mirror of
https://github.com/ClickHouse/ClickHouse.git
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91 lines
2.4 KiB
C++
91 lines
2.4 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 <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 CANNOT_ALLOCATE_MEMORY;
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extern const int CANNOT_MUNMAP;
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extern const int CANNOT_STAT;
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extern const int BAD_ARGUMENTS;
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extern const int LOGICAL_ERROR;
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}
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void MMapReadBufferFromFileDescriptor::init(int fd_, size_t offset, size_t length_)
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{
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fd = fd_;
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length = length_;
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if (length)
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{
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void * buf = mmap(nullptr, length, PROT_READ, MAP_PRIVATE, fd, offset);
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if (MAP_FAILED == buf)
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throwFromErrno("MMapReadBufferFromFileDescriptor: Cannot mmap " + formatReadableSizeWithBinarySuffix(length) + ".",
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ErrorCodes::CANNOT_ALLOCATE_MEMORY);
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BufferBase::set(static_cast<char *>(buf), length, 0);
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}
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}
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void MMapReadBufferFromFileDescriptor::init(int fd_, size_t offset)
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{
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fd = fd_;
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struct stat stat_res {};
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if (0 != fstat(fd, &stat_res))
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throwFromErrno("MMapReadBufferFromFileDescriptor: Cannot fstat.", ErrorCodes::CANNOT_STAT);
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off_t file_size = stat_res.st_size;
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if (file_size < 0)
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throw Exception("MMapReadBufferFromFileDescriptor: fstat returned negative file size", ErrorCodes::LOGICAL_ERROR);
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if (offset > static_cast<size_t>(file_size))
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throw Exception("MMapReadBufferFromFileDescriptor: requested offset is greater than file size", ErrorCodes::BAD_ARGUMENTS);
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init(fd, offset, file_size - offset);
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}
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MMapReadBufferFromFileDescriptor::MMapReadBufferFromFileDescriptor(int fd, size_t offset, size_t length)
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: MMapReadBufferFromFileDescriptor()
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{
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init(fd, offset, length);
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}
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MMapReadBufferFromFileDescriptor::MMapReadBufferFromFileDescriptor(int fd, size_t offset)
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: MMapReadBufferFromFileDescriptor()
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{
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init(fd, offset);
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}
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MMapReadBufferFromFileDescriptor::~MMapReadBufferFromFileDescriptor()
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{
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if (length)
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finish(); /// Exceptions will lead to std::terminate and that's Ok.
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}
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void MMapReadBufferFromFileDescriptor::finish()
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{
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if (0 != munmap(internalBuffer().begin(), length))
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throwFromErrno("MMapReadBufferFromFileDescriptor: Cannot munmap " + formatReadableSizeWithBinarySuffix(length) + ".",
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ErrorCodes::CANNOT_MUNMAP);
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length = 0;
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}
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}
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