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59 lines
1.7 KiB
C++
59 lines
1.7 KiB
C++
#pragma once
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <DB/IO/WriteBufferFromFileDescriptor.h>
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namespace DB
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{
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/** Принимает имя файла. Самостоятельно открывает и закрывает файл.
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*/
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class WriteBufferFromFile : public WriteBufferFromFileDescriptor
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{
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private:
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std::string file_name;
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public:
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WriteBufferFromFile(const std::string & file_name_, size_t buf_size = DBMS_DEFAULT_BUFFER_SIZE, int flags = -1, mode_t mode = 0666)
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: WriteBufferFromFileDescriptor(-1, buf_size), file_name(file_name_)
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{
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fd = open(file_name.c_str(), flags == -1 ? O_WRONLY | O_TRUNC | O_CREAT : flags, mode);
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if (-1 == fd)
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throwFromErrno("Cannot open file " + file_name, errno == ENOENT ? ErrorCodes::FILE_DOESNT_EXIST : ErrorCodes::CANNOT_OPEN_FILE);
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}
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~WriteBufferFromFile()
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{
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bool uncaught_exception = std::uncaught_exception();
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if (!uncaught_exception)
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next();
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if (0 != close(fd) && !uncaught_exception)
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throwFromErrno("Cannot close file " + file_name, ErrorCodes::CANNOT_CLOSE_FILE);
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}
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/** fsync() transfers ("flushes") all modified in-core data of (i.e., modified buffer cache pages for) the file
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* referred to by the file descriptor fd to the disk device (or other permanent storage device)
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* so that all changed information can be retrieved even after the system crashed or was rebooted.
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* This includes writing through or flushing a disk cache if present. The call blocks until the device
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* reports that the transfer has completed. It also flushes metadata information associated with the file (see stat(2)).
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* - man fsync */
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void sync()
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{
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fsync(fd);
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}
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virtual std::string getFileName()
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{
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return file_name;
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}
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};
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}
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