ClickHouse/dbms/src/IO/MMapReadBufferFromFile.cpp
2018-06-13 05:52:03 +03:00

73 lines
1.5 KiB
C++

#include <unistd.h>
#include <fcntl.h>
#include <Common/ProfileEvents.h>
#include <Common/formatReadable.h>
#include <IO/MMapReadBufferFromFile.h>
namespace ProfileEvents
{
extern const Event FileOpen;
extern const Event FileOpenFailed;
}
namespace DB
{
namespace ErrorCodes
{
extern const int FILE_DOESNT_EXIST;
extern const int CANNOT_OPEN_FILE;
extern const int CANNOT_CLOSE_FILE;
}
void MMapReadBufferFromFile::open(const std::string & file_name)
{
ProfileEvents::increment(ProfileEvents::FileOpen);
fd = ::open(file_name.c_str(), O_RDONLY);
if (-1 == fd)
{
ProfileEvents::increment(ProfileEvents::FileOpenFailed);
throwFromErrno("Cannot open file " + file_name, errno == ENOENT ? ErrorCodes::FILE_DOESNT_EXIST : ErrorCodes::CANNOT_OPEN_FILE);
}
}
MMapReadBufferFromFile::MMapReadBufferFromFile(const std::string & file_name, size_t offset, size_t length)
{
open(file_name);
init(fd, offset, length);
}
MMapReadBufferFromFile::MMapReadBufferFromFile(const std::string & file_name, size_t offset)
{
open(file_name);
init(fd, offset);
}
MMapReadBufferFromFile::~MMapReadBufferFromFile()
{
if (fd != -1)
close(); /// Exceptions will lead to std::terminate and that's Ok.
}
void MMapReadBufferFromFile::close()
{
finish();
if (0 != ::close(fd))
throw Exception("Cannot close file", ErrorCodes::CANNOT_CLOSE_FILE);
fd = -1;
metric_increment.destroy();
}
}