Converting utf16 to utf8 costs a lot time

[JasonYang-MSFT]

As mentioned in the title, utf16_to_utf8 costs a lot time. For 1 MB utf16 string, it would costs 5 seconds on Win10 with E5-1620 machine. And the costs increased by linear, 11 seconds for 2 MB, 22 seconds for 4 MB e.g.

Here is the sample code:

#include "stdafx.h"
#include "cpprest/asyncrt_utils.h"

int main()
{
    int length = 1 * 1024 * 1024;
    utility::datetime start = utility::datetime::utc_now();
    utility::string_t text(length, _XPLATSTR('C'));
    auto content = utility::conversions::utf16_to_utf8(text);
    utility::datetime end = utility::datetime::utc_now();
    ucout << "String Length: " << length << std::endl;
    ucout << "Time Cost: " << end - start << " second(s)" << std::endl;
    return 0;
}

Is there a better way to do the conversion? Could the performance of utf16_to_utf8 be improved?

[grahamreeds]

This is minimally related to #72.

[JasonYang-MSFT]

72 was discussing about to avoid such kind of conversion. But I am more concerned about the conversion performance here.

[grahamreeds]

The fastest code is code that isn't ran, and I did say it was kind of related. Fixes in this area would help both.

Sent from my Nexus 6P

On 27 Sep 2016 04:47, "Jason Yang" notifications@github.com wrote:

72 https://github.com/Microsoft/cpprestsdk/issues/72 was discussing

about to avoid such kind of conversion. But I am more concerned about the conversion performance here.

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