mirror of
https://github.com/ClickHouse/ClickHouse.git
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90 lines
2.1 KiB
C++
90 lines
2.1 KiB
C++
#include <sys/mman.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <unistd.h>
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#include <Common/ProfileEvents.h>
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#include <Common/formatReadable.h>
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#include <Common/Exception.h>
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#include <common/getPageSize.h>
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#include <IO/WriteHelpers.h>
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#include <IO/MMapReadBufferFromFileDescriptor.h>
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namespace DB
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{
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namespace ErrorCodes
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{
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extern const int ARGUMENT_OUT_OF_BOUND;
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extern const int CANNOT_SEEK_THROUGH_FILE;
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}
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void MMapReadBufferFromFileDescriptor::init()
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{
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size_t length = mapped.getLength();
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BufferBase::set(mapped.getData(), length, 0);
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size_t page_size = static_cast<size_t>(::getPageSize());
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ReadBuffer::padded = (length % page_size) > 0 && (length % page_size) <= (page_size - 15);
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}
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MMapReadBufferFromFileDescriptor::MMapReadBufferFromFileDescriptor(int fd, size_t offset, size_t length)
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: mapped(fd, offset, length)
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{
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init();
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}
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MMapReadBufferFromFileDescriptor::MMapReadBufferFromFileDescriptor(int fd, size_t offset)
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: mapped(fd, offset)
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{
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init();
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}
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void MMapReadBufferFromFileDescriptor::finish()
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{
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mapped.finish();
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}
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std::string MMapReadBufferFromFileDescriptor::getFileName() const
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{
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return "(fd = " + toString(mapped.getFD()) + ")";
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}
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int MMapReadBufferFromFileDescriptor::getFD() const
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{
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return mapped.getFD();
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}
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off_t MMapReadBufferFromFileDescriptor::getPosition()
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{
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return count();
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}
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off_t MMapReadBufferFromFileDescriptor::seek(off_t offset, int whence)
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{
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off_t new_pos;
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if (whence == SEEK_SET)
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new_pos = offset;
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else if (whence == SEEK_CUR)
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new_pos = count() + offset;
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else
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throw Exception(ErrorCodes::ARGUMENT_OUT_OF_BOUND, "MMapReadBufferFromFileDescriptor::seek expects SEEK_SET or SEEK_CUR as whence");
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working_buffer = internal_buffer;
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if (new_pos < 0 || new_pos > off_t(working_buffer.size()))
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throw Exception(ErrorCodes::CANNOT_SEEK_THROUGH_FILE,
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"Cannot seek through file {} because seek position ({}) is out of bounds [0, {}]",
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getFileName(), new_pos, working_buffer.size());
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position() = working_buffer.begin() + new_pos;
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return new_pos;
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}
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}
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