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#include <sys/mman.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <Common/ProfileEvents.h>
#include <Common/formatReadable.h>
#include <Common/Exception.h>
#include <Common/filesystemHelpers.h>
#include <base/getPageSize.h>
#include <IO/WriteHelpers.h>
#include <IO/MMapReadBufferFromFileDescriptor.h>
namespace DB
{
namespace ErrorCodes
{
extern const int ARGUMENT_OUT_OF_BOUND;
extern const int CANNOT_SEEK_THROUGH_FILE;
}
void MMapReadBufferFromFileDescriptor::init()
{
size_t length = mapped.getLength();
BufferBase::set(mapped.getData(), length, 0);
size_t page_size = static_cast<size_t>(::getPageSize());
ReadBuffer::padded = (length % page_size) > 0 && (length % page_size) <= (page_size - (PADDING_FOR_SIMD - 1));
}
MMapReadBufferFromFileDescriptor::MMapReadBufferFromFileDescriptor(int fd, size_t offset, size_t length)
: mapped(fd, offset, length)
{
init();
}
MMapReadBufferFromFileDescriptor::MMapReadBufferFromFileDescriptor(int fd, size_t offset)
: mapped(fd, offset)
{
init();
}
void MMapReadBufferFromFileDescriptor::finish()
{
mapped.finish();
}
std::string MMapReadBufferFromFileDescriptor::getFileName() const
{
return "(fd = " + toString(mapped.getFD()) + ")";
}
int MMapReadBufferFromFileDescriptor::getFD() const
{
return mapped.getFD();
}
off_t MMapReadBufferFromFileDescriptor::getPosition()
{
return count();
}
off_t MMapReadBufferFromFileDescriptor::seek(off_t offset, int whence)
{
off_t new_pos;
if (whence == SEEK_SET)
new_pos = offset;
else if (whence == SEEK_CUR)
new_pos = count() + offset;
else
throw Exception(ErrorCodes::ARGUMENT_OUT_OF_BOUND, "MMapReadBufferFromFileDescriptor::seek expects SEEK_SET or SEEK_CUR as whence");
working_buffer = internal_buffer;
if (new_pos < 0 || new_pos > off_t(working_buffer.size()))
throw Exception(ErrorCodes::CANNOT_SEEK_THROUGH_FILE,
"Cannot seek through file {} because seek position ({}) is out of bounds [0, {}]",
getFileName(), new_pos, working_buffer.size());
position() = working_buffer.begin() + new_pos;
return new_pos;
}
size_t MMapReadBufferFromFileDescriptor::getFileSize()
{
return getSizeFromFileDescriptor(getFD(), getFileName());
}
size_t MMapReadBufferFromFileDescriptor::readBigAt(char * to, size_t n, size_t offset, const std::function<bool(size_t)> &)
{
if (offset >= mapped.getLength())
return 0;
n = std::min(n, mapped.getLength() - offset);
memcpy(to, mapped.getData() + offset, n);
return n;
}
}
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