ClickHouse/dbms/include/DB/IO/WriteBufferFromFile.h

99 lines
2.1 KiB
C++

#pragma once
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <DB/Common/ProfileEvents.h>
#include <DB/Common/CurrentMetrics.h>
#include <DB/IO/WriteBufferFromFileDescriptor.h>
namespace ProfileEvents
{
extern const Event FileOpen;
}
namespace CurrentMetrics
{
extern const Metric OpenFileForWrite;
}
namespace DB
{
namespace ErrorCodes
{
extern const int FILE_DOESNT_EXIST;
extern const int CANNOT_OPEN_FILE;
extern const int CANNOT_CLOSE_FILE;
}
/** Accepts path to file and opens it, or pre-opened file descriptor.
* Closes file by himself (thus "owns" a file descriptor).
*/
class WriteBufferFromFile : public WriteBufferFromFileDescriptor
{
private:
std::string file_name;
CurrentMetrics::Increment metric_increment{CurrentMetrics::OpenFileForWrite};
public:
WriteBufferFromFile(const std::string & file_name_, size_t buf_size = DBMS_DEFAULT_BUFFER_SIZE, int flags = -1, mode_t mode = 0666,
char * existing_memory = nullptr, size_t alignment = 0)
: WriteBufferFromFileDescriptor(-1, buf_size, existing_memory, alignment), file_name(file_name_)
{
ProfileEvents::increment(ProfileEvents::FileOpen);
fd = open(file_name.c_str(), flags == -1 ? O_WRONLY | O_TRUNC | O_CREAT : flags, mode);
if (-1 == fd)
throwFromErrno("Cannot open file " + file_name, errno == ENOENT ? ErrorCodes::FILE_DOESNT_EXIST : ErrorCodes::CANNOT_OPEN_FILE);
}
/// Use pre-opened file descriptor.
WriteBufferFromFile(int fd, size_t buf_size = DBMS_DEFAULT_BUFFER_SIZE, int flags = -1, mode_t mode = 0666,
char * existing_memory = nullptr, size_t alignment = 0)
: WriteBufferFromFileDescriptor(fd, buf_size, existing_memory, alignment), file_name("(fd = " + toString(fd) + ")")
{
}
~WriteBufferFromFile()
{
if (fd < 0)
return;
try
{
next();
}
catch (...)
{
tryLogCurrentException(__PRETTY_FUNCTION__);
}
::close(fd);
}
/// Close file before destruction of object.
void close()
{
next();
if (0 != ::close(fd))
throw Exception("Cannot close file", ErrorCodes::CANNOT_CLOSE_FILE);
fd = -1;
metric_increment.destroy();
}
std::string getFileName() const override
{
return file_name;
}
};
}