mirror of
https://github.com/ClickHouse/ClickHouse.git
synced 2024-09-20 16:50:48 +00:00
66 lines
1.7 KiB
C++
66 lines
1.7 KiB
C++
#include <iostream>
|
|
#include <iomanip>
|
|
|
|
#if __SSE2__
|
|
#include <emmintrin.h>
|
|
#endif
|
|
|
|
#include <common/Types.h>
|
|
#include <IO/ReadHelpers.h>
|
|
#include <IO/ReadBufferFromFileDescriptor.h>
|
|
|
|
/** Counts number of 0 in a file.
|
|
* Outputs "fullness" of file - ration of non-0 bytes to the expected number of non-0 bytes in file with random bytes.
|
|
*/
|
|
|
|
int main(int argc, char ** argv)
|
|
{
|
|
#if __SSE2__
|
|
try
|
|
{
|
|
DB::ReadBufferFromFileDescriptor in(STDIN_FILENO);
|
|
size_t zeros = 0;
|
|
UInt64 limit = 0;
|
|
|
|
if (argc == 2)
|
|
limit = DB::parse<UInt64>(argv[1]);
|
|
|
|
while (!in.eof())
|
|
{
|
|
const __m128i zero = {0};
|
|
for (; in.position() + 15 < in.buffer().end(); in.position() += 16)
|
|
{
|
|
__m128i bytes = *reinterpret_cast<const __m128i *>(in.position());
|
|
__m128i byte_mask = _mm_cmpeq_epi8(bytes, zero);
|
|
UInt16 bit_mask = _mm_movemask_epi8(byte_mask);
|
|
zeros += __builtin_popcount(bit_mask);
|
|
}
|
|
|
|
for (; in.position() < in.buffer().end(); ++in.position())
|
|
if (*in.position() == 0)
|
|
++zeros;
|
|
|
|
if (limit && in.count() >= limit)
|
|
break;
|
|
}
|
|
|
|
std::cout << std::fixed
|
|
<< 1 - std::max(0.0, static_cast<double>(zeros) / in.count() - 1.0 / 256)
|
|
<< std::endl;
|
|
}
|
|
catch (const DB::Exception & e)
|
|
{
|
|
std::cerr << e.what() << ", " << e.message() << std::endl
|
|
<< std::endl
|
|
<< "Stack trace:" << std::endl
|
|
<< e.getStackTrace().toString()
|
|
<< std::endl;
|
|
throw;
|
|
}
|
|
#else
|
|
std::cerr << "Only for x86_64 arch " << std::endl;
|
|
#endif
|
|
|
|
return 0;
|
|
}
|