[webkit-dev] size_t vs unsigned in WTF::Vector API ?
mjs at apple.com
Thu Nov 20 16:51:46 PST 2014
> On Nov 20, 2014, at 9:26 AM, Alexey Proskuryakov <ap at webkit.org> wrote:
> 19 нояб. 2014 г., в 14:58, Alexey Proskuryakov <ap at webkit.org <mailto:ap at webkit.org>> написал(а):
>> These and related uses are all over the place - see also Vectors in FormDataBuilder, data returned from FrameLoader::loadResourceSynchronously, plug-in code that loads from network, SharedBuffer etc.
> Another way to say this is: we need to deal with large data arrays throughout loading code. We do not really need full size vectors in most other code - it's sort of OK for HTML parser or for image decoder to fail catastrophically when there is too much data fed to it.
> This is somewhat questionable design, but if we are going to stick to it, then magnitude checks should be centralized, not sprinkled throughout the code. We should not make this check explicitly when feeding a network resource to the parser, for example.
> A 64-bit API for Vector solves this nearly flawlessly. We do not perform the checks manually every time we use a Vector, Vector does them for us.
> Other options are:
> - uint64_t everywhere. This way, we'll solve practical problems with large resources once and for all. Also, this may prove to be necessary to solve even YouTube/Google Drive uploads, I do not know that yet.
> - size_t everywhere. Same effect on 64-bit platforms, while 32-bit ones will still be limited. I like this option, because it won't make us pay the memory and performance cost on old crippled 32-bit machines, which are unlikely to be used for manipulating huge volumes of data anyway.
We probably want YouTube upload of large files to work on 32-bit machines. Though presumably if you want to upload a file larger than the virtual address space, you need to represent it in some way other than a Vector.
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