing buffers in NSData/NSMutableData under garbage collection (From: mmalc crawford <email@hidden>)
 >Re: Accessing buffers in NSData/NSMutableData under garbage collection (From: Adam P Jenkins <email@hidden>)
 >Re: Accessing buffers in NSData/NSMutableData under garbage collection (From: Adam P Jenkins <email@hidden>)
 >Re: Accessing buffers in NSData/NSMutableData under garbage collection (From: Chris Suter <email@hidden>)
 >Re: Accessing buffers in NSData/NSMutableData under garbage collection (From: Alastair Houghton <email@hidden>)
 >Re: Accessing buffers in NSData/NSMutableData under garbage collection (From: Quincey Morris <email@hidden>)
 >Re: Accessing buffers in NSData/NSMutableData under garbage collection (From: "Michael Ash" <email@hidden>)
 >Re: Accessing buffers in NSData/NSMutableData under garbage collection (From: Quincey Morris <email@hidden>)
 >Re: Accessing buffers in NSData/NSMutableData under garbage collection (From: Chris Suter <email@hidden>)
 >Re: Accessing buffers in NSData/NSMutableData under garbage collection (From: Quincey Morris <email@hidden>)

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