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57 lines
1.3 KiB
C++
57 lines
1.3 KiB
C++
#pragma once
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#include <unistd.h>
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#include <errno.h>
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#include <Poco/NumberFormatter.h>
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#include <DB/Core/Exception.h>
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#include <DB/Core/ErrorCodes.h>
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#include <DB/IO/WriteBuffer.h>
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#include <DB/IO/BufferWithOwnMemory.h>
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namespace DB
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{
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/** Работает с готовым файловым дескриптором. Не открывает и не закрывает файл.
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*/
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class WriteBufferFromFileDescriptor : public BufferWithOwnMemory<WriteBuffer>
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{
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protected:
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int fd;
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void nextImpl()
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{
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if (!offset())
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return;
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ssize_t bytes_written = ::write(fd, working_buffer.begin(), offset());
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if (-1 == bytes_written || 0 == bytes_written)
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throwFromErrno("Cannot write to file " + getFileName(), ErrorCodes::CANNOT_WRITE_TO_FILE_DESCRIPTOR);
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}
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void throwFromErrno(const std::string & s, int code)
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{
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char buf[128];
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throw Exception(s + ", errno: " + Poco::NumberFormatter::format(errno) + ", strerror: " + std::string(strerror_r(errno, buf, sizeof(buf))), code);
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}
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/// Имя или описание файла
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virtual std::string getFileName()
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{
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return "(fd = " + Poco::NumberFormatter::format(fd) + ")";
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}
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public:
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WriteBufferFromFileDescriptor(int fd_) : fd(fd_) {}
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virtual ~WriteBufferFromFileDescriptor()
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{
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nextImpl();
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}
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};
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}
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