[squid-dev] [PATCH] Increase request buffer size to 64kb

[Alex Rousskov]

On 04/13/2016 06:29 PM, Amos Jeffries wrote:
> On 14/04/2016 4:18 a.m., Alex Rousskov wrote:
>> On 04/13/2016 08:22 AM, Amos Jeffries wrote:
>>> I am wondering if the class StoreIOBuffer needs to have move
>>> constructor/assignment added now that getClientStreamBuffer() is
>>> returning a temporary variable by-value.


>> Sorry, I do not follow your logic:
>>
>> 1. AFAIK, move methods are _optimizations_ so any "X needs move
>> constructor/assignment" statement does not compute for me in a seemingly
>> non-optimization context like "getClientStreamBuffer() is returning a
>> temporary variable by-value".
>>
>> 2. AFAIK, StoreIOBuffer already has move constructor and assignment
>> operator (provided by the compiler).


> I was wondering if we were paying unnecessary cycles doing the object
> data copy. If it's provided then thats fine and I'm happy with this if you are.

Yes, I believe that we can assume that the compiler provides a move
constructor for StoreIOBuffer. However, that move constructor does not
optimize any "object data copy" AFAICT. StoreIOBuffer is essentially a
POD so the entire object (about 20 bytes) gets "copied" and nothing can
be "moved" instead, even if we write something by hand. One cannot
"move" an integer or a raw pointer!

This is a new area for me, but I think that "move" methods optimize
copying of objects that have non-trivial copy constructors and
destructors. By definition, PODs do not have those. StoreIOBuffer does
not either. Am I missing something?


Thank you,

Alex.