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100 lines
2.7 KiB
C++
100 lines
2.7 KiB
C++
#pragma once
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#include <IO/WriteBufferFromFileBase.h>
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#include <IO/WriteBuffer.h>
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#include <IO/BufferWithOwnMemory.h>
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#include <Core/Defines.h>
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#include <Common/AIO.h>
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#include <Common/CurrentMetrics.h>
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#include <string>
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#include <unistd.h>
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#include <fcntl.h>
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namespace CurrentMetrics
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{
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extern const Metric OpenFileForWrite;
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}
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namespace DB
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{
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/** Class for asynchronous data writing.
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*/
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class WriteBufferAIO : public WriteBufferFromFileBase
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{
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public:
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WriteBufferAIO(const std::string & filename_, size_t buffer_size_ = DBMS_DEFAULT_BUFFER_SIZE, int flags_ = -1, mode_t mode_ = 0666,
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char * existing_memory_ = nullptr);
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~WriteBufferAIO() override;
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WriteBufferAIO(const WriteBufferAIO &) = delete;
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WriteBufferAIO & operator=(const WriteBufferAIO &) = delete;
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off_t getPositionInFile() override;
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void sync() override;
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std::string getFileName() const override { return filename; }
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int getFD() const override { return fd; }
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private:
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void nextImpl() override;
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off_t doSeek(off_t off, int whence) override;
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void doTruncate(off_t length) override;
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/// If there's still data in the buffer, we'll write them.
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void flush();
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/// Wait for the end of the current asynchronous task.
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bool waitForAIOCompletion();
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/// Prepare an asynchronous request.
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void prepare();
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///
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void finalize();
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private:
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/// Buffer for asynchronous data writes.
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BufferWithOwnMemory<WriteBuffer> flush_buffer;
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/// Description of the asynchronous write request.
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iocb request = { 0 };
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std::vector<iocb *> request_ptrs{&request};
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std::vector<io_event> events{1};
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AIOContext aio_context{1};
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const std::string filename;
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/// The number of bytes to be written to the disk.
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off_t bytes_to_write = 0;
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/// Number of bytes written with the last request.
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off_t bytes_written = 0;
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/// The number of zero bytes to be cut from the end of the file
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/// after the data write operation completes.
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off_t truncation_count = 0;
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/// The current position in the file.
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off_t pos_in_file = 0;
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/// The maximum position reached in the file.
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off_t max_pos_in_file = 0;
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/// The starting position of the aligned region of the disk to which the data is written.
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off_t region_aligned_begin = 0;
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/// The size of the aligned region of the disk.
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size_t region_aligned_size = 0;
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/// The file descriptor for writing.
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int fd = -1;
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/// The data buffer that we want to write to the disk.
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Position buffer_begin = nullptr;
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/// Is the asynchronous write operation still in progress?
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bool is_pending_write = false;
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/// Did the asynchronous operation fail?
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bool aio_failed = false;
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CurrentMetrics::Increment metric_increment{CurrentMetrics::OpenFileForWrite};
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};
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}
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